USMLE Dermatology I

  1. Skin Conditions and associated Diseases
    Image Upload 1
  2. Acanthosis nigricans (AN)
    Image Upload 2
  3. Acanthosis nigricans
    • which is characterized by hyperkeratotic, hyperpigmented plaques with a classic "velvety" texture.
    • Most common locations: flexural areas, particularly the axilla, groin, and posterior neck .
    • Depending on the etiology, AN can be divided into benign and malignant forms:
    • • Benign AN: is typically seen in younger individuals and is associated with insulin-resistant states (eg, diabetes mellitus, obesity, polycystic ovarian syndrome). Increased levels of insulin and/or insulin like growth factors are thought to stimulate epidermal and dermal proliferation. Similarly, skin tags (acrochordons), which are pedunculated outgrowths of normal skin, are also commonly present on regions affected by AN.
    • • Malignant AN: is associated with underlying neoplasms, especially of the gastrointestinal and genitourinary tracts. The sudden appearance of such skin changes in middle-aged or elderly patients is suggestive of underlying malignancy. In addition, these patients are not obese (but instead may have lost weight), and lesions can occur in uncommon areas (eg, mucous membranes, palms, soles).
  4. Treatment of Acne
    • Image Upload 3
    • Contributing factors in acne include increased sebum production, follicular hyperkeratinization, bacterial colonization (Propionibacterium acnes), and, in some cases, an inflammatory response.
    • Initial management of comedonal acne without a significant inflammatory component includes topical retinoids with the addition of organic acid preparations (eg, salicylic, azelaic, or glycolic acid) if initial therapy fails.
    • Benzoyl peroxide, a widely used antibacterial agent, is another option for patients with comedonal acne, although it is preferred for inflammatory acne.
    • Some patients with comedonal acne will develop inflammatory features, and benzoyl peroxide can be added at that time
    • Image Upload 4
  5. Actinic keratosis (AK),
    • which presents as scaly papules or plaques, most commonly in fair-skinned individuals.
    • Chronic sun exposure is the major risk
    • factor, and surrounding skin often displays features of solar damage (eg, telangiectasias, hyperpigmentation).
    • AK is found predominantly on the scalp, face, lateral neck, and dorsal surface of the hands.
    • It has a potential for progression to squamous cell carcinoma, although the likelihood of malignant progression of an individual lesion is low.
    • AK is diagnosed: based on appearance, but biopsy is indicated for lesions that are >1 cm in diameter, have an indurated appearance, exhibit ulceration, are rapidly growing, or fail appropriate treatment.
    • Histopathology: shows thickening of the epidermis (acanthosis), retention of nuclei in the stratum corneum (parakeratosis), nuclear atypia, and abnormal keratinization with thickening of the stratum corneum.
    • Rx: Individual lesions can be treated with focal cryotherapy (eg, liquid nitrogen), but involvement of a large area may require field therapy (eg, fluorouracil).
    • Image Upload 5
  6. Actinic Keratosis
    Image Upload 6
  7. Common drugs associated with photosensitivity reactions
    • Antibiotics: Tetracyclines (eg, doxycycline)
    • Anti psychotics: Chlorpromazine, prochlorperazine
    • Diuretics: Furosemide, hydrochlorothiazide
    • Others: Amiodarone, promethazine, piroxicam
  8. Phototoxic drug reactions
    • result from the production of reactive oxygen species by the interaction of drug metabolites with ultraviolet radiation.
    • These reactive oxygen products then directly damage cell membranes and DNA.
    • Symptoms resemble common sunburn, with erythema, pain, and bullae formation in sun-exposed areas.
    • Tetracyclines (eg, doxycycline) are frequently prescribed in the treatment of acne and are a very common cause of phototoxic drug reactions.
    • Patients being prescribed tetracyclines should be advised to minimize sun exposure and use appropriate sunscreens and barrier solar protection when outdoors.
  9. Photoallergic Reactions:
    • Topical (eg, sunscreens) and systemic medications can also cause photoallergic reactions, in which ultraviolet light alters the structure of the drug, which then induces a delayed hypersensitivity reaction.
    • These skin manifestations are typically eczematous in appearance.
    • Prior sensitization is required for a photoallergic response, but not a phototoxic reaction.
  10. Bullous pemphigoid
    • is an autoimmune disorder characterized by severe pruritus and tense bullae on an erythematous base.
