Atypical villonodular synovitis in a horse
Vickers, K.L.; Ross, M.W.
Journal of the American Veterinary Medical Association 209(9): 1602-1603
1996
ISSN/ISBN: 0003-1488 PMID: 8899026 Document Number: 468791
A 4-year-old sexually intact male Standardbred trotter was evaluated for left forelimb lameness. A presumptive diagnosis of severe cartilage damage was made because the horse had a history of infectious arthritis involving the left metacarpophalangeal joint. Arthroscopic evaluation revealed what was presumed to be a large villonodular lesion. The mass was surgically removed, and the horse was treated with procaine penicillin G, trimethoprim-sulfamethoxazole, phenylbutazone, and polysulfated glycosaminoglycans and eventually returned to racing. Histologic examination of the mass revealed a bed of granulation tissue covered with keratinized epithelium. We hypothesize that the lesion developed secondarily to implantation of epithelial cells into a reactive villonodular lesion.