A 10-year-old male patient presented to the emergency department after a car accident with abdominal and thoracic impact. He was referred to our radiology department for a full-body CT scan. No traumatic lesion was noted. However, the scan showed a large kidney mass consisting of two fused lateral lobes forming a central isthmus of normal tissue, placed in the hypogastrium-right iliac region anteriorly to the plane between L4-S1. This renal fusion anomaly is called a pancake kidney (Figures 1,2). The right and the left arteries originate from the aorta just above the level of aortic bifurcation. No evidence of calculi or hydronephrosis was noted, and no other visceral anomalies were associated. Pancake or cake kidney (also known as discoid kidney or fused pelvic kidney) is a rare renal fusion anomaly of the kidneys of the crossed fused variety. It is usually an incidental finding (such as in our case). However, rarely, it can present clinically because of conditions affecting normal kidneys, such as recurrent infection, calculi, or ureteropelvic junction obstruction. The upper and lower poles of the kidneys are fused, thus giving the kidneys a pancake appearance. There are usually two separate ureters, which enter the bladder in a normal relationship. An even rarer variant is when a single ureter drains the cake kidney (which has been previously reported in only four patients). It is usually an incidental finding, and in these asymptomatic cases, a conservative approach, with an appropriate follow-up, is advised. Surgical intervention may be required when urological issues arise.

Figure 1: Coronal (a), sagittal (b), and virtual reality (c) reconstructions of a full-body CT scan showing the mass formed by the fused lateral lobes of both kidneys in the hypogastrium-right iliac region. Note the two separate ureters (white and red arrows).

Figure 2: Abdominal axial planes of the full-body CT scan, show the fused lateral lobes of the kidneys (or pancake kidney) with the right ureter (white arrow) and the left ureter (red arrow).