Spontaneous regression of a congenital melanocytic nevus

We report a case of congenital, melanocytic nevus showing spontaneous regression. At birth, a pigmented lesion, 4 x 6.5 cm, was already present on the scalp. At the age of 20 days, the center of the lesion became crusted with a purulent discharge. Following healing of the inflammed lesion, the nevus showed a tendency to regress, starting from the prevously inflammed site. At the age of 11 months, the nevus showed a marked regression, leaving an atrophic and depigmented center with pea-sized papules and a thin, pigmented rim. Skin section taken from the central depigmented area showed marked fibrosis and scanty nevus cell nests in the dermis. Histological examination of the pea-sized papule in the center of the lesion revealed large epithelioid cells with abundant cytoplasm dispersed between the collagen fibers; it resembled a spindle cell and epithelioid cell nevus with epithelioid cells predominating. There were no clinical or histologically malignant changes.