Primary mucinous adenocarcinoma of the renal pelvis misdiagnosed as calculous pyonephrosis: a case report and literature review.

Primary mucinous adenocarcinoma of the renal pelvis is a rare malignant disease that is difficult to diagnose preoperatively. There are still no characteristic symptoms, radiological features, or standard treatment for this tumor with only ~100 cases reported. The prognosis is poor. We report a case of a 66-year-old man who presented with a 2-month history of fever and right waist pain. He was misdiagnosed with calculous pyonephrosis and underwent percutaneous nephrostomy (PCN) at a local hospital. Gelatinous material was drained via a PCN catheter. He was then transferred to our hospital. He had elevated CEA and CA19-9. We performed an open radical nephrectomy and found polypoid, gelatinous material and stones filling the renal pelvis. He was diagnosed with primary mucinous adenocarcinoma of the renal pelvis by pathology. He refused adjuvant chemotherapy and there was no sign of recurrence after one year of follow-up. By assessing a literature review of all of the cases reported since 2000, we recommend that careful history taking, serum tumor markers, and CT scans may improve the diagnostic accuracy rates and radical nephrectomy with total ureterectomy accompanied by adjuvant therapy may improve the prognosis.