557 - Calcific tendinitis of the supraspinatus tendon with intraosseous extension

Case Diagnosis: Calcific tendinitis with intraosseous extension

Case Description: A 32-year-old male construction worker presented with severe left shoulder pain for 1 week without any trauma. The pain became so severe that he was unable to perform his job duties. The patient had a left shoulder X-ray 2 months prior, which showed prominent calcific tendinopathy at the supraspinatus insertion site. Due to worsening of his symptoms, the patient was further evaluated with magnetic resonance imaging (MRI) which revealed calcific tendinopathy at the supraspinatus tendon insertion with intraosseous extension into the greater tuberosity, with surrounding reactive bone marrow edema pattern within the proximal humerus. The patient was treated with ultrasound-guided percutaneous irrigation.

Discussions: Calcific tendonitis is a condition in which there is pathologic deposition of hydroxyapatite crystals in tendons. Depending on the size of the deposits, they may cause pain related to impingement. Reactive inflammation from the deposits can also be painful. The exact pathogenesis of calcific tendonitis is still under investigation, though it may be related to a cell-mediated response in which the tendon progenitor cells differentiate into chondrocytes or osteoblasts, depositing erroneous extracellular matrix and calcium. A rare complication of calcific tendonitis is migration of calcium into surrounding tissue structures such as supraspinatus, infraspinatus, subscapularis, humerus, and subacromial-subdeltoid bursa. The patient described in this case presented with intraosseous migration of calcific deposits which can cause reactive bone marrow edema pattern on MRI. Therefore, other pathologies that may also appear similarly on MRI such as infectious or neoplastic processes must be ruled out.

Conclusions: Intraosseous extension of calcific deposits is a rare complication of calcific tendinitis. This case serves to reinforce the potential complication of a relatively common entity in calcific tendinitis.