Fetus-in-fetu in the scrotal sac of a newborn infant: imaging, surgical and pathological findings

Fetus in Fetu: A Rare Congenital Anomaly Diagnosed Postnatally by Ultrasonography and MRI

Fetus in fetu (FIF) is a rare congenital anomaly with two controversial theories regarding its embryogenesis. Although it is an extremely rare condition, it should be kept in mind as a differential diagnosis while evaluating children with abdominal calcification. Radiological findings on postnatal days 2 and 5 of a neonate with an antenatal scan showing an abdominal mass in the fetus are described here. Ultrasonography and magnetic resonance imaging (MRI) revealed the mass in which the contents favored a diagnosis of the FIF. Characteristic features of FIF on MRI have been less explored and knowledge regarding the same will be of immense help to the radiologist. Complete surgical excision followed by histopathology confirmed the diagnosis.

The First Case of Fetus in Fetu in Nicaragua: The Management Experience of the Pediatric Neurosurgery Team

Fetus in fetu (FIF) is a rare congenital anomaly of asymmetric monozygotic twins, where the parasitic twin develops abnormally inside the body of the host twin. In most cases, it is incorporated into the sibling's abdomen, which frequently presents as a retroperitoneal mass. Currently, at least 200 cases have been reported worldwide, being this the first case in Nicaragua. We describe a case of a male newborn, born via cesarean section, with a history of multiple congenital malformations observed via ultrasound examination. At birth, a mass is observed on its dorsum that impresses a skull, but without the presence of bones, with three limbs, two upper and one lower, with an outline located transversely on the pelvic girdle and the presence of two male genitalia with agenesis of the testicles and an accessory kidney. A preoperative diagnosis of FIF and spinal dysraphism was made by computed tomography (CT) and magnetic resonance imaging (MRI). They shared a spinal cord and had the presence of an open spinal defect type meningocele with aberrant roots. After the diagnosis and discussion, the multidisciplinary team proceeded to surgery to perform the separation of the twin (FIF). The subsequent anatomopathological examination revealed that the fetus was anencephalic and had reliable FIF characteristics. The resection was performed followed by the closure of the 430 mL meningocele and complete separation of the spine and the parasitic twin. We present the first case of fetus in fetu in Nicaragua.

Scrotal fetus in fetu in a newborn: A rare case report

Fetus in fetu is a rare phenomenon of infancy, separate from conjoined twins, teratomas, and acardiac twins. The pathogenesis is not well understood but has been theorized to originate from either the involution of a twin or the differentiation of a teratoma. While the majority of these are found in the retroperitoneum, the presence of a fetus in fetu within the scrotum is exceedingly rare. We present the diagnosis and management of a case of fetus in fetu in the scrotum of a newborn male including radiologic imaging and pathologic examination.

Fetus in fetu: use of intraoperative ultrasound for safe excision of a rare entity

A prenatally diagnosed abdominal mass at 36 weeks and 0 days was further characterised by postnatal ultrasound and MRI to be likely a rare case of fetus in fetu in an otherwise healthy male. Due to close proximity to both the coeliac axis and superior mesenteric artery (SMA), surgical excision was delayed for several months. Interim CT with intravenous contrast performed at 2 months of age demonstrated the SMA travelling through the posterior aspect of the mass. Surgery proceeded at 2 months of age. Intraoperative ultrasound was used to definitively identify both the coeliac axis and SMA in order to facilitate a safe excision. The patient recovered well with an uneventful discharge to home on postoperative day 8. Pathology confirmed the diagnosis of fetus in fetu.

A rare case of fetus in fetu in the sacrococcygeal region: CT and MRI findings

BACKGROUND

Fetus in fetu is a rare condition in which a malformed fetus is found in the body of a living twin. The retroperitoneum is the most common location of this condition. However, the sacrococcygeal region is a rare site of the disease. The presence of vertebral bodies and limbs differentiates FIF from teratoma. Imaging modalities are important for diagnosing FIF.

