Cutaneous melanoma in a black rhinoceros (Biceros bicornis)

Abstract

A 10-year-old, male, captive-bred black rhinoceros (Diceros bicornis) presented with a several day history of a firm, nodular cutaneous mass on the dorsal midline. Cytology results of a fine needle aspirate were consistent with probable melanoma. The rhinoceros was placed under general anesthesia and the mass was removed in entirety via a partial thickness skin incision, which was allowed to heal by second intention. Histopathology results confirmed melanoma with no observed evidence of vascular invasion. Histopathologic characteristics are compared to recognized patterns of melanocytic neoplasms of the domestic horse and of man, and potential clinical implications are discussed. This is the first report of a cutaneous melanoma in a rhinoceros.