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Primary Skin Lesions

The identification Identification Defense Mechanisms and classification of 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 lesions in a patient are important steps in the diagnosis of any 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 disorder. Primary lesions represent the initial presentation Presentation The position or orientation of the fetus at near term or during obstetric labor, determined by its relation to the spine of the mother and the birth canal. The normal position is a vertical, cephalic presentation with the fetal vertex flexed on the neck. Normal and Abnormal Labor of the disease process. Secondary lesions develop from irritated or manipulated primary lesions, and/or disease progression. Along with history, a comprehensive examination 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, appendages, and mucous membranes is required to differentiate between conditions. The key features noted during examination include the type, morphology, size, color, shape, arrangement, and distribution of the presenting lesions. At times, diagnostic procedures may be necessary.

Last updated: 29 Nov, 2021

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Macule

  • A flat, non-palpable 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 lesion measuring ≤ 1 cm in size
  • Differs in color from surrounding 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 (hypopigmented/hyperpigmented or erythematous)
  • Not raised or depressed compared to 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 surface
  • Examples: 
    • Freckles
    • Moles
    • Café-au-lait macules
    • Macules in rubella Rubella An acute infectious disease caused by the rubella virus. The virus enters the respiratory tract via airborne droplet and spreads to the lymphatic system. Rubella Virus
    • Macules in measles Measles Measles (also known as rubeola) is caused by a single-stranded, linear, negative-sense RNA virus of the family Paramyxoviridae. It is highly contagious and spreads by respiratory droplets or direct-contact transmission from an infected person. Typically a disease of childhood, measles classically starts with cough, coryza, and conjunctivitis, followed by a maculopapular rash. Measles Virus
Hyperpigmented cafe-au-lait macules

Hyperpigmented café-au-lait macules in a patient with neurofibromatosis type 1 Type 1 Spinal Muscular Atrophy

Image: “ Breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer associated with neurofibromatosis type 1 Type 1 Spinal Muscular Atrophy: A case series and review of the literature” by Khalil J, Afif M, Elkacemi H, Benoulaid M, Kebdani T, Benjaafar N. License: CC BY 4.0

Patch

  • A flat 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 lesion measuring > 1 cm in size
  • Differs in color from the surrounding 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
  • Nonpalpable and larger than a macule Macule Nonpalpable lesion < 1 cm in diameter Generalized and Localized Rashes
  • Examples include vitiligo Vitiligo Vitiligo is the most common depigmenting disorder and is caused by the destruction of melanocytes. Patients present with hypo- or depigmented macules or patches which often occur on the face, hands, knees, and/or genitalia. Vitiligo and melasma Melasma Melasma is a benign skin condition characterized by hyperpigmentation of sun-exposed regions due to excess melanin production and deposition. The condition mainly affects women during their reproductive years, particularly those with darker skin tones. Melasma.

Papule

  • A raised, palpable 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 lesion measuring ≤ 1 cm in diameter
  • The color can indicate the diagnosis:
    • Brown or black papules are often melanocytic lesions.
    • Red papules are often vascular lesions.
  • Examples: 
    • Nevi Nevi Nevi (singular nevus), also known as “moles,” are benign neoplasms of the skin. Nevus is a non-specific medical term because it encompasses both congenital and acquired lesions, hyper- and hypopigmented lesions, and raised or flat lesions. Nevus/Nevi
    • Warts Warts Benign epidermal proliferations or tumors; some are viral in origin. Female Genitourinary Examination
    • Lichen planus Lichen planus Lichen planus (LP) is an idiopathic, cell-mediated inflammatory skin disease. It is characterized by pruritic, flat-topped, papular, purple skin lesions commonly found on the flexural surfaces of the extremities. Other areas affected include genitalia, nails, scalp, and mucous membranes. Lichen Planus
    • Insect bites
    • Seborrheic keratoses
    • Molluscum contagiosum Molluscum contagiosum Molluscum contagiosum is a viral infection limited to the epidermis and is common in children below 5 years of age. Lesions appear as grouped, flesh-colored, dome-shaped papules with central umbilication. Molluscum Contagiosum
    • Angiomas
    • 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 cancers

