Fetus In Fetu: Everything You Need To Know
The first known case of fetus in fetu was reported in 1800. Since then there have been reports of about 200 cases worldwide. The rarity of this anomaly and its geographical dispersion have prevented in-depth studies on this phenomenon.
The discoverer of this strange condition was Johann Friedrich Meckel. He coined the expression fetus in fetu to refer to those cases in which a parasitic twin forms inside the healthy brother, who acts as a host.
It happens very often that this disease is initially diagnosed as a painless tumor. 89% of cases were detected within the first 18 months of life, but in some cases the diagnosis is made in adulthood.
The fetus in fetu is a rare or orphan
The fetus in fetu is part of so-called orphan diseases, rare or minority. To date, around 7,000 diseases belonging to this category have been identified. Among the ten rarest diseases we find the fetus in fetu .
Only 200 cases are documented worldwide. It is estimated that this anomaly affects one in 500,000 births. In most cases it is diagnosed in childhood, but has also been found in adults up to 47 years of age.
It represents a variant of the parasitic twin syndrome
Fetus in fetu is a variant of the phenomenon known as parasitic twin syndrome. It is a condition in which two twins are joined together, but one has a much smaller body.
In these cases, the host twin, or self-determination, allows the parasite to survive, since the latter has no organs of its own. The fetus in fetu is considered an extreme case of Siamese twins.
The fetus in fetu is a random event
The exact cause of this phenomenon is not known. We only know that it is an unpredictable event that occurs at an imprecise moment during the formation of the zygote. For some reason, the twins do not separate completely and remain united.
All this happens before the embryo is formed. Later, one of the twins develops normally, while the other atrophies. He thus remains inside the healthy twin and his survival completely depends on the latter.
The fetus in fetu has a strange appearance
It often happens that the host fetus dies before being born. When this does not happen, the newborn has a swelling in the area where the parasitic twin is lodged. In 80% of cases, it is the abdominal region, but the parasitic twin can be lodged in the scrotum, skull, etc.
The fetus in fetu is a humanoid, wrapped in a membrane that makes it similar to an extremely hard and rather large chicken egg. Once extracted from this species of shell, it appears white in color. Following this procedure, however, he dies, because his life is completely dependent on the healthy twin.
The fetus in fetus and the teratoma
Teratoma is an encapsulated tumor that contains remnants of tissues, even organs. There are cases of teratomas containing hair, teeth, bones and even hearts, although this is an infrequent phenomenon.
Due to its characteristics, teratoma is sometimes confused with fetus in fetu . The researchers therefore established some differential criteria to distinguish one phenomenon from another. Teratomas can become malignant, while fetus in fetu does not. Furthermore, in order to speak of fetus in fetu, the vertebral column must be present.
It poses a risk to the host
The parasitic twin poses a potential risk to the healthy twin. The latter, in fact, must carry a weight within its own organism that does not perform any function. The parasite can weigh up to 1 kilogram. It does not have a brain, but a hollow cranial cavity. It does not even have a thoracic cavity, while massive flesh is present in its place.
An additional risk is posed by the location of the parasitic twin. As already indicated, it is almost always found in the abdomen, but cases of fetus in fetu have been recorded in the oral cavity (6), in the skull (7-9), in the liver (10) and in other dangerous areas. Finally, 13 cases of coexistence of more than one parasitic twin have been documented.
