RESUMEN
A 16-year-old male patient was diagnosed as chondroid osteosarcoma of the left humeral shaft. He showed normal serum creatinine level and no complications following the first course of high-dose methotrexate (HD-MTX) chemotherapy with a total dose of 12g/m2. After the 2nd HD-MTX chemotherapy with the same dosage as in the 1st course, plasma MTX levels soared up to 72micromol/L and serum creatinine level increased to 1.39mg/dL. We failed to lower the plasma MTX levels and to recover the renal function by high-dose leucovorin rescue and plasmapheresis. Plasma MTX level was successfully lowered after three consecutive total plasma exchanges and the withdrawal of aceclofenac which was suspected as an aggravating agent. No rebound in plasma MTX level was observed. We report that total plasma exchanges were effective in a patient with renal failure and delayed MTX excretion which occurred after HD-MTX chemotherapy.