Intracapsular osteochondroma of the humeral head in an adult causing restriction of motion: A case report Roberto Padua, MD a,b,c,d, *, Alex Castagna, MD e , Enrico Ceccarelli, MD a , Rosaria Bondı `, MD a , Federica Alviti, MD g , Luca Padua, PhD c,f a Orthopedics Department, S. Giacomo Hospital, Rome, Italy b GLOBE Evidence Based Orthopedics Working Group of Italian Society of Orthopedics and Traumatology, Rome, Italy c Don Gnocchi Foundation, Rome, Italy d Nicola’s Foudation, Arrezzo, Italy e Orthopedics Department, Humanitas Institute, Rozzano, Italy f Neurology Department, Catholic University, Rome, Italy g Department of Human Physiology and Pharmacology, School of Specialization in Sports Medicine, University "La Sapienza", Rome, Italy Osteochondroma are the most common benign bone tumors. They represent approximately 40% of benign and 10% of all primary skeletal tumors. 2 They are believed to arise from aberrant, cartilaginous, physeal tissue that proliferates autonomously and increases in size by enchondral ossification. 2,7,9 They are usually located in the metaphysis of bones that develop by enchondral ossifica- tion, corresponding to the sites of most rapid bone growth. 3,5 The third highest site of occurrence is the proximal aspect of the humerus, after the femur and tibia. The lesion often enlarges during skeletal growth, but growth of the tumor cases or slows considerably when skeletal maturity is reached. 1,8 Although it is uncommon for a solitary osteochondroma to become symptomatic after skeletal maturity, malignant transformation must be sus- pected, as the most common reason for extensive growth of an osteochondroma after skeletal maturity is transformation into a chondrosarcoma. 3,8,4,6,10 We present a case in which a patient had a limited range of motion (ROM) of the shoulder due to an exostosis of the proximal humerus. The lesion grew extensively after skeletal maturity and was excised. Case report A 36-year-old man, with no history of trauma, presented with the onset of progressive pain in the right shoulder. Pain and limitation of movement had been increasing over the past six months. In particular, forward elevation was limited to 60  , abduction to 50  , and a mechanical painful stop was felt only in external rotation at 90  of elbow flexion, which was limited to 20  and of the extension of the shoulder. No deficit in strength was detected, and tests for impingement and the evaluation of the rotator cuff were negative. An AP (anterior-posterior) x-ray revealed the presence of a bony mass on the posterior part of the humeral head with the typical features of an osteochondroma (Figure 1). A CT scan confirmed its presence. The scan showed an exostosis in the posterior part of the humeral head, close to the glenoid (Figure 2). The picture suggested impingement of the mass against the gle- noid. Because of the rapid progression of symptoms, we suspected malignant transformation of a solitary exostoses. We used a posterior capsular approach, passing through the interval between the infraspinatus and teres minor muscles. The specimen consisted of a lobulated mass with a cartilaginous cap; the thickness of the cap varied from 0.1 to 0.3 cm. Histological *Reprint requests: Roberto Padua, MD, Via P.S. Mancini 2, 00196, Rome, Italy. E-mail address: roberto.padua@fastwebnet.it (R. Padua). J Shoulder Elbow Surg (2009) 18, e30-e31 www.elsevier.com/locate/ymse 1058-2746/2009/$36.00 - see front matter Ó 2009 Journal of Shoulder and Elbow Surgery Board of Trustees. doi:10.1016/j.jse.2008.09.008