Mammary comedocarcinoma in a rabbit.

A 4.5-year-old, nulliparous female New Zealand White Rabbit (Oryctolagus cuniculus) was presented for evaluation of a mammary mass located in right axillary mammary gland. The surgically excised mammary mass was submitted for histopathological and immunohistochemical evaluation. Histopathologically, neoplastic cells were arranged in sheets and nests of irregular sizes. The tissue was composed of amorphous eosinophilic material and necrotic cells. The neoplastic cells had round to oval nuclei with prominent nucleoli, scant basophilic cytoplasm and high mitotic activity. Cytokeratin and vimentin expressions of neoplastic cells were observed in immunohistochemical findings. Based on the microscopic characteristics and immunohisto-chemical staining, a diagnosis of a non-invasive comedocarcinoma was established. In this case, cytokeratin positivity confirmed the epithelial origin, whereas the vimentin positivity supported the presence of epithelial-mesenchymal transition and/or increased malignancy.