Bilateral Geyser Sign Secondary to Calcium Pyrophosphate Deposition Disease: A Rare Presentation.

The Geyser Sign (GS) is a rare imaging sign characterized by synovial fluid leakage through a full-thickness rotator cuff tear into the subacromial bursa and acromioclavicular joint (ACJ), resulting in capsular distension and cyst formation. We report the case of a 72-year-old man who presented with bilateral shoulder pain and a firm and compressible swelling over both ACJs with marked inflammatory signs. Radiographs demonstrated ACJ soft-tissue swelling, degenerative changes of the glenohumeral joint (GHJ) and ACJ, and features of chronic rotator cuff arthropathy. Computed tomography revealed severe omarthrosis, complete rotator cuff tear, glenohumeral effusion, subacromial bursal distension, and large ACJ cysts measuring 5.4 cm on the right and 6.3 cm on the left, confirming bilateral GS. Ultrasound-guided right ACJ cyst aspiration revealed viscous yellow synovial fluid with 14,822 white blood cells/mm³ (89% polymorphonuclear cells) and calcium pyrophosphate crystals, consistent with calcium pyrophosphate deposition disease. Triamcinolone injection resulted in symptomatic relief over six months of follow-up. Bilateral presentation of GS is uncommon, and calcium pyrophosphate crystals in these cysts are rarely reported despite their common occurrence in degenerative joints. Management strategies range from conservative to surgical, depending on symptoms, functional status, extension of rotator cuff tears, and comorbidities.