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 Table of Contents  
Year : 2021  |  Volume : 54  |  Issue : 3  |  Page : 114-117

Retroperitoneal fetiform teratoma in an infant

1 Department of Paediatric Surgery, Sawai Man Singh Medical College, Jaipur, Rajasthan, India
2 Department of Pathology, Sawai Man Singh Medical College, Jaipur, Rajasthan, India
3 Department of Radiodiagnosis, Sawai Man Singh Medical College, Jaipur, Rajasthan, India

Date of Submission13-Jan-2021
Date of Decision26-Jan-2021
Date of Acceptance16-Apr-2021
Date of Web Publication12-Jun-2021

Correspondence Address:
Rahul Gupta
Department of Paediatric Surgery, Sawai Man Singh Medical College, Jaipur, Rajasthan
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/fjs.fjs_9_21

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Fetus in fetu is a rare intra-abdominal mass secondary to abnormal embryogenesis in a diamniotic monochorionic pregnancy. Teratoma, unlike fetus in fetu, does not show the vertebral axis or regional distribution of the organs. We report a 9-month-old male infant who presented with a large abdominal lump. The retroperitoneal mass was excised. On opening the sac, well-formed fetus-like structure was seen. The mass was connected to a yolk sac-like structure. The mass had the rudimentary head, thorax, abdomen, and finger-like buds giving a fetiform appearance but without vertebral column. Histopathological examination confirmed fetiform teratoma. The outcome was favorable.

Keywords: Fetiform, infant, retroperitoneal, teratoma

How to cite this article:
Gupta R, Mittal P, Jindal A, Mathur P, Jakhar S, Bhandari A. Retroperitoneal fetiform teratoma in an infant. Formos J Surg 2021;54:114-7

How to cite this URL:
Gupta R, Mittal P, Jindal A, Mathur P, Jakhar S, Bhandari A. Retroperitoneal fetiform teratoma in an infant. Formos J Surg [serial online] 2021 [cited 2021 Jul 24];54:114-7. Available from: https://www.e-fjs.org/text.asp?2021/54/3/114/318216

  Introduction Top

Fetiform teratoma (homunculus) has been recognized as a rare form of teratoma resembling fetus.[1] There are less than 30 cases of Fetiform teratoma described in the literature with only one recent report in an infant.[2] We present a very rare case of retroperitoneal fetiform teratoma in an 9 months-old infant.

  Case Report Top

A 9-month-old male child weighing 7 kg, presented with an abdominal lump. His mother noticed a gradually increasing abdominal swelling 3 months ago (at around 6 months of age). No history of drugs, twinning, and the congenital anomaly was present in the family. The child was pale. Abdominal examination revealed fullness in the right hypochondrium. There was a large round non-tender mass of variable consistency occupying the whole right half of the abdomen [Figure 1]. Plain X-ray showed a soft tissue mass in the right of the abdomen with bones and calcification giving suspicion of teratoma. Abdominal ultrasonography showed a well-defined, thick-walled, multi-cystic, soft tissue mass with fat content and calcifications or bony elements [Figure 1]. An abdominopelvic computerized tomography scan revealed a well-defined 8 cm × 6.8 cm × 6.4 cm heterogeneous density solid and cystic mass [Figure 2]. The mass occupied the whole right side of the retroperitoneum. The internal structure of the mass contained fluid, fat, soft tissues, and bony elements. Baseline blood investigations revealed anemia (Hb-8.5% g); Alpha-fetoprotein (AFP) level was 9.03 ng/ml. Renal and liver functions were normal. The preoperative radiological diagnosis was retroperitoneal teratoma.
Figure 1: Preoperative clinical photographs (a and b) of the patient revealing large abdominal lump occupying right half of the abdomen; abdominal ultrasound film revealing solid-cystic retroperitoneal mass

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Figure 2: Contrast-enhanced computed tomography images (coronal images-[a-e]; c-sagittal; [f]-transverse) revealing large heterogeneous density solid-cystic mass with internal calcification, fatty attenuation and fetiform appearance

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Preoperative preparation was performed. At laparotomy, the mass was enclosed in a complete sac and retroperitoneal (right hypochondrium) in location. It was abutting the C-loop of the duodenum and the pancreas, leading to widening and stretching of the duodenum. It was also pushing the mesentery of the small bowel and right colon anteriorly, right kidney inferiorly, and indenting the right lobe of the liver. Dense adhesions to surrounding structures were noted. The mass was supplied by major vessels originating from the aorta, superior mesenteric artery, and surrounding retroperitoneum [Figure 3]. It was dissected from surrounding structures and excised completely [Figure 3].
Figure 3: Intra-operative photographs of the patient revealing large encapsulated tumor in the retroperitoneum (a) pushing the small bowel mesentery and right colon anteriorly; excised tumor with gap in the mesentery (b); tumor bed (c)

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The excised retroperitoneal mass was encapsulated. It was brown, globoid, measuring 9.0 cm × 5.0 cm × 5.0 cm and weighted 350 g [Figure 4]. Plain radiograms of the specimen showed well-formed bony structures [Figure 5]. On opening the sac, well-formed fetus-like structure was seen. The mass was connected to a yolk sac-like structure. It had the rudimentary head, thorax, abdomen, and finger-like buds representing lower limbs giving a fetiform appearance [Figure 4]. Fetiform structure was covered by skin, bearing fine lanugo hair. Further dissection of the mass revealed the absence of vertebral column nor recognizable intra-abdominal structures [Figure 4]. Postoperative recovery was smooth.
Figure 4: Photographs showing excised encapsulated tumor (a); on opening the tumor, fetus like mass connected to yolk sac like structure is appreciated (b); long hairs arising from head end of the fetiform structure (c) absence of vertebral column on dissecting the fetiform structure (d)