Plaque

  • Raised 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 lesion measuring > 1 cm in diameter
  • Usually have palpable surface change as lesion arises from the epidermis Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of epithelium: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis). Skin: Structure and Functions
  • May have a flat-topped or rounded appearance.
  • Examples:
    • Psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis
    • Granuloma annulare Granuloma Annulare Benign granulomatous disease of unknown etiology characterized by a ring of localized or disseminated papules or nodules on the skin and palisading histiocytes surrounding necrobiotic tissue resulting from altered collagen structures. Secondary Skin Lesions
    • Seborrheic dermatitis Seborrheic dermatitis Seborrheic dermatitis is a common chronic, relapsing skin disorder that presents as erythematous plaques with greasy, yellow scales in susceptible areas (scalp, face, and trunk). Seborrheic dermatitis has a biphasic incidence, occurring in two peaks: first in infants, then in adolescence and early adulthood. Seborrheic Dermatitis
    • Eczema Eczema Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Atopic Dermatitis (Eczema)
Severe plaque psoriasis

Severe plaque psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis

Image: “ Psoriasis Psoriasis Psoriasis is a common T-cell-mediated inflammatory skin condition. The etiology is unknown, but is thought to be due to genetic inheritance and environmental triggers. There are 4 major subtypes, with the most common form being chronic plaque psoriasis. Psoriasis manum” by George Henry Fox. License: Public Domain

Nodule

  • A large, firm lesion raised above the surface of the surrounding 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 and measuring 1–5 cm
  • Usually extends into the dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions and subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess
  • The surface may be smooth, keratotic, ulcerated, or fungating.
  • Examples: 
    • Neurofibromas
    • Cysts Cysts Any fluid-filled closed cavity or sac that is lined by an epithelium. Cysts can be of normal, abnormal, non-neoplastic, or neoplastic tissues. Fibrocystic Change
    • Lipomas
Neurofibromas

Neurofibromas

Image: “ Breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer associated with neurofibromatosis type 1 Type 1 Spinal Muscular Atrophy: A case series and review of the literature” by Khalil J, Afif M, Elkacemi H, Benoulaid M, Kebdani T, Benjaafar N. License: CC BY 4.0, cropped by Lecturio.

Vesicle

  • A small, fluid-containing blister Blister Bullous Pemphigoid and Pemphigus Vulgaris (collection of fluid in 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) measuring ≤ 1 cm in diameter
  • Raised above the plane of the surrounding 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
  • The fluid is visible as the lesions are translucent.
  • Observed in:
    • Chickenpox Chickenpox A highly contagious infectious disease caused by the varicella-zoster virus. It usually affects children, is spread by direct contact or respiratory route via droplet nuclei, and is characterized by the appearance on the skin and mucous membranes of successive crops of typical pruritic vesicular lesions that are easily broken and become scabbed. Chickenpox is relatively benign in children, but may be complicated by pneumonia and encephalitis in adults. Varicella-Zoster Virus/Chickenpox
    • Herpes zoster Herpes Zoster Varicella-zoster virus (VZV) is a linear, double-stranded DNA virus in the Herpesviridae family. Shingles (also known as herpes zoster) is more common in adults and occurs due to the reactivation of VZV. Varicella-Zoster Virus/Chickenpox
    • Impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic “honey-colored” crusts. Impetigo
    • Dermatitis herpetiformis Dermatitis herpetiformis Rare, chronic, papulo-vesicular disease characterized by an intensely pruritic eruption consisting of various combinations of symmetrical, erythematous, papular, vesicular, or bullous lesions. The disease is strongly associated with the presence of hla-b8 and hla-dr3 antigens. A variety of different autoantibodies has been detected in small numbers in patients with dermatitis herpetiformis. Celiac Disease
Vesicles from herpes simplex virus

Vesicles Vesicles Female Genitourinary Examination caused by herpes simplex Herpes Simplex A group of acute infections caused by herpes simplex virus type 1 or type 2 that is characterized by the development of one or more small fluid-filled vesicles with a raised erythematous base on the skin or mucous membrane. It occurs as a primary infection or recurs due to a reactivation of a latent infection. Congenital TORCH Infections virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology

Image: “Transplant biology at a crossroads” by Sedwick C. License: CC BY 4.0, cropped by Lecturio.