CASE PRESENTATION

A 12-months old boy was hospitalized because of a mass in the sacrococcygeal region. CT showed a large, complex mass with bony structure resembling sacrococcygeal bone, hip bone and the femur in the sacrococcygeal region of the boy. The blood supply of the mass was from the aorta of the host. MRI revealed the mass was connected with the dilated sacral canal of the host, which resulted in tethered cord. A preoperative diagnosis of FIF was made and surgery was performed to remove the mass. Surgical removal and subsequent pathological examination revealed the anencephalic fetus had limb buds and a sacrum but no axial skeleton, which supported the diagnosis of FIF. Conclusions CT and MRI played important roles in diagnosing FIF based on the location of the lesion.

Perinatal diagnosis and management of oropharyngeal fetus in fetu: A case report

Fetus in fetu is an extremely rare congenital anomaly. We describe the perinatal diagnosis and management of a fetus with oropharyngeal and cervical fetus in fetu. High-resolution ultrasonography with 3-dimensional rendering can identify increased risks of airway obstruction in utero. Early identification allows a multidisciplinary team to be assembled for a scheduled ex utero intrapartum treatment procedure.

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.

Fetus in fetu: two case reports and literature review

BACKGROUND

Fetus in fetu is a rare congenital anomaly and is defined as a monozygotic twin incorporated into the abdomen of its sibling during development. Fetus in fetu is often overlooked in the differential diagnosis of an abdominal mass. Unlike teratomas, fetus in fetu is a benign disorder.

CASE PRESENTATION

We describe the clinical characteristics of two patients, a thirty-months old boy who was found to have abdominal distension and a neonate who was diagnosed antenatally with abdominal mass. Computed tomography scan revealed the mass in which the contents favor a fetus in fetu rather than a teratoma. Surgical removal revealed that the anencephalic fetus have limb buds situated relative to a palpable vertebral column, supporting the diagnosis of fetus in fetu. In the present report, presentation, diagnosis, pathology, management, and recent literature are also reviewed.

CONCLUSION

Fetus in fetu is a rare entity that typically presents in infancy and early childhood. It should be differentiated from a teratoma because of the teratoma's malignant potential. Preoperative diagnosis is based on radiologic findings. The treatment of fetus in fetu is operative to relieve obstruction, prevent further compression and possible complications. Complete excision allows confirmation of the diagnosis and lowers the risk of recurrence.

Fetus in fetu: a medical curiosity--considerations based upon an intracranially located case

INTRODUCTION

"Fetus in fetu" (FIF) is defined as the abnormal monozygotic twin inside the body of its "host twin." Intracranial FIFs are extremely rare.

CASE PRESENTATION

A male premature newborn was admitted to the hospital due to a large intracranial tumor diagnosed in the 31st week of gestation. The child died before surgical treatment because of failure of the respiratory system due to fetal respiratory distress syndrome. During general autopsy, a large intracranial tumor with four relatively well-developed limbs was found. Microscopically, apart from relatively well-formed musculoskeletal structures of limbs that were covered with skin, there were haphazardly distributed different tissues or fragments of organs. However, various neuroectodermal derivatives were dominant.

CONCLUSION

We believe that intracranial FIFs, theoretically with poor prognosis, can be successfully curable in cases revealed prenatally, provided that optimal treatment is introduced and the achievement of proper pulmonary maturity of the host is accomplished prior to the operation of the tumor.

Antenatal diagnosis of a third ventricular mass: fetus in fetu or teratoma?

BACKGROUND

Fetus in fetu (FIF) is a rare condition in medicine where an aberrant monozygotic twining results in inclusion of a degenerated fetus inside its twin bearer. Whereas FIF is generally defined as a fetiform vertebrate mass, teratoma is considered as a tumor composed of disorganized tissues derived from the three embryological layers. Recent data plead for a common origin and suggest a continuum between FIF and teratoma.

CASE HISTORY

We describe the case of an intraventricular mass diagnosed by prenatal imaging and associated with triventricular hydrocephalus. Surgical removal of a non-vertebrate mass covered by normal skin was performed when the child was 15 months old. Now aged of 30 months, the child continues to develop normally. Histological data were in favor of a FIF.

