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Journal of Indian Association of Pediatric Surgeons
     Journal of Indian Association of Pediatric Surgeons
Official journal of the Indian Association of Pediatric Surgeons         
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Year : 2007  |  Volume : 12  |  Issue : 3  |  Page : 158-160

Giant retroperitoneal fetus-in-fetu: An unusual cause of respiratory distress

1 Department of Anesthesia, BP Koirala Institute of Health Sciences, Dharan, Nepal
2 Department of Surgery, BP Koirala Institute of Health Sciences, Dharan, Nepal
3 Department of Pathology, BP Koirala Institute of Health Sciences, Dharan, Nepal
4 Department of Medicine, BP Koirala Institute of Health Sciences, Dharan, Nepal

Correspondence Address:
Akshay Pratap
Department of Surgery, B. P. Koirala Institute of Health Sciences, Dharan
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-9261.34961

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Fetus-in-fetu (FIF) is a rare congenital condition in which a vertebrate fetus is incorporated within its host, a newborn or an infant. We report an interesting case of FIF presenting as an abdominal mass with respiratory distress in a 4-month-old girl, and review the existing literature. An ultrasound abdomen showed a right sided cystic mass containing multiple calcifications. Laparotomy revealed a well-encapsulated right retroperitoneal mass above the right kidney with two rudimentary limbs attached to an amniotic bag by an umbilical cord. Excision of the capsule revealed a yellowish fluid and an incompletely developed fetus covered by vernix caseosa. Pathologic examination showed an irregular fetiforme mass, weighing 1200 gm, with two rudimentary limbs, encephalus, stomach, duodenum, bowel, bone, cartilage, bone marrow, upper and lower respiratory tissue, and spleen. Complete excision of the FIF was performed. The postoperative period was uneventful and the patient was discharged on the seventh postoperative day.

Keywords: Fetus-in-fetu, intra-abdominal mass, monozygotic diamniotic twinning, teratoma

How to cite this article:
Singh SN, Pratap A, Sinha AK, Kumar A, Lakshmi R, Shakya VC, Agrawal A. Giant retroperitoneal fetus-in-fetu: An unusual cause of respiratory distress. J Indian Assoc Pediatr Surg 2007;12:158-60

How to cite this URL:
Singh SN, Pratap A, Sinha AK, Kumar A, Lakshmi R, Shakya VC, Agrawal A. Giant retroperitoneal fetus-in-fetu: An unusual cause of respiratory distress. J Indian Assoc Pediatr Surg [serial online] 2007 [cited 2023 Nov 29];12:158-60. Available from: https://www.jiaps.com/text.asp?2007/12/3/158/34961

   Introduction Top

Fetus-in-fetu (FIF) is a very rare condition, with a reported incidence of 1 in 500,000 live births. [1] It most likely represents a monozygotic diamniotic twin that implants itself and grows within the body of its normal karyotypically identical sibling. [2] Although abdominal masses are commonly encountered in pediatric oncology, the finding of a giant FIF causing severe respiratory distress is certainly unexpected. We report such a case of a giant FIF and highlight important features of this rare disorder.

