Presentation
Chronic left knee pain and limited range of motion. Negative trauma.
Patient Data
There are no acute bony abnormalities present. There is a suprapatellar effusion. There is developing patellofemoral osteoarthritis with osteophytic spurring. The joint spaces are maintained.
Diffuse, multifocal, and irregular, synovial thickening and proliferation give rise to a villonodular appearance. This involves the anterior and posterior joint recesses, supra and infrapatellar including the popliteal bursae. There is a large joint effusion and a moderate, intact, popliteal cyst. There are extensive bone erosions, best visualized on the coronal T1 sequence. These are poorly appreciated in plain films but post-MRI review, are present. There is hemosiderin deposition as evidenced by the blooming on the T2* GRE.
There is incidental mucoid degeneration of the anterior cruciate ligament (ACL).
Case Discussion
As demonstrated, features suggest a diffuse tenosynovial giant cell tumor of the knee (previously called pigmented villonodular synovitis or PVNS).
The broad differential diagnosis includes:
synovial chondromatosis (unossified, in this instance, see the plain films!)
hemophiliac arthropathy
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