Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis

Overview

Definition

Antineutrophil cytoplasmic antibody ( ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis)-associated vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus (AAV) is characterized by necrotizing small-vessel vasculitis Small-Vessel Vasculitis Henoch-Schönlein Purpura and a positive ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis test without significant immune complex deposition.

Background

Antineutrophil cytoplasmic antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions (ANCAs) are:

• Autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques directed against proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis contained within neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation (and monocytes Monocytes Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles. Innate Immunity: Phagocytes and Antigen Presentation, to a lesser degree)
• Specific to protein targets associated with cytoplasmic granules of neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation and, on binding, trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation an exaggerated inflammatory response (i.e., an autoimmune reaction)

There are 2 clinically significant subtypes of ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis:

• Anti-myeloperoxidase ( MPO MPO Acute Myeloid Leukemia) autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques:
  • Also known as pANCA 
  • Carry a net positive charge
  • Bind BIND Hyperbilirubinemia of the Newborn to MPO MPO Acute Myeloid Leukemia (there are less clinically significant pANCA autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques that target elastase Elastase A protease of broad specificity, obtained from dried pancreas. Molecular weight is approximately 25, 000. The enzyme breaks down elastin, the specific protein of elastic fibers, and digests other proteins such as fibrin, hemoglobin, and albumin. Proteins and Peptides, cathepsin G, lysozyme, and lactoferrin).
    • MPO MPO Acute Myeloid Leukemia is a protein found in neutrophil granules that is involved in the formation of reactive oxygen species Reactive oxygen species Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include singlet oxygen; superoxides; peroxides; hydroxyl radical; and hypochlorous acid. They contribute to the microbicidal activity of phagocytes, regulation of signal transduction and gene expression, and the oxidative damage to nucleic acids; proteins; and lipids. Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD) for antimicrobial purposes.
    • MPO MPO Acute Myeloid Leukemia deficiency (secondary to autoimmune neutrophil destruction) results in an exaggerated inflammatory response.
  • The “p” in pANCA stands for perinuclear because on staining, these antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions stain the perinuclear area of the neutrophil (where MPO MPO Acute Myeloid Leukemia and other negatively charged proteins Proteins Linear polypeptides that are synthesized on ribosomes and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of amino acids determines the shape the polypeptide will take, during protein folding, and the function of the protein. Energy Homeostasis are highly concentrated).
• Anti– proteinase 3 Proteinase 3 Granulomatosis with Polyangiitis (PR3) autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques:
  • Also known as cANCA  
  • Carry a net negative charge
  • Bind BIND Hyperbilirubinemia of the Newborn to PR3
    • PR3 is a protein found in neutrophil azurophilic granules Azurophilic granules Myeloperoxidase Deficiency that is involved in the proteolysis of antimicrobial peptides Antimicrobial peptides Innate Immunity: Barriers, Complement, and Cytokines for antimicrobial purposes.
    • PR3 deficiency (secondary to autoimmune neutrophil destruction) results in an exaggerated inflammatory response.
  • The “c” in cANCA stands for cytoplasmic because on staining, these antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions stain the peripheral cytoplasmic area of the neutrophil (where PR3, which is positively charged, is highly concentrated).

The presence of ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis (i.e., a positive ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis test):

• Does not:
  • Diagnose a disease entity
  • Correlate with symptom severity
  • Correlate with disease activity
• Is simply a marker that helps establish patterns of disease  

ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis positivity is associated with autoimmune disease processes (the following pANCA/cANCA designations are only a guide; significant variability exists):

• Vasculitides Vasculitides Vasculitides are a group of conditions characterized by vasculitis, ischemia, and damage to the organs supplied by the affected vessels. The affected arteries are of different sizes and locations and vary by the type of vasculitis. Vasculitides:
  • Granulomatosis with polyangiitis Granulomatosis with Polyangiitis A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis (cANCA)
  • Microscopic polyangiitis Microscopic polyangiitis A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides (pANCA)
  • Eosinophilic granulomatosis with polyangiitis Granulomatosis with Polyangiitis A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis (pANCA)
  • Primary pauci-immune necrotizing crescenteric glomerulonephritis (aka rapidly progressive glomerulonephritis Rapidly Progressive Glomerulonephritis Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis ( RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis) or renal-limited vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus) (pANCA)
  • Drug-induced ANCA-associated vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus (pANCA)
• Anti–glomerular basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) (GBM) autoantibody disease (pANCA)
• Interstitial nephritis (pANCA)
• Ulcerative colitis Colitis Inflammation of the colon section of the large intestine, usually with symptoms such as diarrhea (often with blood and mucus), abdominal pain, and fever. Pseudomembranous Colitis (pANCA)
• Primary sclerosing cholangitis Primary Sclerosing Cholangitis Primary sclerosing cholangitis (PSC) is an inflammatory disease that causes fibrosis and strictures of the bile ducts. The exact etiology is unknown, but there is a strong association with IBD. Patients typically present with an insidious onset of fatigue, pruritus, and jaundice, which can progress to cirrhosis and complications related to biliary obstruction. Primary Sclerosing Cholangitis (pANCA)
• Autoimmune hepatitis Autoimmune hepatitis Autoimmune hepatitis (AIH) is a rare form of chronic liver disease in which the immune system attacks the liver causing inflammation. It predominantly affects women. Clinical presentation ranges from asymptomatic cases to patients that present with symptoms of acute liver failure (jaundice, right upper quadrant pain). Autoimmune Hepatitis (pANCA)
• Rheumatoid arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis (pANCA)
• Cystic Cystic Fibrocystic Change fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans (pANCA)