   Case Report Top

A 4-month-old girl presented in the emergency department with massive abdominal distention and respiratory distress. Her SpO 2 was 82% on room air. Abdominal examination showed massive distention and a mass in the upper right abdomen. Abdominal ultrasonography showed a hypoechoic retroperitoneal mass containing multiple central irregular calcifications, which extended from the lower border of the liver to the hypogastric region. Based on these findings, teratoma was presumed to be the most likely diagnosis. Because of her deteriorating respiratory distress an emergency laparotomy was planned. On laparotomy, a well-encapsulated retroperitoneal mass behind the transverse mesocolon, measuring 20 cm 10 cm was found [Figure - 1]. This mass had a pedicle that was arising from the superior mesenteric artery. Excision of the capsule revealed a yellowish fluid and an incompletely developed fetus covered by vernix caseosa. Complete excision of the mass was performed. On macroscopic examination, the mass weighed 1200 gm, measured 20 15 8 cm, was ovoid, smooth surface, with two rudimentary limbs, a head and a trunk, corresponding to an incompletely developed fetus, [Figure - 2]A and B. A radiograph of the specimen showed presence of bone calcification; however, no vertebral axis was observed [Figure - 3]. The postoperative course was uneventful and the patient was discharged on the tenth postoperative day. On microscopic pathologic examination, it showed mature embryonic tissue containing elements of the three germinative layers. It was possible to show the presence of skin, germinative buds of limbs, central nervous tissue, alimentary tissue, bone, cartilage, and choroids plexus [Figure - 4]. Most of these cells were well-differentiated. The bony tissue was essentially composed of osteoblasts with little bone marrow. The nervous tissue was mostly formed by glial cells and choroids plexus. Even after an elaborate search, vertebral column was not seen.

   Discussion Top

FIF is a malformed parasitic monozygotic diamniotic twin that is found inside the body of the living child or adult. [2] It was first described by Meckel in 1800 and defined by Willis in 1953 as a mass containing a vertebral axis often associated with other organs or limbs around this axis. [3] It is a rare pathology, with an incidence of 1 in 500,000 births. [1] Majority of these cases occur in children younger than 18 months with the chief complaint of an abdominal mass. [4] As far as location is concerned, it is predominantly retroperitoneal in 80% of cases, [5] but could also be found in atypical locations, such as skull, [6] scrotum, [7] sacrum, [8] mouth, [9] and adrenal gland. [10] The fetus is usually single in 88% of the cases, although upto five fetuses have been found in the skull of a newborn. [11] Symptoms of FIF relate to its mass effect in the area of its occurrence and in its most common location cause abdominal distention, feeding difficulty, emesis, and rarely jaundice. [10],[12] In our knowledge, this is the first reported case where FIF presented with massive abdominal distention leading to respiratory distress. Only in 16.7% of these cases it is possible to show a preoperative diagnosis of FIF, differential diagnosis usually being teratoma and meconium pseudocyst. Occasionally, FIF can be identified on a prenatal ultrasound. [13] Plain abdominal radiograph may be helpful in diagnosis, which may show presence of vertebral column and axial skeleton. [10] With the advent of computed tomography and MRI it is possible to confirm the diagnosis pre-operatively. [14],[15],[16] Early and complete resection of the fetus and associated membranes is expected to offer complete cure. [4] The fetus is typically suspended by a pedicle within a sac containing fluid or vernix caseosa. Definite vascular connections to the host are rarely seen and if present arise from superior mesenteric artery or inferior mesenteric artery. [1],[10] The size of the FIF is related to its blood supply and can range from 13 to 2000 gm. [10],[17] The vascular pedicle in our case was significantly large, which accounted the weight of 1200 gm. The distinction between FIF and teratoma has for long been the subject of controversy. [18] According to Willis, the distinction is classically based on the absence of an axial skeleton in a teratoma. However, the radiology and pathology findings in our case and supported by other reports, clearly suggest that FIF can exist even in the absence of a vertebral axis. [19] To resolve this controversy, Gonzalez-Crussi have proposed that the definition of FIF is applied to any structure in which the fetal form is either in a very high development of organogenesis, as in our case or there is presence of a vertebral axis. [19] Although the prognosis for FIF is more favorable than for cystic teratoma, the presence of immature elements warrants early and frequent postoperative surveillance by clinical examination, imaging studies, and alpha fetoprotein. [20]

