Corneal invasion by hemangiosarcoma in a horse.

Area of Science:

• Veterinary Ophthalmology
• Equine Neoplasia
• Surgical Pathology

Background:

• Ocular tumors in horses can significantly impact vision and health.
• Hemangiosarcoma (HSA) is a vascular tumor rarely reported in equine ocular tissues.
• Accurate diagnosis and effective treatment strategies are crucial for favorable outcomes.

Observation:

• A 15-year-old Arabian gelding presented with a large, nonpigmented limbal mass involving 30% of the cornea.
• The mass exhibited central necrosis and serosanguinous discharge.
• Histopathology revealed features consistent with hemangiosarcoma.

Findings:

• Lamellar keratectomy successfully removed the ocular mass.
• Immunohistochemistry confirmed hemangiosarcoma, with positive staining for von Willebrand Factor and smooth muscle actin.
• Atypical cytokeratin staining was absent, ruling out squamous cell carcinoma.
• Unusual smooth muscle actin staining in perivascular cells was noted, not previously reported in equine ocular HSA.

Implications:

• Lamellar keratectomy offers a viable, less invasive treatment option for equine ocular hemangiosarcoma.
• The case demonstrates a longer survival time than previously reported for equine ocular HSA.
• Further research into the immunophenotype of equine ocular HSA may be warranted.