Classification

AAV includes the following 3 main diseases:

• Granulomatosis with polyangiitis Granulomatosis with Polyangiitis A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis ( GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis):
  • The majority of cases are cANCA+ (80%–90%).
  • A small percentage are pANCA+ or ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis–.
• Microscopic polyangiitis Microscopic polyangiitis A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides ( MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides):
  • The majority of cases are pANCA+ (nearly 90%).
  • A small percentage are cANCA+ or ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis–.
• Eosinophilic granulomatosis with polyangiitis Granulomatosis with Polyangiitis A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis (EGPA; also known as Churg-Strauss syndrome Churg-Strauss syndrome Widespread necrotizing angiitis with granulomas. Pulmonary involvement is frequent. Asthma or other respiratory infection may precede evidence of vasculitis. Eosinophilia and lung involvement differentiate this disease from polyarteritis nodosa. Vasculitides):
  • The majority of cases are ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis– (50%–70%).
  • A minority of cases are ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis+ (30%–50%).
  • The majority of ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis+ cases are pANCA+ (75%–80%).
  • A small percentage are cANCA+.

Some sources also include the following 2 diseases:

• Renal-limited necrotizing and crescentic glomerulonephritis:
  • The majority of cases are pANCA+ (75%–80%).
  • A small percentage are cANCA+ or ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis–.
• Drug-induced ANCA-associated vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus:
  • The majority of cases are pANCA+.
  • A small percentage are cANCA+.

Epidemiology

• Incidence Incidence The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from prevalence, which refers to all cases in the population at a given time. Measures of Disease Frequency: approximately 3/100,000
• Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency: approximately 42/100,000
• MPO-AAV is more common than PR3-AAV
• Often presents in the 6th and 7th decades of life
• Affects women and men equally
• More common in White individuals
• Drug-induced ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus:
  • More common in young females
  • More commonly associated with skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions damage than other AAVs
  • Relatively rare involvement of kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy, GI tract, nervous system Nervous system The nervous system is a small and complex system that consists of an intricate network of neural cells (or neurons) and even more glial cells (for support and insulation). It is divided according to its anatomical components as well as its functional characteristics. The brain and spinal cord are referred to as the central nervous system, and the branches of nerves from these structures are referred to as the peripheral nervous system. Nervous System: Anatomy, Structure, and Classification
  • More commonly associated with pANCA
  • May be associated with anti-histone antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions
  • Generally milder disease severity with better prognosis Prognosis A prediction of the probable outcome of a disease based on a individual’s condition and the usual course of the disease as seen in similar situations. Non-Hodgkin Lymphomas

Pathophysiology

• Multifactorial
• Contributing factors:
  • Genetics Genetics Genetics is the study of genes and their functions and behaviors. Basic Terms of Genetics
  • Environmental exposure
  • Infection
  • Innate and adaptive immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs responses
  • Intensity and duration of underlying disease process
• Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation play a central role:
  • Neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation have ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis autoantigens sequestered in cytoplasmic granules within the cell (cannot be accessed by serum antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions).
  • Initiating inflammatory event (e.g., infection, drugs) → cytokine/complement ( tumor Tumor Inflammation necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage factor ɑ (TNF-ɑ), IL-1β, C5a)-induced priming of neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation 
  • Neutrophil priming → MPO MPO Acute Myeloid Leukemia and PR3 move from the cytoplasm to the cell surface → binding to ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques 
  • Binding of ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques to MPO MPO Acute Myeloid Leukemia/PR3 → Fcɣ-mediated neutrophil activation Neutrophil activation The process in which the neutrophil is stimulated by diverse substances, resulting in degranulation and/or generation of reactive oxygen products, and culminating in the destruction of invading pathogens. The stimulatory substances, including opsonized particles, immune complexes, and chemotactic factors, bind to specific cell-surface receptors on the neutrophil. Ehrlichiosis and Anaplasmosis
  • Neutrophil activation Neutrophil activation The process in which the neutrophil is stimulated by diverse substances, resulting in degranulation and/or generation of reactive oxygen products, and culminating in the destruction of invading pathogens. The stimulatory substances, including opsonized particles, immune complexes, and chemotactic factors, bind to specific cell-surface receptors on the neutrophil. Ehrlichiosis and Anaplasmosis → complement pathway activation → elaboration of C5a (attracts more neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation and acts as an additional neutrophil primer)
  • Activated neutrophils Neutrophils Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes. Innate Immunity: Phagocytes and Antigen Presentation adhere to/penetrate vessel walls → acute inflammation Acute Inflammation Inflammation/generation of reactive oxygen species Reactive oxygen species Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include singlet oxygen; superoxides; peroxides; hydroxyl radical; and hypochlorous acid. They contribute to the microbicidal activity of phagocytes, regulation of signal transduction and gene expression, and the oxidative damage to nucleic acids; proteins; and lipids. Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD) → endothelial damage
  • Acute inflammation Acute Inflammation Inflammation → activation of fibrin Fibrin A protein derived from fibrinogen in the presence of thrombin, which forms part of the blood clot. Rapidly Progressive Glomerulonephritis/ collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology deposition (formation of neutrophil extracellular traps (NETs)) →  chronic inflammation Chronic Inflammation Inflammation ( apoptosis Apoptosis A regulated cell death mechanism characterized by distinctive morphologic changes in the nucleus and cytoplasm, including the endonucleolytic cleavage of genomic DNA, at regularly spaced, internucleosomal sites, I.e., DNA fragmentation. It is genetically-programmed and serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth. Ischemic Cell Damage, necrosis Necrosis The death of cells in an organ or tissue due to disease, injury or failure of the blood supply. Ischemic Cell Damage, fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans)

