Do some tumors contain the beginnings of a baby?

Dear Cecil: A friend told me about a woman who had a tumor removed from her ovary (or something in that area), and the tumor had hair and teeth. She was young and I think a virgin, so this couldn’t have been the beginnings of a baby. Have you heard of this happening, or is my friend pulling my leg? MelGag, via AOL

Cecil replies:

All together now: Ewwwwww.

No, the tumor wasn’t the beginnings of a baby. But yeah, it might have had hair and teeth. Dunno about you, but this ranks way up there on the list of things I could stand not to know. On the other hand, if you can stand to read about Bill Clinton’s cigar, you can certainly stand to read about this.

The tumor we’re talking about here is called a teratoma. At one time teratomas (which are usually benign) were thought to originate in some sort of embryonic or quasi-embryonic cell gone wrong. But most experts now consider them a type of germ-cell tumor — in this case a tumor involving an egg. Though the egg is unfertilized, tumor-driven cell division results in a lot of the same stuff you see in a developing fetus, including cartilage, bone, teeth, hair, brain tissue, and sometimes even bowel, skull, vertebrae, and eyes. It’s all chaotically arranged and bears no resemblance to an actual embryo. Nonetheless, since larger teratomas can weigh several pounds … well, I suppose all cancer is pretty weird. But this kind is weirder than most.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.