Hairy Cell Leukemia

Hairy cell leukemia (HCL) is a rare, chronic, B-cell leukemia characterized by the accumulation of small mature B lymphocytes B lymphocytes B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells that have “hair-like projections” visible on microscopy. The abnormal cells accumulate in the peripheral blood, bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow (causing fibrosis), and red pulp of the spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen, leading to cytopenias, including 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, thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia, neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia, and monocytopenia. HCL typically affects middle-aged men and presents with weakness, fatigue, opportunistic infections, and splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly (which is often severe). Hairy cell leukemia is diagnosed by identifying hairy cells on a peripheral blood smear, characteristic cytopenias on CBC/DIFF, bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow biopsy, and immunophenotyping. Management consists of observation for asymptomatic patients and purine analogs for symptomatic patients. Both the disease itself and its treatments can cause immunosuppression, so prevention and prompt treatment of infections is also important.

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Overview

Definition

Hairy cell leukemia (HCL) is a rare, chronic B-cell leukemia characterized by the accumulation of small mature B lymphocytes B lymphocytes B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells that have hair-like projections visible on microscopy.

Epidemiology

  • Incidence: 
    • 3 per 1 million persons per year in the United States
    • Rare: approximately 2% of all leukemia cases
  • Median age at diagnosis: approximately 50 years
  • Sex: male > female (4:1)
  • Race/ethnicity:
    • More common in Caucasians (incidence is 3× higher than in African Americans)
    • Rare in people of African and Japanese descent
  • First-degree family members have an 8× higher risk than the general population.

Etiology

Hairy cell leukemia is a clonal B-cell malignancy. The exact etiology is unknown, but several environmental exposures appear to increase the risk of developing HCL.

  • Exposures as possible causes:
    • Ionizing radiation
    • Organophosphorus pesticides
    • Farming and agricultural chemicals
    • Wood dust
    • Previous history of infectious mononucleosis Mononucleosis Infectious mononucleosis (IM), also known as "the kissing disease," is a highly contagious viral infection caused by the Epstein-Barr virus. Its common name is derived from its main method of transmission: the spread of infected saliva via kissing. Clinical manifestations of IM include fever, tonsillar pharyngitis, and lymphadenopathy. Mononucleosis
  • Familial relationships: due to sharing an HLA haplotype

Pathophysiology

The underlying issue in HCL is that the bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow produces far too many B lymphocytes B lymphocytes B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells, which crowd out the other types of blood cells. These abnormal B cells B cells B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells are unable to protect the body from infectious invaders the way normal B cells B cells B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells can.

Pathophysiology

  • B-cell lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes with hair-like projections (hairy cells) undergo clonal proliferation
  • Hairy cells accumulate in:
    • Peripheral blood
    • Bone marrow
    • Spleen
    • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver (less common)
    • Lymph nodes (uncommon)
  • Infiltration of the reticuloendothelial system:
    • Interferes with bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow function
    • Results in bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow failure and/or pancytopenia
  • Infiltrates the liver and spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen: results in organomegaly
  • Infections due to disease- and treatment-related immunosuppression:
    • Major cause of death
    • Infections may be bacterial, viral, fungal, or nontuberculous mycobacterial.

Pathogenesis

The pathogenesis is incompletely understood, but most cases appear to arise from late activated memory B cells B cells B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells, which acquire an activating BRAF V600E gene mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations.

  • BRAF V600E activating mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations (fundamental cause of biologic features of HCL): 
    • Results in constitutive activation of the RAF-MEK-ERK signaling pathway → leads to inhibition of apoptosis/enhanced cell survival
    • Acts as a molecular trigger and marker
    • Present in nearly 100% of cases
  • Hairy cells have the following features:
    • Expression of pan-B-cell surface antigens: CD19, CD20, and CD22
    • Nonexpression of immature B-cell markers CD10 and CD21
    • Expression of surface antigens that are not common on B cells B cells B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells, such as:
      • ≥1 Ig heavy chains and monotypic light chains
      • CD11c (typically found in monocytes and neutrophils)
      • CD25 (typically found in activated T cells T cells T cells, also called T lymphocytes, are important components of the adaptive immune system. Production starts from the hematopoietic stem cells in the bone marrow, from which T-cell progenitor cells arise. These cells migrate to the thymus for further maturation. T Cells)
      • CD103 (typically found in intraepithelial T cells T cells T cells, also called T lymphocytes, are important components of the adaptive immune system. Production starts from the hematopoietic stem cells in the bone marrow, from which T-cell progenitor cells arise. These cells migrate to the thymus for further maturation. T Cells)
  • Other mutations that may play a role in the molecular pathogenesis:
    • Overexpression of cyclin D1 protein (an important cell-cycle regulator)
    • Mutations in CDKN1B/p27 (a cell-cycle inhibitor)
    • Mutations in KLF2 (a transcription Transcription Transcription of genetic information is the first step in gene expression. Transcription is the process by which DNA is used as a template to make mRNA. This process is divided into 3 stages: initiation, elongation, and termination. Stages of Transcription factor)
  • Associated with other systemic immunologic disorders:
    • Scleroderma Scleroderma Scleroderma (systemic sclerosis) is an autoimmune condition characterized by diffuse collagen deposition and fibrosis. The clinical presentation varies from limited skin involvement to diffuse involvement of internal organs. Scleroderma
    • Polymyositis Polymyositis Polymyositis (PM) is an autoimmune inflammatory myopathy caused by T cell-mediated muscle injury. The etiology of PM is unclear, but there are several genetic and environmental associations. Polymyositis is most common in middle-aged women and rarely affects children. Polymyositis
    • Polyarteritis nodosa
    • Erythematous maculopapules
    • Pyoderma gangrenosum

