Conjoined twins are monozygotic twins in which the inner cell mass does not completely split. The two embryos are joined by a tissue bridge. Incomplete division of embryonic disk after 13th day post conception results in the formation of conjoined twins. Spencer proposed an alternative theory of fusion of two originally separate monozygotic embryonic disks, to explain the conjoined twin etiology. Some authors suggested that parasitic twin occur as a result of selective ischemic damage in-utero leading to death or partial resorption of, one of the twins, resulting in an incomplete parasitic twin attached to a fully developed twin [
3,
4,
5].
Conjoined twin can be symmetrical or asymmetrical. Asymmetrical conjoined twins are called parasitic or heteropagus twins. It is further classified as
1- Externally attached parasitic twin
2- An enclosed fetus in fetu
3- An internal teratoma
4- Ancardiac connected via the placenta
The site and extent of twin fusion is extremely variable and the nomenclature is usually based on fused anatomical region as in this case the parasite was attached to the host in epigastric region so named as epigastric heteropagus [
6,
7]. In our case, parasitic twin had rudimentary limbs and external genitalia. As in many of the reported cases, parasitic twin had limbs and trunk formed to variable extent but was acephalic and acardiac. In our case the blood supply of the parasite was from falciform ligament as noted in most reported cases [
8,
9]. Epigastric heteropagus is a rare congenital malformation. The outcome and prognosis depends on the extent of visceral sharing and associated anomalies.
and Mahmood Shaukat
