Lower Extremity Benign Bone Lesions and Related Conditions

Benign bone lesions in the lower extremities of children may produce pain, pathologic fracture, shortening, restriction of joint motion, or angular deformity. The common benign lesions seen in the lower extremities include osteochondromas, nonossifying fibromas, and fibrous dysplasia, while conditions such as multiple enchondromatosis, dysplasia epiphysealis hemimelica, and osteofibrous dysplasia are seen very rarely. Treatment is usually guided by the symptoms of the patients. Patients with conditions which create masses such as osteochondromas and dysplasia epiphysealis hemimelica frequently require excision for symptomatic improvement. Lesions with abnormal ossification, such as fibrous dysplasia and enchondromatosis, can cause pain and decreased osseous integrity while complicating treatment as a result of compromised bone mechanics. Extraosseous involvement may be seen in children with McCune Albright Syndrome (precocious puberty) and Maffucci’s syndrome (enchondromatosis, hemangiomatosis, and increased risk of malignancy). Malignant transformation may rarely occur in some conditions, namely osteochondromas, enchondromatosis, and osteofibrous dysplasia. This chapter will describe the etiologies, presentations, radiographic and histologic characteristics, and common treatments for these benign conditions.