Condition	Characteristics
Actinic keratosis	Red, poorly defined papules and plaques with adherent scale; usually involves multiple lesions in sun-exposed areas
Lichen planus	Violaceous, polygonal papules and plaques with overlying fine white lines (Wickham striae); usually involves the wrists, lower back, and ankles
Nummular eczema	Pruritic, scaly, erythematous patches and plaques affecting numerous body surfaces; often occurs with xerosis (dry skin)
Psoriasis	Well-circumscribed, salmon-colored plaques that bleed when the overlying silver-to-white scale is peeled from the plaque (Auspitz sign); usually involves areas of friction (e.g., elbows, knees, umbilicus, gluteal cleft)
Tinea	Mildly pruritic, scaly, oval-to-round, red patches; common in body folds; diagnosis is confirmed with microscopy or culture of skin scrapings