Polyomavirus infection of the urinary tract presenting as hemorrhagic cystitis in an immunocompetent five-year-old boy.

Human polyomavirus infection, which can be detected morphologically on Pap-stained routine urine cytology specimens, is most commonly encountered in immunocompromised patients and is a well-described complication of renal transplantation. We present a case of an immunocompetent 5-year-old boy with a sudden onset of dysuria and hematuria due to a self-limited polyomavirus urinary tract infection detected on routine urine cytology and confirmed with real-time PCR. Although rare cases of nonhemorrhagic cystitis have been reported, to the best of our knowledge this is the first case of hemorrhagic cystitis occurring in this setting.