A case of frequently relapsing nephrotic syndrome combined with Perthes disease.

Orally-administered steroids often induce osteonecrosis of the femoral head. In cases of Perthes disease, osteonecrosis of the femoral head occurs in children due to an unknown cause. Our subject was a 4-year-old boy who had to be given large amounts of steroids because of frequently relapsing nephrotic syndrome (FRNS) developed after the onset of Perthes disease. One month earlier, he would limp with his right leg, but his radiographs were normal. Later, facial edema appeared and he was brought to our hospital with heavy proteinuria. He was diagnosed with NS and prescribed prednisolone for 2 months. As he would limp occasionally during the treatment, he had an orthopedic examination at our hospital, and shrinkage of the right femoral head was disclosed. Perthes disease was diagnosed on the basis of his MRI and clinical history. Meanwhile, NS relapsed twice over a half year, and he was diagnosed as having FRNS. Cyclophosphamide was administered for 12 weeks. Four years later, MRI indicated that the femoral head slowly improved and he was able to walk without prosthetic support. These results suggest that in the course of healing from Perthes disease, the conventional method of using prednisolone has little impact on the femoral head.