Miscellaneous skin disorders

lilyo's version from 2016-06-04 01:25


Question Answer
Acanthosis nigricansepidermal hyperplasia causing symmetric, hyperpigmented thickening of skin, especially in axilla or on neck. Associated with insulin resistance (eg, diabetes, obesity, Cushing syndrome), visceral malignancy (eg, gastric adenocarcinoma).
Actinic keratosisPremalignant lesions caused by sun exposure. Small, rough, erythematous or brownish papules or plaques. Risk of squamous cell carcinoma is proportional to degree of epithelial dysplasia.
Erythema nodosumPainful inflammatory lesions of subcutaneous fat, usually on anterior shins. Often idiopathic, but can be associated with sarcoidosis, coccidioidomycosis, histoplasmosis, TB, streptococcal infections, leprosy, inflammatory bowel disease.
Lichen PlanusPruritic, Purple, Polygonal Planar Papules and Plaques are the 6 P’s of lichen Planus. Mucosal involvement manifests as Wickham striae (reticular white lines). Sawtooth infiltrate of lymphocytes at dermal-epidermal junction. Associated with hepatitis C.
Pityriasis rosea“Herald patch” followed days later by other scaly erythematous plaques, often in a “Christmas tree” distribution on trunk. Multiple plaques with collarette scale. Self-resolving in 6–8 weeks.
SunburnAcute cutaneous inflammatory reaction due to excessive UV irradiation. Causes DNA mutations, inducing apoptosis of keratinocytes. UVB is dominant in sunBurn, UVA in tAnning and photoAging. Can lead to impetigo, skin cancers (basal cell carcinoma, squamous cell carcinoma, melanoma).