Bulla

  • A large, clear fluid-containing blister Blister Bullous Pemphigoid and Pemphigus Vulgaris measuring > 1 cm in diameter
  • May be caused by:
    • Burns Burns A burn is a type of injury to the skin and deeper tissues caused by exposure to heat, electricity, chemicals, friction, or radiation. Burns are classified according to their depth as superficial (1st-degree), partial-thickness (2nd-degree), full-thickness (3rd-degree), and 4th-degree burns. Burns
    • Bites
    • Irritant/allergic contact dermatitis Contact dermatitis A type of acute or chronic skin reaction in which sensitivity is manifested by reactivity to materials or substances coming in contact with the skin. It may involve allergic or non-allergic mechanisms. Male Genitourinary Examination
    • Drug reactions
  • Classic autoimmune bullous diseases include pemphigus vulgaris Pemphigus vulgaris Bullous pemphigoid and pemphigus vulgaris are two different blistering autoimmune diseases. In pemphigus vulgaris, autoantibodies attack the desmosomal proteins, which connect the keratinocytes to one another. This attack results in a more severe, potentially fatal condition with fragile, flaccid blisters, usually with significant mucosal involvement. Bullous Pemphigoid and Pemphigus Vulgaris and bullous pemphigoid Bullous pemphigoid Bullous pemphigoid and pemphigus vulgaris are two different blistering autoimmune diseases. In bullous pemphigoid, autoantibodies attack the hemidesmosomes, which connect epidermal keratinocytes to the basement membrane. This attack results in large, tense subepidermal blisters. Bullous Pemphigoid and Pemphigus Vulgaris.
Findings in bullous pemphigoid

Cutaneous findings in bullous pemphigoid Bullous pemphigoid Bullous pemphigoid and pemphigus vulgaris are two different blistering autoimmune diseases. In bullous pemphigoid, autoantibodies attack the hemidesmosomes, which connect epidermal keratinocytes to the basement membrane. This attack results in large, tense subepidermal blisters. Bullous Pemphigoid and Pemphigus Vulgaris:
Multiple large, tense vesicles Vesicles Female Genitourinary Examination and bullae Bullae Erythema Multiforme in the groin Groin The external junctural region between the lower part of the abdomen and the thigh. Male Genitourinary Examination on normal to mildly erythematous 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

Image: “Localized flexural bullous pemphigoid Bullous pemphigoid Bullous pemphigoid and pemphigus vulgaris are two different blistering autoimmune diseases. In bullous pemphigoid, autoantibodies attack the hemidesmosomes, which connect epidermal keratinocytes to the basement membrane. This attack results in large, tense subepidermal blisters. Bullous Pemphigoid and Pemphigus Vulgaris” by Mehta V., Balachandran C. License: CC BY 2.0

Urticaria (Wheals or Hives)

  • Sharply demarcated and elevated lesions with irregular borders:
    • Usually erythematous and may have central pallor
    • Formed due to sudden extravasation of fluid into the dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions
  • Wheals are pruritic and ALWAYS disappear within 24 hours.
  • Can be caused by:
    • Medication hypersensitivity
    • Insect stings Insect stings Insect and scorpion stings are a rare cause of mortality. Hymenoptera insects and Centruroides scorpions can potentially lead to serious symptoms due to envenomation. Pain, swelling, erythema, and warmth are common at the site of a sting. Insect and Scorpion Stings or bites
    • Autoimmune conditions
  • Physical stimuli Physical stimuli Act of eliciting a response from a person or organism through physical contact. Angioedema (e.g., temperature, pressure, sunlight)
Urticaria

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)

Image: “Urticarial 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 in a Teenage Girl” by McGuffin A, Vaughan A, Wolford J. License: CC BY 3.0

