Primary adenocarcinoma of the renal pelvis is a rare and a under-documented cancer, representing <1 % of all tumors of the upper urinary tract. There are less than 100 cases reported since 1946. Thus, we want to emphasize the importance of evaluating Non functioning Kidney (NFK) for the possibilty of malignancy. We present a case of a 67-year-old lady who has a history of untreated right ureteric calculus and a mid-ureteric stricture, which has led to a non-functioning kidney (NFK).

Her condition was further complicated with pyonephrosis and formation of cutaneous fistula over the years, requiring a Nephrostomy Tube (NT). This time, she came to our center with a dislodged right NT, pus discharge from the NT side, and right-sided abdominal pain.

As the imaging confirmed the presence of gross hydronephrosis of the right kidney and perinephric collection, the patient subsequently underwent a open retroperitoneal right nephrectomy and fistulectomy. Unexpectedly, histopathological examination revealed moderately differentiated adenocarcinoma with an intestinal phenotype, likely originating from the renal pelvis.

This case highlights the importance of evaluating chronic non-functioning kidneys for the possibility of malignancy, especially in long-standing nephrolithiasis and chronic infection. Urologists should maintain a high index of suspicion for malignancy in chronic non-functioning kidneys with nephrolithiasis and recurrent infections and act accordingly.