Intraventricular twin fetuses in fetu

Area of Science:

• Developmental Biology
• Medical Genetics
• Neurology

Background:

• Fetus in fetu is a rare congenital anomaly where one twin is enclosed within the body of the other.
• Intracranial fetuses in fetu is exceptionally rare, with few documented cases.

Observation:

• A neonate presented with ventriculomegaly and intracranial calcifications suggestive of an axial skeleton.
• Imaging revealed two complex intraventricular masses containing skeletal and soft tissue elements.
• Surgical resection at 3 months of age confirmed the presence of fetuses in fetu with well-developed structures.

Findings:

• The intracranial masses exhibited axial and appendicular skeletons, skin, hair, muscle, bone marrow, and multiple viscera.
• Genetic analysis, including single nucleotide polymorphism array, demonstrated that the fetuses in fetu were genetically identical to the host infant.
• This confirms a monozygotic twin embryonic origin for this rare intracranial presentation.

Implications:

• This case expands the understanding of fetuses in fetu, particularly its rare intracranial intraventricular occurrence.
• Genome-wide genetic analysis provides definitive evidence for monozygotic twinning as the origin.
• Highlights the importance of advanced imaging and genetic testing in diagnosing and understanding complex congenital anomalies.