Imagerie des exostoses solitaires

The osteochondroma or exostosis is the most common benign bone tumor, accounting for 20 to 50% of all benign bone tumors and 10 to 15% of all bone tumors. Osteochondromas may occur as solitary or multiple tumors, the multiple form being associated with an autosomal dominant syndrome, hereditary multiple exostoses. Solitary osteochondromas are composed of cortical and medullary bone with an overlying hyalin cartilage cap and must demonstrate continuity with the underlying parent bone cortex and medullary canal. Its radiologic features are often pathognomonic and identically reflect its pathologic appearance. Serial imaging can be particularly useful for certain particular localizations posing a problem of differential diagnosis, in the event of complications. The two most frequent symptoms are increased volume and pain. The long bones of the lower limb are most frequently affected (50% of cases). But the fortuitous discovery of osteochondromas on radiographic assessments confirms that a great number of solitary exostoses are asymptomatic. Complications associated with osteochondromas include cosmetic and osseous deformity, fracture, vascular compromise, neurologic sequelae, overlying bursa formation, and malignant transformation.