Clinical Presentation

AAV presents with a wide range of signs and symptoms depending on the organ system(s) involved.

Constitutional symptoms

Constitutional symptoms may be present weeks or months before specific clinical features develop: 

• Arthralgias
• Fevers, night sweats Night sweats Tuberculosis
• Fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, lethargy Lethargy A general state of sluggishness, listless, or uninterested, with being tired, and having difficulty concentrating and doing simple tasks. It may be related to depression or drug addiction. Hyponatremia
• Loss of appetite
• Weight loss Weight loss Decrease in existing body weight. Bariatric Surgery

Upper respiratory tract involvement

• More common in GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis (95%) than in MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides (35%)
• Manifestations include:
  • Sinusitis Sinusitis Sinusitis refers to inflammation of the mucosal lining of the paranasal sinuses. The condition usually occurs concurrently with inflammation of the nasal mucosa (rhinitis), a condition known as rhinosinusitis. Acute sinusitis is due to an upper respiratory infection caused by a viral, bacterial, or fungal agent. Sinusitis
  • Otitis media
  • Purulent/bloody nasal discharge
  • Mucosal ulcers
  • Polychondritis
  • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types/ cartilage Cartilage Cartilage is a type of connective tissue derived from embryonic mesenchyme that is responsible for structural support, resilience, and the smoothness of physical actions. Perichondrium (connective tissue membrane surrounding cartilage) compensates for the absence of vasculature in cartilage by providing nutrition and support. Cartilage: Histology destruction:
    • Loss of teeth Teeth Normally, an adult has 32 teeth: 16 maxillary and 16 mandibular. These teeth are divided into 4 quadrants with 8 teeth each. Each quadrant consists of 2 incisors (dentes incisivi), 1 canine (dens caninus), 2 premolars (dentes premolares), and 3 molars (dentes molares). Teeth are composed of enamel, dentin, and dental cement. Teeth: Anatomy
    • Saddle nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal) deformity Deformity Examination of the Upper Limbs
    • Conductive hearing loss Conductive hearing loss Hearing loss due to interference with the mechanical reception or amplification of sound to the cochlea. The interference is in the outer or middle ear involving the ear canal; tympanic membrane; or ear ossicles. Hearing Loss or saddle nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose Anatomy (External & Internal) deformity Deformity Examination of the Upper Limbs (typical for GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis) 
  • Airways:
    • Hoarseness Hoarseness An unnaturally deep or rough quality of voice. Parapharyngeal Abscess
    • Stridor Stridor Laryngomalacia and Tracheomalacia
    • Cough
    • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
    • Rhonchi Rhonchi Asthma
    • Wheezing Wheezing Wheezing is an abnormal breath sound characterized by a whistling noise that can be relatively high-pitched and shrill (more common) or coarse. Wheezing is produced by the movement of air through narrowed or compressed small (intrathoracic) airways. Wheezing
    • Hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis

Lower respiratory tract involvement

• Parenchyma:
  • Rales Rales Respiratory Syncytial Virus
  • Diffuse alveolar hemorrhage
  • Signs of consolidation Consolidation Pulmonary Function Tests and/or pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion, including dullness to percussion Percussion Act of striking a part with short, sharp blows as an aid in diagnosing the condition beneath the sound obtained. Pulmonary Examination
• History of asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma suggests EGPA over GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis/ MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides.

