Pigmented Villonodular Synovitis Presenting as a Baker Cyst

Pigmented villonodular synovitis (PVNS), a rare hyper-proliferation of the synovial lining, commonly mimics other conditions. As a result, the diagnosis may remain elusive, as the classic signs of tenderness and effusion are not specific. Occasionally, PVNS presents as a popliteal cyst, which may divert attention from intra-articular pathology.

In this article, we describe a case of PVNS that pre­sented with a popliteal cyst as the chief problem report. In other cases PVNS presented as a popliteal cyst, and evidence was reported of PVNS within the cyst stalk and presumable intra-articular involvement. Our case did not present this way.

We recommend that the diagnosis of PVNS be consid­ered in young adults who present with a popliteal cyst.