Clinical Presentation

Symptoms related to cytopenias

  • Anemia (most common presenting symptoms):
    • Weakness
    • Fatigue
  • Thrombocytopenia → bleeding symptoms (⅓ of patients):
    • Ecchymosis
    • Epistaxis
    • Gingival bleeding
    • Menorrhagia
  • Neutropenia (⅓ of patients):
    • Fever (due to infection)
    • Infections

Symptoms related to infiltration in the spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen and liver

  • Splenomegaly causing abdominal discomfort (classic feature of HCL, seen in 80%–90% of patients):
    • Spleen may be massive: splenic edge extending > 8 cm beyond the left costal margin in 25% of patients 
    • Incidence and severity of splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly may be decreasing as patients are being diagnosed earlier.
    • Spontaneous splenic rupture Splenic rupture Splenic rupture is a medical emergency that carries a significant risk of hypovolemic shock and death. Injury to the spleen accounts for nearly half of all injuries to intra-abdominal organs. The most common reason for a rupture of the spleen is blunt abdominal trauma, specifically, motor vehicle accidents. Rupture of the Spleen may occur → a medical emergency
  • Hepatomegaly and lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy are not major features of HCL:
    • Hepatomegaly present in 20% of HCL patients
    • Lymphadenopathy present in 10% of HCL patients

Asymptomatic

  • Incidental finding during workup for unrelated cause
  • ¼ of patients

Diagnosis

The diagnosis is based on identifying hairy cells on a peripheral blood smear, immunohistochemistry, and/or flow cytometry and, potentially, a bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow biopsy.

Laboratory

Laboratory findings may include:

  • Peripheral blood smear: identification of hairy cells
    • Fine, hairlike cytoplasmic projections
    • Large mononuclear cells 
    • Nuclei are most commonly ovoid and eccentrically located.
    • Can be identified with a Romanowsky stain
  • CBC/DIFF:
    • Anemia (normochromic–normocytic): 85% of patients
    • Thrombocytopenia: 80%
    • Neutropenia: 80%
    • Monocytopenia: 80%
    • Leukocytosis (> 10,000 cells/µL): 10%–20% of patients
  • Other serologic testing:
    • BUN elevated: 30%
    • Liver function tests Liver function tests Liver function tests, also known as hepatic function panels, are one of the most commonly performed screening blood tests. Such tests are also used to detect, evaluate, and monitor acute and chronic liver diseases. Liver Function Tests abnormal: 20%
    • Hepatitis B Hepatitis B Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis B Virus and C serologies for patients whose planned treatment is with rituximab
  • Flow cytometry of peripheral blood: can confirm immunophenotype of circulating B cells B cells B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells
Peripheral blood smear showing a hairy cell

Peripheral blood smear showing a hairy cell

Image: “Primary hairy cell leukemia/lymphoma of the breast: a case report and review of the literature” by Pilichowska M, Shariftabrizi A, Mukand-Cerro I, Miller K. License: CC BY 3.0

Biopsy

  • Difficult or impossible to aspirate (“dry tap”) due to HCL-induced marrow fibrosis
  • Requires a trephine bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow biopsy
  • Immunohistochemistry (IHC) staining:
    • Best method to determine diagnosis and extent of involvement 
    • To distinguish classic HCL from other peripheral small B-cell neoplasms
    • Assess for the BRAF V600E somatic mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations: highly sensitive but not specific to HCL (also detected in other entities)
    • Allows for assessment of typical HCL antigens: CD19, CD20, CD22, CD11c, CD25, and CD103
Bone marrow biopsy hairy cell leukemia

Bone marrow biopsy:
(a): Rather inconspicuous diffuse infiltrate of small mature lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes (H&E, ×200).
(b): Immunohistochemical staining for CD20 reveals B-cell nature of the infiltrate (immunoperoxidase, ×200).

