A case report of fetus in fetu with an aorta-like structure visualized by contrast-enhanced CT

Abstract

Fetus in fetu (FIF) is a rare congenital anomaly resulting from abnormal embyogenesis in monochorionic diamniotic twins and appears as a cystic mass containing fetus-like structures mainly in the retroperitoneum of infants. Although there is a theory that FIF is a highly differentiated teratoma, it is commonly distinguished from teratoma as a mass containing a vertebral axis with appropriate arrangement of limbs or other organs around this axis. Here we present a case of FIF with aorta-like structure visualized by contrast-enhanced computed tomography. A 5-day-old girl was pointed out a cystic mass in the abdomen by ultrasound examination. Abdominal contrast-enhanced computed tomography revealed a retroperitoneal cystic mass with spine- and limb-like bone structures and blood vessel-like elongated structures and it was confirmed as FIF by surgery. The presence of major vascular structures along the skeletal axis is clearly different from teratoma and suggests that it occurred as an embryo and underwent some stage of development. Our findings strongly support the monozygotic twin theory.

Rare Fetus-in-Fetu: Experience From a Large Tertiary Pediatric Referral Center

“…According to the teratoma theory, FIF is a specialized form of teratoma with well-differentiated, highly organized, and mature organs. It shows organ differentiation, including the original heart, brain, eyeballs, intestines, and limbs, and thus, FIF is considered a highly differentiated teratoma ( 4 ). It has also been reported that teratomas and FIF appear at the same time.…”

“…Normal twins are deformed as symmetrical conjoined twins. FIF might result from abnormal embryogenesis in a diamniotic monochorionic twin pregnancy ( 4 , 6 ). In the early stage of embryonic development (blastocyst stage) of the fertilized egg, the totipotent cell cluster in the blastocyst divides into two or more cell clusters.…”

Retroperitoneal fetus in fetu presenting in a male infant: A case report and literature review

“…However, fetus in fetu can be found in adults [4] and in pregnant women [5] , the oldest patient with fetus in fetu recorded in the literature was 47 years old at diagnosis [6] . Fetus in fetu can parasitize any part of the host's body; however, the abdominal cavity and retroperitoneum are the most common sites [2 , 7 , 8] followed by the sacrococcygeal region and the abdominal wall. Other rare sites, such as the back, mouth and upper jaw, have also been reported, and very few cases have occurred in the brain [9 , 10] , mouth [11 , 12] , neck [13] , chest [14] and scrotum [15] .…”

A rare case of intrathoracic fetus in fetu / mature teratoma – pathological and imagistic aspects

“…Fetus in fetu (FIF) is a rare congenital anomaly with an incidence of one per 500 000 births [ 1 ]. Taher et al found 224 FIF reported cases [ 2 ].…”