Renal cholesteatoma is an extremely uncommon disease. The renal pelvis is the most common site, but the lesion can be localized, even if rarely, in a calix or in the ureter. Histologically it consists of a keratinizing desquamative squamous metaplasia, with absence of cellular atypia in the urothelium, therefore cholesteatoma is not considered as a premalignant lesion. Authors report a case of renal cholesteatoma and take into consideration particularly the question regarding the diagnostic approach, that in spite of the help of new imaging techniques, as TC, is unable to arrive at a certain diagnosis, and the therapeutic approach, that must be conservative, when it's possible and according to the majority of Authors.