An 82-year-old man presented with neck pain, right upper limb radiculopathy and right shoulder pain. Physical examination revealed a soft lump over the right shoulder joint, as well as reduced range of shoulder movements. On magnetic resonance imaging, the soft lump was shown to be a cystic mass over the acromioclavicular joint and was related to a full-thickness supraspinatus tendon tear. This is the classic geyser sign. The pathophysiology and clinical features of the geyser sign, and its imaging features with various imaging modalities, are discussed.
Acromioclavicular Joint ; diagnostic imaging ; injuries ; Aged ; Aged, 80 and over ; Fluoroscopy ; Humans ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging ; Male ; Range of Motion, Articular ; Shoulder ; physiology ; Shoulder Joint ; pathology ; Tendon Injuries ; pathology