Fetus in fetu: an institutional experience

Retroperitoneal fetus in fetu presenting in a male infant: A case report and literature review

Fetus in fetu (FIF) is a rare congenital disease caused by the abnormal development of monochorionic diamniotic twins that appears as a cystic mass containing fetus-like structures mainly in the retroperitoneum of infants. The clinical manifestations of fetus in fetu vary, but they mostly present at infancy, hence, it should be differentiated from a teratoma. Here, we report a case of an infant with fetus in fetu in the retroperitoneum. Enhanced computed tomography scans and three-dimensional images showed a huge mixed-density mass on the left side of the abdominopelvic cavity with patchy distribution of fat, intact bones, and soft tissue. The child underwent fetus in fetu resection under general anaesthesia. Histopathology confirmed that the mass contained skin, muscle, intestinal mucosa, bones and cartilage, nerves, muscles, fat, and bone marrow tissue.

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.

Fetus in Fetu in the Scrotal Sac: Case Report and Literature Review

Fetus in fetu (FIF) is a rare congenital anomaly. The most common site at which FIF occurs is the retroperitoneum. The mechanisms underlying the development of FIF have not been fully elucidated. The monozygotic twin theory postulates that FIF results from the unequal division of the totipotent cells of the blastocyst. However, the monozygotic twin theory does not explain all cases of FIF.Herein, we describe the clinical characteristics of a 20-day-old infant with scrotal sac swelling. Ultrasonography and computed tomography revealed the presence of a mass consistent with a FIF rather than a teratoma. Surgical removal and a subsequent pathological evaluation demonstrated that the anencephalic fetus exhibited limb buds adjacent to a palpable vertebral column, supporting the diagnosis of FIF. The infant had an uneventful recovery and was discharged on the fifth postoperative day. In the present report, the pathogenesis, presentation, diagnosis, and management of FIF, as well as new concepts emerging in this area of research, are discussed.Although the majority of cases of FIF may be diagnosed preoperatively, FIF should be distinguished from teratoma because the latter has substantial malignant potential. The recommended treatment for FIF is complete resection. To confirm the diagnosis of FIF, pathological examination, karyotyping, serologic marker assessment, and DNA restriction site mapping should be performed after removing the mass. Although FIF is thought to be a benign disorder, follow-up is necessary as a precaution against malignant recurrence, which has been described once.