Diagnosis and treatment of concurrent dermal malignant melanoma and melanocytomas in a pygmy hippopotamus (Choeropsis liberiensis).

Background: Dermal melanocytic neoplasms are common in some even-toed ungulates (Artiodactyla), yet this entity has not been reported in the pygmy hippopotamus to date. Concurrent occurrence of multiple benign and malignant melanocytic neoplasms is unusual. Malignant transformation occurs in a small percentage of benign melanocytic tumours in people but this phenomenon has not been well documented in animals.