A rare cause of shoulder pain: calcific tendonitis at the pectoralis major humeral insertion

Background/Aims Shoulder pain in the elderly is very common and often caused by calcific tendonitis of the rotator cuff muscles. We report the case of a lady presenting with unilateral shoulder pain who had an X-Ray which showed calcification over the proximal humerus. This calcification turned out to be due to calcific tendonitis of the humeral insertion of the pectoralis major, which is very rare. Unfamiliarity with this unusual condition could lead to inappropriate investigation, such as invasive biopsy, and possible mismanagement. Methods A 61-year-old lady of Pakistani origin with dual antibody positive rheumatoid arthritis, well controlled on methotrexate, reported new and severe right shoulder pain during her outpatient appointment. Her past history included coeliac disease, osteoarthritis, hypertension, iron and vitamin D deficiency, and she was not currently taking any calcium supplements. The pain had rapidly progressed over weeks to months without any trauma history and was significantly limiting all shoulder movements, particularly shoulder abduction and rotation. Her rheumatoid arthritis was in remission. Concerningly, she reported nocturnal pain, which alongside the rapidly progressive nature of the pain raises suspicions of a more sinister cause like malignancy. Results Blood tests showed a normal CRP, calcium profile and ALP. An X-Ray of the right shoulder showed no calcification or osteoarthritis affecting the glenohumeral joint, but demonstrated the unusual finding of a prominent focus of calcification close to the lateral aspect of the proximal humerus. An MSK radiologist advised further imaging to confirm nature of lesion. Subsequent USS confirms a focus of calcification (14mm x 18mm) in the pectoralis major humeral insertion, adjacent to the long head of the biceps tendon. Features that are suggestive of benign calcification rather than neoplasm include the characteristic location of the calcification and absence of an overlying soft tissue mass. The patient was reassured regarding the benign nature of the calcification and was managed conservatively with simple analgesia and physiotherapy. Conclusion Calcific tendinopathy is a common disease, but calcification of the pectoralis major at its humeral insertion point is very rare. This case highlights the importance of familiarity with this condition to enable the clinician to make an accurate diagnosis, and reduce the likelihood of unnecessary investigations and stress for the patient. Conservative management, such as simple analgesia and physiotherapy, is very effective for the majority of patients and should be used as first-line treatment. Steroid injection can be considered with orthopaedic intervention advised for those who have not responded to conservative management. Disclosure E.M. Quinlan: None. M. Kazmi: None.