Kidney involvement

• Glomerulonephritis is seen in 20% of individuals at the time of diagnosis and 80% of individuals after 2 years.
• Manifestations include:
  • Hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma
  • Cellular casts
  • Hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
  • ↑ Creatinine
• Rapidly progressive glomerulonephritis Rapidly Progressive Glomerulonephritis Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis ( RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis): rapidly ↓ renal function over days-to-weeks and glomerular crescent Crescent Rapidly Progressive Glomerulonephritis formation on histology

Cutaneous manifestations

• Affects 50% of individuals
• More commonly observed in drug-associated ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus than in other forms of AAV
• Includes:
  • Purpura
  • Ulcerations
  • Urticaria Urticaria Urticaria is raised, well-circumscribed areas (wheals) of edema (swelling) and erythema (redness) involving the dermis and epidermis with associated pruritus (itch). Urticaria is not a single disease but rather is a reaction pattern representing cutaneous mast cell degranulation. Urticaria (Hives)
  • Livedo reticularis Livedo reticularis A condition characterized by a reticular or fishnet pattern on the skin of lower extremities and other parts of the body. This red and blue pattern is due to deoxygenated blood in unstable dermal blood vessels. The condition is intensified by cold exposure and relieved by rewarming. Chronic Kidney Disease
  • Nodules

Ophthalmic manifestations

• Pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways
• Blurred vision Blurred Vision Retinal Detachment/ diplopia Diplopia A visual symptom in which a single object is perceived by the visual cortex as two objects rather than one. Disorders associated with this condition include refractive errors; strabismus; oculomotor nerve diseases; trochlear nerve diseases; abducens nerve diseases; and diseases of the brain stem and occipital lobe. Myasthenia Gravis
• Conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis
• Episcleritis/ scleritis Scleritis Refers to any inflammation of the sclera including episcleritis, a benign condition affecting only the episclera, which is generally short-lived and easily treated. Classic scleritis, on the other hand, affects deeper tissue and is characterized by higher rates of visual acuity loss and even mortality, particularly in necrotizing form. Crohn’s Disease
• Corneal ulceration Ulceration Corneal Abrasions, Erosion, and Ulcers, uveitis Uveitis Uveitis is the inflammation of the uvea, the pigmented middle layer of the eye, which comprises the iris, ciliary body, and choroid. The condition is categorized based on the site of disease; anterior uveitis is the most common. Diseases of the Uvea, retinitis
• Optic neuropathy Neuropathy Leprosy

Neurologic manifestations

• Mononeuritis multiplex Mononeuritis Multiplex Chronic Diabetic Complications ( multifocal Multifocal Retinoblastoma peripheral neuropathy Neuropathy Leprosy)
• Sensory Sensory Neurons which conduct nerve impulses to the central nervous system. Nervous System: Histology deficits
• Cranial nerve abnormalities
• Sensorineural hearing loss Sensorineural hearing loss Hearing loss resulting from damage to the cochlea and the sensorineural elements which lie internally beyond the oval and round windows. These elements include the auditory nerve and its connections in the brainstem. Hearing Loss
• Meningismus Meningismus Subarachnoid Hemorrhage

Heart disease

• Pericarditis Pericarditis Pericarditis is an inflammation of the pericardium, often with fluid accumulation. It can be caused by infection (often viral), myocardial infarction, drugs, malignancies, metabolic disorders, autoimmune disorders, or trauma. Acute, subacute, and chronic forms exist. Pericarditis
• Myocarditis Myocarditis Myocarditis is an inflammatory disease of the myocardium, which may occur alone or in association with a systemic process. There are numerous etiologies of myocarditis, but all lead to inflammation and myocyte injury, most often leading to signs and symptoms of heart failure. Myocarditis
• Conduction abnormalities

Other organs (rare)

• GI involvement
• Arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis
• Thyroid Thyroid The thyroid gland is one of the largest endocrine glands in the human body. The thyroid gland is a highly vascular, brownish-red gland located in the visceral compartment of the anterior region of the neck. Thyroid Gland: Anatomy or parathyroid Parathyroid The parathyroid glands are 2 pairs of small endocrine glands found in close proximity to the thyroid gland. The superior parathyroid glands are lodged within the parenchyma of the upper poles of the right and left thyroid lobes; the inferior parathyroid glands are close to the inferior tips or poles of the lobes. Parathyroid Glands: Anatomy disease

