A young woman in India unknowingly lived with one of the rarest and most unsettling medical conditions for nearly two decades, her doctors say. According to a [recent] case report … the woman had a sac containing her still-growing “twin” lodged in her abdomen for 17 years. The twin had hair, teeth, and even a spine.
Formally known as fetus in fetu, the condition is thought to happen when one fetal twin gets enveloped by the other very early in pregnancy. The fetus doesn’t go on to develop its own nervous system and brain, but it’s still capable of living. And it sustains itself through its sibling, essentially becoming a parasite. Another theory holds that the second “fetus” is actually a complex form of tumor called a teratoma; these tumors can develop different types of tissues at once.
Prior to this case, according to the woman’s doctors, there had been only seven other reported cases of adults living with a fetal twin. And up until now, they had all been men.
Thankfully, with the mass gone, the woman had a speedy and uneventful recovery, and two years later is still doing well.
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