    • Most common age: is more than 65
    • It has an increased incidence in those with malignancy or neurological disorders (eg, Parkinson disease, multiple sclerosis).
    • The extent of involvement may range from just a few lesions to hundreds covering a large portion of the body, although mucous membrane involvement occurs only in a minority of patients.
    • Pre-bullous prodrome: is common and can present as urticarial or eczematous lesions.
    • Pathophysiology: Bullous pemphigoid is caused by lgG autoantibodies against the hemidesmosome and basement membrane zone. Antibody binding activates complement and inflammatory mediators, and the resultant inflammation leads to blister formation.
    • Diagnosis: is made by skin biopsy; light microscopy shows subepidermal cleavage, and direct immunofluorescence microscopy shows linear lgG and C3 deposits along the basement membrane.
    • Treatment: First-line treatment for bullous pemphigoid is a high potency topical glucocorticoid (eg, clobetasol), which is effective even for extensive disease. Systemic glucocorticoids are not more effective and are associated with an increased incidence of treatment-related complications
    • Image Upload 7
  11. Common skin Manifestations
    Image Upload 8
  12. Cellulitis:
    • Cellulitis is a skin infection of the deep dermis and subcutaneous fat usually caused by beta hemolytic Streptococcus (nonpurulent) or Staphylococcus aureus (purulent).
    • Infections take root in areas of skin disruption (eg, insect bite, toe-web impetigo, stasis edema).
    • Patients typically develop a slowly spreading rash that is warm, tender, and erythematous with flat, indistinct borders.
    • Fever and regional lymphangitis/lymphadenitis may be present.
    • Laboratory studies usually show leukocytosis with a predominance of neutrophils, a characteristic of most acute bacterial infections.
    • Diagnosis is based largely on clinical findings, but blood cultures may be useful in patients with systemic toxicity, extensive rash, or certain comorbidities (eg, immunocompromised).
  13. Cherry Angiomas
    • Small, vascular, bright-red papular lesions shown in the image are cherry angiomas (CA).
    • CAs, also known as senile hemangiomas, are the most common benign vascular tumors in adults.
    • They are typically first seen in the 3rd or 4th decade of life and their number increases with age. They appear as sharply circumscribed areas of congested capillaries and posttapillary venules in the papillary dermis.
    • CAs are always cutaneous and are not found on mucosa or deep tissues.
    • They do not regress spontaneously and may bleed if disturbed, but they are benign and do not require treatment for any other than cosmetic reasons.Image Upload 9
  14. Cavernous hemangiomas
    • also known as cavernous malformations, consist of dilated vascular spaces with thin-walled endothelial cells.
    • They present as soft blue, compressible masses growing up to a few centimeters.
    • Cavernous hemangiomas may appear on the skin, mucosa, deep tissues, and viscera.
    • Cavernous hemangiomas of the brain and viscera are associated with von Hippei Lindau disease.
    • Image Upload 10
  15. Condylomata acuminata (anogenital warts)
    • are caused by the human papillomavirus (HPV), which is the most common sexually transmitted disease in the United States.
    • Characteristic lesions are verrucous, papilliform, and either pink or skin-colored.
    • Lesions are usually asymptomatic but may have mild itching or burning. Systemic symptoms are usually absent.
    • Diagnosis of condyloma acuminata: primarily based on clinical presentation.
    • Biopsy may be considered in atypical cases.
    • HPV infection (especially serotypes 16 and 18) is associated with increased risk for squamous cell carcinoma of the anus, genital organs, and throat.
    • HPV is also associated with increased risk for other sexually transmitted diseases, especially HIV.
    • HIV screening should be offered to patients with a new diagnosis of HPV. The condition is self-limited in most cases.
    • If specific treatment is desired, options include:
    • 1. Chemical or physical agents (eg, trichloroacetic acid, podophyllin)
    • 2. Immune therapy (eg, imiquimod)
    • 3. Surgery (eg, cryosurgery, excision, laser treatment)
    • Image Upload 11
  16. Contact Dermatitis
    Image Upload 12
  17. Allergic contact dermatitis (ACD)
    • Triggers: ACD can be triggered by a variety of allergens, including plants (eg, poison oak/ivy), natural rubber, formaldehyde, leather dyes, and topical medications and skin care products.
