Fetus in fetu
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Fetus_in_fetu".

Fetus in fetus (or fœtus in fœtu) is a developmental abnormality in which a fetus gets enveloped inside its twin and an entire living organ system with torso and limbs can develop inside the host.^[1] The abnormality occurs in 1 in 500,000 live births.^[2]

Is it alive?

A fetus in fetu can be considered alive, but only in the sense that its component tissues have not yet died or been eliminated. Thus, the life of a fetus in fetu is inherently limited to that of an invasive tumor. In principle, its cells must have some degree of normal metabolic activity to have remained viable. However, without the gestational conditions attainable (so far) only in utero with the amnion and placenta, a fetus in fetu can develop into, at best, an especially well-differentiated teratoma; or, at worst, a high-grade metastatic teratocarcinoma. In terms of physical maturation, its organs have a working blood supply from the host, but all cases of fetus in fetu present critical defects, such as no functional brain, heart, lungs, gastrointestinal tract, or urinary tract. Accordingly, while a fetus in fetu can share select morphological features with a normal fetus, it has no prospect of any life outside of the host twin. Moreover, it poses clear threats to the life of the host twin on whom its own life depends.

Theories of development

There are two main theories about the development of fetus in fetu; one simple, the other complex.

Teratoma theory

Fetus in fetu may be a very highly differentiated form of dermoid cyst, itself a highly differentiated form of mature teratoma.^[3]

Main article: Teratoma

Parasitic twin theory

Fetus in fetu may be a parasitic twin fetus growing within its host twin. Very early in a monozygotic twin pregnancy, in which both fetuses share a common placenta, one fetus wraps around and envelops the other. The enveloped twin becomes a parasite, in that its survival depends on the survival of its host twin, by drawing on the host twin's blood supply. The parasitic twin is anencephalic (without a brain) and lacks some internal organs, and as such is almost always unable to survive on its own.

Sometimes, however, the host twin survives and is delivered. The parasitic twin grows so large that it starts to harm the host, at which point doctors usually intervene. The condition causes the host to look pregnant, and can occur in both males and females.

Main article: Parasitic twin

Examples in the media

Cases of fetus in fetu sometimes attract worldwide media attention. These cases are a small minority of the known cases and rarely overlap with cases reported in the medical literature, but they are widely accessible.

• Alamjan Nematilaev was the surviving host of a fetus in fetu. In 2003, aged 7, his school physician in Kazakhstan referred him to hospital after movements were detected in the boy's enlarged stomach. An operation intended to remove a cyst uncovered the fetus of Alamjan's identical twin brother, which had lived as parasitic growth inside the boy throughout his entire life. The fetus was comparatively highly developed, with hair, arms, fingers, nails, legs, toes, genitals, a head, and a vague approximation of a face.^[4][5]

• In June 1999, the case of Sanju Bhagat a man from Nagpur, India attracted attention for the length of time (36 years) he had carried his parasitic "twin" inside his body, and the size of the growth. As Bhagat had no placenta the growth had connected directly to his blood supply.^[6]

• In November 2006, a Chilean boy in Santiago was diagnosed with fetus in fetu shortly before birth. ^[7]

• In August 2007, a two month old baby in Baguio from the Philippines named Eljie Millapes was diagnosed with fetus in fetu. The parents of Eljie Millapes were alarmed by the abnormal growth of the stomach of their two-month-old baby. Doctors later discovered that she was suffering from fetus in fetu.^[8]

• In January 2008, a two month old baby in Medan, Indonesia named Afiah Syafina was diagnosed with tumor in her stomach. After the operation was done at January 19, 2008, the results were startling enough. The suspected tumor was a five month old fetus.^{citation needed}

• In May 2008, a two-inch embryo was removed from the belly of a 9-year-old girl at Larissa General Hospital in Athens after she was diagnosed with a tumor on the right side of her belly. The embryo was a fetus with a head, hair and eyes, but no brain or umbilical cord. ^[9]

• In June 2008, an extra penis was removed from the back of a month-old boy from Hejian City, China. ^[10]

Appearances in popular culture

There are a number of examples of writers using fetus in fetu as part of a storyline. In Stephen King's novel The Dark Half, a writer's fetus in fetu which had been found and removed in childhood, is linked to the later appearance of a murderous "evil twin" version of himself that takes on the pseudonymous identity the writer had used for a dark series of novels, and that he had just retired. Following that evil twin theme, the X-Files episode "Humbug" has a parasitic twin who detaches from his "host" and kills people.

A more complex development of the idea takes place in the animated television series The Venture Bros., where the main character Dr. Thaddeus Venture has a fetus in fetu (Jonas Venture Jr.) growing inside him for forty-three years. After Jonas Venture Jr. is surgically removed in the first season finale, he initially attempts to kill his brother in retaliation for being engulfed, though later the brothers make peace and the fetus in fetu becomes a jovial genius.

The concept is also the central theme of the novel Passenger by Billy Cowie (published by Old Street Publishing 2008) where the main character Milan discovers his sister Roma is embedded in himself and spends the remainder of the book attempting to communicate with her.^[11]

The South Park episode "Conjoined Fetus Lady" concerns a school nurse with a similar (albeit fictional) condition called "conjoined twin myslexia". In this case, the fetus in question protrudes from the nurse's face, rather than being contained within her body.

In the film My Big Fat Greek Wedding, the protagonist's relative tells an off color story of how her twin's spinal column and skull was removed from body.

See also

• Male pregnancy
• Teratoma

References