Multicentric cutaneous keratoacanthomas in a free-living marmoset (Callithrix sp.).

Cutaneous neoplasia is common in non-human primates. We describe the gross and microscopic features of multicentric cutaneous keratoacanthomas in a free-living marmoset (Callithrix sp.). Immunohistochemistry for human papillomavirus and herpes simplex virus type I and simplex virus type II was negative. Keratoacanthomas should be included in the differential diagnosis for cutaneous masses in non-human primates.

Hepatocellular carcinoma in a free-living marmoset (Callithrix sp.) with concomitant biliary trematodiasis.

Hepatocellular carcinoma (HCC) is rare in New World primates. We report the gross, microscopical, and immunocytochemical features of a spontaneous HCC in a free-living marmoset (Callithrix sp.). Hepatitis B and C virus and aflatoxin immunohistochemistry were negative; however, concomitant intra- and extrahepatic biliary trematodiasis could have played a role.

Parotid Salivary Gland Basal Cell Adenocarcinoma in a Big-eared Opossum (Didelphis aurita).

The opossum (family Didelphidae) is a marsupial endemic to the Americas. Apart from the South American short-tailed opossum (Monodelphis domestica) and the Virginia opossum (Didelphis virginiana), there is considerable lack of knowledge about the health and diseases of most opossum species. Among these, the big-eared opossum (Didelphis aurita) is found in Argentina, Brazil and Paraguay. Natural and experimental studies have shown this species to be susceptible to infectious agents with zoonotic potential and the animals may play a role in transmission of such agents. However, neoplasia appears to be uncommon in this species. We describe the gross, microscopical and immunohistochemical features of a parotid salivary gland basal cell adenocarcinoma in a free-living big-eared opossum. This case represents the first report of salivary gland neoplasia in opossums.