Fetus-in-fetu: two case reports

A Unique Case of Eight Fetuses in a Single Fetu

Fetus in fetu is a rare congenital anomaly in which a malformed parasitic twin is found within the body of a living child or adult. In this case report, a 1-day-old child presented with a large firm abdominal mass on the left side of the upper abdomen. Imaging studies misdiagnosed the mass as an intraperitoneal benign dermoid cyst displacing the bowel loops and internal viscera. A surgical resection was performed on 21 days of life, and pathology confirmed eight fetuses inside the cyst.

Prenatal diagnosis of well-developed fetus in fetu with spontaneous movement in a resource-limited setting: A case report

Fetus in fetu (FIF) is a rare congenital anomaly characterized by the presence of a parasitic monozygotic twin encased within the body of its host twin. Because FIF is asymptomatic throughout pregnancy, it is mainly diagnosed in children with an abdominal mass after birth. In the case reported here, at 38-39 weeks of gestation, a 33-year-old woman (gravida 4, para 3) was referred for routine obstetric ultrasonography. Fluid accumulation was identified along with calcification resembling two well-developed legs and trunk with undifferentiated organs inside. Slight spontaneous movement of the legs was observed. The fetus was delivered based on the presumed diagnosis of FIF. Postnatal sonography and computed tomography (CT) supported the diagnosis. The neonate underwent surgical excision of the tumor and was discharged on the eighth postoperative day. Ultrasound can be used to provide accurate prenatal diagnosis of FIF. Early diagnosis is important to improve outcomes.

Ultrasound diagnosis of a retroperitoneal fetus in fetu: A case report

Fetus in fetu (FIF) is a rare anomaly of diamniotic monochorionic twins, where a malformed fetus resides within the body of its twin. Most FIF occurs in the retroperitoneal region around the host spine and appears prenatally as a solid-cystic mass consisting of fetal-like structures. Imaging has an important role in the diagnosis of FIF. The present study reported a single case, a 45-year-old woman, with a teratoma in a third-trimester fetus diagnosed after prenatal ultrasonography (US), which showed a mass containing fetus-like echoes. FIF was considered after the US showed that the mixed solid-cystic retroperitoneal mass around the vertebral axis of the host fetus consisted of two separate masses, each containing distinct fetal visceral structures. One fetus was acardiac and the other parasitic fetus was visible with a weak heartbeat. Postpartum magnetic resonance imaging and ultrasonography (US) scans of the newborn showed a retroperitoneal cystic space-occupying mass with distinctive limbs and visceral structures. The pathological examination further confirmed the diagnosis of retroperitoneal FIF. Also, a prenatal US could detect FIF in utero. A cystic-solid mass containing long bones, vascular pedicles, or visceral structures around the vertebral axis of the host fetus in the US might suggest the possibility of a FIF.

Intrathoracic mass in a 5-month-old infant: fetus in fetu—a case report

Background

The fetu in fetu (FIF) is an extremely rare congenital condition characterized by a 2nd fetus that grows into the body of the healthy twin. Its thoracic location is more exceptional.

Case presentation

We report a case of intrathoracic mass in a 5-month-old female infant, diagnosed after an assessment for respiratory distress. She underwent an emergency left thoracotomy which allowed for the removal of a large thoraco-mediastinal mass inside a membranous sac containing a clear liquid mixed with vernix caseosa. The mass was completely covered with normal skin, three lobes similar to rudimentary outline of the head and limb. It was attached to a single large vascular pedicle. The pathological examination concluded that there was a high possibility of FIF. The postoperative follow-up was uncomplicated, and the child is still in good clinical condition after the 5-month follow-up.

Conclusion

The assessment of the respiratory distress in an infant with a mass centered by an axial skeleton on the chest x-ray and thoracic CT scan may suggest a diagnosis of intrathoracic FIF.

Retroperitoneal parasitic fetus: A case report

BACKGROUND

Fetus-in-fetu (FIF) is an extremely rare congenital abnormal mass, in which a normal fetus’s vertebral axis frequently connected with malformed fetus around this axis. Here, we report the case of a male infant aged 26 d presenting with retroperitoneal parasitic fetus.

CASE SUMMARY

In a prenatal examination, we first detected an abdominal mass measuring 7.8 cm × 5.1 cm × 6.8 cm in a mother’s abdomen at 25 gestational weeks and teratoma was suspected. After the fetal was born, we did a magnetic resonance imaging (MRI) and ultrasonography on him and saw a distinctive limb with five-toes. According to the result of MRI, ultrasonography and postoperative pathology, he finally was diagnosed with FIF.

CONCLUSION

A laparotomy was performed at 26 d of age with excision of the retroperitoneal cystic tumor, which measured about 10 cm in diameter. According to the result of imaging and histological test, FIF was confirmed.

Prenatal and postnatal MRI imaging findings of intracranial parasitic fetus: a case report

Fetus in fetu (FIF) is an extremely rare anomaly. It is predominantly seen retroperitoneally in 80% of cases but can present at atypical sites like the skull, sacrum, scrotum and the mouth. We reported a rare case of intracranial parasitic fetus. We described the prenatal and postnatal MRI findings of the case. There was no obvious spinal signal on the imaging findings at 35 weeks of gestation. However, the postnatal MRI revealed spinal column signal at 5 months and 11 days.

Fetus in fetu: two case reports from North African country

Background

Fetus in fetu is a rare congenital anomaly. The exact etiology is unclear; one of the mostly accepted theories is the occurrence of an embryological insult occurring in a diamniotic monochorionic twin leading to asymmetrical division of the blastocyst mass. Commonly, they present in the infancy with clinical picture related to their mass effect. About 80% of cases are in the abdomen retroperitoneally.

Case presentation

We present two cases of this rare condition. The first case was for a 10-year-old girl that presented with anemia and abdominal mass, while the second case was for a 4-month-old boy that was diagnosed antenatally by ultrasound. Both cases had vertebrae, recognizable fetal organs, and skin coverage. Both had a distinct sac. The second case had a vascular connection with the host arising from the superior mesenteric artery. Both cases were intra-abdominal and showed normal levels of alpha-fetoprotein. Histopathological examination revealed elements from the three germ layers without any evidence of immature cells ruling out teratoma as a differential diagnosis.

Conclusions

Owing to its rarity, fetus in fetu requires a high degree of suspicion and meticulous surgical techniques to avoid either injury of the adjacent vital structures or bleeding from the main blood supply connection to the host. It should be differentiated from mature teratoma.

Prenatal diagnosis of a "living" oropharyngeal fetus in fetu: a case report

BACKGROUD

Fetus in fetu (FIF) is a rare malformation in which a parasitic twin within its more mature twin. Most of the FIF locate in the retroperitoneum and are acardiac and anencephalic.

CASE PRESENTATION

Here, we describe a unique case of oropharyngeal fetus in fetu with a rudimentary two-chambered heart detected by prenatal ultrasonography. The parents terminated this pregnancy after counseling. Macroscopic examination found a solid mass between the oral and fetal chest, with a rudimentary two-chambered heart at the lowest part of the mass. Microscopic findings showed amniotic membrane, skin, cartilage, gastrointestinal and neural tissue.

CONCLUSIONS

Prenatal ultrasound can identify rudimentary organs suspecting FIF from early pregnancy. Detection of fetal heart beat facilitates differential diagnosis with teratomas, providing essential information for parental consulting and management.