Year : 2010 | Volume
: 53 | Issue : 1 | Page : 128--129
Fetus-in-fetu presenting as acute intestinal obstruction
Sunita Singh1, Kamal Rattan2, Navtej1, Meenu Gil2, SK Mathur1, Rajeev Sen1,
1 Department of Pathology, Pt. B.D. Sharma PGIMS, Rohtak, Haryana-124 001, India
2 Department of Paediatric Surgery, Pt. B.D. Sharma PGIMS, Rohtak, Haryana-124 001, India
881/23, DLF Colony, Rohtak, Haryana-124 001
Fetus-in-fetu is a rare condition in which a fetiform calcified mass is often present in the abdomen of its host; a newborn or infant. We present the case of a three-month-old male baby with acute intestinal obstruction and abdominal mass. X-ray abdomen and ultrasonogram revealed a cystic mass with calcification. On laparotomy, a well encapsulated retroperitoneal mass causing high intestinal obstruction was identified. Total excision of the mass was done. Diagnosis of fetus-in-fetu was confirmed on histopathology. Postoperative recovery was uneventful.
|How to cite this article:|
Singh S, Rattan K, Navtej, Gil M, Mathur S K, Sen R. Fetus-in-fetu presenting as acute intestinal obstruction.Indian J Pathol Microbiol 2010;53:128-129
|How to cite this URL:|
Singh S, Rattan K, Navtej, Gil M, Mathur S K, Sen R. Fetus-in-fetu presenting as acute intestinal obstruction. Indian J Pathol Microbiol [serial online] 2010 [cited 2021 Dec 9 ];53:128-129
Available from: https://www.ijpmonline.org/text.asp?2010/53/1/128/59203
Meckel  coined the term fetus-in-fetu (FIF), defined as a parasitic twin, in the 18 th century. Since then sporadic cases have been reported. It has a reported incidence of 1 per 5,00,000 live births.  This rare malformation has some similarities with retroperitoneal teratoma but is different from the latter by its fetiform aspect and metameric segmentation of its spinal axis. 
A three-month-old male child presented with vomiting, massive abdominal distension and respiratory distress. On examination, the abdomen was distended with a palpable mass in upper abdomen.
After adequate resuscitation, intra venous fluids, nasogastric intubation and antibiotics, the child was taken for laparotomy. On laparotomy, there was a well encapsulated retroperitoneal mass in the upper abdomen causing superior displacement of pancreas and compression of duodenum in the lesser sac. Total excision of the mass was done. Gross examination showed a multinodular, multicystic, gray-brown soft tissue mass measuring 9x8x6 cm. Cut surface showed chondroid areas, developing vertebral axis along with multiple cysts filled with clear fluid and a tubular gut like structure (marked with needles, [Figure 1]). Microscopically, well formed gut wall [Figure 2], chondroid tissue, neural tissue, developing vertebral column [Figure 3] and cystic spaces lined by stratified squamous epithelium were seen. Postoperative recovery was uneventful. The child is on regular follow-up and is well after eight months.
FIF is discovered most commonly in infancy as a retroperitoneal mass.  Majority of the cases occur in children younger than 18 months of age.  In most cases (80%), FIF is present intra abdominally in the upper part of retroperitoneal space.  Rare locations like cranial cavity, pelvis, scrotal sac, sacrococcygeal region, mesentery and right iliac fossa are also reported. Usually there is a single parasitic fetus but some cases of more than one have been reported.  The size and weight of fetus varied from 4 cm to 2.5m and 1.2 gms to 1.8 kg respectively. 
Symptoms of FIF relate to its mass effect in the area of its occurrence and in its most common location causes abdominal distension, feeding difficulty, emesis and rarely jaundice. , In our case, the presentation was upper intestinal obstruction with respiratory distress due to the large size of FIF in the upper retroperitoneal area. Like most of the cases described in literature, vertebral column was detected by the pathologist. In our case, it was radiolucent on radiography because of insufficient calcification.  It was, therefore, in accordance with Willis theory, according to which FIF is a mass containing a vertebral axis often associated with other organs or limbs around this axis. It arises from inclusion of monozygotic diamniotic twin within the bearer. Presence of vertebral axis (which develops from the primitive streak), appropriate arrangement of other organs or limbs with respect to the vertebral axis are the diagnostic features of FIF and these features help in differentiating this entity from the highly differentiated teratoma. 
FIF has characteristic imaging features. Plain abdominal radiographs may show a vertebral column and/or bony structures within a soft tissue mass.  Computerized Tomography (CT) features are diagnostic of this entity. This information aids in surgery, the treatment of choice for this condition.
FIF shows varying degree of organ system differentiation and deformity. Symmetric arrangement of the vertebral axis is required for diagnosis. The masses are often enclosed within membranes resembling amnion. The closest differential diagnosis is a retroperitoneal teratoma. The distinction can be made from teratoma, as there is evidence of axial skeleton formation in FIF. It is a histologically proven benign entity but one case of malignant transformation and recurrence has been reported.  The treatment of choice is complete surgical resection.
In conclusion, the diagnosis of FIF should be considered in a child with a history of a slowly growing lump in abdomen in an appropriate clinical setting. A CT scan allows the prospective diagnosis of this very rare disease entity and aids in differentiation from retroperitoneal teratoma.
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