Teratomas of cardiac tissue with their own "heartbeat"?

Question

I half-remember some mainstream media article about a peculiar growth/tumor in which the vascular tissue itself had started to beat/pulse as if it were a sort of heart.

I cannot remember any other significant details about it, especially not whether this was unique or if more than one instance had been documented.

I am aware of teratomas and how they can develop into all sorts of different tissue (sometimes even multiple tissues in a single occurrence), but I had thought that these relegated themselves to other tissues more boring than cardiac tissue.

Am I misremembering this, or (more likely still) had science/medical reporting just conflated something, or have any such occurrences ever been documented?

I am curious for any details, though ideally someone can provide something closer to actual medical reports.

Answer 1

The term you're looking for is pericardial teratoma. Another related term you'll be interested in is fetus-in-fetu, which is essentially a parasitic twin growing somewhere within the body, usually the abdominal cavity.

There have been at least two examples of pericardial teratomas that developed sufficiently to produce heart-like pumping activity. The following case history is from 2002, so it's possible more examples exist now, but you'll see that it describes exactly what you remember reading about. The authors conclude it may be an example of an intermediate combination of fetus-in-fetu and teratoma.

Case Report:

A mature teratoma was identified in a two-month-old girl who was operated for a sacrococcygeal mass. The cystic components of the mass were accidentally opened during surgery, and a solid, rudimentary organ resembling a heart emerged. It had a vascular pedicle and a pulsation like cardiac activity different from the infant's heart rate. The mass was totally excised together with the coccyx, and in histological examinations, it was diagnosed as a mature teratoma and a rudimentary heart. To the best of our knowledge, the case presented in this report is only the second case of a cardiac development in a teratoma in the literature. In the light of data obtained about this case and related literature, we consider that fetus-in-fetu and teratoma may not be irrelevant entities, and that they possibly have the same developmental malformation. We also suggest that such an intermediate case is a combination of fetus-in-fetu and teratoma.