A 17-year-old boy presented with a 2-month history of pain in his right wrist. Physical examination did not reveal any local swelling, redness, tenderness or deformity. Radiograph of both wrists and hands revealed multiple symmetric, well-defined, sclerotic lesions involving the carpal bones, metacarpals and phalanges (figure 1A,B). Radiograph of pelvis showed similar lesions (figure 1D). Biochemical profile revealed normocalcaemia, normophosphataemia and age-appropriate serum alkaline phosphatase. Bone scintigraphy did not reveal any increased osteoblastic activity (figure 1C,E). Family screening showed radiologically …