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

Intracranial Parasitic Fetus in a Living Infant: A Case Study with Surgical Intervention and Prognosis Analysis

BACKGROUND Fetus in fetu (FIF), or parasitic fetus, is a rare malformation that typically occurs in the retroperitoneum, but can be found in other unusual locations, such as the skull, sacrum, and mouth. The presence of a spine is necessary for diagnosis. CASE REPORT Intracranial FIFs were retrospectively studied. Abnormalities were detected in the fetal head during a 33-week prenatal examination; however, MRI could not provide more information, due to space occupation. A baby girl was born via cesarean delivery at 37 weeks, with a large head circumference. She had delays in motor skills and speech development, only able to say "mom". There was a large mass in the cerebral hemisphere, with a 13-cm maximum diameter, smooth boundary, and internal bone structure visible on head CT scan. Both ventricles and third ventricle had hydrops, with a fetal shape at a continuous level, along with apparent compression near the cerebral parenchyma. After performing preoperative examinations, laboratory tests, and surgical planning, craniotomy was performed on the FIF, under general anesthesia. Following complete mass resection, mouth, eye, arm, and hand shapes could be observed. The patient was unconscious after surgery and had seizures that were difficult to control. She died 12 days after surgery. Teratomas can be distinguished based on anatomy and imaging. Surgical resection is the only curative treatment and its prognosis is poor. CONCLUSIONS Intracranial FIF cases are rare and require early diagnosis and surgical treatment. Differentiating between FIF and teratoma is crucial, and monitoring alpha-fetoprotein levels after surgery can help detect recurrence.

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.

Fetus In Fetu With Myelomeningocele

Fetus in fetu is an uncommon medical anomaly characterized by the presence of a malformed fetus within the body of a living twin. Although the retroperitoneum is the most typical location, occurrences in the sacrococcygeal and dorsolumbar regions are rare. Ongoing debates center around its embryopathogenesis, debating whether it is a highly specialized teratoma or a result of parasitic twinning in a monozygotic monochorionic diamniotic pregnancy. Notably, distinguishing factors such as vertebral bodies and limbs are pivotal in discerning FIF from teratomas. Diagnostic imaging techniques are integral for preoperative diagnosis, with histopathological examination confirming the condition's presence.

External fetus in fetu presenting in the second trimester: A case report and literature review

Fetus in fetu (FIF) is a rare congenital anomaly that originates from various sites of the host twin's body. The clinical manifestations of FIF are diverse and the location and size of FIF indicate the degree of threat, which may directly affect the prognosis. A 33-year-old woman presented at the hospital with an abdominal mass in her fetus. Prenatal ultrasound observed that mass included soft tissue, bone-like structures, and fluid. Immature cartilage, nerve tissue, muscle tissue, and glands in the parasitic fetus without signs of neoplastic lesions were reported by histological examination. CNV (copy number variation) and WES (whole exome sequencing) did not detect any abnormal mutations. FIF can continue to grow with gestational age or host infant growth. So complete resection is essential for improving the outcome of the host twin. It is also important that long-term follow-up is recommended to monitor any residual or recurrent cysts or malignancies.

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.

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.

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.

Fetus-in-Fetu: A Differential Diagnosis of Neonatal Fetiform Encysted Abdominal Mass

Fetus-in-fetu (FIF) is a rare embryological anomaly in which an encysted fetiform mass develops within the infant or adult host body. It mainly occurs intraabdominal. There are embryo-pathogenetic debates over whether it belongs to the spectrum of highly differentiated teratomas or is a parasitic twinning from a monozygotic monochorionic diamniotic pregnancy. The presence of vertebral segments and an encapsulating cyst can reliably distinguish FIF from teratoma. The diagnosis may be initially made by imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI), and a confirmatory diagnosis made by histopathology of the excised mass. Our center experienced a case of a male neonate presented after emergency cesarean delivery at 40-week gestation with the suspicion of an intraabdominal mass identified antenatally. Antenatal ultrasonography at 34 weeks gestation suggested the presence of an intraabdominal cystic mass measuring 6.5 cm with a hyperechoic focus. A follow-up MRI performed after the delivery showed a well-defined mass with the cystic formation in the left abdominal region with a centrally located fetiform structure. Vertebral bodies and long limb bones were visualized. The diagnosis of FIF was initially made preoperatively by the characteristic findings of imaging studies. Laparotomy was scheduled on day 6, revealing a large encysted mass with fetiform content. FIF should be considered a possible differential diagnosis of neonatal encysted fetiform mass. Routine antenatal imaging permits more frequent antenatal detection with earlier workup and management.