Diagnosis

Laboratory evaluation

• Serum chemistry:
  • ↑ Creatinine indicates renal involvement.
  • ↓ Albumin Albumin Serum albumin from humans. It is an essential carrier of both endogenous substances, such as fatty acids and bilirubin, and of xenobiotics in the blood. Liver Function Tests indicates renal protein losses.
  • ↑ AST AST Enzymes of the transferase class that catalyze the conversion of l-aspartate and 2-ketoglutarate to oxaloacetate and l-glutamate. Liver Function Tests/ ALT ALT An enzyme that catalyzes the conversion of l-alanine and 2-oxoglutarate to pyruvate and l-glutamate. Liver Function Tests indicates hepatic involvement.
  • Possible electrolyte disturbance due to renal dysfunction
  • Possible acid–base disorder due to renal dysfunction
• Urinalysis Urinalysis Examination of urine by chemical, physical, or microscopic means. Routine urinalysis usually includes performing chemical screening tests, determining specific gravity, observing any unusual color or odor, screening for bacteriuria, and examining the sediment microscopically. Urinary Tract Infections (UTIs) in Children:
  • Proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children due to glomerular damage
  • Hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma due to glomerular damage
• Inflammatory markers:
  • Nonspecific elevation in erythrocyte sedimentation rate Erythrocyte Sedimentation Rate Soft Tissue Abscess ( ESR ESR Soft Tissue Abscess) and C-reactive protein (CRP)
  • ↑ IgE IgE An immunoglobulin associated with mast cells. Overexpression has been associated with allergic hypersensitivity. Immunoglobulins: Types and Functions (in EPGA)
• CBC:
  • Leukocytosis Leukocytosis A transient increase in the number of leukocytes in a body fluid. West Nile Virus
  • Thrombocytosis
  • Normocytic normochromic anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types
  • Eosinophilia Eosinophilia Abnormal increase of eosinophils in the blood, tissues or organs. Autosomal Dominant Hyperimmunoglobulin E Syndrome (in EPGA)
• Positive immunofluorescence and/or enzyme-linked immunosorbent assay ( ELISA ELISA An immunoassay utilizing an antibody labeled with an enzyme marker such as horseradish peroxidase. While either the enzyme or the antibody is bound to an immunosorbent substrate, they both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically or with the naked eye. Many variations of the method have been developed. St. Louis Encephalitis Virus) for ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis (serum):
  • Proteinase 3 Proteinase 3 Granulomatosis with Polyangiitis (PR3)-ANCA (c-ANCA): more commonly associated with GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis
  • Myeloperoxidase Myeloperoxidase Acute Myeloid Leukemia ( MPO MPO Acute Myeloid Leukemia)-ANCA (p-ANCA): more commonly associated with MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides, EGPA

Imaging

Chest X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests and CT findings may include:

• Consolidation Consolidation Pulmonary Function Tests
• Nodules
• Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion
• Fleeting infiltrates
• Hilar adenopathy

Diagnostic criteria

American College of Rheumatology diagnosis for EGPA includes 4 of the 6 following criteria with a specificity of almost 100%:

• Asthma Asthma Asthma is a chronic inflammatory respiratory condition characterized by bronchial hyperresponsiveness and airflow obstruction. The disease is believed to result from the complex interaction of host and environmental factors that increase disease predisposition, with inflammation causing symptoms and structural changes. Patients typically present with wheezing, cough, and dyspnea. Asthma
• > 10% eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation on CBC with differential
• Mononeuropathy Mononeuropathy Disease or trauma involving a single peripheral nerve in isolation, or out of proportion to evidence of diffuse peripheral nerve dysfunction. Mononeuropathy multiplex refers to a condition characterized by multiple isolated nerve injuries. Mononeuropathies may result from a wide variety of causes, including ischemia; traumatic injury; compression; connective tissue diseases; cumulative trauma disorders; and other conditions. Mononeuropathy and Plexopathy (e.g., foot drop Foot Drop Leprosy) or polyneuropathy Polyneuropathy Polyneuropathy is any disease process affecting the function of or causing damage to multiple nerves of the peripheral nervous system. There are numerous etiologies of polyneuropathy, most of which are systemic and the most common of which is diabetic neuropathy. Polyneuropathy 
• Fleeting pulmonary infiltrates
• Paranasal sinus abnormality
• Extravascular accumulation of eosinophils Eosinophils Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin. Innate Immunity: Phagocytes and Antigen Presentation on biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma

Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma

Confirmation of diagnosis includes biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma of affected organs:

• Suspected diagnosis can be confirmed with a biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma of lung, skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, or peripheral nerve (may show granulomas Granulomas A relatively small nodular inflammatory lesion containing grouped mononuclear phagocytes, caused by infectious and noninfectious agents. Sarcoidosis).
• Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma sites and findings:
  • GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis: Tissue biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma from a site of the active disease shows segmental, crescentic-necrotizing glomerulonephritis with little/no immunoglobulin or complement deposition (pauci-immune); renal and lung biopsies are the most specific.
  • MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides: Lung biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma and/or renal biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma (crescentic glomerulonephritis) shows necrotizing arteritis (histologically identical to polyarteritis nodosa Polyarteritis nodosa A form of necrotizing non-granulomatous inflammation occurring primarily in medium-sized arteries, often with microaneurysms. It is characterized by muscle, joint, and abdominal pain resulting from arterial infarction and scarring in affected organs. Polyarteritis nodosa with lung involvement is called churg-strauss syndrome. Vasculitides).
  • EGPA: Lung biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma shows eosinophilia Eosinophilia Abnormal increase of eosinophils in the blood, tissues or organs. Autosomal Dominant Hyperimmunoglobulin E Syndrome and small, necrotizing eosinophilic granulomas Granulomas A relatively small nodular inflammatory lesion containing grouped mononuclear phagocytes, caused by infectious and noninfectious agents. Sarcoidosis with necrotizing vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus involving small arteries Small arteries Arteries: Histology and venules Venules The minute vessels that collect blood from the capillary plexuses and join together to form veins. Veins: Histology
  • Anti-GBM autoantibody disease: Kidney biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma shows necrotizing glomerulonephritis with little or no deposition of immune complex or complement deposition.
  • Drug-induced ANCA-associated vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus: No distinguishing pathologic findings for discrimination between drug-induced vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus and other vasculitides Vasculitides Vasculitides are a group of conditions characterized by vasculitis, ischemia, and damage to the organs supplied by the affected vessels. The affected arteries are of different sizes and locations and vary by the type of vasculitis. Vasculitides.

