A non-joint tissue biphasic synovial sarcoma in a dog

Area of Science:

• Veterinary Pathology
• Canine Oncology

Background:

• Synovial sarcoma is a rare soft tissue sarcoma that can occur in various locations.
• While commonly associated with joints, synovial sarcomas have been reported in extrarticular sites in humans.

Observation:

• A subcutaneous tumor was found in the malar region of a 14-year-old dog.
• The tumor exhibited multinucleated giant cells, chondrocyte differentiation, and cystic structures.
• Immunohistochemistry confirmed both mesenchymal and cytokeratin-positive epithelioid components.

Findings:

• The tumor was diagnosed as a biphasic synovial sarcoma.
• This represents the first documented case of a non-joint synovial sarcoma in a dog.
• The tumor did not invade adjacent tissues or metastasize.

Implications:

• This case expands the understanding of synovial sarcoma presentation in veterinary medicine.
• It suggests that canine synovial sarcomas, similar to human counterparts, can arise in non-joint tissues.
• Further research into the etiology and behavior of extrarticular synovial sarcomas in dogs is warranted.