Image: “Bone marrow biopsy” by Pilichowska M, Shariftabrizi A, Mukand-Cerro I, Miller K. License: CC BY 3.0

Management

Goals of care

  • Improve symptoms.
  • Reverse cytopenias.
  • Prolong survival to a near-normal lifespan (though the disease is technically not curable)

Asymptomatic patients: observation

Asymptomatic patients should be observed rather than treated.

  • Can be observed for months or years
  • Approximately 10% of patients never require therapy.
  • No clear advantage to early treatment (risk of therapy may be greater than benefit)
  • Patients can be followed with interval histories, exams, and CBC/DIFF approximately every 3 months.

Symptomatic patients: treatment

Treatment is indicated in the following clinical situations:

  • Significant cytopenias: 
    • Absolute neutrophil count: < 1000/µL
    • Hemoglobin: < 11 g/dL
    • Platelet count: < 100,000/µL
  • Less severe cytopenias with the following:
    • Repeated infections
    • Clinical bleeding
    • Progressive lymphocytosis Lymphocytosis WBCs develop from stem cells in the bone marrow and are called leukocytes when circulating in the bloodstream. Lymphocytes are 1 of the 5 subclasses of WBCs. Lymphocytosis is an increase in the number or proportion of the lymphocyte subclass of WBCs, often as a result of an immune response to infection (known as reactive lymphocytosis). Lymphocytosis
  • Symptomatic splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly (common)
  • Symptomatic adenopathy (uncommon)
  • Constitutional symptoms: 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 and/or night sweats (signs of infection), weight loss

Treatment options

  • Purine analogs: cladribine, pentostatin
    • Cytotoxic effects on both B and T lymphocytes T lymphocytes T cells, also called T lymphocytes, are important components of the adaptive immune system. Production starts from the hematopoietic stem cells in the bone marrow, from which T-cell progenitor cells arise. These cells migrate to the thymus for further maturation. T Cells
    • 1st-line treatment for patients with normal renal function
    • Complete remission is achieved in > 90% of patients with progression-free survival (PFS) of 9‒11 years.
    • Induces a profound neutropenia Neutropenia Neutrophils are an important component of the immune system and play a significant role in the eradication of infections. Low numbers of circulating neutrophils, referred to as neutropenia, predispose the body to recurrent infections or sepsis, though patients can also be asymptomatic. Neutropenia → risk of infection due to treatment
  • Interferon alfa:
    • Inhibits cell growth, interferes with oncogene and surface antigen expression
    • Can be used as an alternative agent in patients who would benefit from ↑ blood counts prior to starting purine analog therapy.
    • Indications: 
      • Severe pancytopenia
      • Active infections
      • Pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care (though most can just be observed until after delivery)
  • Rituximab:
    • A monoclonal antibody against CD20 (found on B lymphocytes B lymphocytes B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells)
    • May be added to purine analog therapies to improve response
    • Associated with immunosuppression
    • Hepatitis B Hepatitis B Hepatitis B virus (HBV) is a partially double-stranded DNA virus, which belongs to the Orthohepadnavirus genus and the Hepadnaviridae family. Most individuals with acute HBV infection are asymptomatic or have mild, self-limiting symptoms. Chronic infection can be asymptomatic or create hepatic inflammation, leading to liver cirrhosis and hepatocellular carcinoma (HCC). Hepatitis B Virus and C patients are at risk for reactivation and severe hepatitis.
  • Splenectomy:
    • May temporarily improve blood counts
    • Not done routinely, but indications include:
      • Palliative therapy for symptomatic splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly (e.g., pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, severe enlargement)
      • Emergency treatment for splenic rupture Splenic rupture Splenic rupture is a medical emergency that carries a significant risk of hypovolemic shock and death. Injury to the spleen accounts for nearly half of all injuries to intra-abdominal organs. The most common reason for a rupture of the spleen is blunt abdominal trauma, specifically, motor vehicle accidents. Rupture of the Spleen
      • Pancytopenia due to splenic sequestration
      • Pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care
  • Other therapies:
    • Antibiotics to treat infections
    • Vaccines to prevent infections 
    • Transfusions to treat severe/symptomatic cytopenias (patients require irradiated blood products)

Prognosis

  • With treatment, patients can achieve long-term remission.
  • 5-year survival rate: 84%–94%
  • Long treatment-free periods
  • Patients with symptomatic relapses should be given further therapy.