    • It is a T cell-mediated, type IV hypersensitivity reaction. This type of reaction requires prior exposure to the allergen, allowing antigen-specific T cells to proliferate and, on reexposure, create a delayed inflammatory response.
    • Classic antigens include urushiol (Toxicodendron plants [poison ivy, oak, sumac]), nickel uewelry, belt buckles), and neomycin (a topical antibiotic).
    • Image Upload 13
    • Pathophysiology: Corrosion of metal alloys by electrolytes in sweat releases soluble metal ions that trigger a hypersensitivity reaction.
    • Nickel allergy: is typically caused by jewelry or clothing fasteners and occurs at the neck, wrists, ear lobes, or umbilicus.
    • ACD represents a type IV (cell-mediated) hypersensitivity reaction, with initial sensitization occurring within days of contact with the causative substance. On re-exposure, the antigen is presented to sensitized lymphocytes, leading to inflammation within hours.
    • Acute symptoms: include erythema, vesicles, weeping, and crusting.
    • Chronic, low-level exposure: as is typical in nickel allergy, leads to itching, scaling, and lichenification.
    • Treatment: Most patients respond to low- or mid-potency topical corticosteroids and elimination of exposure to the allergen.
  18. Poison Ivy Dermatitis
    • Toxicodendron (poison ivy/oak/sumac) can grow as small shrubs or vines and produces urushiol, a highly allergenic resin.
    • These plants are most common in undeveloped, wooded areas but can be seen in urban and suburban environments that have not been regularly maintained.
    • The rash, which can appear days after exposure, is usually limited to exposed skin and frequently forms linear streaks where skin has brushed against the plant leaves.
    • Starting 12 hours after exposure, severe pruritus and erythematous streaks develop with edema and vesicles, often leading to weeping drainage and crusting.
    • Diagnosis is clinical, and lesions typically resolve within 1-3 weeks.
    • Prevention is achieved by allergen avoidance (eg, wearing pants and long-sleeved shirts), and treatment includes reduction of post exposure spread (eg, removing exposed clothing, washing fingernails) and topical/oral corticosteroids .
    • However, diffuse or atypical patterns can be seen after exposure to contaminated cloth, pets, or smoke from burning plants.
    • Image Upload 14
  19. Dermatitis herpetiformis (DH)
    • causes intensely pruritic erythematous papules, vesicles, and bullae that occur symmetrically in grouped ("herpetiform") clusters on the extensor surfaces of the elbows, knees, back, and buttocks.
    • DH represents an autoimmune dermal reaction due to dietary gluten and is commonly associated with celiac disease (the likely cause of this patient's diarrhea and weight loss), although it may precede the gastrointestinal manifestations.
    • Skin biopsy in DH: shows subepidermal microabscesses (blisters) at the tips of the dermal papillae; immunofluorescence studies show deposits of anti-epidermal transglutaminase lgA in the dermis.
    • Initial treatment: includes dapsone, which has anti-inflammatory and immunomodulatory properties and provides rapid relief of symptoms.
    • Long-term management requires a gluten-free diet.
    • Image Upload 15
  20. Dermatofibroma (DF)
    • is due to fibroblast proliferation causing isolated or multiple lesions, most commonly on the lower extremities.
    • Etiology: unknown, but some patients may develop lesions after trauma or insect bites.
    • Typical lesions are nontender and appear as discrete, firm, hyperpigmented nodules that are usually less than 1 cm in diameter. The lesions have a fibrous component that may cause dimpling in the center when the area is pinched ("dimple" or "buttonhole" sign).
    • Diagnosis of DF: is made clinically based on the appearance of the lesion.
    • Treatment: cryosurgery or shave excision is usually not required unless the lesion is symptomatic, bleeds, or changes in color or size.
    • Patients may also request treatment for cosmetic reasons or because of recurrent cuts when shaving the legs
    • Image Upload 16
  21. Drug-induced hypersensitivity reaction
    • Some patients can form drug-specific immunoglobulin E (lgE) on exposure to a medication, although most do not.
    • Once formed, the drug-specific lgE occupies receptors on mast cells and basophils. If the drug is encountered again, these cells may activate, resulting in symptoms.
    • Onset is rapid (seconds to minutes) and symptoms can range from mild (eg, urticaria, pruritus, flushing) to more severe (eg, angioedema of the larynx, anaphylaxis).