Pustule

  • A vesicle filled with pus
  • Formed due to the collection of inflammatory exudate Exudate Exudates are fluids, cells, or other cellular substances that are slowly discharged from blood vessels usually from inflamed tissues. Pleural Effusion that is rich in leukocytes Leukocytes White blood cells. These include granular leukocytes (basophils; eosinophils; and neutrophils) as well as non-granular leukocytes (lymphocytes and monocytes). White Myeloid Cells: Histology
  • May contain bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology or may be sterile Sterile Basic Procedures
  • Pustules are common in: 
    • Folliculitis
    • Pustular psoriasis Pustular Psoriasis Psoriasis
    • Scabies Scabies Scabies is an infestation of the skin by the Sarcoptes scabiei mite, which presents most commonly with intense pruritus, characteristic linear burrows, and erythematous papules, particularly in the interdigital folds and the flexor aspects of the wrists. Scabies
    • Acne
Folliculitis example

Bacterial folliculitis on the lower leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy presenting as follicular pustules

Image: “Folliculitis on lower leg Leg The lower leg, or just “leg” in anatomical terms, is the part of the lower limb between the knee and the ankle joint. The bony structure is composed of the tibia and fibula bones, and the muscles of the leg are grouped into the anterior, lateral, and posterior compartments by extensions of fascia. Leg: Anatomy” by Da pacem Domine. License: Public Domain

Telangiectasia

  • Also known as “spider veins
  • Appear as fine, bright red lines or a net-like pattern
  • Represent a dilation of capillaries Capillaries Capillaries are the primary structures in the circulatory system that allow the exchange of gas, nutrients, and other materials between the blood and the extracellular fluid (ECF). Capillaries are the smallest of the blood vessels. Because a capillary diameter is so small, only 1 RBC may pass through at a time. Capillaries: Histology that blanch upon pressure
  • Not elevated and are often found on the face, trunk, and around the nail bed Nail bed Skin: Structure and Functions
  • Telangiectasias Telangiectasias Ataxia-telangiectasia occur in:
    • CREST ( calcinosis Calcinosis Pathologic deposition of calcium salts in tissues. Scleroderma, Raynaud’s phenomenon, esophageal dysmotility Esophageal Dysmotility Scleroderma, sclerodactyly Sclerodactyly Scleroderma, and telangiectasia Telangiectasia Permanent dilation of preexisting blood vessels creating small focal red lesions, most commonly in the skin or mucous membranes. It is characterized by the prominence of skin blood vessels, such as vascular spiders. Chronic Venous Insufficiency) syndrome
    • Dermatomyositis Dermatomyositis A subacute or chronic inflammatory disease of muscle and skin, marked by proximal muscle weakness and a characteristic skin rash. The illness occurs with approximately equal frequency in children and adults. The skin lesions usually take the form of a purplish rash (or less often an exfoliative dermatitis) involving the nose, cheeks, forehead, upper trunk, and arms. The disease is associated with a complement mediated intramuscular microangiopathy, leading to loss of capillaries, muscle ischemia, muscle-fiber necrosis, and perifascicular atrophy. The childhood form of this disease tends to evolve into a systemic vasculitis. Dermatomyositis may occur in association with malignant neoplasms. Paraneoplastic Syndromes
    • Systemic sclerosis Sclerosis A pathological process consisting of hardening or fibrosis of an anatomical structure, often a vessel or a nerve. Wilms Tumor
    • Ataxia Ataxia Impairment of the ability to perform smoothly coordinated voluntary movements. This condition may affect the limbs, trunk, eyes, pharynx, larynx, and other structures. Ataxia may result from impaired sensory or motor function. Sensory ataxia may result from posterior column injury or peripheral nerve diseases. Motor ataxia may be associated with cerebellar diseases; cerebral cortex diseases; thalamic diseases; basal ganglia diseases; injury to the red nucleus; and other conditions. Ataxia-telangiectasia telangiectasia Telangiectasia Permanent dilation of preexisting blood vessels creating small focal red lesions, most commonly in the skin or mucous membranes. It is characterized by the prominence of skin blood vessels, such as vascular spiders. Chronic Venous Insufficiency
    • 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 cancers
Nose telangiectasias

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 and Nasal Cavity: Anatomy telangiectasias Telangiectasias Ataxia-telangiectasia:
a: Telangiectasias Telangiectasias Ataxia-telangiectasia (arrows)
b: After treatment with cautery

Image: “Management of Facial Telangiectasias Telangiectasias Ataxia-telangiectasia with Hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy Cautery” by E Liapakis I, Englander M, Sinani R, I Paschalis E. License: CC BY 3.0

Petechiae

  • Punctate foci of hemorrhage (seen as small red, purple, or brown spots) measuring < 3 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma in size
  • Petechiae are seen in the setting of: 
    • 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
    • Platelet dysfunction
    • 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
    • Infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease (e.g., meningococcemia Meningococcemia Terminal Complement Pathway Deficiency, Rocky Mountain spotted 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)
Petechiae around intravenous site

Petechiae around intravenous site

Image by Jeremy Greer, MD (Lecturio).

