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Invasive carcinoma of the renal pelvis following cyclophosphamide therapy for nonmalignant disease

A 47‐year‐old woman with right hydroureteronephrosis due to ureterovesical junction obstruction had gross hematuria after being treated for five years with cyclophosphamide for cerebral vasculitis. A right nephroureterectomy was required for control of bleeding. The pathology specimen contained clinically occult invasive carcinoma of the renal pelvis. Although the ability of cyclophosphamide to cause hemorrhagic cystitis and urine cytologic abnormalities indistinguishable from high grade carcinoma is well known, it is less widely appreciated that it is also associated with carcinoma of the urinary tract. Twenty carcinomas of the urinary bladder and one carcinoma of the prostate have been reported in association with its use. The present case is the first carcinoma of the renal pelvis reported in association with cyclophosphamide treatment. It is the third urinary tract cancer reported in association with cyclophosphamide treatment for nonmalignant disease. The association of the tumor with preexisting hydroureteronephrosis suggests that stasis prolonged and intensified exposure of upper urinary tract epithelium to cyclophosphamide. Patients who are candidates for long‐term cyclophosphamide treatment should be routinely evaluated for obstructive uropathy.