A case report of arthroscopic treatment of a retro-patellar GCTTS causing anterior knee pain

Giant cell tumor of tendon sheath (GCTTS) is a common soft tissue tumor in hands and feet; however, it is rare in knee joints. We present a case of a 52-year-old female who had a retropatellar tendon giant cell tumor (GCT) in the right knee, causing vague anterior knee pain. Anterior knee pain is a challenging complaint in orthopedics due to the multiple causative reasons, the combination of several complex etiologies, and the lack of clear guidelines for an effective treatment. This case report aims to shed light on unlikely pathologies in complex cases. GCTTS is a rare lesion to affect the retropatellar region. However, we must keep it in mind when dealing with challenging anterior vague knee pain complaints. A comprehensive examination is essential; surgical experience and extended follow-up are mandatory for avoiding complications.