Eruptive fascicular nevi on scars of cystic acne.

Abstract

A 15-year-old young man was followed up for a long period of time because affected by cystic acne. He underwent SAPHO syndrome during treatment with isotretinoin and then recovered with severe scarring residua. Six months after the end of treatment with isotretinoin he was observed because of three pigmented lesions on the trunk. On physical examination the scarring residua of cystic acne were evident. On the back, in the left scapular and mid dorsal region there were two nevi with partially linear shape on a previous scar. On the sternal region level with the nipples inside a scar there was a 2 centimeters long melanocytic nevus. It consisted of a round, 6 millimeters in size central body, from which originated towards the left and the right side two linear pigmented lesions. The latter were 4 millimeters in size centrally and tapered distally as well as wings. Dermoscopy showed a fascicular pattern in the wings, which was reminiscent of fascicular pseudomelanoma already reported as a consequence of removal of congenital nevi. In the present case, however, we documented the lack of any preexisting melanocytic nevus, visible to the naked eye. Therefore, we hypothesize that the severe inflammation following cystic acne favored the appearance "de novo" of a nevus, as well as in bullous dermatoses, particularly in epidermolysis bullosa. The nevus probably acquired a linear pattern of distribution due to the presence of a scarring tissue, as for pseudomelanoma arising on keloid or scars secondary to removal of a nevus.