Renal leiomyosarcoma in a cat

Area of Science:

• Veterinary Pathology
• Oncology
• Comparative Pathology

Background:

• Chronic renal disease is a common condition in older cats.
• Renal tumors are rare in feline patients.
• Leiomyosarcoma is a malignant smooth muscle tumor with rare occurrences in the kidney.

Observation:

• A 10-year-old Domestic Shorthair cat with a history of chronic renal disease experienced sudden death.
• Postmortem examination revealed gross features suggestive of hydronephrosis in one kidney and a nephrolith in the other.
• Histological examination identified an infiltrative, poorly differentiated spindle cell sarcoma.

Findings:

• Immunohistochemistry confirmed neoplastic cells were immunoreactive for vimentin and smooth muscle actin.
• The diagnosis of renal leiomyosarcoma was established.
• This represents the first reported case of feline renal leiomyosarcoma in the English literature.

Implications:

• The macroscopic appearance of renal leiomyosarcoma can be misleading, mimicking conditions like hydronephrosis.
• This case expands the differential diagnosis for renal masses in cats.
• Understanding rare feline neoplasms contributes to veterinary diagnostic accuracy and comparative oncology research.