Cutaneous T-Cell Lymphoma With Conjunctival T-Lymphocyte Infiltration in a Dog.

[BACKGROUND AND OBJECTIVE] Conjunctival lymphoma is rare in dogs, with most cases exhibiting the B cell phenotype. Concurrent cutaneous and conjunctival T cell involvement is exceptionally uncommon. This case report describes a dog with cutaneous T-cell lymphoma that presented with chronic conjunctivitis and conjunctival T-lymphocyte infiltration.

[ANIMAL STUDIED] A 15-year-old spayed female Chihuahua presented with a 3-month history of bilateral conjunctivitis that was unresponsive to conventional therapy.

[PROCEDURES AND RESULTS] Physical examination revealed severe conjunctival inflammation extending into the corneal limbus and perinasal depigmentation. Conjunctival cytology revealed the presence of mixed inflammatory cells. Histopathological examination of the nasal skin confirmed an epitheliotropic T-cell lymphoma with dense atypical lymphoid infiltration. Immunohistochemistry revealed CD3-positive, CD79α-negative cells. Conjunctival biopsy demonstrated lymphocytic infiltration with a similar immunophenotype, although cellular atypia was minimal and mitotic figures were rare. The patient was initially managed with topical corticosteroids, followed by oral prednisolone, and the patient survived for 191 days post-diagnosis.

[CLINICAL SIGNIFICANCE] This case underscores the need to consider neoplastic disease in dogs presenting with chronic conjunctivitis, particularly when mucocutaneous lesions are also present. The identification of T-lymphocyte-predominant conjunctival infiltration in a dog with confirmed cutaneous T-cell lymphoma suggests either an early stage of neoplastic involvement or a reactive inflammatory process. These findings emphasize the value of careful diagnostic evaluation, including tissue biopsy and immunohistochemistry, when managing refractory ocular inflammatory conditions.