Purpura

  • Extravasation of RBCs RBCs Erythrocytes, or red blood cells (RBCs), are the most abundant cells in the blood. While erythrocytes in the fetus are initially produced in the yolk sac then the liver, the bone marrow eventually becomes the main site of production. Erythrocytes: Histology from cutaneous vessels in 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 and mucous membranes:
  • Purpura is seen in leukocytoclastic 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 (e.g., Henoch-Schöenlein purpura and 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 large area of purpura may be called an ecchymosis Ecchymosis Extravasation of blood into the skin, resulting in a nonelevated, rounded or irregular, blue or purplish patch, larger than a petechia. Orbital Fractures.
Petechiae or purpura on the lower limb

Petechiae/purpura on the lower limb seen in Henoch-Schöenlein purpura

Image: “ 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 in an older man presenting as rectal bleeding and 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 mesangioproliferative glomerulonephritis: A case report” by Cheungpasitporn W, Jirajariyavej T, Howarth CB, Rosen RM. License: CC BY 2.0

Approach to Diagnosing Skin Conditions

Complete medical history

  • Underlying conditions (e.g., autoimmune disorders, diabetes Diabetes Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia and dysfunction of the regulation of glucose metabolism by insulin. Type 1 DM is diagnosed mostly in children and young adults as the result of autoimmune destruction of β cells in the pancreas and the resulting lack of insulin. Type 2 DM has a significant association with obesity and is characterized by insulin resistance. Diabetes Mellitus)
  • Accompanying symptoms (e.g., burning, itching)
  • Medications
  • Allergies Allergies A medical specialty concerned with the hypersensitivity of the individual to foreign substances and protection from the resultant infection or disorder. Selective IgA Deficiency
  • Evolution and duration of 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 lesions, and aggravating and alleviating factors
  • Social, sexual, and travel history

Physical examination

A general physical examination as well as a focused dermatological examination should be performed:

  • 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 and its appendages as well as mucous membranes
  • Performed with the naked eye and using a dermatoscope

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 features and commonly associated 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 conditions and/or lesions to consider:

  • Texture Texture Dermatologic Examination
  • Morphology: 
  • Diameter: varies depending on the condition
  • Composition: fluid-filled, pus-filled, blood-filled, or solid structures
  • Borders: regular Regular Insulin or irregular, flat or raised
  • Color: hypopigmented, hyperpigmented, or erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion
  • Arrangement: grouped (herpetiform)/scattered
  • Configuration: 
    • Annular Annular Dermatologic Examination: tinea corporis Tinea corporis Dermatophytes/Tinea Infections, granuloma annulare Granuloma Annulare Benign granulomatous disease of unknown etiology characterized by a ring of localized or disseminated papules or nodules on the skin and palisading histiocytes surrounding necrobiotic tissue resulting from altered collagen structures. Secondary Skin Lesions
    • Round/discoid/nummular: eczema Eczema Atopic dermatitis, also known as eczema, is a chronic, relapsing, pruritic, inflammatory skin disease that occurs more frequently in children, although adults can also be affected. The condition is often associated with elevated serum levels of IgE and a personal or family history of atopy. Skin dryness, erythema, oozing, crusting, and lichenification are present. Atopic Dermatitis (Eczema), discoid lupus
    • Polycyclic: 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)
    • Arcuate: 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)
    • Linear: scabies Scabies Scabies is an infestation of the skin by the Sarcoptes scabiei mite, which presents most commonly with intense pruritus, characteristic linear burrows, and erythematous papules, particularly in the interdigital folds and the flexor aspects of the wrists. Scabies burrow, lichen nitidus Lichen nitidus A chronic inflammatory disease characterized by shiny, flat-topped, usually flesh-colored micropapules no larger than the head of a pin. Lesions are localized in the early stages, found chiefly on the lower abdomen, penis, and inner surface of the thighs. Distribution may become generalized as the disease progresses. Secondary Skin Lesions
    • Reticular: 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
    • Serpiginous: cutaneous larva migrans Cutaneous Larva Migrans Hookworm Infections
    • Targetoid lesions: erythema Erythema Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of disease processes. Chalazion multiforme
    • Whorled: incontinentia pigmenti
Primary skin lesions

