Non-popliteal synovial rupture.

The ruptured popliteal synovial cyst is a common complication of chronic knee arthritis. In contrast, non-popliteal synovial rupture is less well recognized and may present a diagnostic dilemma. We report an 81-year-old woman who presented with chest wall pain and ecchymosis. Ultrasonography of the shoulder region readily diagnosed a dissecting parasynovial cyst. She developed the unusual complication of contralateral recurrence. Literature review revealed a small but important set of non-popliteal synovial ruptures in the regions of the shoulder, elbow, wrist, spine, hip, knee, and ankle. Local swelling, inflammation, ecchymosis, and nerve impingement may mimic other conditions. Awareness of the clinical presentations and a high index of suspicion are required to avoid diagnostic confusion. Management data are limited to case reports of arthrocentesis, injection, and very rarely, surgery.