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Miniature Brain and Skull Found Inside Ovary of 16 Year Old Girl

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  • Doctors who were removing the appendix of a 16-year-old girl found a tumor in her ovary.
  • These benign tumors called teratomas, develop from rebellious, immature egg cells and usually contain foreign tissue, including hair, teeth, cartilage, fat and muscle.
  • In the girl's case, the cells had organized themselves into proper brain-like structures and the brain had developed in such a way that electric impulses could be transmitted between neurons.

Miniature Brain and Skull Found Inside Ovary of 16 Year Old Girl

A 16-year-old girl in Japan who underwent an emergency appendectomy for her acute appendicitis was found to have a tumor containing miniature brain parts in her ovary.

The tumor that was 10-centimetre-wide had clumps of greasy, matted hair inside, and a 3-centimetre-wide brain-like structure covered by a thin plate of skull bone.


Closer analysis revealed that it was a smaller version of a cerebellum, which usually sits underneath the cerebrum.

The cerebellum is responsible for motor control, and some cognitive functions such as attention and language.

A mass on one side resembled a brain stem.

The surgery to remove the "teratoma" took place three months after the appendectomy.

Mature Ovarian Cystic Teratomas

The term teratoma originates from the Greek word "teras" meaning monsters. These are the most common ovarian germ cell tumors.

Mature ovarian cystic teratomas are benign growths in the ovaries that usually contain foreign tissue, including hair, teeth, cartilage, fat and muscle.

The growths occur when an immature egg in the ovary turns rogue and starts creating different body parts.

An egg in the ovaries is just one of the two components needed to create a human life. In case of teratomas, the egg cell functions independently and starts to create incomplete body parts such as hair, teeth, muscle, and other malformed parts of the body.

Though brain cells are often found in ovarian teratomas, it is extremely unusual for them to organize themselves into proper brain-like structures, says Masayuki Shintaku at the Shiga Medical Center for Adults in Japan, who studied the tumor.

Angelique Riepsamen at the University of New South Wales in Australia, agrees "Neural elements similar to that of the central nervous system are frequently reported in ovarian teratomas, but structures resembling the adult brain are rare."

In the case of the 16 year old, miniature brain had developed to an extent where electric impulses were transmitted between neurons, just like in a normal brain, says Shintaku.

Anti-NMDA-receptor Encephalitis

A possible syndrome resulting from teratomas is the Anti-N-methyl-D-aspartate (NMDA)-receptor Encephalitis.

This syndrome can lead to psychiatric symptoms such as auditory hallucinations, personality changes, paranoid thoughts, confusion, agitation, seizures or memory loss.

The syndrome usually begins with symptoms such as nausea, fever, and headache, which will gradually lead to a spectrum of psychiatric symptoms.

Some of these neurological symptoms can arise when the immune system recognizes brain cells in the ovary as foreign and launches an attack. Inflammation occurs when some cells in the woman's real brain can end up being attacked as well,.

Removal of the tumor can undo the symptoms.

The 16 year old girl did not experience any such symptoms or develop complications and has recovered well.

The findings were published in Neuropathology.


  1. Masayuki Shintaku et al. Well-formed cerebellum and brainstem-like structures in a mature ovarian teratoma: Neuropathological observations. Neuropathology; (2017) DOI: 10.1111/neup.12360

Source: Medindia

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