Management

All individuals with a confirmed diagnosis of AAV require immunosuppressive therapy. Therapy can be initiated early based on a presumptive diagnosis of the following criteria:

• Suggestive clinical features
• + ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis test
• ↓ Probability Probability Probability is a mathematical tool used to study randomness and provide predictions about the likelihood of something happening. There are several basic rules of probability that can be used to help determine the probability of multiple events happening together, separately, or sequentially. Basics of Probability of other etiologies 

Induction of remission Remission A spontaneous diminution or abatement of a disease over time, without formal treatment. Cluster Headaches

• MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides and GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis:
  • Cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants + glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids are the criterion standard for induction of remission Remission A spontaneous diminution or abatement of a disease over time, without formal treatment. Cluster Headaches.
  • Rituximab Rituximab A murine-derived monoclonal antibody and antineoplastic agent that binds specifically to the cd20 antigen and is used in the treatment of leukemia; lymphoma and rheumatoid arthritis. Immunosuppressants is a less toxic alternative to cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants for induction of remission Remission A spontaneous diminution or abatement of a disease over time, without formal treatment. Cluster Headaches in GPA GPA A multisystemic disease of a complex genetic background. It is characterized by inflammation of the blood vessels (vasculitis) leading to damage in any number of organs. The common features include granulomatous inflammation of the respiratory tract and kidneys. Most patients have measurable autoantibodies (antineutrophil cytoplasmic antibodies) against myeloblastin. Granulomatosis with Polyangiitis or MPA MPA A primary systemic vasculitis of small- and some medium-sized vessels. It is characterized by a tropism for kidneys and lungs, positive association with anti-neutrophil cytoplasmic antibodies (ANCA), and a paucity of immunoglobulin deposits in vessel walls. Vasculitides and is the 1st treatment approved by the FDA.
• EGPA:
  • Glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids alone are usually adequate for the treatment of EGPA.
  • Cytotoxic Cytotoxic Parvovirus B19 drugs ( cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants) are necessary in < 20% of individuals.
• Plasma exchange Plasma exchange Removal of plasma and replacement with various fluids, e.g., fresh frozen plasma, plasma protein fractions (ppf), albumin preparations, dextran solutions, saline. Used in treatment of autoimmune diseases, immune complex diseases, diseases of excess plasma factors, and other conditions. Thrombotic Thrombocytopenic Purpura may be required with disease (e.g., RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis or pulmonary hemorrhage).

Maintenance of remission Remission A spontaneous diminution or abatement of a disease over time, without formal treatment. Cluster Headaches

Once remission Remission A spontaneous diminution or abatement of a disease over time, without formal treatment. Cluster Headaches is achieved, individuals switch to less toxic agents:

• Azathioprine Azathioprine An immunosuppressive agent used in combination with cyclophosphamide and hydroxychloroquine in the treatment of rheumatoid arthritis. According to the fourth annual report on carcinogens, this substance has been listed as a known carcinogen. Immunosuppressants
• Rituximab Rituximab A murine-derived monoclonal antibody and antineoplastic agent that binds specifically to the cd20 antigen and is used in the treatment of leukemia; lymphoma and rheumatoid arthritis. Immunosuppressants
• Mycophenolate Mycophenolate Immunosuppressants mofetil
• Methotrexate Methotrexate An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of tetrahydrofolate dehydrogenase and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA. Antimetabolite Chemotherapy

General measures

• Antibiotic prophylaxis Prophylaxis Cephalosporins while on immunosuppressive therapy
• Trimethoprim-sulfamethoxazole to prevent pneumocystis pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia ( PCP PCP Pneumocystis jiroveci is a yeast-like fungus causing pneumocystis pneumonia (PCP) in immunocompromised patients. Pneumocystis pneumonia is spread through airborne transmission and classically affects patients with AIDS, functioning as an AIDS-defining illness. Patients may present with insidious onset of fever, chills, dry cough, chest pain, and shortness of breath. Pneumocystis jirovecii/Pneumocystis Pneumonia (PCP))

Comparison Table

Table showing suggestive laboratory and clinical features of the 3 main types of AAV:

