[Simple renal cyst open into the urinary tract].

The authors present the case of a three-year old girl in whose left kidney, they observed a cystic image communicating with a calyx. The authors class the said lesion as a simple, renal cyst open to ducts. They make a differential diagnosis with other entities (calicial diverticulum, hydrocalicosis, hydatidic cyst and kidney tumour) on the basis of histological, radiological and clinical findings. To reach the same, they assess the structure of the cyst epithelium which is at all times simple cuboid; the radiographic image and the intravenous urography by filling the cyst cavity retrogressively with contrast and the record of macroscopic hematuria which would correspond to the rupture of the cyst in the excretory duct. The suggest a traumatic origin in the mechanism which opened the cyst into the excretory duct.