Presentation
Knee pain without trauma. Incidental finding.
Patient Data
MRI Left Knee without and with contrast
In the popliteal fossa, laterally, at the posterior surface of the femoral condyle in the gradient echo T2 sequences, is visible oval formation with blooming artifact caused by magnetic susceptibility from intracellular hemosiderin deposits.
Case Discussion
Pigmented villonodular synovitis (PVNS) is a rare, benign, proliferative disease of the synovial membrane of joints, tendon sheaths, and bursas.
It presents in two forms: diffuse and localized.
The localized form is usually a single pedunculated mass or, less frequently, two or three nodules.
Histologically there is active proliferation of fibroblastic and histiocytic elements, showing macrophagic activity with phagocytosis of blood pigment (hemosiderin) and lipids.
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).
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