You’re brushing your hair and suddenly—thump. Your brush hits a hard, marble-like knot tucked right under your hair. It doesn't hurt, mostly, but it feels weird. You grab a hand mirror, trying to angle it just right against the bathroom vanity, but all you see is hair. Naturally, you go to the internet. You start searching for images of pilar cysts because you need to know if that lump is something to panic about or just another "getting older" quirk.
Honestly? It’s probably a pilar cyst.
These things are incredibly common. About 90% of them show up on the scalp. If you look at medical photography or patient-submitted photos, you’ll notice a pattern: they look like smooth, dome-shaped hills rising out of the skin. They aren't like the angry, red pimples you dealt with in high school. They’re stoic. They just sit there.
What do images of pilar cysts actually show?
When you look at high-resolution images of pilar cysts, the first thing that jumps out is the lack of a "central punctum." That’s medical speak for a blackhead or a hole in the middle. Unlike sebaceous cysts, which often have a visible dark pore where you can see the trapped gunk, pilar cysts are sealed tight. The skin over them looks normal, maybe a bit shiny or stretched if the cyst is large.
They grow from the hair follicle—specifically the outer root sheath. Because the scalp is thick and underlaid by a tough layer of tissue, these cysts get compressed into firm, round balls. If you were to see an image of one that has been surgically removed (and there are plenty of those "Dr. Pimple Popper" style videos out there), you’d see a white, pearly sac. It looks like a tiny, wet hard-boiled egg.
The wall of the cyst is thick. That’s why they feel so firm to the touch compared to other skin growths. Inside isn't liquid pus; it’s a dense, cheesy collection of keratin. Keratin is the same protein that makes up your hair and nails. In a pilar cyst, the keratin is just... confused. It’s trapped in a bag.
Distinguishing them from other lumps
It's easy to get confused when scrolling through Google Images. You might see something that looks similar but is actually a lipoma. Lipomas are fatty tumors. They feel soft, almost doughy. If you push a lipoma, it usually slides around under the skin. A pilar cyst is different. It’s "tethered" to the skin level, even if it feels deep.
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Then there’s the epidermoid cyst. These look almost identical in photos. However, epidermoid cysts can show up anywhere on the body—the face, the back, the chest. Pilar cysts are scalp specialists. If the bump is on your head, the betting odds are heavily in favor of a pilar cyst.
Why do they happen?
It isn't about hygiene. You could scrub your scalp with the finest artisanal soaps every hour and still get one. They’re often hereditary. If your mom or dad had "head bumps," you likely will too.
The technical term is a trichilemmal cyst. As the hair follicle produces keratin, something goes sideways in the cellular signaling. Instead of the keratin moving up the hair shaft, it begins to shed into a localized pocket. Over years—and yes, these things take years to get big—the pocket expands.
The "Rupture" Reality
Sometimes, an image of a pilar cyst will look nasty. Red, inflamed, maybe oozing some yellowish-white gunk. This happens when the cyst wall breaks under the skin.
When that keratin leaks into the surrounding tissue, your body's immune system freaks out. It treats the keratin like a foreign invader. This leads to "sterile inflammation." It isn't necessarily an infection, but it looks and feels like one. It gets hot. It throbs. In these photos, the hair around the cyst might be thinning because the inflammation is temporarily damaging the follicles.
If you see a photo where the cyst looks like it has a "horn" coming out of it, that's a rare variation. Usually, though, they stay subcutaneous.
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Does it ever turn into cancer?
This is the big fear, right? You see a lump, you think the worst.
Statistically, pilar cysts are benign. Almost always. There is a very rare version called a proliferating trichilemmal tumor. In images, these look much more aggressive—they might be ulcerated (meaning they have an open sore) and can grow quite large, several centimeters across. According to research published in the Journal of Cutaneous and Aesthetic Surgery, these proliferating versions are still usually benign but can behave more aggressively. If your "bump" is growing fast or bleeding, that’s when a biopsy becomes mandatory.
Getting rid of it: What the photos don't tell you
You cannot squeeze these away. Please, don't try.
If you look at images of pilar cysts that someone tried to "pop" at home, you’ll see bruising, scabbing, and often a much larger mess than what they started with. Because the sac wall is so tough, it won't just rupture through the skin like a whitehead. You’ll just traumatize the tissue.
The only real fix is surgical excision. It’s a quick office procedure.
- The doctor numbs the area with lidocaine (the sting is the worst part).
- They make a small "nick" in the skin.
- Because the cyst is so firm and has a thick wall, it often "pops" out in one piece. Doctors love this. It’s satisfying.
- They stitch it up, and you’re left with a tiny scar that your hair covers anyway.
The most important part of the surgery is removing the entire sac. If even a tiny piece of that "bag" is left behind, the cyst will just slowly refill over the next few years. It’s like a balloon that keeps reinflating.
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Managing your scalp health
If you’ve identified your bump through images of pilar cysts and decided to live with it, that’s usually fine. Many people have them for decades without issue. Just keep an eye on it.
- Avoid irritation: Be careful with combs and hairbrushes. Snagging the cyst can cause it to inflame.
- Watch for changes: If it goes from the size of a pea to the size of a golf ball in a month, see a dermatologist.
- Check for multiples: If you have one, you probably have three. Run your fingers across your entire scalp to see if others are "hiding."
Dealing with scalp issues is mostly about patience. These aren't emergencies, but they are annoying. Understanding the anatomy—that thick keratin-filled sac—helps take the mystery out of why that bump feels so weirdly hard.
Moving forward with a diagnosis
If you are staring at a lump in the mirror and comparing it to online galleries, your best next step is a physical exam. A dermatologist can usually diagnose a pilar cyst just by feeling it; the "firmness" is a dead giveaway.
Don't bother with expensive creams or "drawing salves" you see advertised on social media. They can't penetrate the thick scalp skin and the cyst wall. If the appearance bothers you or if it’s getting in the way of your hair stylist's scissors, schedule a consultation for a simple excision. It’s a permanent solution to a very common, albeit slightly gross, biological glitch.
Keep the area clean, don't pick at it, and if it starts to hurt, that's your signal that the internal wall might have leaked. At that point, skip the DIY remedies and get a professional to drain it properly.