Doctors in Japan were left stunned recently after discovering a tiny brain growing inside a tumor in the ovary of a 16-year-old girl.
The tumor itself was only noticed when doctors were removing the girl’s appendix. She had not suffered from any negative symptoms prior to its discovery. A much bigger shock then followed when surgeons went to work on the tumor itself, as it was found to contain a small mass of highly organized neural tissue, roughly 3 centimeters (1 inch) in width, that resembled a cerebellum – the brain region that coordinates motor control and balance.
Ovarian tumors that contain other types of body tissue are known as teratomas, and are fairly common. Usually they harbor nothing more than hair, muscle, or fat, although in some instances they have been found to contain miniature structures that resemble actual body parts, which are called homunculi.
On rare occasions, doctors have reported teratomas featuring brain cells, although finding such a complete and well organized chunk of neural tissue is virtually unheard of. Describing the amazing discovery in the journal Neuropathology, the surgeons who removed the tumor explain that “three layers of the cerebellar cortex were well formed,” and that the fibers that connect neurons to one another – known as dendrites – were starting to take shape.
Myelin, which insulates nerve fibers in order to allow for the speedy transmission of electrical impulses, was also found on much of the white matter. This, say the researchers, reflects the advanced maturation of the neural tissue.
Next to the cerebellum-like structure was a club-shaped clump of central nervous system tissue resembling a brainstem, which normally connects the brain to the spinal cord.
Fortunately, the girl has now had the tumor removed and is recovering well.