Clinical and morphological features of corneal lymphoma in 26 horses (27 eyes).
Authors: Morris Jacob M, Lassaline Mary E, Nunnery Catherine M, Teixeira Leandro B C, Martins Bianca C, Moore Bret A, Knickelbein Kelly E, Scherrer Nicole M, Plummer Caryn E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Corneal Lymphoma in Horses Corneal lymphoma remains poorly characterised in equine practice, prompting this retrospective analysis of 26 horses (27 eyes) diagnosed between 2012 and 2022 across multiple centres to establish clinical presentation, histological features, and treatment outcomes. The cohort comprised predominantly middle-aged horses (mean 10.5 years), with males and Warmbloods overrepresented; notably, 77.7% had preceding history of immune-mediated keratitis (IMMK) or eosinophilic keratitis, and morphological evidence suggests malignant transformation occurred in at least four cases. B-cell lymphoma predominated among the 24 eyes submitted for immunohistochemistry (19 cases), typically intermediate to large cell type, whilst all cases remained unilateral with no evidence of systemic involvement. Treatment outcomes favoured adjunctive therapy following superficial keratectomy: zero recurrence occurred in 15 eyes receiving additional intervention post-excision, compared to 4 of 4 recurrences in eyes managed by keratectomy alone, although cases with extensive surface area or deep stromal involvement carried higher recurrence risk. For equine practitioners, these findings establish lymphoma as a significant differential diagnosis in progressive or refractory nonulcerative keratitis, justifying keratectomy with histopathological examination in such cases, and supporting multimodal post-operative management to minimise recurrence and preserve globe function.
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Practical Takeaways
- •Consider corneal lymphoma as a differential diagnosis in horses presenting with progressive or refractory nonulcerative keratitis, particularly cases with a history of suspected immune-mediated keratitis
- •Keratectomy with histopathology should be performed on refractory or progressive corneal lesions to rule out neoplastic disease and enable early detection of malignant transformation
- •Adjunctive therapy following surgical excision significantly reduces recurrence risk; eyes with large corneal surface area or deep stromal involvement may require additional vigilance for recurrence
Key Findings
- •B-cell lymphoma was diagnosed in 19/24 eyes (79.2%) with intermediate to large B-cell lymphoma being most common
- •Mean age at diagnosis was 10.5 years with male predominance (18/26 cases) and unilateral involvement in 25/26 cases
- •77.7% of eyes had a history of suspected IMMK or eosinophilic keratitis, suggesting malignant transformation of immune-mediated disease
- •No recurrence occurred in eyes receiving adjunctive therapy following keratectomy (15/15 eyes), whereas 4/4 eyes without adjunctive therapy experienced recurrence