Ocular lymphoma in dogs and cats - what to know

Abstract

OBJECTIVE: To immunologically phenotype and histologically classify canine and feline intraocular and periocular lymphomas. METHODS: The databases of four veterinary medical diagnostic laboratories were searched to identify cases of intraocular or periocular lymphoma in dogs and cats between 2001 and 2012. Hematoxylin and eosin (H&E) stained slides were reviewed for confirmation and classification of lymphoma, and immunohistochemistry for CD3 (T-cell marker) and CD79a and/or CD20 (B-cell markers) was examined to determine the lineage of the neoplastic lymphocytes. RESULTS: Six canine and 15 feline cases of ocular lymphoma were identified. In the canine cases, there were three intraocular and three periocular lymphomas where two intraocular and one periocular lymphomas were B-cell, one of each intraocular and periocular lymphomas were T-cell and one periocular lymphoma was nonreactive with CD3, CD79a or CD20. In the feline cases, there were six intraocular and nine periocular lymphomas where five intraocular and six periocular lymphomas were B-cell, and one intraocular and three periocular lymphomas were T-cell. Only one canine case had concurrent generalized lymphadenopathy, only one canine conjunctival lymphoma had simultaneous cutaneous lymphoma, and only one feline case had bilateral ocular involvement when they were diagnosed. CONCLUSION: Canine and feline intraocular and periocular lymphomas are often of B-cell phenotype. Although in general terms lymphoma is not considered a primary tumor when it occurs in or adjacent to the globe, these tumors frequently first become evident in the globe and/or periocular area. An accurate early diagnostic approach is crucial for the patient's quality of life because B-cell lymphomas are generally more amenable to chemotherapy than T-cell lymphomas.