Osteochondroma

Excerpt

Osteochondromas represent the most common bone tumor, accounting for 20% to 50% of all benign osseous tumors. Osteochondromas are surface bone lesions composed of both cortical and medullary bone with hyaline cartilage caps. The presence of cortical and medullary continuity of the tumor with the underlying bone is a pathognomonic feature that establishes the diagnosis. Osteochondromas may be solitary or multiple. The multiple form is an autosomal dominant syndrome referred to as hereditary multiple exostosis (HME) or familial osteochondromatosis.

Osteochondromas can be an incidental finding or present with a palpable mass or symptoms due to compression of the adjacent structures, which varies based on the involved structure. Complications associated with osteochondromas are common, including osseous deformities, fractures, bursa formation with or without bursitis, vascular compromise, neurologic symptoms, and malignant transformation.

Radiographs are often diagnostic; however, cross-sectional imaging may be indicated to assess for complications, assess the cartilage cap, or, in some challenging cases, establish the presence of medullary continuity. The lesions may increase in size in skeletally immature patients; however, growth or changes in morphology after skeletal maturation are concerning features for malignant transformation. The lesions may be sessile or pedunculated. When pedunculated, they extend away from the nearest joint.

There are multiple osteochondroma variants or mimickers. Including subungual exostosis, dysplasia epiphysealis hemimelica (Trevor disease), turret exostosis, traction exostosis, bizarre parosteal osteochondromatous proliferation (BPOP) (or Nora lesion), and florid reactive periostitis. Differential considerations also include subperiosteal hematoma, parosteal osteosarcoma, or juxtacortical chondroma, none of which have medullary continuity.

Nonoperative treatment is indicated for the majority of solitary osteochondromas. Retinoid acid receptor gamma (RARy) agonists are an emerging potential treatment. Operative management can involve marginal surgical excision of the lesion, with wide surgical excision reserved for cases of malignant transformation.