Renal Fusion Presenting as Pancake Kidney

We present the case of a male patient who, at 3 months of age, underwent abdominal and pelvic ultrasound due to acute gastroenteritis.Incidentally, the ultrasound revealed bilateral absence of the kidneys in the renal fossae.The pelvic ultrasound [Figure 1a] showed a single discoid renal mass in the midline of the pelvic cavity, consistent with complete renal fusion (pancake kidney).Magnetic resonance imaging [Figure 1b] corroborated the diagnosis.At 10 years, the patient demonstrated a decline in renal function.The estimated glomerular filtration rate was