Rhabdomyosarcoma in a child with nephrotic syndrome treated with cyclosporine: a case report with literature review.

BACKGROUND: In patients with frequently relapsing nephrotic syndrome, immunosuppressive therapy such as cyclosporine are often required to maintain remission. Cyclosporine has been noted to have tumorgenesis effects. In this case report, we present a child with relapsing nephrotic syndrom developed a rhabdomyosarcoma on her tongue after adout 4 years of continual immunosuppressive therapy. CASE PRESENTATION: A 2-year-old female child had nephrotic syndrome (urine protein-creatinine ratio 749.1 mg/mg; blood urea nitrogen 11 mg/dL; serum creatinine 0.3 mg/dL; and serum albumin 1.8 g/dL.) Proteinuria resolved on treatment with daily prednisolone for 4 weeks at the dose of 45 mg (2.5 mg/kg/day) but recurred with taper from 25 mg/day to 10 mg/day. At least five more episodes of relapse occurred within about a 3-year period. After the third relapse, she was treated with prednisolone and cyclosporine (at initial dose of 50 mg/day [1.7 mg/kg/day]) for immunosuppression. About 4 years after the diagnosis of nephrotic syndrome had been made, an embryonal rhabdomyosarcoma developed on her tongue. The cancer was treated with TPOG-RMS-LR protocol, with vincristine, actinomycin, and cyclophosphamide. Magnetic resonance imaging scan, performed about 3 years after the start of TPOG-RMS-LR therapy, revealed complete remission of the cancer. CONCLUSIONS: Although treatment with cyclosporine cannot be conclusively implicated as the cause the rhabdomyosarcoma in this patient, the association should prompt consideration of its use in the treatment of frequently relapsing nephrotic syndrome in children.

Cell-specific toxicity of fibrates in human embryonal rhabdomyosarcoma cells.

The effects of a variety of fibrates on the cell viability were examined in human embryonal rhabdomyosarcoma cells (HRMSC). Five fibrates, including fenofibrate, clofibrate, gemfibrozil, bezafibrate and ciprofibrate, all concentration-dependently reduced the cell viability determined by the mitochondrial enzyme activity. The cell injury occurred time-dependently and was marked at 24-48 h. The toxic action of fibrates was specific to HRMSC, since bezafibrate did not induce any marked changes in the viability of human microvascular endothelial cells or arterial smooth muscle cells. Synergistic cell injury was observed after a combined treatment with bezafibrate and simvastatin, although simvastatin alone reduced the cell viability. The cell injury was characterized by a typical nuclear damage, as evidenced by Hoechst 33342 staining and deoxynucleotidyl transferase dUTP nick-end label-positive staining. Similar cell-specific injury was induced by 8(S)-hydroxyeicosatetraenoic acid, a potent peroxisome proliferator-activated receptor alpha (PPARalpha) agonist. Consistent with these data, a marked expression for PPARalpha mRNA was observed in HRMSC but not in the endothelial or smooth muscle cells. Therefore, it is suggested that fibrates cause a cell-specific injury in HRMSC via activation of PPARalpha. Moreover, our present cell injury model using HRMSC may be useful for elucidating the mechanisms of clinical rhabdomyolysis induced by lipid-lowering agents.