Different primary 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 lesions:
A macule Macule Nonpalpable lesion < 1 cm in diameter Generalized and Localized Rashes is a flat ≤ 1 cm non-palpable 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 lesion.
A papule Papule Elevated lesion < 1 cm in diameter Generalized and Localized Rashes is a raised ≤ 1 cm palpable 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 lesion.
A nodule Nodule Chalazion is a large 1–5 cm firm raised lesion, usually extending into the dermis Dermis A layer of vascularized connective tissue underneath the epidermis. The surface of the dermis contains innervated papillae. Embedded in or beneath the dermis are sweat glands; hair follicles; and sebaceous glands. Skin: Structure and Functions and subcutaneous tissue Subcutaneous tissue Loose connective tissue lying under the dermis, which binds skin loosely to subjacent tissues. It may contain a pad of adipocytes, which vary in number according to the area of the body and vary in size according to the nutritional state. Soft Tissue Abscess.
A plaque is a raised > 1 cm 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 lesion with palpable surface change as it arises from the epidermis Epidermis The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of epithelium: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis). Skin: Structure and Functions.
A vesicle is a small ≤ 1 cm fluid-containing blister Blister Bullous Pemphigoid and Pemphigus Vulgaris while a bulla Bulla Blister filled with fluid, > 1 cm diameter Generalized and Localized Rashes is a large > 1 cm clear fluid-containing blister Blister Bullous Pemphigoid and Pemphigus Vulgaris.

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Diagnostic procedures

  • 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 biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma (lesion excised, saucerized, or obtained by punch biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma)
  • KOH preparation: 
    • Lesion scraped and placed on a glass microscope slide, where it is treated with 1 or 2 drops of 10%–20% KOH
    • If fungal infection suspected
  • Tzanck smear Tzanck smear Herpes Simplex Virus 1 and 2: cytologic technique when vesicular conditions are noted ( herpes simplex Herpes Simplex A group of acute infections caused by herpes simplex virus type 1 or type 2 that is characterized by the development of one or more small fluid-filled vesicles with a raised erythematous base on the skin or mucous membrane. It occurs as a primary infection or recurs due to a reactivation of a latent infection. Congenital TORCH Infections or varicella zoster infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease)
  • Diascopy: to determine if a lesion will blanch on pressure, differentiating a hemorrhagic (does not blanch) from a fluid-filled lesion
  • Wood’s light: 
    • Utilizes 360 nm UV light UV light That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-uv or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-uv or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants. Bullous Pemphigoid and Pemphigus Vulgaris to evaluate lesions
    • Conditions: erythrasma (coral pink color), Pseudomonas Pseudomonas Pseudomonas is a non-lactose-fermenting, gram-negative bacillus that produces pyocyanin, which gives it a characteristic blue-green color. Pseudomonas is found ubiquitously in the environment, as well as in moist reservoirs, such as hospital sinks and respiratory equipment. Pseudomonas wound infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease (blue), vitiligo Vitiligo Vitiligo is the most common depigmenting disorder and is caused by the destruction of melanocytes. Patients present with hypo- or depigmented macules or patches which often occur on the face, hands, knees, and/or genitalia. Vitiligo (white)
  • Patch Patch Nonpalpable lesion > 1 cm in diameter Generalized and Localized Rashes test: allergens placed on patient’s back under occlusive dressings and checked for hypersensitivity reactions after 48 hours.

References

  1. Yancey, K.B., Lawley, T.J. (2018). Approach to the patient with a skin disorder. In Jameson, J., et al. (Eds.). Harrison’s Principles of Internal Medicine, 20e. McGraw-Hill.

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