Nummular (discoid) eczema

Nummular eczema is a subset of atopic dermatitis. It is usually located on extremities. 

Acutely, lesions may begin as papules or vesicles that coalesce into plaques. When established, lesions will appear symmetrically distributed, sharply defined, round or coin-shaped, and erythematous; eczematous plaques will range in size from 1 to 10 cm. Late-stage lesions may develop a drier scale and lichenification. Lesions may be associated with mild to intense pruritus. Lesion and symptom severity are exacerbated by behaviors that decrease the skin's natural moisture barrier, such as harsh soaps and long, hot, frequent showering. The lower extremities are most commonly involved, followed by the upper extremities and trunk. The face and scalp are spared. Postinflammatory pigmentary changes typically persist after resolution. Dermoscopic findings may reveal scales, shiny yellow clods, and irregularly distributed brownish-red globules.[1]