In a very rare case, doctors surgically removed a fetus from the brain of a one-year-old child. Doctors found the fetus when the child showed delayed skill development, large head circumference and fluid accumulation in the brain.
A report published on December 12, 2022 in the magazine Neurology published, indicated that the mass inside the infant’s head was an incomplete monochorionic diamnion. This means that inside the womb, the fetuses once had the same placenta, but a separate amnion sac. The amniotic sac is a thin-walled, fluid-filled sac that surrounds the developing fetus. These types of twins come from one fertilized egg and are identical as a result.
A malformation in which an embryo is surrounded by another embryo is known as “embryo-in-embryo” or sometimes “parasitic twinning”. The growth of the absorbed twin usually stops; While the growth of the other fetus continues.
Live Science He writes that the phenomenon of parasitic twins occurs with a frequency of about 1 in 500,000 live births. Usually, the incomplete fetus is stuck in the form of a mass in the abdomen of another fetus and behind the tissues that cover the abdominal wall; However, in this case, the mass appeared on the head of the host’s baby, and it probably appeared at a very early stage of development, the stage when the fertilized egg forms a collection of cells called a blastocyst.
The authors of the case report suggested that this case of an intracranial embryo was created from separated blastocysts, meaning that clusters of cells that would normally divide into two separate embryos became stuck together. The attached parts become the forebrain of the host embryo and engulf the other embryo during the folding of the neural plate. The neural plate is a structure that forms in the early stages of development and creates the nervous system.
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