The Case:
A 28-year-old male with no significant past medical history presented to the Emergency Department with a left shoulder mass that he first noticed as a 12 year old (16 years ago). The mass has been slowly growing since onset and is intermittently painful but has not limited his range of motion of the shoulder. The patient recently immigrated from Mexico and was seeking initial evaluation of this mass.
On examination, the patient had a large, hard, and irregularly-shaped mass around the left shoulder. The patient retained full range of motion of the shoulder joint and had normal strength and sensation throughout the arm.
Large shoulder mass, but with retained range of motion
Interpretation: 24 x 22 x 17 cm densely calcified cauliflower-like mass in projection of the proximal left humerus and scapula.
Patient Course:
Radiographs were obtained, which revealed a large, calcified mass in the proximal humerus and scapula. The patient subsequently underwent CT and MRI of the left upper extremity for better characterization of the mass. These studies revealed a broad-based, pedunculated lesion arising from the proximal left humeral metaphysis and diaphysis with cartilaginous caps measuring up to 2 cm in thickness. Findings were most consistent with a large osteochondroma. Orthopedic Surgery and Surgical Oncology services were consulted and the patient was provided with outpatient follow-up with Surgical Oncology.
Why It Matters:
Osteochondromas are benign tumors of bone and cartilage that arise from the growth plate. Osteochonrdromas are the most common bone tumor, accounting for approximately 10% of all bone tumors and 35% of all benign bone tumors. They are most frequently located in the extremities, specifically around the knee and proximal humerus. The majority of these growths are discovered before the age of 20, often incidentally, although they can become symptomatic if they grow large enough to form a palpable mass or cause impingement on nearby neurovascular structures.
More than three-quarters of osteochondromas are solitary lesions, although a minority of patients can have multiple lesions, such as in multiple hereditary exostoses (HME), an inherited condition. Malignant transformation of osteochondromas is rare, occurring in less than 1% of solitary osteochondromas and 10% of HME cases. Concerning signs of malignant transformation of osteochondromas includes significant tumor growth after skeletal maturity or a cartilage cap greater than 2 cm in adults, which is best evaluated via MRI. Surgical resection is the preferred management in these cases, with a recurrence rate of less than 2%.
Written By:
Parker Lewis, MD.
Emergency Medicine Resident | PGY2
Cook County Emergency Medicine
Reviewed By:
Scott Sherman, M.D.
Associate Program Director | Cook County Emergency Medicine
References:
1. Tepelenis K, Papathanakos G, Kitsouli A, et al. Osteochondromas: An Updated Review of Epidemiology, Pathogenesis, Clinical Presentation, Radiological Features and Treatment Options. In Vivo. 2021;35(2):681-691. doi:10.21873/invivo.12308
2. Murphey MD, Choi JJ, Kransdorf MJ, Flemming DJ, Gannon FH. Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation. Radiographics 2000 Sep-Oct; 20(5): 1407-1434.