DISCUSSION

We discuss the diagnosis, pathogenesis, and prognosis in the light of data from the recent literature.

CONCLUSIONS

Aberrant monozygotic twining leading to inclusion of a degenerate fetus inside its twin bearer results in FIF or teratomas. Surgical removal represents the main treatment. Intracranial FIF remains an extremely rare congenital condition, with a favorable oncological prognosis; the developmental prognosis appears conditioned by the absence of other malformation, the small size of the lesion, and the early management of intracranial hypertension.

Prenatal diagnostic clue for fetus in fetu

The purpose of this paper is to define a prenatal diagnostic clue for fetus in fetu (FIF) based on the characteristic findings of four FIF cases studied by the authors. A retrospective analyses of prenatal ultrasonography (US), postnatal US, computed tomography (CT) scans and operative findings were carried out on each of the four FIF cases collected from a multi-center. Prenatal US findings for each of the four cases showed a fluid-filled sac with a solid portion "floating" within it. In addition, bony structures were found in the solid portion. In each of the four cases, the postpartum imaging studies were consistent with the prenatal US findings. Operative findings revealed a solid mass within a fluid-filled sac surrounded by a transparent membrane. The solid mass was connected to the membrane by a stalk. Histopathologically, the cells making up the sac were of the same type as those of the amnion, while the solid mass had the general characteristics of FIF. In conclusion, FIF can be suspected when prenatal US shows a solid mass with bony structures within a fluid-filled sac in a newborn.

A neonate with cleft palate and a fetal mass in the oral cavity: a rare case of an oral fetus-in-fetu

Fetus-in-fetu is a rare congenital condition in which a malformed fetus-like structure is found in the body of its twin. We report a unique case of a male neonate with cleft palate and a fetus-like structure arising in his oral cavity. The neonate underwent emergent surgical removal of the mass immediately after delivery. Radiological and pathological studies of the resected mass provided supportive evidence for the case of an oral fetus-in-fetu. To our knowledge, there are few cases of oral fetus-in-fetu in the literature. Moreover, the presence of cleft palate in this neonate is of potential interest and clinical importance.

Mediastinal Fetus in fetu

Fetus in fetu is an extremely rare condition defined by the presence of both axial skeleton and organoid formations in the parasitic mass. Besides some authors assuming that fetus in fetu and highly-differentiated teratomas are part of the same pathogenic spectrum, it has been emphasized that these criteria indicate a rather different embryogenetic mechanism. We herein report the first case to our knowledge developed in the ventral mediastinum that was thought to be a tumor before birth. The literature is reviewed and we propose a new explanation for the development of this rare anomaly, based on a defective implantation.

Management of other complications specific to monochorionic twin pregnancies

Monochorionic (MC) twins have a 3-10-fold higher perinatal mortality and morbidity than dichorionic twins. This is largely attributable to their common vascular architecture and the high rate of discordant fetal growth, growth restriction and congenital abnormalities. In the event of a single intrauterine death (IUD), intertwin agonal transfusion results in up to a 38% risk of death and a 46% risk of neurological injury to the co-twin. This chapter addresses the management of complications unique to MC twins. The primary aim of management is to prevent single IUD or, if inevitable, prevent agonal transfusion occurring by vascular occlusive selective feticide. Older fetoscopic techniques have been replaced by the simpler ultrasound-guided techniques of interstitial laser and bipolar cord occlusion. Their application in twin reversed-arterial perfusion sequence has been associated with a 50% reduction of perinatal mortality in the pump twin. Moreover, prophylactic interstitial laser therapy in early pregnancy might obviate the technical and clinical difficulties in the presence of fetal decompensation in later pregnancy. Recent strategies to reduce the high perinatal mortality due to cord entanglement in antenatally diagnosed monoamniotic twins including medical amnioreduction and elective caesarean delivery at 32 weeks, are also discussed.