Intramuscular Tenosynovial Giant Cell Tumor, Diffuse-Type.

Tenosynovial giant cell tumors (TSGCT), a group of tumors that originate in tendon sheaths, joints, bursae, or adjacent soft tissue, were first described in 1941 by Jaffe et al. [1]. Diffuse-type TSGCT are known to be located in the periarticular soft tissue, while pure intramuscular tumors are rare. This case describes a diffuse-type TSGCT located in the hamstring muscle, which was determined to be a pure intramuscular type.