Fetus in fetu--from prenatal ultrasound and MRI diagnosis to postnatal confirmation

Preoperative diagnosis of a "humanoid" fetus in fetu using multimode ultrasound: a case report

Background

Fetus in fetu (FIF) is a rare congenital anomaly. The preoperative diagnosis of FIF and differentiating it from teratoma and other abdominal tumors can be challenging for radiologists. Clarification of the blood supply and the relationship with the surrounding vessels is especially helpful for successful surgery; however, multimode ultrasound (US) performed for FIF has rarely been explored. Here, we first report a “humanoid” FIF case diagnosed by multimode US examinations, with the use of contrast-enhanced ultrasound (CEUS) for clarifying the blood supply features.

Case presentation

A 25-day-old preterm male infant was referred to our hospital for surgery. The US and computed tomography (CT) examinations led to a diagnosis of teratoma at the local hospital. The laboratory workup at our hospital revealed an elevation of total bilirubin, direct bilirubin, indirect bilirubin, alpha-fetoprotein, and neuron-specific enolase levels. A precise diagnosis and differentiation from teratoma, hepatoblastoma, neuroblastoma and other abdominal tumors were needed. In addition, the blood supply and the relationship with the surrounding vessels needed clarification prior to surgery. Multimode US examinations were performed and the features of a “humanoid” FIF as well as the blood supply for the abdominal lesion of the infant were suggested by grayscale US, color Doppler flow imaging (CDFI), and CEUS. Furthermore, CDFI and CEUS revealed an aorta-like structure and umbilical cord-like blood vessels in the “humanoid” FIF, and the CEUS helped with marking the surface of the infant’s abdominal wall. To the best of our knowledge, this is the first case report of CEUS in FIF, and the blood supply was clearly demonstrated in the FIF. The intraoperative findings confirmed our multimode US findings and revealed a “humanoid” FIF. The infant quickly recovered after the operation and had no positive findings at the 2-year follow-up visit.

Conclusions

Multimode US was helpful in diagnosing the rare FIF without radiation exposure. Specifically, CEUS clearly demonstrated the limb branch vessel-like structures, the abdominal aorta-like structure and the blood supply, which was useful for the FIF diagnosis and for avoiding damage to important vessels during the operation.

Fetus-in-fetu: two case reports

The objective of our study is to describe the sonographic findings of an extremely rare pathology. We therefore present two case reports of prenatal diagnosis of fetus-in-fetu (FIF) with a review of the literature. FIF is a benign disorder, unlike the teratoma with which often enter into the differential diagnosis, localized in most cases in the retroperitoneal space. Prenatal diagnosis is based mainly on ultrasound and radiological characteristics. The treatment of choice is surgical excision. The importance of prenatal diagnosis of fetus-in-fetu and the effect on subsequent management are described.

Impact of prenatal diagnosis of fetus-in-fetu

Fetus in fetu (FIF) is an extremely rare condition (1/500,000 live births) in which a fetiform structure is incorporated into the body of its twin. FIF can be a diagnostic dilemma due to its similarity to a teratoma, but identification of FIF is important for subsequent medical and surgical management. We compare two cases of fetal masses diagnosed on prenatal imaging that were later identified as FIF through further radiological, surgical, and pathologic evaluation. We use these cases to illustrate key pre- and postnatal features of FIF and highlight the benefits of prenatal detection and follow-up for postnatal management.

Fetus-in-fetu: imaging and pathologic findings

A 3.5-month-old boy was hospitalized because of an abdominal mass found accidentally. On physical examination, a smooth, firm, nontender mass was present in the right upper quadrant. Abdominal ultrasonography revealed a large, hyperechoic, heterogenous mass with clear boundaries, and scarce blood flow. Abdominal CT scan showed a bulky right retroperitoneal mass. Three-dimensional CT imaging demonstrated spine, iliac bone, and long bones of limbs. The mass was excised successfully. After opening the sac it was noted to contain an incompletely developed fetus with grossly visible limbs, clearly discernible male genitalia, hairs, and a poorly formed head. The fetus was connected to the sac via an 8 cm cord-like structure. Microscopic examination of the mass revealed the presence of skin, cartilage, bone, intestine, and cysts with simple cuboidal epithelium. The use of CT scans enhanced the accuracy of pre-operative diagnosis. Identification of the vertebral column and the long bones of limbs are important indications for the diagnosis. Pathologically, fetus in fetu has many characteristics different from teratoma.

Orocervical foetus-in-foetu with prenatal sonographic diagnosis: a case report

Introduction

Foetus-in-foetu is a very rare congenital abnormality where a malformed foetus is included within the body of another foetus. Less than 200 cases have been reported with over 80% occurring in the abdomen. Only three cases of cervical foetus in foetu have been reported. The present case of giant orocervical foetus-in-foetu appears to be an index case.

Case presentation

This is a report of an extremely rare orocervical foetus-in-foetu with grotesque oddity diagnosed on prenatal ultrasonography at 35 weeks gestational age in a 28-year-old, G2P1+0, Nigerian woman who was unsure of her last menstrual date or month. The included foetus had two eyes, cranium, nose, long bones and a spine. The mother's attempts at vaginal delivery rather than the elective Caesarean delivery she was offered resulted in obstructed labour and intrauterine foetal demise.

Conclusion

Giant cervical foetus-in-foetu is extremely rare. It could result in obstructed labour if vaginal delivery is attempted.