Total removal of the malformed fetus was performed and confirmed to be fetus in fetu.

Fetus-in-fetu is a rare benign condition in which a non viable fetus is found in the body of its twin.

It is extremely rare with an incidence of 1:500,000 births. It is a type of monozygotic diamniotic twin.

Differential diagnosis is organized teratoma. Total excision of this malformed fetus is a definite cure.