In non-functioning kidneys, Malignancy may be overlooked due to radiological difficulties. Differentiating between benign condition and malignancy may be difficult on pre-operative assessment in non-functioning kidneys unless nephrectomy is performed. We aimed to report our pathological and post-operative radiological findings in simple nephrectomy specimen from a patients treated for non-functioning kidney due to a large obstructing PUJ stone.

42 years old male patient presented with Right flank pain and a lump in right flank. On evaluation with contrast enhanced CT KUB, the patient was found to have right sided hydronephrosis due to a pelviureteric junction calculus 43x32mm in size with reduced contrast excretion on delayed phase. On DTPA Renogram, the right kidney showed no significant perfusion with 0.6% split function and a Glomerular Filtration Rate of 0.34 ml/min. Patient subsequently underwent Right simple nephrectomy.

On Histopathological assessment it was found out to be Clear cell Renal cell carcinoma with margins positive into perinephric fat. On post-operative radiological evaluation with CECT whole abdomen and chest, CEMRI Brain and Spine patient had brain, spine and liver metastases. Patient received radiation therapy for brain metastases and started on immune check inhibitors. Unfortunately patient succumbed to death after 2 months of detections of metastases

This case turned out to be an eye opener for us. We used to work up Renal Stone disease associated with Non functional kidney with Contrast enhanced CT KUB with CT Urography along with 99mTC DTPA Renal scan. Diagnosing tumors in non-functioning kidneys is difficult since these kidneys do not show normal blood flow on imaging studies. After this case, we have changed our management protocol. Pre-operative assessment should not be limited to KUB region a through radiological assessment with CECT whole abdomen with CTU along with HRCT chest is advocated in each nonfunctional kidney.