It occurs in the first and second decades, in the metaphyseal region of long bones, radiographically characterized by a tumor that forms cartilage and bone. Characteristically, the central cancellous bone of the exostosis continues with the medullary of the affected bone and the dense, cortical layer of the tumor continues with the normal cortical bone. On the surface of this lesion there is a band of cartilage, through which the lesion grows (hence the name  osteo-chondroma: tumor forming cartilage and bone ).

It presents with a sessile base (enlarged base) or pedicled shape.

May be single or multiple (hereditary osteochondromatosis)

Osteochondromas require surgical treatment ( resection ) when they alter aesthetics, compress vascular-nervous structures or limit function. They generally grow while the patient is in the growth phase.

When an osteochondroma increases in size after completion of skeletal maturity, it may mean post-traumatic bursitis or malignancy to chondrosarcoma and must be resected with an oncological margin.

Solitary osteochondroma can have a 1% malignancy rate, whereas multiple osteochondromatosis can reach 10%.

Among benign cartilaginous lesions, we cannot forget chondroblastoma.