A case of irreducible shoulder dislocation as an initial manifestation of osteosarcoma of the proximal humerus

We experienced a case of osteosarcoma of proximal humerus with an initial clinical manifestation of irreducible shoulder dislocation. An eleven-year-old girl was transferred due to shoulder dislocation after minor collision, which could not be reduced even under anesthesia. After failed closed reduction under anesthesia, open reduction through deltopectoral exposure was performed evacuating the organized fibrous tissue, even without the suspicion of primary bone malignancy. Histopathologic report was osteosarcoma. Retrospective review of the imaging studies revealed subperiosteal hemorrhage, organized hematoma underneath the deltoid musculature, and osseous parenchymal changes, which suggested bone tumor. Subsequently, lung metastases were detected, and the chemotherapy was accompanied by neutropenic fever and Stevens Johnson syndrome. She expired 1 month thereafter. High index of suspicion would have led to more early diagnosis and established more appropriate management plan. Osteosarcoma of proximal humerus should be included in the differential diagnosis of a shoulder dislocation that could not be readily reduced.