Disclosures: Justin Chau, BS: No financial relationships or conflicts of interest

Case Diagnosis: Metastatic Osteosarcoma of the Shoulder

Case Description or Program Description: A 73-year-old female with right shoulder pain was referred from orthopedic surgery for a right glenohumeral joint injection. She had previously undergone a right subacromial bursa steroid injection. Right shoulder x-ray demonstrated reduced acromiohumeral interval and degenerative changes within the glenohumeral joint. Physical exam was significant for limited range of motion in all planes due to pain, positive empty can, Neer sign, and Hawkins. During ultrasound-guided injection, evaluation of the area demonstrated a mixed-echogenicity mass with posterior acoustic shadowing and cortical irregularity of the spine of the scapula medial to the right glenohumeral joint. The injection was aborted and the patient was recommended for MRI of the right shoulder.

Setting: Outpatient Physiatry Clinic

Assessment/Results: Right shoulder MRI demonstrated a mass obliterating the right scapula and surrounding the axillary neurovascular bundle. She was referred to orthopedic oncology and underwent a CT showing metastasis to the lungs. Bone biopsy was positive for osteosarcoma. She was then referred to oncology and began chemotherapy.

Discussion (relevance): Osteosarcoma is a rare primary malignancy of the bone with an incidence of 1000 cases per year in the US. Diagnostic evaluation begins with plain radiograph followed by MRI. CT is then used for evaluation of metastasis. Bone biopsy is definitive. Ultrasound is less commonly used in the workup of possible osteosarcoma. However, it is a quick and inexpensive diagnostic tool that is popular amongst physiatrists for evaluation of musculoskeletal pathologies. In this case report, the use of ultrasound ultimately led to a diagnosis of metastatic osteosarcoma that was otherwise unseen on x-ray.

Conclusions: Musculoskeletal ultrasound may not only improve guidance of peripheral joint injections but may also diagnose abnormalities which alter plan of care. Providers should also consider the utility of ultrasound in the initial evaluation of musculoskeletal pathologies that could be missed on plain radiograph.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/osteosarcoma-diagnosed-by-musculoskeletal-ultrasound-a-case-report/