These images are from Dr. John Hunter's amazing MSK collection. Dr. John Hunter is a professor in the department of radiology (musculoskeletal section) at UC Davis School of Medicine.

This case was donated to Radiopaedia.org by Radswiki.net.

Editor's note: Per the 2020 WHO Soft Tissue and Bone Tumors Classification (5th ed.), the recommended terminology is tenosynovial giant cell tumor with pigmented villonodular synovitis no longer recommended (although remains in common use).