Cutaneous melanoma and related melanosis of regional lymph nodes in Nero Siciliano pigs.

In this paper, some melanocytic cutaneous lesions in Nero Siciliano pigs are reported and discussed. Two conventionally slaughtered animals showed skin melanomas and a black discoloration of the regional lymph nodes. Lymph nodes were normal in size and shape, but showed diffuse black discoloration of the cortex and medulla. Histochemical tests performed on tissues let us differentiate and identify the pigment. Immunohistochemical staining for macrophage markers showed macrophages containing a variable amount of melanin-like granules. Stains for anti human melanoma, as well as S-100 protein, showed positive reactions. As for other black swine breeds, our data suggest for such local pig the presence of congenital melanoma and the possibility of its regression mediated by leucocytes, leading to melanosis of regional lymph nodes.