EQUINE VETERINARY EDUCATION Equine vet. Educ. (2022) 34 (11) 569 doi: 10.1111/eve.13601_1
Case Report Primary bilateral corneal T cell lymphoma in a horse
T. A. Opgenorth†, C. S. Monk†, D. E. Brooks†‡, R. V. Ramos†, S. L. Craft§ and C. E. Plummer†‡,* †Department of Small Animal Clinical Sciences; ‡Department of Large Animal Clinical Sciences; and §Department of Comparative, Diagnostic & Population Medicine, College of Veterinary Medicine, University of
Florida, Gainesville, Florida, USA *Corresponding author email:
PlummerC@ufl.edu
R. V. Ramos's present address: Department of Small Animal Clinical Sciences Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, USA
Keywords: horse; cornea; IMMK; chronic keratitis; neoplasia
Case summary A 5-year-old Belgian Warmblood gelding presented for evaluation of increased opacity in both eyes. Initial ophthalmic examination revealed bilateral mild blepharospasm, multifocal axial and dorsal anterior stromal corneal opacities with mild axial mid-stromal haze and oedema, and superficial, branching corneal vascularisation. A presumptive diagnosis of bilateral immune-mediated keratitis (IMMK) was made. The lesions progressed despite 2#x2009;= years of exhaustive options for medical management. Surgical intervention in the left eye with lamellar keratectomy and ocular surface reconstruction with amnion membrane transplantation was elected. The keratectomy specimen was submitted for histopathology and was consistent with IMMK. When surgical intervention in the right eye was performed, histopathology revealed sheets of atypical round cells with a high mitotic index. Immunohistochemistry of both left and right corneal specimens had immunoreactivity to CD3 antibodies. An amended diagnosis of bilateral T cell lymphoma was made. The patient recovered well from surgery, and there have been no signs of recurrence or systemic involvement following surgical intervention. This is a unique case of primary corneal T cell lymphoma in a horse. Prior to electing surgical
569
1.00mm
Fig 2: Left keratectomy sample (H&E stained, 1003 magnification) revealing densely cellular mass composed of sheets of round cells with moderate amount of pale eosinophilic cytoplasm with small multifocal areas of necrosis and haemorrhage.
management, the patient received topical immunomodulating medications including cyclosporine and tacrolimus for significant lengths of time. Both chronic inflammation and chronic
administration
immunosuppressive agents are associated with neoplastic transformation. Surgical intervention provides both a diagnostic sample and therapeutic relief (Figs 1 and 2).
of
Key points
• Immune-mediated keratitis (IMMK) presents as chronic nonulcerative corneal opacities with limited signs of pain or uveitis; corneal lymphoma is an important differential.
• Superficial keratectomy provides a diagnostic sample and therapeutic relief for lesions suspicious for IMMK.
• Chronic inflammation and use of immunomodulating agents may influence neoplastic transformation.
Fig 1: Lesions of the left cornea progressing despite medical therapy.
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