Fetus in Fetu: A Rare Case Report and its Embryo-Pathogenesis

Fetus- in- fetu (fif), is a rare congenital anomaly that occurs due to malformed fetus growing inside the twin. it occurs due to the aberration in the diamniotic monochorionic monozygotic twinning with unequal division of inner cell mass of blastocyst leading to inclusion of small cell mass inside the developing sister fetus. the most common presentation will be with intra-abdominal mass located in the upper quadrant retroperitoneally. complete excision with meticulous dissection is curative and allows confirmation of diagnosis.