A fetus in fetu (FIF), also known as an inclusion fetus or parasite fetus, is a fetus that includes one or more extra fetuses within a full fetus. Its distinctive diagnostic criteria include the vertebral system and organoid production. It is frequently accompanied by ribs and quadrilimb bone formation. Most FIFs (80%) dwell in the retroperitoneum. While others can be detected in the oral cavity, brain, mediastinum, thoracic cavity, pelvic cavity, sacrum, and scrotum. Several manifestations, including hydrocephalus in this example, can result from the mass’s subsequent effect on neighboring organs. Early identification and surgical removal are the only viable therapy options.
This is the case of a 1-year-old infant with delayed milestones born via cesarean delivery with a large head circumference.
Case Report
A 1-year-old female patient, 70 cm tall and weighing 13.5 kg, was referred to the hospital due to her inability to stand and an increasing head circumference.
At 33 weeks gestation, a regular prenatal check-up indicated an increased fetal head circumference on abdominal ultrasound. Because the fetus was in a breech position, magnetic resonance imaging (MRI) could not be used to identify fetal features in the intracranial space. The patient gave birth via cesarean delivery at 37 weeks.
At birth, the infant’s head circumference was greater than that of a child of the same age. At the presentation, she showed no signs of nausea or vomiting. The child could only raise her head slightly. However, she couldn’t sit or walk and could only say “mom.” In addition, she also had weak fine motor control in her hands and was incontinent.
Investigations
The patient’s head circumference was 56.6 cm. A CT scan of the head showed soft tissue, limb-like bone, and mixed bone tissue shadows in the intracranial area. Along with a mixed density mass measuring 15.0×13×12.5 mm. Blood tumour indicators revealed an alpha-fetoprotein level of 5.6 ng/mL and a human chorionic gonadotropin level of less than 0.1 IU/L, indicating an intracranial Fetus in fetu (FIF).
Surgery
Intraoperative head MRI indicated that the Fetus in fetu (FIF) had been completely removed. The FIF’s MRI enabled the viewing of spinal and long bone structures. Furthermore, the pathology report described one embryo, 18 cm in length, with deformed features and limbs (Figure 3). The fibrous capsular skin was investigated, revealing an interior coated in squamous epithelium with hyperkeratosis. That was compatible with a fetus in fetu (FIF). Three days following surgery, the cystic fluid was discovered to contain amniotic fluid. A-fetoprotein was detected at 1.6 ng/mL, and human chorionic gonadotropin at 0.1 IU/l.
A craniotomy was done under general anaesthesia and tracheal intubation. That exposes a white capsule within the brain tissue. After opening the brown viscous capsule, around 50 mL of the contents were drained, displaying a finger-like limb projecting from the opening. They extracted an early embryo with visible vernixes and organs, including the mouth, eyes, fetal head, fetal hair, torso, forearm, hands, and feet.
Discussion
Infants with intracranial FIFs that show human-caused mutations are uncommon. Willis characterized them in 1935 as masses containing the spinal column and other visible organs or limbs. A fetus in fetu (FIF) is made up of well-developed fetal organs, spines, and limbs. A spine signifies that the fetus has passed the primary stages of gastrulation: neural tube creation, polymerization, and symmetrical growth around the vertebral axis.
In this case, a head CT scan of the child revealed a strongly defined spinal structure and lengthy bone structure. That supported the diagnosis of parasitic pregnancy. It has been noted that the existence of fingers in FIFs helps in diagnosis. FIFs remain unknown, and their origins and processes may be related to environmental pollution, genetics, low temperatures, oocyte senescence, pesticide exposure during early pregnancy, and other aspects.
In this study, the mother was diagnosed during a prenatal examination at 33 weeks gestation. It has been stated that 89% of instances are diagnosed before 18 months of age, probably due to the disease’s tendency to develop late in pregnancy, making it difficult to detect during normal screening in the second trimester. A prenatal ultrasound examination is the most effective approach for diagnosing a FIF during pregnancy, emphasizing the significance of routine prenatal check-ups.
The residue left after eliminating the FIF has been shown to contain malignant alterations; in this example, blood alpha-fetoprotein levels declined considerably. Tumor indicators such as alpha-fetoprotein and human chorionic gonadotropin can be utilized to diagnose, follow-up, and determine a FIF cure, and long-term follow-up following surgery is advised.
