How likely is it the new lump on your scalp is a brain tumor protruding through, pressing against the bone and you can feel it with your fingers?

Yes, it is a scary thought.

The lump or bump on your scalp is something you’re not sure has always been there, which really makes this frightening.

“In almost all cases, a brain tumor will not cause any lumps on the scalp,” says Kathryn Boling, MD, a board certified family medicine practitioner with Mercy Medical Center in Baltimore, MD.

“The bones of the skull keep brain tumors from showing up as lumps,” adds Dr. Boling, whom I interviewed for this article.

“That is why brain tumors are so serious, because the skull does not allow the tumor to grow without increasing the pressure within the skull.”

Now think of it like this: The brain is like gelatin. A tumor begins growing in it. The brain is encased by the skull, and even getting bonked hard on the head from a fall or punch won’t always fracture the skull; the skull is pretty tough.

A tumor is not made of steel; it’s dense but not hard like metal or wood.

So even though it grows and presses against the skull, it cannot cause the skull (bone) to start expanding as though the bone is made of rubber like a balloon.

But of course, the tumor gets bigger and something has to give way as it gets larger, but this giving-way is not the bone of the skull expanding or protruding against your scalp skin creating a lump or bump.

Instead, as the brain tumor grows, there is, like Dr. Boling says, increased pressure in the brain, and one of the possible symptoms is a very bad, non-retractable headache, which is usually accompanied by at least one other troubling symptom such as a visual disturbance or nausea.

But a brain tumor, for all practical purposes, will not cause a lump in your scalp.

“Of course, in medicine there is almost never an ability to say with 100 percent certainty that something will or will not happen,” says Dr. Boling.

Just like you can be pretty sure that the next time you step outside, you won’t get struck by a meteor—but no scientist can say this with 100 percent assurance.

“There have been a few cases where melanoma [skin cancer] has presented as a solitary scalp swelling, underlying skull bone erosion and extension into the brain cavity. But this is not a brain tumor per se.”

In fact, this is the reverse: The melanoma tumor begins on the skin of the scalp, then burrows its way through the skull, encroaching the brain cavity.

“The symptoms of a brain tumor are neurologic – headaches (worse in the morning), seizures, vomiting, confusion, vertigo, stroke symptoms and numbness and tingling of the extremities.”

Check your scalp once a month for suspicious or new spots, pigmented lesions or crusty lesions as part of your overall body exam for skin cancer—but you need not worry that any lumps or bumps are from a brain tumor trying to get through.

dr. boling

Dr. Boling diagnoses and treats a wide range of conditions from acute illnesses to chronic diseases such as diabetes and hypertension.