Focal fibrocartilaginous dysplasia in the upper extremity.

Focal fibrocartilaginous dysplasia is a benign lesion known to cause tibia vara in young children. To date, this lesion has been recognized in only the proximal medial tibia. This study reports two additional cases of focal fibrocartilaginous dysplasia occurring in the long bones of the upper extremity. The clinical presentation, radiographic appearance, histopathology, and natural history of focal fibrocartilaginous dysplasia in the humerus and ulna are analogous to published descriptions involving the tibia. Spontaneous resolution of the lesion and the resultant angular deformity is possible but not entirely predictable. Limb-length discrepancy should be anticipated.