Benign fibrous histiocytoma of the proximal tibial epiphysis in a 12-year-old girl

Abstract

A 12-year-old girl presented with a 3-week history of pain and tenderness in the left knee. The pain was worse on activity and was relieved, at least partly, by salicylates. There was no history of recent trauma. This child also had a stormy past history of imperforate anus and rectovaginal fistula repair, as well as a left multicystic dysplastic kidney which was removed. She had no fever and no contracture. The patellar tap was positive. The erythrocyte sedimentation rate was mildly elevated at 18 mm/h. A left knee effusion aspirate did not yield any bactelial growth and there was no sign of fungus, leukocyte, or tumor cells in the aspirate. Plain radiographs showed a small knee joint effusion as well as a lytic lesion measuring lx0.8 cm in the proximal tibial epiphysis (Fig. 1). There was no adjacent sclerosis and no periosteal calcification. Conventional tomography demonstrated the purely epiphyseal lytic lesion to better advantage. The lesion itself was very well circumscribed with a thin