    • Most commonly implicated in type 1 reactions are beta lactam drugs, neuromuscular blocking agents, quinolones, platinum-containing chemotherapeutic agents, and foreign proteins (eg, chimeric antibodies).
    • Urticaria and pruritus without systemic symptoms are usually treated with antihistamines, and treatment with the offending drug is discontinued
    • Image Upload 17
  22. Epidermal inclusion cyst (EIC),
    • also known as an epidermal cyst, a discrete benign nodule lined with squamous epithelium that contains a semisolid core of keratin and lipid.
    • An EIC occurs when the epidermis becomes lodged in the dermis due to trauma or comedones, or it can arise de novo.
    • EICs can be seen anywhere on the body, but are most common on the face, neck, scalp, or trunk.
    • The lesion can gradually increase in size and may inte rmittently produce a cheesy white discharge.
    • An EIC will usually resolve spontaneously but can recur.
    • Diagnosis: is made clinically with examination showing a dome-shaped, firm, and freely movable cyst or nodule with a central punctum (small, dilated, pore like opening).
    • Excision is typically performed only for cosmetic reasons.
    • Incision and drainage are occasionally needed for infected and fluctuant cysts that are painful and erythematous.
    • Image Upload 18
  23. Herpes Zooster
    • caused by reactivation of latent varicella zoster virus infection.
    • The rash typically begins with small papules that can become confluent and evolve into vesicles or bullae, with subsequent crusting in 7-10 days.
    • Rash is usually limited to a single dermatome, but may involve adjacent dermatomes; a few scattered lesions may develop in distant areas.
    • Most patients will have associated neuritic symptoms, including pain, itching, burning, and anodynia, which may precede the onset of a visible rash.
    • Age and immunocompromised status(immunosuppressive drugs) predispose to shingles.
    • Treatment with antiviral agents (eg, acyclovir, famciclovir, valacyclovir) decreases the duration of symptoms and the incidence of post-herpetic neuralgia, especially if initiated within 72 hours of the onset of symptoms.
    • Image Upload 19
  24. hidradenitis suppurativa (HS, also known as acne inversa)
    • Most commonly occurs in intertriginous areas (eg, axilla; inguinal, perineal areas) but can occur in any hair-bearing skin.
    • HS is due to chronic inflammatory occlusion of folliculopilosebaceous units, which prevents keratinocytes from properly shedding from the follicular epithelium.
    • Risk factors: include family history of HS, smoking, obesity, diabetes, and mechanical stress on the skin (eg, friction, pressure).
    • C/F: solitary, painful, inflamed nodules that can last for several days to months. The nodules may regress or can progress to abscesses that open to the surface with purulent or serosanguineous drainage.
    • Complications include sinus tracts, comedones, and scarring.
    • Severe scarring can lead to dense, rope-like bands in the skin with strictures and lymphedema.Diagnosis is clinical without need for biopsy or cultures.
    • Image Upload 20
  25. Herpetic whitlow
    • Herpetic whitlow arises when herpes simplex virus (HSV) inoculates a cutaneous defect of the hand.
    • In adults, infections typically occur after hand contact with an active genital herpes lesion (HSV-2).
    • Risk is also increased in health care workers who do not use adequate hand protection and are exposed to infected orotracheal secretions (HSV- 1).
    • Symptoms: usually include a mild prodrome (fever, malaise), followed by the development of a focal area of grouped vesicles on an erythematous base.
    • Tingling, burning, and pain are common, and some patients may have epitrochlear or axillary lymphadenopathy.
    • Most lesions resolve spontaneously within 2-3 weeks, but patients with immunocompromise may require antiviral medication (eg, acyclovir).
    • Recurrent lesions occur in 20%-50% of cases.
    • Image Upload 21
    • Image Upload 22

    Image Upload 23
  26. Hand foot and Mouth Disease
    Image Upload 24
  27. Ichthyosis vulgaris
    • a chronic, inherited skin disorder characterized by diffuse dermal scaling.
    • It is caused by mutations in the filaggrin gene and is significantly worse in individuals who are homozygous.
    • Skin appears: dry and rough with horny plates resembling fish or reptile scales ("ikhthys" is Greek for "fish").
    • Ichthyosis is a lifelong condition, but symptoms in early life are frequently mild and may be attributed to simple dryness.
