[Urothelial carcinoma in a pyelocaliceal cyst].

Renal complex cysts are lesions whose nature can be either benign or malignant. Depending on the presence of septa, solid components, enhancement or calcifications, they are distinguished according to the Bosniak classification based on CT findings, as well as MRI and ETG. We report a rare case of urothelial carcinoma, originating over a pyelocalyceal cyst in a 50-year-old man, and classified as Bosniak IIF by CT and MRI investigations.