SKIN DISORDERS (PART II)

Pemphigus vulgaris	Potentially fatal autoimmune skin disorder with IgG autoantibody against desmosome. Achantolysis (intraepidermal bullae involving skin and oral mucosa). Nikolsky’s sign positive (separation of epidermis upon manual stroking the skin).
Bullous pemphigoid	Autoimmune disorder with IgG antibody against hemidesmosomes. Eosinophils within blister. Similar but less severe than Pemphigus vulgaris. Affects skin but spares the oral mucosa. Nikolsky’s sign negative.
Dermatitis herpetiformis	Pruritic papules and vesicles. Associated with celiac disease.
Erythema multiforme	Associated with infection (Mycoplasma pneumoniae, HSV), drugs (sulfas, β lactams, phenytoin), cancer and autoimmune diseases. Presents with multiples types of lesions.
Stevens-Johnson syndrome	Fever, bulla formation and necrosis, sloughing of skin, and high mortality rate. Associated with adverse drug reaction. Toxic epidermal necrolysis (more severe form of S-J synd.)
Lichen planus	Pruritic, purple polygonal papules. Associated with hepatitis C.
Actinic keratosis	Premalignant lesions caused by sun exposure. Small, rough, erythemotous or brownish papules. Risk of carcinoma is proportional to epithelial dysplasia
Achantosis nigricans	Hyperplasia of stratum spinosum, associated with hyperinsulinemias (Cushing diseases, diabetes) and visceral malignancy.
Erythema nodosum	Inflammatory lesion of subcutaneous fat, usually on anterior shins. Associated with coccidioidomycosis, histoplasmosis, TB, leprosies. Streptococcal infections and sarcoidosis.
Pityriasis rosea	Multiple papular eruptions, remits spontaneously. “Herald patch” followed days late by “Christmas tree” distributions.
Strawberry hemangioma	First few weeks of life. Grows rapidly and regresses spontaneously at 5-8 years of age.
Cherry hemangioma	Appears in 30s-40s, does not regress.

Bibliography:  First aid for USMLE step 1, 2011