A two-and-a-half-month-old, first-born, Asian Indian baby boy was admitted to the department of Pediatric surgery, S.S hospital, BHU, due to recurrent episodes of vomiting and abdominal distension since he was one month old. Upon examination of the baby's abdomen we discovered that a smooth, firm and non-tender mass was present in the left half of his abdomen. Conventional X-ray of the abdomen showed a soft tissue mass with a vertebrae-like column (Figure ). An ultrasound of the baby's abdomen showed a large, encysted, hyperechoic and calcified heterogenous complex mass. A 64-slice CT scan of his abdomen revealed a soft tissue mass that had a bony outline resembling a fetus (Figures and ). Interestingly, we found nothing significant in the baby's family history.
Plain X-ray of the vertical calcification on the left side of the abdomen.
Abdominal computed tomography of the fetus with a large encapsulated peritoneal cavity mass and mature vertebral skeleton.
A 64-slice computed tomography scan of the bony outline of the fetus in fetu.
We performed an elective laparotomy after correcting the baby's fluid and electrolyte levels. We then found a well-encapsulated cystic retroperitoneal mass that was displacing his spleen, transverse colon and pancreas. This displacement presented laterally and caudally toward his cephaloid and left kidney (Figure ). The mass had a separate blood supply connected to the baby's abdominal aorta just below his left renal artery. We mobilized, without complication, his left colon, pancreas, duodenum and small bowel, after which we were able to excise the mass completely.
Intra-operative picture of the fetus in fetu enveloped by a sac.
The sac contained two miniature fetuses connected to each other by a cord-like structure at the umbilicus. The miniature fetuses had a well-defined foot, skin with hairs, a convex and pliable skull bone, and other undifferentiated tissues (Figure ). A radiograph of the specimen showed cranial bones and long bones with vertebral columns (Figure ). We then performed a macroscopic pathological examination, from which we were able to note that the mass measured 20 × 8 × 5 cm. It was also composed of a head with hair, a trunk, and rudimentary limbs connected by cord-like structures. The mass corresponded to an incompletely developed twin fetus.
Twin fetus in fetu connected by a cord-like structure.
Plain X-ray of the fetal specimen with a vertebral column.
A microscopic examination showed that the underdeveloped twin had mature embryonic tissues containing elements of the three germinative layers. Skin, a vertebral column, germinative buds of limbs, central nervous tissue (encephalus and coroidal plexus), a stomach, small and large bowels, pancreas, adrenal glands, kidneys, upper and lower airways, cardiac striated muscles, and lymphoid tissue-like spleen were found. The histopathological study of the specimen supported the conclusion that the previously imaged calcifications could be assumed to be the skull and bony constituents of the vertebral axis, some parts of the skull, and bony constituents of the rudimentary limbs.
Our patient recovered well after the surgery and was discharged. To rule out any recurrence he was followed up through clinical examination, plain abdominal X-ray examination, abdominal ultrasound, and serum alpha-fetoprotein (AFP). We were unable to detect any recurrence of his previous symptoms one year after the operation.