Expansile bone lesions in a three-generation family.

We report on a three-generation family with "expansile" bone lesions of the distal radius and ulna, cortical thickening of the proximal long bones, and pathologic fractures. The differential diagnosis of expansile bone lesions includes isolated bone cysts and tumors, such as enchondromas and fibrous dysplasia; familial expansile osteolysis; and the genochondromatoses. Our patients have findings most similar to the genochondromatoses; however, the distribution of the lesions and the accompanying manifestations may be evidence for a unique genetic condition in this family.