Q. What’s a dermoid cyst?

A. “Dermoid cyst” is a term that’s sometimes used to describe a benign form of a tumor called a teratoma (a pretty descriptive term, as we’ll see, as it comes from the Greek word for monster). Teratomas can occur in either men or women, but they are much more common in women during the reproductive years.

Teratomas in general are a special type of germ cell tumor in which you see actual tissue development (not just the germ cells themselves). In most teratomas, you see mature tissues – like hair, sebaceous glands, skin, and teeth. Usually there are multiple different tissues from different germ cell layers (so you can see bone, cartilage, thyroid tissue, neural tissue – anything, really). This type of teratoma is usually benign, and often cystic (hence the term “dermoid cyst,” describing a cystic structure with an epithelial component).

Some teratomas are composed of immature tissues (which often have a malignant component); still others are highly specialized, consisting entirely of one tissue, like thyroid tissue (this is called “struma ovarii”). But much more common is the benign, multiple-mature-tissue type of teratoma.

Now as to the name…it’s easy to see from the above photo of a teratoma why the term monster might be applied to such a tumor. Certainly, some teratomas look like little monsters, complete with hair, skin and teeth. However, the term also hints at some sinister misconceptions as to the etiology of this tumor. Many years ago, these tumors were thought to arise from all sorts of monstrous activities – adultery with the devil, witchcraft, nightmares, you name it. How painful it must have been to have one of these tumors, and then to be blamed for the tumor  – and accused of unspeakable acts! Fortunately, we now know that the tumor is caused simply by an error in meiosis – a random occurrence that, of course, has nothing to do with morality or behavior.

Today, patients with dermoid cysts almost always have good outcomes. Most dermoid cysts, being benign, can simply be removed with no further treatment; prognosis is excellent.