Ocular myxoid leiomyosarcoma in a cat.

Area of Science:

• Veterinary Ophthalmology
• Comparative Pathology
• Ocular Oncology

Background:

• Leiomyosarcomas are malignant tumors arising from smooth muscle cells.
• Ocular tumors in domestic animals are uncommon, making case reports valuable for understanding disease.
• Myxoid leiomyosarcomas are a subtype characterized by abundant extracellular myxoid material.

Observation:

• A 6-year-old domestic short-haired cat presented with an enucleated eye containing a poorly demarcated mass.
• The mass originated from the iris dilator muscle, expanding the iris, filling the globe, and invading the optic nerve.

Findings:

• Histopathological examination revealed spindle-shaped neoplastic cells embedded in abundant mucopolysaccharide-rich matrix.
• Immunohistochemistry showed tumor cells were positive for smooth muscle actin (SMA), S100, and vimentin.
• Neoplastic cells were negative for cytokeratin, Melan-A, glial fibrillary acidic protein (GFAP), and desmin, aiding in differential diagnosis.

Implications:

• This case highlights myxoid leiomyosarcoma as a potential diagnosis for feline ocular masses.
• The findings contribute to the understanding of smooth muscle tumors in veterinary ophthalmology.
• Successful enucleation without recurrence suggests a potentially favorable prognosis for localized feline ocular leiomyosarcoma.