text: Plagued by a feeling something wasn't right, student Yamini Karanam sought medical help. She was struggling to understand things she had read, and felt lost in conversations. But the Indiana University PhD student could never have comprehended the source of the problem - an 'evil twin sister growing' in her brain. Surgeons operating to extract what they believed to be a tumour in her brain, were shocked to discover the growth was in fact an embryonic twin, complete with bone, hair and teeth. Yamini Karanam, 26, a student at Indiana University, was diagnosed with a pineal tumour in her brain after noticing she was struggling to comprehend things she had read, and felt lost in conversations . Known by its medical name, a brain teratoma, the growth is very rare. Indeed, Dr Hrayr Shahinian, the expert at the Skullbase Institute in Los Angeles who operated on Miss Karanam, has removed around 7,000 brain tumours and has seen just two teratomas. In the past, teratomas have been reported to contain hair, teeth, bone and rarely more complex organs including eyes, hands, feet and limbs. And in some cases they have been found to resemble a foetus. Miss Karanam first noticed something wasn't right last September, when she struggled to register things in her mind, NBC reported. 'If a couple of people were talking in a room, I wouldn't understand what was happening,' she said. Frustrated at doctors' apparent inability to find an answer, the 26-year-old launched her own search for answers online. It led her to the Skullbase Institute and Dr Shahinian, who has developed a minimally-invasive way of reaching deep into a person's brain to extract tumours. The procedure, he said, is a type of keyhole surgery rather than traditional brain surgery, which involves opening the skull and using metal retractors to allow him to insert a microscope deep into the brain. Instead, Dr Shahinian makes a half-inch incision in the brain to use fibre-optic technology and digital imagery to gently chisel away at the tumour. Shocked when she woke to learn of Dr Shahinian's discovery, Miss Karanam branded the tumour her 'evil twin sister who's been torturing me for the past 26 years'. Dr Shahinian said he feared the tumour could be cancerous. But surgeons operating on the 26-year-old discovered the growth, indicated just above the red dot above, was in fact a teratoma - a growth containing bone, hair and teeth . WHAT ARE TERATOMAS? A teratoma is a tumour with tissue or organ components from more than one different part of the body. They have been reported to contain hair, teeth, bone and rarely more complex organs including eyes, hands, feet and limbs. In some cases a teratoma has been found to resemble a foetus. They are usually benign masses, though some cancerous forms of teratoma are known to exist. Mature teratomas, which are typically benign, are more commonly found in women. Immature teratoma, which are typically cancerous, are more often found in men. They are thought to be present at birth, but are often not discovered until later in life. Teratomas can occur in the testes in men and ovaries in women, as well as the brain, skull, nose, tongue, under the tongue and in the neck. WHAT ARE PINEAL TUMOURS? Pineal tumours are those that affect the pineal gland in the brain. The gland produces the hormone melatonin, which helps control sleeping. There are different types of pineal tumour, their name depending on the kind of cells from which they develop. The majority are germ cell tumours. Different tumours cause different symptoms. They are generally caused by a build-up of fluid in the brain, which leads to increased pressure, or caused the tumour itself. They include: . But tests revealed the mass was benign, and Miss Karanam is expected to make a full recovery in just three weeks. She said she wanted to raise awareness of Dr Shahinian's technique. 'This has to be mainstream,' she added. 'When they know you have a pineal tumour, they should tell you "you know what? There's a minimally invasive approach in which they won't kill you, they won't leave you with a disability.' Prior to Dr Shahinian's keyhole approach, he said the only option was to remove half of the patient's skull to reach the tumour. He added: 'We want to be in and out without the brain knowing we were there, and I think that's the beauty of this technique.'
target: Yamini Karanam, 26, was diagnosed with a pineal brain tumour .
  Surgeons operating to extract the growth made a startling discovery .
  They found a teratoma - an embryonic twin with bone, hair and teeth .
  Teratomas are often found in ovaries, testes but more rarely in the brain .