Interesting question. People have been fascinated by bumpso n the
skull since prehistoric times.
In the late 18th century an Austrian physician, Franz Joseph founded a
scientific movement based on irregularities of these bones. It was
called phrenology. In 1796, not much was known about how the brain
worked. Gall noticed that his intelligent friends tended to have large
foreheads. He decided that growth of the part of the brain that
controls intelligence caused the front part of skull to expand.
Thinking the brain was like a muscle, he guessed that a well exercised
area of the brain would get larger. This would cause a corresponding
bump on the surface of the skull. The New England Journal of
Skepticism has a decent, short review of the movement. It was very
popular for a while, but fell out of fashion when neuroscience
developed the ability to analyze brain function and anatomy.
The reason some lumps go away when you bump your head and others don't
has to do with the severity of the damage to the underlying tissue.
You know that you get a bump or a bruise because you break small blood
vessels under the skin and the blood pools causing discoloration and
swelling in the surrounding tissue. As the blood clot (hematoma)
breaks down it gets reabsorbed and disappears. If you bumped yourself
hard enough to damage the tissues beneath this, you've graduated from
a bruise to a contusion. If the injury is on your armor leg the muscle
may be involved. If it's on your skull, the bone may be injured. Bone
is living tissue that has blood vessels and layers of cells. Smashing
into this can hurt your skull with out causing a fracture. Sometimes,
as the bone heals, it will get thicker in the damaged area. The same
way your skin might form a scar. That's why you sometimes wind up with
a knot that doesn't go away.
explains a little about the physiology of bumps to the head.
But that won't explain the fleshy lump that you describe.
I am relieved that you said you checked with a doctor. Unusual lumps
anywhere should be checked to make sure that there is no malignancy
There are plenty of other conditions that might be responsible for
your long term "goose egg."
It could be:
a fluid filled cyst
a sebaceous cyst sometimes called a "wen"
The last three of these would be classified as benign skull tumors.
These are not uncommon and ARE NOT CANCER. A tumor happens when a cell
gets misprogramed. It lives longer than it should and reproduces more
often than it needs to.
Malignant tumors, or cancer, are greedy cells that not only want to
live forever and multiply, they also want to take the nutrition that
other cells need to live. They spew out networks of little blood cells
that siphon off the food supply and bring it to them to feed on.
That's why cancer is dangerous. It interferes with the functions of
other cells near it. A malignant tumor on your skull would be
dangerous because it can decide to move in on your brain and that's
Benign tumors are very different. The cell that doesn't die as
programmed by youe body is a neighborly sort. It doesn't steal
resources from other nearby cells. All it does it sit in one place and
reproduce. After a while it has a little colony of cells that form a
lump. As the colony grows so does the lump, but many benign tumors are
incredibly slow growing or grow to a certain size and then stop.
The cell that started the tumor could have been:
Tumors of connective tissue
Tumors of blood or blood vessel origin
Other types including fibrous dysplasia, Paget disease, or epidermoid,
dermoid, or aneurysmal bone."
The primary cell will determine the tumor type.
You should find out what it is, for curiosity if not for health
reasons. It's probably nothing serious if you've had it ever since you
can remember. Removing it would be your choice if it's a benign
Search terms used: Osteoma cranial skull lump contusion
Hope this didn't get to complicated as an explanation of a simple bump
on your head!