Skull Lumps or ProtrusionsQ: Do people often have lumps or protrusions on their skull? My wife has a couple of small protrusions in the crown area. You can't see them (only feel them), but it worries her. Have you seen it before?
A: Actually, they are fairly common. They usually are caused by childhood injury (falls and accidental bangs to the head) which causes minor adjustments in the thickness of the skull or the areas where the skull plates join. In some cases, a person's skull simply forms a certain way. I knew a young man in high school who literally had a "squared" head. There were corners along the top of his skull (they were rounded, but were corners nonetheless).
Although the skull is "solid" it is actually formed from 22 different bones - 14 of which are in the face. The other 8 bones comprise the upper and rear portions of the skull, known as the cranium. The most common areas to find "lumps and protrusions" in the skull are where the bone plates of the cranium meet. In some people with shaved heads you can clearly see outlines of certain bone plates, while other people may appear to have perfectly smooth skulls.
In your wife's case, she may remember hitting her head as a child in which case, that is the likely explanation. If these protrusions are new (she doesn't remember how they may have gotten there) or seem to be getting bigger, she might want to see her doctor and have him check them out. While many lumps found on the skull/scalp are typically benign (ingrown hairs that have calcified, impacted sebaceous glands, etc.) they are often indistinguishable from those that signify real problems. It's always a good idea to consult a physician about any unexplained changes in your body.
Anatomy of the head for hairdressing
Hairstyle for when the back of your skull is flat