Differential Diagnosis

• Drug-induced ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus: ANCA ANCA Group of systemic vasculitis with a strong association with anca. The disorders are characterized by necrotizing inflammation of small and medium size vessels, with little or no immune-complex deposits in vessel walls. Rapidly Progressive Glomerulonephritis positive vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus from medication exposures are linked to the development of vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus ( propylthiouracil Propylthiouracil A thiourea antithyroid agent. Propylthiouracil inhibits the synthesis of thyroxine and inhibits the peripheral conversion of thyroxine to triiodothyronine. It is used in the treatment of hyperthyroidism. Antithyroid Drugs, methimazole Methimazole A thioureylene antithyroid agent that inhibits the formation of thyroid hormones by interfering with the incorporation of iodine into tyrosyl residues of thyroglobulin. This is done by interfering with the oxidation of iodide ion and iodotyrosyl groups through inhibition of the peroxidase enzyme. Antithyroid Drugs, carbimazole, hydralazine Hydralazine A direct-acting vasodilator that is used as an antihypertensive agent. Heart Failure and Angina Medication, and minocycline Minocycline A tetracycline analog, having a 7-dimethylamino and lacking the 5 methyl and hydroxyl groups, which is effective against tetracycline-resistant staphylococcus infections. Tetracyclines), causing constitutional symptoms such as arthralgias, fatigue Fatigue The state of weariness following a period of exertion, mental or physical, characterized by a decreased capacity for work and reduced efficiency to respond to stimuli. Fibromyalgia, and skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions rash Rash Rocky Mountain Spotted Fever. However, the full range of clinical features (including rapidly progressive renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome and alveolar hemorrhage) can also occur.
• Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Goodpasture Syndrome: a rare autoimmune disease where antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins: Types and Functions attack the basement membrane Basement membrane A darkly stained mat-like extracellular matrix (ecm) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue. The ecm layer that supports an overlying epithelium or endothelium is called basal lamina. Basement membrane (bm) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. Bm, composed mainly of type IV collagen; glycoprotein laminin; and proteoglycan, provides barriers as well as channels between interacting cell layers. Thin Basement Membrane Nephropathy (TBMN) in the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy and kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy, which leads to bleeding from the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy and kidney failure. Goodpasture syndrome Goodpasture Syndrome Goodpasture syndrome, also known as anti-glomerular basement membrane (GBM) disease, is an autoimmune disease characterized by circulating antibodies directed against glomerular and alveolar basement membranes. Affected individuals present with symptoms of rapidly progressive glomerulonephritis and alveolar hemorrhage. Goodpasture Syndrome results in permanent lung and kidney damage and often leads to death. Treatment includes immune system Immune system The body’s defense mechanism against foreign organisms or substances and deviant native cells. It includes the humoral immune response and the cell-mediated response and consists of a complex of interrelated cellular, molecular, and genetic components. Primary Lymphatic Organs suppressing medications (e.g., corticosteroids Corticosteroids Chorioretinitis and cyclophosphamide Cyclophosphamide Precursor of an alkylating nitrogen mustard antineoplastic and immunosuppressive agent that must be activated in the liver to form the active aldophosphamide. It has been used in the treatment of lymphoma and leukemia. Its side effect, alopecia, has been used for defleecing sheep. Cyclophosphamide may also cause sterility, birth defects, mutations, and cancer. Immunosuppressants) and plasmapheresis Plasmapheresis Procedure whereby plasma is separated and extracted from anticoagulated whole blood and the red cells retransfused to the donor. Plasmapheresis is also employed for therapeutic use. Stevens-Johnson Syndrome.
• Polyarteritis nodosa Polyarteritis nodosa A form of necrotizing non-granulomatous inflammation occurring primarily in medium-sized arteries, often with microaneurysms. It is characterized by muscle, joint, and abdominal pain resulting from arterial infarction and scarring in affected organs. Polyarteritis nodosa with lung involvement is called churg-strauss syndrome. Vasculitides: a systemic vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus of small and medium vessels. Polyarteritis nodosa Polyarteritis nodosa A form of necrotizing non-granulomatous inflammation occurring primarily in medium-sized arteries, often with microaneurysms. It is characterized by muscle, joint, and abdominal pain resulting from arterial infarction and scarring in affected organs. Polyarteritis nodosa with lung involvement is called churg-strauss syndrome. Vasculitides involves the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, peripheral nerves Peripheral Nerves The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium. Nervous System: Histology, muscles, joints, gastrointestinal tract, and kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy. Individuals present with nonspecific symptoms, hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension, risk of myocardial infarction Myocardial infarction MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction, and polyneuropathy Polyneuropathy Polyneuropathy is any disease process affecting the function of or causing damage to multiple nerves of the peripheral nervous system. There are numerous etiologies of polyneuropathy, most of which are systemic and the most common of which is diabetic neuropathy. Polyneuropathy. Angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery shows a beading appearance of alternating aneurysms and vessel stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS). Management is immunosuppressive regimens.
