Solitary osteochondroma, hereditary multiple exostoses, post-traumatic osteochondroma, post irradiation osteochondroma, osteocartilaginous exostosis, Ollier's disease.
An osteochondroma is a cartilage-covered osseous excrescence that arises from the surface of a bone. The most frequent type of osteochondroma is a solitary osteochondroma which is relatively frequent. Solitary osteochondromas are 20–50% of all benign bone tumors. Etiology is unclear. 70–80% of osteochondromas occur in patients who are younger than twenty years of age. The vast majority of solitary osteochondromas are asymptomatic and detected as an incidental finding. Typical characteristic course is a non-tender, painless, slowly growing mass. However, some subjects may experience pathologic fracture through the exostosis, irritation or damage to adjacent nerves or vessels, spinal cord compression if they occur on the vertebral bodies or even urinary tract obstruction. The anatomic location of solitary osteochondromas in decreasing order of frequency is as follows: femur, humerus, tibia, small bones of the hand and foot, scapula and vertebral body. They have also been reported rarely to occur arising from a rib, skull, scapula and clavicle. Radiographically, they have the appearance of an osseous protuberance arising from the external surface of the long tuberal bone, containing spongiosa and cortex that are continuous with those of the parent bone. Osteochondromas have the potential to continue growth throughout the period of overall skeletal growth. This growth of solitary osteochondromas usually stops at the latest during at puberty, but it may stop anytime prior to that. There have been cases of spontaneous resolution of chondromas. Potential complications of osteochondroma are fracture, osseous deformity, vascular injury from mechanical displacement or blockage of arterial flow, neurologic compromise secondary to compression of a nerve or nerve root, bursae formation at the tip of the lesion and malignant transformation. The risk of malignant transformation of a solitary osteochondroma is approximately 1% or less.
Hereditary multiple osteoses (Ollier's disease) is an autosomal dominant disorder associated with clinical abnormalities in the first or second decade of life. Positive family history for the same disorder is present in two thirds of the patients. Common findings are multiple palpable osseous protuberances secondary bony deformities caused by shortening and bowing of bones and mechanical joint restriction. Patients may exhibit more than one hundred osteochondromas. Sites of distribution are similar to solitary osteochondromas; except in hereditary multiple exostoses, there is a greater tendency for involvement of the scapula, innominate bone and ribs. Complications associated with hereditary multiple exostoses are the same as solitary lesions, except they are more frequent in the hereditary form. The most striking difference is the malignant transformation in up to 27% of patients with hereditary multiple exostoses.
Analgesia for painful lesions.
The primary treatment for osteochondromas, whether they are solitary or multiple, is surgical excision. The mere presence of an osteochondroma is not an indication for surgery. Reasonable indications include: 1) pain from external trauma or irritation of surrounding soft tissues, 2) growth disturbance leading to angular deformity or limb length discrepancy, 3) joint motion compromised by juxta-articular lesions, 4) soft tissue impingement or tethering, including tendon, nerve or vessel, 5) spinal cord compression, 6) false aneurysm produced by an osteochondroma, 7) painful bursal formation, 8) obvious cosmetic deformity, and 9) a rapid increase in the size of a lesion. In addition, surgical biopsy is indicated for any osteochondroma that suggests risk for malignant transformation.
Both solitary and hereditary multiple exostoses are long-standing lesions. The prognosis is determined primarily by the risk for malignant transformation.