It was pretty lucky that Sam Esquibel's mom put off having labor induced when she neared her delivery date. If she hadn't, she may not have been given the last ultrasound that revealed the large tumor growing in her son's brain. Three days after Sam was delivered, he underwent brain surgery to explore and remove the growth.
When surgeons reached the tumor and cut it open, they were astonished to see a tiny foot pop out of the incision. Yes, you read that correctly; Sam Esquibel's brain had grown a small, normally developed foot. Two diagnoses quickly emerged, teratoma or fetus in fetu. The former is an uncommon type of tumor where recognizable growths like hair, teeth, skin and nails develop within a tumor. The latter, which means "fetus in fetus", is an even rarer condition (less than 10 reported cases in the brain) where one twin absorbs the other in the womb [source: Newsome]. The absorbed twin becomes parasitic, eventually killing the twin that absorbed it.
After exploring more deeply in the tumor, surgeons at Memorial Children's Hospital in Colorado determined that the growth was indeed the result of fetus in fetu. In addition to the foot, they discovered a thigh, hand and intestine [source: Celizic]. Surgeons successfully removed the tumor and Sam Esquibel is alive and well.