Pleomorphic oral squamous cell carcinoma in a captive Dumeril's ground boa ( <i>Acrantophis dumerili</i> ) with immunohistochemical analysis

Abstract Oral squamous cell carcinoma (oSCC) is an invasive tumour reported in humans and domestic animals, and poorly differentiated forms are rarely reported in snakes. We describe a case of pleomorphic oSCC in a 12‐year‐old female Dumeril's boa ( Acrantophis dumerili ) kept in the terrarium of a zoo. Histopathological examination revealed polygonal neoplastic cells with marked atypia, high mitotic activity, multinucleated cells and invasive growth in the bone tissue. Immunohistochemical analysis displayed cytokeratin‐5 and p63 positivity, while markers for vimentin, Melan‐A, MAC387, CD1a and p16 were negative. Approximately 75% of tumour cells expressed proliferating cell nuclear antigen, which indicates significant proliferative activity. This case highlights the important role of immunohistochemistry in the diagnosis of poorly differentiated types of tumours in a Dumeril's boa snake. Our observations aim to contribute to the limited literature on reptilian SCC and underline the need for continued research on tumour aetiology and diagnostic strategies in exotic species.