    • However, the condition often worsens later in life, leading to the diagnosis.
    • Ichthyosis often worsens in the winter due to decreased ambient humidity.
    • If simple emollients are ineffective, keratolytics (eg, coal tar, salicylic acid) and topical retinoids are useful for controlling symptoms.
    • Image Upload 25
  28. Malignant melanoma
    • is most common in the skin, although it may occur wherever there are pigmented cells, such as the eye and gastrointestinal mucosa.
    • Sunlight exposure is an important factor in the pathogenesis of dermal melanoma, and light-skinned individuals are at greatest risk.
    • Melanomas frequently arise in preexistent dysplastic nevi.
    • Gross findings that suggest melanoma rather than a benign melanocytic nevus include:
    • Asymmetric shape,
    • irregular or jagged Border,
    • variability of Color (brown, black, red, blue, or unpigmented),
    • Diameter more than 6 mm, and
    • Evolution in size and appearance over time (ABCDE criteria).
    • In patients with multiple nevi, a lesion that is significantly different from the patient's typical moles also warrants increased suspicion ("ugly duckling" sign).
    • Image Upload 26
  29. Several Features Concerning for malignant Melanoma
    • Several features are concerning for malignancy and warrant further workup:
    • 1.ln a patient who has multiple pigmented lesions, a lesion with an appearance that is substantially different from the others (eg, dark brown rather than light brown, nodule rather than flat) may represent melanoma ("ugly duckling sign"). The "ugly duckling sign" has a sensitivity of up to 90% for melanoma.
    • 2.Vertical growth of a melanoma often corresponds to a palpable nodularity, as in this patient, and increases metastatic risk. The Breslow depth (distance from the epidermal granular cell layer to the deepest visible melanoma cells) is the most important prognostic indicator in malignant melanoma.
    • 3. Benign pigmented lesions are usually asymptomatic; therefore, biopsy should be considered for moles that itch or bleed, particularly in the presence of other concerning features.
    • Image Upload 27
  30. ABCDEs of Melanoma
    Image Upload 28
  31. Melanoma Depth of Invasion
    Image Upload 29
  32. Keratoacanthoma
    • Keratoacanthomas are rapidly growing, "volcano-like" nodular cutaneous tumors that usually present as dome shaped nodules with a central keratinous plug.
    • They are generally benign, although rare cases with malignant transformation and metastasis have been reported.
    • Many are treated as well-differentiated squamous cell carcinomas. Early treatment is indicated if the lesion is near an important structure, such as the eye.
    • Image Upload 30

    Image Upload 31
  33. Molluscum contagiosum (MC)
    • is a self-limited skin infection caused by a poxvirus.
    • Characterized by small skin-colored papules with indented centers that may occur anywhere except the palms and soles.
    • MC lesions may be accompanied by pruritus and local dermatitis and may cause conjunctivitis if the lid margin is involved.
    • The diagnosis is usually made clinically based on characteristic findings.
    • Children are most commonly affected, although adolescents and adults can also develop MC. Transmission occurs via skin-to-skin contact or by fomites.
    • MC is often transmitted through sexual contact and may be seen in association with other sexually transmitted diseases.
    • It is also frequently seen in patients with HIV and may be more widely disseminated and persistent in these patients (especially if CD4 cell count less than 1 00/mm').
    • HIV testing should be considered for patients with MC, especially if the lesions are large ( more than 10 mm),numerous, widespread or involve the face.
    • MC is self-limited (resolution within 6-12 months), but treatment with curettage, cryotherapy, or topical agents (eg, podophyllotoxin) may be considered to prevent further spread, reduce symptoms, or improve cosmesis.
    • Image Upload 32
    • Image Upload 33
  34. Bacillary angiomatosis
    • is characterized by friable papules and subcutaneous plaques.
    • It is caused by Bartonella species in immunocompromised patients.
    • It is often associated with fever and other systemic symptoms and may involve the mucosa and visceral organs.
    • Image Upload 34
  35. Erythema Nodosum
    Image Upload 35
  36. Erythema infectiosum
    Image Upload 36
  37. Basal cell carcinoma (BCC)
    • is the most common form of skin cancer in the United States, accounting for approximately 75% of all skin cancers.
