Intracapsular Osteochondroma of the Proximal Humerus Causing Restriction of Shoulder Joint Movements: An Uncommon Entity.

Osteochondroma, also termed osteocartilaginous exostosis, is the most common benign bone tumour of all benign osseous neoplasms. These lesions typically arise from the metaphyseal region and project away from the adjacent joint. However, intracapsular or intra-articular osteochondromas are rare, especially in the proximal humerus. Here, we report 2 cases of intracapsular osteochondroma of the proximal humerus in a 49-year-old woman and a 14-year-old boy, both with shoulder pain and restricted joint movements. The anteroposterior X-ray and magnetic resonance imaging of the shoulder joint demonstrated a bony lesion with medullary continuity with the parent bone and delineated a thin cartilaginous cap. MRI further enabled precise assessment of the lesion's intra-articular location and cartilage thickness. These cases highlight the emphasis on considering the possibility of intracapsular osteochondroma in the differential diagnosis of unexplained shoulder pain and restricted range of motion. A thorough imaging evaluation, particularly with MRI, is essential for accurate diagnosis, differentiation from other intra-articular pathologies, and appropriate management planning.