Congenital Cutaneous and Visceral Melanomas of Sinclair Miniature Swine: Three Case Reports2

Melanotic lesions of skin and viscera are common in Sinclair miniature swine. Large exophytic melanomas of the skin invariably regress, and regression may be responsible for melanosis of local and regional lymph nodes and some visceral organs. Malignant transformation and metastasis of cutaneous melanomas are uncommon and primary visceral melanomas were heretofore unrecorded. Described are clinical and light microscopic characteristics of melanomas in 3 miniature pigs: a) one pig with a massive, possibly primary, melanoma of the mediastinum, b) one that died with widespread lymphatic and focal pulmonary metastasis of congenital melanomas of the skin, and c) one in which both a large congenital cutaneous melanoma and associated metastatic melanomas in regional lymph nodes regressed completely.