    • Possible features of BCC include:
    • • Persistent open sore that bleeds, oozes, or crusts
    • • Reddish patch or irritated area (superficial BCC)
    • • Pearly or translucent nodule with pink, red, or white color (nodular BCC)
    • • Elevated or rolled border with central ulceration
    • • Pale scar-like area with poorly defined borders
    • The cancer usually remains local and only rarely spreads to distant parts of the body, but it may continue to grow and invade nearby tissues and structures, including the nerves, bones, and brain.
    • Image Upload 37
  38. Treatment of BCC
    • Rx varies, depending on the size, depth, and location of the cancer.
    • 1. Low-risk lesions on the trunk or extremities: can be managed with electrodessication and curettage (ED&C). However, ED&C is not recommended for higher-risk lesions or for BCC on the face, where the resulting scarring and hypopigmentation are undesirable.
    • 2. Surgical excision: is advised for this patient's large facial lesion. Nodular BCC on the trunk or extremities may be easily managed with standard surgical excision, typically with 3-5 mm margins.
  39. Mohs micrographic surgery
    • is employed more often for the face.
    • Mohs surgery is characterized by sequential removal of thin skin layers with microscopic inspection to confirm that the margins have been cleared of malignant tissue.
    • This technique currently has the highest cure rate for BCC and provides the least disruption to surrounding tissues, making it ideal for delicate or cosmetically sensitive areas (eg, perioral region, nose, lips, ears).
    • Image Upload 38
  40. Superficial BCC
    Image Upload 39
  41. Nodular BCC
    Image Upload 40
  42. Sperficial Spreading BCC
    Image Upload 41
  43. Squamous cell carcinoma of skin
    • Risk factors:
    • • UV, ionizing radiation (Sun exposure is the MC risk factor)
    • • Immunosuppression
    • • Chronic scars/wounds/burn injuries
    • SCC is especially common in patients who have a history of organ transplant and are on chronic immunosuppressive therapy
    • Clinical features:
    • (rough, scaly, nodule or nonhealing, painless ulcer that develops in the setting of a scar or chronic inflammatory lesion)
    • • Scaly plaques/nodules
    • • +/- Hyperkeratosis or ulceration
    • • Neurologic signs with perineural invasion ( Numbness, Paresthesia)
    • Diagnosis:
    • • Biopsy: Dysplastic/anaplastic keratinocytes
    • (skin biopsy (punch, shave, or excisional) that includes the deep reticular dermis to assess the depth of invasion)
    • Treatment of SCC:
    • Small or low-risk lesions: are usually managed with surgical excision or local destruction (eg, cryotherapy, electrodessication)
    • Lesions that are high risk or located in cosmetically sensitive areas: should be referred for Mohs micrographic surgery.
    • If left untreated, SCC may eventually cause extensive local destruction and lymphatic or distant metastases SCC is not usually metastatic at the time of diagnosis, but SCC arising in a wound or burn (termed a Marjolin ulcer) is associated with an increased risk of metastasis.
    • Image Upload 42

    • Image Upload 43
    • Image Upload 44
  44. SCC of Lip
    • is the most common malignancy of the lip, with 95% of cases occurring in the lower lip vermilion, likely due to higher exposure to sunlight.
    • In addition to ultraviolet (eg, sunlight) exposure, other risk factors for SCC include fair skin tone, tobacco use (smoking or chewing), heavy alcohol use, chronic inflammation or scar formation, and immunosuppression.
    • Diagnosis of SCC: is confirmed with biopsy.
    • Typical pathologic findings include: invasive cords of squamous cells with keratin pearls.
    • Prognosis: is usually very good
    • Most lesions do not metastasize, but untreated SCC can cause extensive local destruction and may eventually spread to local lymph nodes or distant structures.
    • Adverse prognostic features: include larger size, deeper invasion, and involvement of regional lymph nodes
  45. Angiosarcomas
    • malignant tumors derived from the internal lining of blood vessels or lymphatic vessels.
    • Primary angiosarcoma can occur anywhere in the body (eg, liver, breast), but angiosarcoma secondary to breast cancer therapy is typically confined to the skin.
    • Risk Factors: localized radiation therapy, patients with chronic axillary lymphedema, often precipitated by
    • surgical lymph node resection.
