Supernumerary kidney presenting as pyonephrosis.

Renal anomalies constitute a majority of all congenital anomalies of urinary tract. Many anomalies warrant surgical intervention and some may not. Supernumerary kidney is an extremely rare anomaly; its association with horseshoe kidney is rare. A bizarre presentation in this patient-made preoperative diagnosis impossible. We report this extremely rare anomaly and its recognition and subsequent management.