Imaging of Osteochondroma: Variants and Complications with Radiologic-Pathologic Correlation

Abstract

Osteochondroma represents the most common bone tumor and is a developmental lesion rather than a true neoplasm. It constitutes 20%-50% of all benign bone tumors and 10%-15% of all bone tumors. Its radiologic features are often pathognomonic and identically reflect its pathologic appearance. Osteochondromas are composed of cortical and medullary bone with an overlying hyaline cartilage cap and must demonstrate continuity with the underlying parent bone cortex and medullary canal. Osteochondromas may be solitary or multiple, the latter being associated with the autosomal dominant syndrome, hereditary multiple exostoses (HME). Complications associated with osteochondromas are more frequent with HME and include deformity (cosmetic and osseous), fracture, vascular compromise, neurologic sequelae, overlying bursa formation, and malignant transformation. Malignant transformation is seen in 1% of solitary osteochondromas and in 3%-5% of patients with HME. Continued lesion growth and a hyaline cartilage cap greater than 1.5 cm in thickness, after skeletal maturity, suggest malignant transformation. Variants of osteochondroma include subungual exostosis, dysplasia epiphysealis hemimelica, turret and traction exostoses, bizarre parosteal osteochondromatous proliferation, and florid reactive periostitis. Recognition of the radiologic spectrum of appearances of osteochondroma and its variants usually allows prospective diagnosis and differentiation of the numerous potential complications, thus helping guide therapy and improving patient management.

A calcaneal osteochondroma with recurrence in a skeletally mature patient: a case report

“…Osteochondromas are developmental lesions rather than true neoplasms and they may occur solitary or as multiple lesions, associated with the syndrome multiple hereditary exostoses [1]. Osteochondroma is seen in the 2% to 3% of the general population and represents approximately 36% to 41% of the benign bone tumors [7,8].…”

“…The evaluation of osteochondromas can generally help clinical findings, and imaging methods such as plain radiography, ultrasonography, CT, MR imaging and bone scanning [1]-[3]. …”

“…Additional complications that cause symptoms include osseous deformity, fracture, vascular-nerve compression, neurologic sequelae, bursa formation, and malignant transformation [3,7]. Malignant transformation is seen in less than 1% to 2% of patients of solitary osteochondroma [2,9] and in 5%-25% of patients with multiple hereditary exostoses [1,2,10]. …”

“…The radiographic appearance of this tumor is often diagnostic and reflects its pathologic characteristics. The lesion is composed of native cortical and medullary bone protruding from and continuous with the underlying bone and they appear as sessile or pedunculated [1,2]. However, if there is no extensive mineralization, the thickness of the cartilage cap is usually not well evaluated with radiography [1].…”

“…It usually rises from the metaphyseal or metadiaphyseal region of long bones of the appendicular skeleton and are most commonly seen around the knee [1,2]. Osteochondromas grow during childhood through adolescence, but usually growing ends when the epiphyseal plates close [1,3].…”