  46. Secondary Angiosarcoma
    • most commonly present with multiple ecchymoses or purpuric masses on the skin of the breast, axilla, or upper arm 4-8 years following completion of breast cancer therapy.
    • Lymphedema (nonpitting edema) is often present in the ipsilateral arm, and the skin of the breast may have a dimpled (peau d'orange) appearance.
    • Early hematologic metastasis is common, and patients may also have signs of metastatic disease (eg, dyspnea due to lung involvement).
    • Secondary angiosarcomas are typically high-grade on pathology and generally carry a poor prognosis (worse than primary angiosarcomas).
    • However, when possible, surgical resection is potentially curative.
  47. Pemphigus Vulgaris
    Image Upload 45
  48. Pemphigus Vulgaris
    • PV is an autoimmune disorder caused by antibodies directed against desmogleins 1 and 3, which are components of desmosomes normally involved in adherence between epidermal keratinocytes.
    • C/Fs:
    • painful, flaccid bullae, mucosal erosions, and separation of epidermis from dermis by light friction (Nikolsky sign). The roof of the bullous lesions is fragile and rapidly desquamates, leaving raw ulcers.
    • Light microscopy of a biopsy specimen: from a lesion edge shows intraepithelial cleavage with detached keratinocytes (acantholysis).
    • Because the attachment of keratinocytes to the basement membrane is mediated by hemidesmosomes (which are immunologically distinct from desmosomes), a single cell layer remains along the basement membrane with an appearance described as a "row of tombstones."
    • Immunofluorescence microscopy reveals lgG and C3 deposits in a netlike or "chicken wire" pattern.
    • Serology for antibodies to desmoglein 1 and 3 can further support the diagnosis.
    • Image Upload 46
    • Image Upload 47
  49. Porphyria cutanea tarda
    • PCT is due to deficiency of uroporphyrinogen decarboxylase and is the most common porphyria.
    • Pathophysiology: Enzyme deficiencies in the early steps of porphyrin synthesis (eg, acute intermittent porphyria) cause abdominal pain and neuropsychiatric manifestations (eg, psychosis, neuropathy); abnormalities in the later steps (eg, PCT) lead to photosensitivity due to accumulation of porphyrinogens that react with oxygen on excitation by ultraviolet light.
    • Clinical presentation:
    • • Blisters, bullae, scarring, facial hypertrichosis hypopigmentation/hyperpigmentation on sun exposed skin (eg, back of hands, forearms, face)
    • • Scarring and calcification similar to scleroderma
    • Associated conditions:
    • can be triggered by ingestion of certain substances (eg, ethanol, estrogens)
    • • Hepatitis C
    • • HIV
    • • Excessive alcohol consumption
    • • Estrogen use
    • • Smoking
    • Diagnostic:
    • • Mildly elevated liver enzymes and iron overload testing
    • • Elevated plasma or urine porphyrin levels
    • Treatment:
    • Phlebotomy or hydroxychloroquine may provide relief, as can treatment for hepatitis C.
    • Image Upload 48

    Image Upload 49
  50. Pressure (decubitus) ulcers
    • Pressure ulcers are most common over bony prominences, such as the sacrum, ischial tuberosities, malleoli, heels, and 1st or 5th metatarsal head.
    • Constant, unrelieved pressure causes necrosis of overlying skin and muscle as blood flow to the soft tissues is impeded.
    • Risk factors: include impaired mobility, malnutrition, abnormal mental status (eg, dementia), decreased skin perfusion, and reduced sensation.
    • Initial management of pressure ulcers: includes local wound care, repositioning of the patient to reduce pressure, pain control, and nutritional support.
    • Shallow ulcers: can be managed with occlusive or semipermeable dressings to maintain a moist wound environment.
    • Full-thickness wounds: may require more complex dressings and surgical intervention for debridement or closure.
    • Standard interventions to prevent pressure ulcers in high-risk patients include:
    • • Proper patient positioning
    • • Mobilization
    • • Careful skin care
    • • Moisture control
    • • Maintenance of nutrition
    • Effective modifications include air-fluidized beds, pressure-relieving overlays (eg, sheepskin), higher specification foam mattresses, and active repositioning systems or alternating pressure supports.
    • In addition, patients should be repositioned by the nursing staff at regular intervals (eg, every 2 hours)
    • Image Upload 50
Card Set
USMLE Dermatology I
Lichen Planus, HPV, Wart