Tumoral Calcinosis (Calcinosis Circumscripta) in the Horse

Abstract

SUMMARY The characteristic feature of tumoral calcinosis in 6 horses was the development of hard subcutaneous multiloculated nodules that consisted of amorphous calcified material. In 5 horses the nodules were near the tibiofibular joint. Surgical removal of the lesion was attempted in 3 horses and was accomplished with ease in 2. Removal in the 3rd horse was unsuccessful because the capsule of the stifle was affected and part of it had to be excised. Intractable septic arthritis developed. There has not been a recurrence in the 2 horses successfully treated. The calcified masses were enclosed by a dense fibrous capsule from which many internal trabeculae arose. A few lymphocytes, macrophages, and multinucleated giant cells had gathered around each locus. Differences were not noticed between tumoral calcinosis in the horse and other species in which it occurs. The cause is not known.