Basal Cell Carcinoma of the Cloacal Aperture in a Red Kangaroo (Osphranter rufus)

There have been few reports of neoplasia in kangaroos to date. In this report, we describe a 13-year-old male captive Red kangaroo (<i>Osphranter rufus</i>) that developed a mass on the right side of the cloacal aperture. Histopathological analysis of a biopsy of the mass revealed proliferating, neoplastic epithelial islands with necrotic centres infiltrating a moderately desmoplastic dermis. The islands were generally large with extensive central caseation necrosis consisting of cellular debris and innumerable neutrophils. The neoplastic epithelial cells resembled the basal cells observed in the basal layer of the epidermis and were characterised by scant to moderate eosinophilic cytoplasm with indistinct cytoplasmic margins. The diagnosis was basal cell carcinoma (BCC). This is the first report of a BCC in a kangaroo, and we compare the findings with that seen in dogs, cats and humans.