Skeletal osteochondromas revisited.

Skeletal osteochondromas or osteocartilaginous exostoses represent the most common of all benign bone tumors and 10% to 15% of all bone tumors. Osteochondromas are solitary or multiple, pedunculated or sessile exophytic outgrowths from the bone surface that are composed of cortical and medullary bone with an overlying hyaline cartilage cap. Marrow and cortical continuity with the underlying parent bone defines the lesion. Osteochondromas usually occur in children or adolescents between 10 and 15 years, and increase in size throughout childhood, ranging from 1 to 10 cm. After adolescence and skeletal maturity, osteochondromas usually exhibit no further growth. In adults, growth or imaging alterations of an osteochondroma suggest the rare diagnosis of malignant transformation; however, extensive growth of osteochondromas without histological evidence of malignancy has been reported