Dear Editor,

We report the case of a 40 year-old patient with no urological history, who was admitted to our department because of pain in left kidney fossa, microhaematuria and pyuria. An examination showed tenderness in the left kidney fossa. The simple radiograph showed a radiopaque image in the left ureteral tract, compatible with calculi. With the clinical, laboratory and imaging data a left renoureteral crisis was diagnosed. In the antegrade pyelography, which confirmed the diagnosis, we observed a smaller kidney with its own collection system in the cranial region of the left kidney, independent of the ipsilateral one (Figure 1).

The supernumerary kidney is the rarest of kidney malformations. It is always small and usually located caudal to the ipsilateral one, independent from it by its capsule and with its own irrigation and collecting system.1,2 It does not usually cause any symptoms until adulthood when it can generate pain, hypertension, etc. It can occur in association with other diseases such as VATER syndrome3 or cardiological anomalies.4 The treatment will be the corresponding for the accompanying processes.

Figure 1.