Focal fibrocartilaginous dysplasia in the upper limb: seven additional cases.

Focal fibrocartilaginous dysplasia is a benign bone lesion known to cause deformity around the knee in young children. Three cases affecting the long bones of the upper limb have been reported, and little is known of the natural history. This study reports seven more cases affecting the upper extremity. All patients presented with deformity in early childhood. The location was the radius in two, the ulna in three, the proximal phalanx in one, and the middle phalanx in one. The radiographic appearance of the condition is diagnostic, regardless of the bone it affects. Proportional shortening of the affected segment was present in all patients. The phalangeal cases had marked deformity and were osteotomized, with early recurrence of the deformity in one case. The forearm lesions did not all resolve spontaneously. In the two patients with 7-year follow-up, the length discrepancy increased from 0.5 cm to 2 cm and a degree of cosmetic deformity remained, without functional impairment. Ulna lesions place the radiocapitellar joint at risk for dislocation and should be observed for this complication.