title: Giant Cell Tumor of the Patella Tendon Sheath Presenting as a Painful Locked Knee.
abstract: BACKGROUND
  The giant cell tumor of the tendon sheath (GCT-TS) is a benign proliferative synovial tumor manifesting as an intra-articular solitary nodule. When it involves the infrapatellar fat pad it can present acutely as a painful locked knee.
  
  
  METHODS
  A 26-year-old white male presented with a 2-week history of painful locking in his right knee. Clinical examination revealed lack of extension by approximately 20°. To help establish the diagnosis, an MRI scan of the right knee was performed, showing a large (5×4×2 cm), oval, well-circumscribed mass with a low-intensity homogenous signal. The size of the mass prohibited the removal by arthroscopy and we therefore proceeded with an open arthrotomy. Histological examination showed a tendosynovial giant cell tumor of the patella tendon sheath. At the latest follow-up, 2 years postoperatively, there was no local tumor recurrence.
  
  
  CONCLUSIONS
  These rare tumorous lesions should be included in the differential diagnosis of painful locking knee, especially in the absence of definite traumatic history.
authors: Department of Sports Medicine, Orthopaedic Clinic, Patras University Hospital, Patras, Greece.
authors: Andreas
authors: A
authors: Panagopoulos
authors: Department of Sports Medicine, Orthopaedic Clinic, Patas University Hospital, Patras, Greece.
authors: Pantelis
authors: P
authors: Tsoumpos
authors: Department of Sports Medicine, Orthopaedic Clinic, Patas University Hospital, Patras, Greece.
authors: Irini
authors: I
authors: Tatani
authors: Department of Sports Medicine, Orthopaedic Clinic, Patas University Hospital, Patras, Greece.
authors: Ilias
authors: I
authors: Iliopoulos
authors: Department of Pathoanatomy, Patras University Hospital, Patras, Greece.
authors: Dionysios
authors: D
authors: Papachristou
mesh_terms: D000328:Adult; D005870:Giant Cell Tumors / Q000150:complications / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D007592:Joint Diseases / Q000209:etiology*; D007719:Knee Joint; D008297:Male; D017847:Patellar Ligament; D012983:Soft Tissue Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000601:surgery