Nephrogenic adenoma associated with cytomegalovirus infection of the ureter in a renal transplant patient: presentation as ureteral obstruction

Nephrogenic adenoma (NA), a rare benign lesion of the urinary tract, is widely accepted to be a metaplastic reaction due to urothelial injury. It mainly occurs in the urinary bladder and rarely in the ureter. Renal transplant recipients are prone to the development of NA. However in those patients, NA was diagnosed exclusively in the bladder. Herein, we present the – to our knowledge – first case of NA involving a transplanted ureter. A 42-year-old female kidney transplant recipient suffered hematuria, oliguria, and acute renal failure and presented with ureteral obstruction and hydronephrosis of the renal transplant. To our surprise, evidence of cytomegalovirus (CMV) infection of the NA was demonstrated using special immunohistochemical staining. The findings in this case raise the possibility that CMV infection, as an irritant of the ureteral epithelium, may be an etiological factor of NA.