• Giant cell arteritis Giant Cell Arteritis Giant cell arteritis (GCA), also known as temporal arteritis, is a type of large-vessel vasculitis that predominantly affects the aorta and its major branches, with a predilection for the branches of the carotid (including the temporal artery). Giant cell arteritis is defined by inflammatory leukocytes in the vessel walls leading to reactive damage, ischemia, and necrosis. Giant Cell Arteritis: a vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus of medium and large arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology (particularly the carotid arteries Carotid Arteries Either of the two principal arteries on both sides of the neck that supply blood to the head and neck; each divides into two branches, the internal carotid artery and the external carotid artery. Carotid Arterial System: Anatomy and aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy). Individuals present with new-onset headache Headache The symptom of pain in the cranial region. It may be an isolated benign occurrence or manifestation of a wide variety of headache disorders. Brain Abscess, tender/hardened temporal artery, jaw claudication Jaw claudication Mandibular pain or fatigue during mastication that is relieved with rest Giant Cell Arteritis, and amaurosis fugax Amaurosis fugax Transient complete or partial monocular blindness due to retinal ischemia. This may be caused by emboli from the carotid artery (usually in association with carotid stenosis) and other locations that enter the central retinal artery. Carotid Artery Stenosis. Laboratory studies show elevated ESR ESR Soft Tissue Abscess and CRP. Biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma shows mononuclear infiltration of vessel walls and the formation of giant cells Giant cells Multinucleated masses produced by the fusion of many cells; often associated with viral infections. In aids, they are induced when the envelope glycoprotein of the HIV virus binds to the CD4 antigen of uninfected neighboring T4 cells. The resulting syncytium leads to cell death and thus may account for the cytopathic effect of the virus. Giant Cell Arteritis. Treatment involves prompt administration of glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids.
• Henoch-Schönlein purpura Henoch-Schönlein Purpura Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura: an autoimmune small vessel vasculitis Vasculitis Inflammation of any one of the blood vessels, including the arteries; veins; and rest of the vasculature system in the body. Systemic Lupus Erythematosus. The condition typically presents as a triad of abdominal pain Abdominal Pain Acute Abdomen, hematuria Hematuria Presence of blood in the urine. Renal Cell Carcinoma, and purpuric rash Rash Rocky Mountain Spotted Fever. The pathophysiology involves IgA IgA Represents 15-20% of the human serum immunoglobulins, mostly as the 4-chain polymer in humans or dimer in other mammals. Secretory iga is the main immunoglobulin in secretions. Immunoglobulins: Types and Functions immune complex deposition in multiple vessels following a trigger Trigger The type of signal that initiates the inspiratory phase by the ventilator Invasive Mechanical Ventilation. Symptoms depend on the tissues supplied by the vessels. The disease has a clinical diagnosis and is managed symptomatically. 
• Rheumatoid arthritis Arthritis Acute or chronic inflammation of joints. Osteoarthritis: an inflammatory polyarthritis Polyarthritis Rheumatoid Arthritis presenting with pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways in symmetric joints. The pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways is worse in the morning but improves during the day, The proximal interphalangeal and metacarpophalangeal joints Metacarpophalangeal joints The articulation between a metacarpal bone and a phalanx. Examination of the Upper Limbs are included, but the distal interphalangeal joints Interphalangeal joints Hand: Anatomy are spared. Management is with NSAIDs NSAIDS Primary vs Secondary Headaches, methotrexate Methotrexate An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of tetrahydrofolate dehydrogenase and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA. Antimetabolite Chemotherapy, sulfasalazine Sulfasalazine A drug that is used in the management of inflammatory bowel diseases. Its activity is generally considered to lie in its metabolic breakdown product, 5-aminosalicylic acid released in the colon. Sulfonamides and Trimethoprim, hydroxychloroquine Hydroxychloroquine A chemotherapeutic agent that acts against erythrocytic forms of malarial parasites. Hydroxychloroquine appears to concentrate in food vacuoles of affected protozoa. It inhibits plasmodial heme polymerase. Immunosuppressants, and TNF-α inhibitors.
• Systemic lupus erythematosus Systemic lupus erythematosus Systemic lupus erythematosus (SLE) is a chronic autoimmune, inflammatory condition that causes immune-complex deposition in organs, resulting in systemic manifestations. Women, particularly those of African American descent, are more commonly affected. Systemic Lupus Erythematosus: a chronic inflammatory condition with involvement of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions, joints, kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys: Anatomy, blood cells, and CNS. The condition is an autoimmune disorder Autoimmune Disorder Septic Arthritis associated with the formation of autoantibodies Autoantibodies Antibodies that react with self-antigens (autoantigens) of the organism that produced them. Blotting Techniques such as ANA, anti-Smith, and anti-double-stranded DNA DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA Types and Structure (dsDNA). Features include malar rash Malar Rash Systemic Lupus Erythematosus, joint pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, proteinuria Proteinuria The presence of proteins in the urine, an indicator of kidney diseases. Nephrotic Syndrome in Children, hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension, anemia Anemia Anemia is a condition in which individuals have low Hb levels, which can arise from various causes. Anemia is accompanied by a reduced number of RBCs and may manifest with fatigue, shortness of breath, pallor, and weakness. Subtypes are classified by the size of RBCs, chronicity, and etiology. Anemia: Overview and Types, lymphopenia, seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures, and/or psychosis.