Practice Essentials
Chondromas are benign tumors composed of mature hyaline cartilage. They generally have limited growth potential and are not locally aggressive. [1, 2] These tumors are called enchondromas when they occur in the medullary canal of the bone [3] and are called periosteal or juxtacortical chondromas when they occur on the surface of the bone. Chondromas can also arise from the synovial sheaths of tendons or in the soft tissues adjacent to the tendons in the hand and feet of adults; in such cases, they are referred to as soft-tissue or synovial chondromas.
About 60% of enchondromas occur in the small bones of the hands [4] and feet. The next most common sites are the long tubular bones. Of the long bones, the femur is the most commonly involved (17%), followed by the proximal humerus (7%). The proximal and distal metaphysis of the femur are involved more often than the diaphyses.
Enchondromas are rare in flat bones (eg, pelvis, ribs, scapulae, and vertebrae) and extremely rare in the craniofacial bones. Notably, they rarely affect the bones of the trunk, where chondrosarcomas are common. However, enchondromas are common in the axial skeleton, where chondrosarcomas are rare.
Periosteal chondromas typically appear on the long tubular bones, with 50% observed in the proximal humerus. The next most common sites are the short tubular bones of the hand. The usual locations of periosteal chondromas are at the tendon insertions and hence are metaphyseal; however, these tumors can develop at metaphyseodiaphyseal and diaphyseal sites as well.
Enchondromas of the long bones are usually asymptomatic and do not require treatment. (See Treatment.) Enchondromas of short tubular bones are treated with curettage and bone grafting. Enchondromas found in the ribs, sternum, pelvis, or scapula should be treated with wide local resection and histopathologic evaluation to rule out chondrosarcoma. Periosteal chondromas are treated with wide local excision. For synovial chondromas, removal of loose bodies may be all that is required; however, if the lesion produces frequent symptoms, synovectomy may be needed.
Pathophysiology
Chondromas develop from nests of growth-plate cartilage that have become entrapped in the medullary canal of the metaphysis or in the metaphyseodiaphyseal junction. These hamartomatous proliferations persist as islands in the bone and then develop from enchondral ossification. They are subjected to the same growth factors as normal cartilage and grow until adulthood.
Chromosomal abnormalities involving the 12q13-q15 chromosomal region may be associated with chondroma, especially soft-tissue chondroma. [5] In addition, some authors have reported the involvement of chromosomes 6 and 11 in a soft-tissue chondroma. [6]
Periosteal chondroma tends to develop within and beneath the periosteal connective tissue. [7] This slow-growing tumor erodes and induces sclerosis in the contiguous cortical bone, producing the characteristic “popcorn” appearance.
Synovial chondroma results from cartilage metaplasia of subsynovial connective tissue. Karyotypic aberration has been found to be associated with synovial chondroma (ie, trisomy 5). [8]
Osteochondroma has also been associated with loss of the distal 8q chromosome. Multiple osteochondromatosis is associated with genetic defects in the 8q24.1 region (EXT1 gene) and in the 11p11-13 region (EXT2 gene).
Epidemiology
United States and international statistics
In the United States, benign cartilage tumors account for 27.5% of all bone tumors and 70% of all cartilage tumors. Enchondromas account for 12-24% of benign bone tumors and 3-10% of all bone tumors. Periosteal chondromas account for fewer than 1% of all chondromas and 0.1% of all bone tumors. The incidence of osteochondromas is 30% of all cartilage tumors and 2% of all bone tumors. International figures for chondromas have not differed significantly from figures reported in the United States.
Age- and sex-related demographics
Enchondromas are fairly evenly distributed throughout all decades of life, with no age preponderance; however, incidence peaks occur in the third and fourth decades. Periosteal chondromas are frequently diagnosed in the second or third decades of life. Osteochondromas present during adolescence and late teens. Multiple osteochondromatosis presents slightly earlier in the teens. Synovial chondromas occur from the first to the seventh decade, with a peak in the fifth decade.
No sex predilection is reported for enchondromas: the male-to-female ratio is 1:1. Similarly, there is no sex predilection for Ollier disease. Periosteal chondromas occur more commonly in male individuals than in female individuals. Osteochondroma has a definite male preponderance, with a ratio of 1.8:1. Synovial chondromas also show a male preponderance, with a ratio of 2:1.
Prognosis
Given appropriate treatment, patients with benign chondromas generally have a good prognosis, and most remain asymptomatic.
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Enchondroma of proximal femur.
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Plain radiograph reveals chondroma in left proximal femur (A) and low-grade chondrosarcoma in right superior pubic ramus and symphysis (B).
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MRI showing chondroma (A) and low-grade chondrosarcoma (B).
