[A case of brown tumor mimicking fibrous dysplasia in a patient with chronic renal failure].

Renal osteodystrophy is one of the major causes of morbidity in patients receiving long-term dialysis treatment for renal failure and after transplantation. Its clinical implications include high-turnover bone disease, low-turnover bone disease, osteomalacia, osteosclerosis, and osteoporosis. A 13-year-old boy who had been on dialysis treatment for renal failure was admitted with a pathologic supracondylar femur fracture after a minor trauma. Radiological studies showed cystic lesions in the femoral supracondyle, left acetabular roof, and right proximal and distal tibia. Based on radiologic appearances of the lesions and on histopathologic findings of the lesion excised from the right distal tibia, brown tumor and fibrous dysplasia were considered in the differential diagnosis. Initially, serum parathyroid hormone level was slightly increased and calcium level was normal, but during follow-up, serum parathyroid hormone level increased significantly, enabling the diagnosis of brown tumor.