Fetus in fetu: a very rare cause of abdominal mass in a male infant, case report

Fetus in fetu is an extremely rare congenital pathology that has an incidence of one in 500 000 births.1 The cases reported in the literature are about or fewer than 100 cases in the last two centuries.2 The clinical manifestation is usually resumed to an abdominal mass which is located in the upper right retro-peritoneum space and is often deformed due to compression by the host’s abdominal organ, and there are other manifestations. Our patient presented with abdominal mass and hydronephrosis caused by compression of the ureter via the mass.