Diffuse-Type Tenosynovial Giant Cell Tumor of the Shoulder Evaluated by FDG PET/CT.

Diffuse-type tenosynovial giant cell tumor is a locally aggressive neoplasm that typically involves the knee and hip but rarely involves the shoulder. In this case, a 74-year-old woman presented a painless mass in the right shoulder. FDG PET/CT demonstrated intense FDG uptake with an SUVmax of 19.2 in the lesion. The mass was dissected and confirmed as diffuse-type tenosynovial giant cell tumor by pathology. Follow-up FDG PET/CT assessment revealed more extensive soft tissue infiltration and adjacent bone erosion 3 years after surgery. Thus, FDG PET/CT well demonstrated the hypermetabolic and local aggressive characteristics of the lesion.