Primary epitheliotropic T-cell lymphoma of the urinary bladder in a dog

A 7-year-old, intact female mixed-breed dog was presented for evaluation of hematuria. Physical examination revealed a suprapubic mass. Ultrasonographic examination showed a large lobular mass occupying the urinary bladder. At the owners' request, the dog was euthanatized and a postmortem examination was performed. Necropsy confirmed the presence of a lobular mass of about 5- to 6-cm diameter protruding into the lumen of the bladder. Histologically, the mass was composed of a large number of atypical lymphoid cells in the lamina propria and mucosal epithelium. Immunohistochemically, the neoplastic cells expressed CD3 but not CD79alpha or keratin and vimentin, supporting a diagnosis of T-cell lymphoma.