| Miniature Brain and Skull Found Inside 16-Year-Old Girl's Ovary
A very unusual teratoma was discovered during appendix surgery A tumour containing a miniature brain has been found growing on the ovary of a 16-year-old girl in Japan. The 10-centimetre-wide tumour was discovered when the girl had surgery to remove her appendix. When doctors cut the tumour out, they found 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 brain's two hemispheres. A mass on one side resembled a brain stem – the structure that normally joins to the spinal cord. Monsters within About one-fifth of ovarian tumours contain foreign tissue, including hair, teeth, cartilage, fat and muscle. These tumours, which are normally benign, are named teratomas after the Greek word "teras", meaning monster. Although the cause of ovarian teratomas is unknown, one theory is that they arise when immature egg cells