Presumed solitary ocular lymphoma of large B-cell origin with Mott cell change in a dog

A 4-year-old female Maltese dog was referred to our veterinary hospital with uveitis and conjunctivitis of the right eye. An ophthalmological evaluation revealed an intraocular mass that appeared to originate from the anterior uvea. Metastasis and regional invasion were not detected with CT examination. Enucleation of the right eye was recommended; however, the owner declined treatment. Six months later, the dog was re-presented with a right facial mass. At presentation, superficial lymph node enlargement was not appreciated, and no apparent alterations were noted on blood analysis or urinalysis. Computed tomography revealed an intraocular mass that invaded the surrounding tissues, including the frontal sinus. Presumed solitary ocular lymphoma with a large B-cell phenotype and Mott cell change was diagnosed via histopathological and immunohistochemical examination of a biopsy of the lesion. As the mass was too large for complete excision, neoadjuvant chemotherapy was administered. Complete remission was achieved using the L-COAP protocol and successful exenteration of the right eye. However, the dog was returned with enlargement of the right retropharyngeal lymph nodes. To the best of our knowledge, this is the first case report of presumed solitary ocular lymphoma with a large B-cell phenotype displaying Mott cell change in a dog. Key clinical message: This is the first reported case of a presumed solitary ocular lymphoma with a large B-cell phenotype and Mott cell change. Although systemic involvement was observed 6 mo after the initial visit, neoadjuvant chemotherapy and exenteration were effective.