Immunohistochemical study of a rare case of cutaneous histiocytoma in buffalo

Cutaneous histiocytoma is a benign tumour known to occur in dogs only. The present study deals with a case of cutaneous histiocytoma diagnosed histopathologically in a buffalo. Immunohistochemical investigation revealed strong nuclear immunolabelling of tumour cells for p53 and c-Myc oncoproteins and proliferating cell nuclear antigen (PCNA). The neoplastic cells exhibited very weak expression of telomerase catalytic unit, hTERT. Pericellular fibronectin (FN) was seen in most of the tumour cells while scanty connective tissue stroma showed light FN immunolabelling. Observations of high indices for cell proliferation markers such as mitoses (8.03±2.19), AgNORs (9.76±2.36) and PCNA (545.20±134.00) revealed aggressive proliferative activity of the tumour cells. The study recorded the case of cutaneous histiocytoma for the first time in a buffalo. The findings of immunohistochemistry suggested the aggressive growth behaviour of the cutaneous histiocytoma, however, the absence of cellular immortality, invasiveness and motility proved its benign nature.