Abstract
Costal osteocartilaginous exostoses, also known as osteochondromas, are the most common neoplasms of the long bones but are rare tumors of the ribs. Osteochondroma is often asymptomatic and incidentally observed. Tumors typically begin to grow before puberty and continue until bone maturation is reached. Our paper presents the case of a 16-year-old young male who was admitted to the hospital with nonspecific symptoms and having a family history of exostosis. Chest X-ray and computed tomography imaging revealed multiple costosternal exostoses, manifested as mediastinal masses, with protrusion into the thoracic cavity, exerting compressive effects on the ascending aorta and pulmonary parenchyma. Surgery is required in childhood if lesions are painful. But if tumor formation occurs in adulthood, such pathological bony outgrowths should always be resected for avoiding further complications. In this patient, surgical intervention removed the tumoral masses and improved the symptoms. Subsequently, histological exam confirmed the diagnosis of osteocartilaginous exostoses and showed the lack of dysplastic changes.