Spontaneous epithelioid hemangiosarcoma in a rhesus monkey (Macaca mulatta)

Area of Science:

• Veterinary Pathology
• Oncology
• Primate Research

Background:

• Epithelioid hemangiosarcoma is a rare endothelial neoplasm characterized by epithelioid morphology.
• This tumor type has not been previously documented in rhesus monkeys.

Observation:

• A 4-year-old rhesus monkey presented with multiple neoplastic nodules.
• Tumor sites included digits, skin, muscle, lung, heart, and brain.
• Nodules consisted of pleomorphic, epithelioid neoplastic cells in sheets, nests, and cords.

Findings:

• Distinct neoplastic endothelial cells lined cystic spaces and clefts.
• Immunohistochemistry revealed positivity for CD31, factor VIII-related antigen, and vimentin.
• High mitotic rate and Ki67 staining confirmed malignancy.

Implications:

• This case represents the first documented instance of epithelioid hemangiosarcoma in a rhesus monkey.
• Highlights the importance of considering rare neoplasms in non-human primate research models.
• Contributes to the comparative pathology of vascular tumors.