
Surgeons removed the growth from Sam Esquibel's head days after his birth in October, and the three-month-old boy is now said to be fit and healthy.
New photos of the operation show the blood vessels inside the tumour, which also included other partially-formed body parts including a second foot, a hand and a thigh.
Doctors now believe that the condition was probably a teratoma, a type of tumour that contains hair, teeth, bones and body organs but usually does not occur in the brain.