Acromioclavicular cyst with geyser sign - An uncommon presentation of massive rotator cuff tear.

Rotator cuff muscle tear is a common finding among adults and acromioclavicular cyst is a rare secondary manifestation. This case report describes the clinical presentation and workup diagnosis of a patient with acromioclavicular cyst in context of massive rotator cuff tear. Woman, 83-year-old developed a tumefaction over the left acromioclavicular joint. She had pain, limitation on active range of motion and function limitation of the left shoulder. The X-ray revealed superior humeral head displacement and signs of arthropathy. The MRI revealed "geyser sign" and identified an acromioclavicular cyst secondary to cuff tear arthropathy. Aspiration was not performed due to high recurrence rate and surgical removal was decided. Clinicians should be aware of this rare complication of rotator cuff tear, demanding exclusion of other possible causes of acromioclavicular cyst and offer suitable treatment options.