A case of pancake kidney with a single ureter in the retroperitoneal space.

The pancake kidney (PK) is a rare type of renal anomaly in which both kidneys completely fuse without an isthmus. In the previous reports, PKs have double ureters and are located in the pelvic cavity. We encountered a rare case of PK with a single ureter, which is located in the left retroperitoneal space, in a 95-year-old female cadaver, which was detected during a dissection course. In our case, the major calyces joined to form a single renal pelvis, which continued as a single ureter. To the best of our knowledge, this is the first report on PK with a single ureter that is located not in the pelvic cavity but in the retroperitoneal space. The knowledge of such anomalous presentation is important to avoid any complications during retroperitoneal surgery.