Histopathological and immunohistochemical characterization of testicular T-cell lymphoma in a dog.

Canine lymphoma is the most common neoplasm of the hematopoietic system with the most frequently diagnosed malignancy. Also, dogs affected by T-cell lymphoma displayed a lower rate of complete chemotherapy response and have a high risk of death in the early stage of the disease. A 5-year-old male mixed dog was presented to the Small Animal Hospital, School of Veterinary Medicine, Shiraz University, Shiraz, Iran with a history of left testicle swelling for four months. The testicle had approximately 13.00×10.00 cm size with a greyish-white cut surface. Histopathologically, the testicular tissue was infiltrated by neoplastic cells as only a few degenerated seminiferous tubules have remained. The neoplastic cells were round to oval with pleomorphic nuclei and single or multiple prominent nucleoli. Immunohistochemical analysis revealed positive and negative immunoreactivity for CD3 and CD20, respectively. According to histopathological and immunohistochemical features, the tumor was concluded as a testicular T-cell lymphoma. It seems that recognition of lymphoma type could be helpful for clinicians therapeutic protocols.