Pathological findings, KIT expression, and clinical course of cutaneous mast cell tumours in pet Syrian hamsters (Mesocricetus auratus).

Abstract

This report describes the histopathological and immunohistochemical features, as well as the biological behaviour, of cutaneous mast cell tumours for the first time in two Syrian hamsters. Both cases presented with a raised cutaneous mass, one in the preputial region and one on the ear pinna, respectively. The masses showed similar histological and immunohistochemical findings and were composed of solid sheets of round cells with moderate amounts of basophilic intracytoplasmic granules. These granules showed prominent metachromasia on toluidine blue staining. Immunohistochemically, the neoplastic cells had diffuse, granular cytoplasmic labelling to anti-KIT antibody. There was no evidence of recurrence in both cases, and no metastatic lesions were observed in Case 1 on necropsy and subsequent histopathological examination, suggesting that, compared with other animals, mast cell tumours have a benign clinical course in Syrian hamsters during the initial follow-up period.