Dermatologic System

Intensely pruritic, erythematous, scaly patches in flexural areas (antecubital and popliteal fossae); part of the atopic triad with asthma and allergic rhinitis.

Liberal emollients/moisturizers plus topical corticosteroids for flares; topical calcineurin inhibitors (tacrolimus, pimecrolimus) are steroid-sparing for face/intertriginous areas.

Irritant CD is a non-immunologic direct chemical injury (most common, burning/stinging, sharp borders). Allergic CD is a type IV delayed hypersensitivity (pruritic, can spread beyond contact area); diagnosed with patch testing.

Well-demarcated erythematous plaques with silvery-white scale on extensor surfaces, scalp, and lumbosacral area; pinpoint bleeding when scale is removed = Auspitz sign.

Nail pitting (also onycholysis and oil spots); psoriatic arthritis, a seronegative spondyloarthropathy that may cause dactylitis and a 'pencil-in-cup' deformity.