[The role of endoscopy in the diagnosis and treatment of keratinizing and desquamating malpighian metaplasia of the kidney pelvis].

Keratinized squamous cell metaplasia of the renal pelvis (KSMRP) is a rare lesion, difficult to differentiate from urothelial tumour on the basis of the usual morphological examinations. It is therefore usually diagnosed retrospectively, on histological examination of a nephroureterectomy specimen. However, as its benign nature justifies conservative treatment, preoperative recognition of this lesion is essential. Upper urinary tract endoscopy, which allows diagnosis and treatment of this disease, is therefore very important in this context. Endoscopy is indicated when KSMRP is suspected clinically in a doubtful case of urothelial tumour of the upper urinary tract, in a context of passage of soft stones or a history of renal stones or upper urinary tract infection. Ureteroscopy constitutes the first step to confirm the diagnosis. It must be completed by a percutaneous procedure to eradicate any residual lesion, which could be responsible for recurrence. We report a case of KSMRP in a solitary kidney treated by retrograde and percutaneous endoscopic surgery.