Thomas the Teratoma

Thomas the teratoma was a tumor with tons of types of tissues, like teeth, intestines, tendons, tongue and tear ducts too.
Thomas was always growing, gaining weight and size. So large did Thomas grow that had to be excised.
But Thomas liked his home, he had held on firm and tight. Unfortunately for Thomas a scalpel wields much more might. 

Thomas's grasp was cut, severed with a knife, and thus his life was ended, ended with a knife.
And although Thomas lay there, in a metal dish, luckily for Thomas, granted was his last wish.
Because inside our patient, there remained a little cell. With a hardy membrane and some DNA from hell.