Immunohistochemical characterization of intraocular metastasis of a canine transmissible venereal tumor.

Little has been published on intraocular metastasis of transmissible venereal tumors (TVT) in dogs. This report presents a 4-year-old male Labrador Retriever with a previous history of subcutaneous TVT which underwent total remission after treatment with vincristine. The dog presented with clinical signs of uveitis and increased intraocular pressure (IOP) in both eyes. After enucleation of the left eye, a diagnosis of TVT was made based on morphology, histology and immunohistochemistry (IHC). IHC staining for vimentin, S-100 protein, cytokeratin and HMB45 was performed to differentiate this lesion from TVT, lymphoma, melanoma, carcinomas, neurogenic tumors and fibrosarcoma. The IHC findings supported the diagnosis of TVT for this round cell tumor.