LOS ANGELES (UPI) -- Los Angeles surgeons working to remove a tumor from an Indiana woman's brain said the growth turned out to be the patient's embryonic twin.

Yamini Karanam, 26, a Ph.D. student at Indiana University, said she underwent surgery at the Skull Base Institute after problems she started having with reading and listening comprehension last September were determined to be the result of a tumor in her brain.

Karanam said she was shocked when she woke up after the surgery and Dr. Hrayr Shahinian's team revealed the tumor to be an embryonic twin with bone, hair and teeth.

Shahinian said such a tumor, or "teratoma," is rare to find in modern medicine.

"This is my second one, and I've probably taken out 7,000 or 8,000 brain tumors," Shahinian told NBC Los Angeles.

Shahinian removed the tumor using fully endoscopic resection, a minimally invasive brain surgery.

Karanam said she now refers to the tumor as an "evil twin sister who's been torturing me for the past 26 years."

Shahinian said the tumor was not cancerous and Karanam is expected to make a full recovery.

A study published in the February issue of the Hong Kong Medical Journal examined the case of a newborn girl born "pregnant" with twin fetuses in her abdomen. The girl's unique form of teratoma, known as fetus-in-fetu, occurs about once in every 500,000 births

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