An unusual presentation of peroneal neuropathy secondary to pigmented villonodular synovitis: a case report.

Pigmented villonodular synovitis (PVS) is a benign proliferative disorder of unknown origin that affects synovial joints, most commonly the knee. The joint knee can be affected by localized or diffuse form. Diffuse PVS, the aggressive form of the disease is much more problematic, especially when it extends extra-articularly, and is associated with high recurrence rates. Although this disease is categorized as an inflammatory process rather than a neoplasm, it may be locally destructive and involve muscles, tendons, bone and skin. Neural involvement of the disease is rather rare, and only limited knowledge about neuropathy due to PVS we have yet. The presentation of the disease in our patient is a peroneal neuropathy which is the first reported case in English language literature of PVS of the knee seen with extra-articular tissue involvement.