Hemangiopericytoma in the eyelid of a horse.
Authors: Serena A, Joiner K S, Schumacher J
Journal: Veterinary pathology
Summary
# Editorial Summary: Hemangiopericytoma in a Horse's Eyelid Hemangiopericytoma, a vascular tumour arising from pericyte cells, had been documented only in dogs and humans until this 2006 case report describing its first recognised occurrence in an equine patient. A 14-year-old Arabian mare presented with a 2-cm subcuticular mass on the lower eyelid, which was surgically removed and subjected to detailed histological examination revealing the characteristic loosely arranged spindle cells with distinctive whorled formations around capillaries—a pattern termed Antoni A-like. Immunohistochemical staining confirmed the diagnosis through strong vimentin positivity and focal smooth muscle actin reactivity, whilst negative staining for Factor VIII-related antigen, GFAP and S100 helped exclude other differentials such as haemangioma, glioma and nerve sheath tumours. Although this remains a single case with limited follow-up data on long-term outcomes and recurrence rates in horses, the finding broadens our understanding of neoplastic disease in equine soft tissues and highlights that vascular pericyte tumours should be considered in the differential diagnosis for subcutaneous eyelid masses in older horses.
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Practical Takeaways
- •Hemangiopericytoma should be included in the differential diagnosis for subcuticular eyelid masses in horses, despite being rare
- •Surgical excision is a viable treatment option for eyelid masses of this type, with straightforward removal possible given the discrete nature of the lesion
- •Histopathological and immunohistochemical examination is necessary for definitive diagnosis of vascular neoplasms in equine eyelid lesions
Key Findings
- •First documented case of hemangiopericytoma in an equine patient, a 14-year-old Arabian mare
- •Tumor was a 2-cm expansile subcuticular mass in the lower eyelid successfully excised surgically
- •Histopathology and immunohistochemistry confirmed diagnosis through vimentin and smooth muscle actin reactivity with negative staining for Factor VIII, GFAP, and S100