A six-year-old male Pekinese dog was referred to the Veterinary Medical Center, Chungbuk National University because of intermittent vomiting, anorexia, alopecia, and pruritus. Generalized alopecia, pigmentation, and papular erythema in the skin were observed on physical examination. Hematological studies indicated a severe pancytopenia and hypoalbuminemia. A hormone analysis indicated a hyperestrogenemia. A circumscribed mass, measuring approximately 3-4 cm in diameter, was observed on abdominal radiographs. Grossly, the cryptorchid testis was enlarged by a firm and white spherical mass, measuring approximately 3 cm in diameter, which, on its cut surface, was creamy white with hemorrhage. The normal scrotal testis was markedly atrophic and soft. Histologically, the intra-abdominal cryptorchid testis contained abundant fibrous tissue stroma and the stromal tissues were arranged in a tubular pattern in which the neoplastic cells tended to palisade. The cells had poor and pale eosinophilic cytoplasm streaming into the center of the tubules. The nuclei were round to oval and tended to be in a basilar location. Regions of hyperplasia and marked squamous metaplasia were observed in many areas of the prostate. Based on the histological findings, we were able to identify these masses as Sertoli cell tumors, and made a final diagnosis as Sertoli cell tumors through immunohistochemistry methods using inhibin-α, vimentin, and neuron-specific enolase.

Histologic and immunohistochemical features of canine skin tumours originated from epithelial stem cells were described. The tumors were trichogenic trichoblastoma, trichoepithelioma, sebaceous adenoma, hepatoid gland adenoma and epithelioma, and basal cell tumour. All of the tumors expressed both AE1/AE3 and cytokeratin 5/8, whereas cytokeratin 7 and vimentin not at all. Neuron-specific-enolase was strongly positive in follicular tumours, whereas slightly in basal cell tumour. Moreover, chromogranin A was expressed slightly only in trichogenic trichoblastoma and trichoepithelioma. Since the morphological similarities between these tumors, immunohistochemistry is one of useful tools for differential diagnosis. From the immunohistochemistry data, we conclude that cytokeratins, vimentin and NSE play a main role in the evaluation of canine skin tumours originated from epithelial skin stem cells histogenesis.

Immunohistochemical localization of vimentin, glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), neuron-specific enolase (NSE) were performed to confirm the canine schwannoma diagnosed histologically. Biopsy samples from skin masses occurred on a 6 year old female dog and a 13 year old female dog were used for immunohistochemical analysis. Histologically, the tumor tissues showed the characteristics of schwannoma mainly composed of predominantly fusiform or spindle cells. The cells are arranged in small interwoven bundles with intervening fibrous and mucinous stroma that imitate a herringbone pattern. The cell nuclei have an elongated, wavy, buckled appearnce and closely bunched together. In high magnification, mitotic figure, nuclear hyperchromatism, pleomorphism and poorly defined cytoplasms were noted. the vimentin was highly expressed in the cytoplasm of all neoplastic cells. Positive reactions against NSE and GFAP, widely used to suggest a neural origin of cell types, are observed in cytoplasms of tumor cells. These results can be used as a reference data for definitive diagnosis of canine schwannoma.