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Figure 5: Radiographs (a and b) of the excised specimen showing well formed bony structures within mass

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Histopathological examination revealed a mass partly covered by skin, with the underlying stroma showing pilosebaceous units. The stroma also showed mature adipose tissue, tubular glands lined by respiratory epithelium, sero-mucinous glands, and mature glial tissue [Figure 6] with choroid plexus, lymph nodes, eccrine glands, blood vessels, nerves, cartilage, and bone with marrow. Limb bud was noted in one focus [Figure 6]. Solid areas with mature elements were noted, categorizing the teratoma as mature.
Figure 6: H and E stained sections (10 × 10) of mature teratoma with (a) pigmented epithelium; (b) lymphoid collection and intestinal mucosa; (c) cerebral folia; (d) keratinized squamous epithelium with skin adenexae; (e) thymic tissue; (f) limb bud

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  Discussion Top

Fetiform teratoma is a rare form of teratoma resembling a malformed fetus.[1],[2] Fetus in fetu is a rare intra-abdominal mass usually presenting in pediatric patients.[3] It is a type of parasitic twinning secondary to abnormal embryogenesis in a diamniotic monochorionic pregnancy.[3] It exhibits several organ systems and has an imperfect vertebral column that allows discernment of symmetry.[3]

Teratoma is the presence of a variety of tissues with or without high differentiation in an abnormal location of the body.[1],[2] The word teratoma is derived from the Greek word “teraton,” meaning “monster.” Teratoma is a relatively common embryonic neoplasm arising from totipotent cells and contains elements from all three germ layers. Teratoma, unlike fetus in fetu does not show the vertebral axis (or notochordal axis) or regional distribution of the organs.[4] In infancy and early childhood, the most common site of teratoma is the extragonadal region (including retroperitoneal region) purported to originate from migrated totipotent germ cells.

Although teratoma may present in any age group, the majority are under 17 months and also has a female preponderance. Our case was a 9-month-old male infant.[2] Immature neuroectodermal tissues may be present in teratoma, however, in our case, the tumor was of mature type. No immature elements were noted [Figure 6]. Limb bud structures were noted in the sections along with cerebral folia [Figure 6].

Rarely, teratoma develops a high degree of differentiation and organization resembling a malformed fetus (or fetiform appearance) which is known as fetiform teratoma or homunculus.[5] Homunculus is a Latin word meaning “little man.” In some cases, the cephalic region is more developed; whereas in others, the lower extremities and caudal region are more developed. Due to risk of malignancy, fetiform teratoma should be distinguished from fetus in fetu.[2]

Clinically, fetiform teratoma and fetus in fetu present differently. Most cases of fetuses in fetu present as an abdominal mass (retroperitoneal) in infancy. On the contrary, fetiform teratoma is most commonly discovered as an ovarian mass in the reproductive age group.[5] In the present case, the excised retroperitoneal mass had a fetiform gross appearance. Venkatachala and Shanthakumari have reported a similar case of retroperitoneal fetiform teratoma but with immature elements on microscopic evaluation.[2] Almost all reported cases of fetiform teratoma are composed of mature tissue.[1],[2],[6] Anemia in the presented case was due to (i) nutritional deficiency and (ii) loss of appetite due to large abdominal lump and abdominal fullness following feeds.

Raised serum AFP levels in patients with immature teratoma have a higher risk of malignancy than those with normal serum AFP levels. In our case, the AFP level was not elevated.[7] Fetiform teratoma and fetus in fetu can be differentiated based on zygosity.[1],[5] Cytogenetic or molecular studies may be helpful in further illustrating this entity. Zygosity and/or karyotyping could not be performed due to resource limitations in our setup.

  Conclusion Top

Fetiform teratoma is a rare form of teratoma that is developed and organized, resembling a fetus-like structure. Its identification requires thorough clinical and pathologic examination. Complete surgical excision remains the best choice to manage retroperitoneal fetiform teratoma.

Declaration of patient consent

The authors certify that they have obtained appropriate patient's guardian consent form. In the form, the guardian has given the consent for the child's images and other clinical information to be reported in the journal. The guardian understands that the child's name and initial will not be published and due efforts will be made to conceal the identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Greenberg JA, Clancy TE. Fetiform teratoma (homunculus). Rev Obstet Gynecol 2008;1:95-6.  Back to cited text no. 1
Venkatachala S, Shanthakumari S. Retroperitoneal fetiform teratoma. Indian J Pathol Microbiol 2010;53:581-2.  Back to cited text no. 2
[PUBMED]  [Full text]  
Goyal RB, Gupta R, Prabhakar G, Dagla R. Fetus in fetu: Report of two cases. APSP J Case Rep 2014;5:28.  Back to cited text no. 3
Brand A, Alves MC, Saraiva C, Loío P, Goulão J, Malta J, et al. Fetus in fetu—diagnostic criteria and differential diagnosis – A case report and literature review. J Pediatr Surg 2004;39:616-8.  Back to cited text no. 4
Weiss JR, Burgess JR, Kaplan KJ. Fetiform teratoma (homunculus). Arch Pathol Lab Med 2006;130:1552-6.  Back to cited text no. 5
Kuno N, Kadomatsu K, Nakamura M, Miwa-Fukuchi T, Hirabayashi N, Ishizuka T. Mature ovarian cystic teratoma with a highly differentiated homunculus: A case report. Birth Defects Res A Clin Mol Teratol 2004;70:40-6.  Back to cited text no. 6
Paradies G, Zullino F, Orofino A, Leggio S. Rare extragonadal teratomas in children: Complete tumor excision as a reliable and essential procedure for significant survival. Clinical experience and review of the literature. Ann Ital Chir 2014;85:56-68.  Back to cited text no. 7


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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