Seborrheic Keratoses, Dermatosis Papulosa Nigra, and Dermatofibromas

Abstract

Seborrheic keratoses (SKs) are among the most common benign skin lesions seen in the general population. SKs are such a common incidental skin finding that epidemiological studies are lacking. These lesions typically present as early as the 1930s but become more common with advancing age. Dermatosis papulosa nigra (DPN) is felt to be a subset of seborrheic keratosis as they share common features on microscopic examination. DPNs are seen more commonly in darker-skinned persons, including those of African descent, Hispanics, and Asians. Similar to SKs they have a familial tendency and become more frequent with advancing age. The etiology of these benign lesions is unknown. Although they are harmless, they often are of cosmetic concern to the patient.

Dermatofibromas are common fibrohistiocytic lesions that present as hyperpigmented papules and nodules on the extremities. Their etiology also is unclear but it has been theorized that they may occur secondary to minor trauma to the skin. Patients often present with a concern that dermatofibromas may be a skin malignancy. Dermatofibromasarcoma protuberans is a locally aggressive sarcoma; however, its clinical presentation and histopathology are distinct from benign dermatofibromas.