   References Top

1.Grant P, Pearn JH. Foetus-in-foetu. Med J Aust 1969;1:1016-20.  Back to cited text no. 1  [PUBMED]  
2.Grses N, Grses N, Bernay F. Twin fetuses in fetu and a review of the literature. Z Kinderchir 1990;45:319-22.  Back to cited text no. 2    
3.Willis RA. The structure of teratomata. J Pathol Bacteriol 1935;40:1-36.  Back to cited text no. 3    
4.Thakral CL, Maji DC, Sajwani MJ. Fetus-in-fetu: A case report and review of the literature. J Pediatr Surg 1998;33:1432-4.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]
5.Tada S, Yasukochi H, Ohtaki C, Fukuta A, Takanashi R. Fetus in fetu. Br J Radiol 1974;47:146-8.  Back to cited text no. 5    
6.Afshar F, King TT, Berry CL. Intraventricular fetus-in-fetu. Case report. J Neurosurg 1982;56:845-9.  Back to cited text no. 6    
7.Kakizoe T, Tahara M. Fetus in fetu located in the scrotal sac of a newborn infant: A case report. J Urol 1972;107:506-8.  Back to cited text no. 7  [PUBMED]  
8.Narasimharao KL, Mitra SK, Pathak IC. Sacrococcygeal fetus-in-fetu. Indian Pediatr 1984;21:820-2.  Back to cited text no. 8  [PUBMED]  
9.Seny OF, Rizalar R, Celayir S, Oz F. Fetus in fetu or giant epignathus protruding from the mouth. J Pediatr Surg 1992;27:1493-5.  Back to cited text no. 9    
10.Hoeffel CC, Nguyen KQ, Phan HT, Truong NH, Nguyen TS, Tran TT, et al . Fetus-in-Feto: A case report and literature review. Pediatrics 2000;105:1335-44.  Back to cited text no. 10  [PUBMED]  [FULLTEXT]
11.Kimmel DL, Moyer EK, Peale AR. A cerebral tumor containing five human fetuses: A case of fetus in fetu. Anat Rec 1950;106:141-65.  Back to cited text no. 11    
12.Federici S, Prestipino M, Domenichelli V, Antonellini C, Sciutti R, Dmini R. Fetus in fetu: Report of an additional, well-developed case. Pediatr Surg Int 2001;17:483-5.  Back to cited text no. 12    
13.Mills P, Bornick PW, Morales WJ. Ultrasound prenatal diagnosis of fetus in fetu. Ultrasound Obstet Gynecol 2001;18:69-71.  Back to cited text no. 13    
14.Tsai CH, Lin JS, Tsai FJ. Intraventricular fetus in fetu: Report of one case. Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi 1993;34:143-50.  Back to cited text no. 14  [PUBMED]  
15.Luzzatto C, Talenti E, Tregnaghi A, Fabris S, Scapinello A, Gugliemi M. Double fetus in fetu: Diagnostic imaging. Pediatr Radiol 1994;24:602-3.  Back to cited text no. 15    
16.Hanquinet S, Damry N, Heimann P, Delaet MH, Perlmutter N. Association of a fetus in fetu and two teratomas: US and MRI. Pediatr Radiol 1997;27:336-8.  Back to cited text no. 16  [PUBMED]  [FULLTEXT]
17.Eng HL, Chuang JH, Lee TY, Chen WJ. Fetus in fetu: A case report and review of the literature. J Pediatr Surg 1989;24:296-9.  Back to cited text no. 17  [PUBMED]  [FULLTEXT]
18.de Lagausie P, de Napoli Cocci S, Stempfle N, Truong QD, Vuillard E, Ferkadji L, et al . Highly differentiated teratoma and fetus-in-fetu: a single pathology? J Pediatr Surg 1997;32:115-6.  Back to cited text no. 18  [PUBMED]  [FULLTEXT]
19.Gonzalez-Crussi F. Extragonadal teratomas. In : Atlas of Tumor Pathology . 2 nd ser, fasc. 18. Armed Forces Institute of Pathology: Washington, DC; 1982.  Back to cited text no. 19    
20.Bassetto MA, Franceschi T, Lenotti M, Parise G, Pancheri F, Sabbioni R, et al . AFP and HCG in germ-cell tumors. Int J Biol Markers 1994;9:29-32.  Back to cited text no. 20  [PUBMED]  


  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]

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