Karyomegalic-like nephropathy, Ewing's sarcoma and ifosfamide therapy.

Karyomegalic interstitial nephropathy has been reported as a rare interstitial nephritis in adult patients. Histology shows atypical epithelial cells and large abnormal hyperchromatic nuclei with irregular outlines. We report 3 adolescent patients who all recovered from their initial treatment for Ewing's sarcoma but developed a tubulopathy attributed to ifosfamide therapy. Renal impairment resulted in biopsy, which showed features of karyomegalic nephropathy in all 3. One patient has progressed to haemodialysis. Recognition of the pathology may be important in similar patients. It is surmised that the unusual histological findings in these patients stem from a common pathogenesis which may be related to chemotherapeutic agent related nuclear damage. At present there is no specific treatment to prevent progressive renal impairment.