Differential Diagnosis

  • Primary myelofibrosis Primary myelofibrosis Primary myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by chronic myeloproliferation with nonclonal fibroblastic deposition, resulting in bone marrow fibrosis. The abnormality stems from genetic mutations of the hematopoietic stem cells (typically, JAK2 mutation). Primary symptoms are anemia and extramedullary hematopoiesis,. Primary Myelofibrosis: myeloproliferative neoplasm due to mutations in the hematopoietic stem cells that is characterized by chronic myeloproliferation with fibroblastic deposition, resulting in bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow fibrosis. Symptoms are primarily related to 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 extramedullary hematopoiesis and include severe fatigue, weight loss, and hepatosplenomegaly. Laboratory studies show 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 other cytopenias), and bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow biopsy reveals extensive fibrosis. Management is with hematopoietic cell transplantation (HCT) and symptom-directed interventions.
  • CLL CLL Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia: mature B-cell neoplasm characterized by a progressive accumulation of functionally incompetent monoclonal B lymphocytes B lymphocytes B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells. Most cases of CLL CLL Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia are asymptomatic, with exam findings of painless lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy and splenomegaly Splenomegaly Splenomegaly is pathologic enlargement of the spleen that is attributable to numerous causes, including infections, hemoglobinopathies, infiltrative processes, and outflow obstruction of the portal vein. Splenomegaly. CLL CLL Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by excess production of monoclonal B lymphocytes in the peripheral blood. When the involvement is primarily nodal, the condition is called small lymphocytic lymphoma (SLL). The disease usually presents in older adults, with a median age of 70 years. Chronic Lymphocytic Leukemia can be differentiated from HCL on the basis of differences in the peripheral blood smear, bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow biopsy, and immunophenotype of circulating lymphocytes Lymphocytes Lymphocytes are heterogeneous WBCs involved in immune response. Lymphocytes develop from the bone marrow, starting from hematopoietic stem cells (HSCs) and progressing to common lymphoid progenitors (CLPs). B and T lymphocytes and natural killer (NK) cells arise from the lineage. Lymphocytes on flow cytometry. Management is with observation for asymptomatic patients and chemotherapy in later stages. 
  • Aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia: rare life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow, in the absence of any abnormal cells, reflecting damage to the hematopoietic stem cells (HSCs). Aplastic anemia Aplastic Anemia Aplastic anemia (AA) is a rare, life-threatening condition characterized by pancytopenia and hypocellularity of the bone marrow (in the absence of any abnormal cells) reflecting damage to hematopoietic stem cells. Aplastic anemia can be acquired or inherited, however, most cases of AA are acquired and caused by autoimmune damage to hematopoietic stem cells. Aplastic Anemia can be acquired or inherited. Multiple causes are known, including autoimmune damage to HSCs, medications, chemicals, whole-body radiation, viral infections, immune diseases, pregnancy, Fanconi 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 Down syndrome Down syndrome Down syndrome, or trisomy 21, is the most common chromosomal aberration and the most frequent genetic cause of developmental delay. Both boys and girls are affected and have characteristic craniofacial and musculoskeletal features, as well as multiple medical anomalies involving the cardiac, gastrointestinal, ocular, and auditory systems. Down Syndrome.
  • Mantle-cell lymphoma: aggressive, rare form of non- Hodgkin lymphoma Hodgkin lymphoma Hodgkin lymphoma (HL) is a malignancy of B lymphocytes originating in the lymph nodes. The pathognomonic histologic finding of HL is a Hodgkin/Reed-Sternberg (HRS) cell (giant multinucleated B cells with eosinophilic inclusions). The disease presents most commonly with lymphadenopathy, night sweats, weight loss, fever, splenomegaly and hepatomegaly. Hodgkin Lymphoma (NHL) involving mature B cells B cells B lymphocytes, also known as B cells, are important components of the adaptive immune system. In the bone marrow, the hematopoietic stem cells go through a series of steps to become mature naive B cells. The cells migrate to secondary lymphoid organs for activation and further maturation. B Cells. Mantle-cell lymphoma is caused by overexpression of cyclin D2 and tends to occur in older men. Patients tend to present with advanced disease and may have symptoms including 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, night sweats, and unintentional weight loss (B-cell symptoms). Diagnosis is by tissue biopsy and immunohistochemistry. Management may include chemotherapy, immunotherapy, and possibly hematopoietic stem cell transplantation.

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