A cyst under the skin typically feels like a firm, round lump that you can move slightly with your fingers. Most are small, painless, and sit just beneath the surface, feeling almost like a marble or pea embedded under the skin. The texture, size, and tenderness of the lump can vary depending on the type of cyst and whether it’s inflamed.
How a Typical Skin Cyst Feels
The most common type of cyst you’ll feel under your skin is an epidermoid cyst (often called a sebaceous cyst, though that’s technically a different thing). When you press on one, it feels firm but slightly compressible, similar to pressing on a rubber ball. The cyst is fixed to the skin surface, meaning the skin moves with it, but it slides freely over the deeper tissue and muscle beneath. That mobility is one of the hallmarks of a benign cyst.
Most epidermoid cysts are flesh-colored or slightly yellowish. If you look closely at the center, you may notice a tiny dark dot, called a punctum, which is essentially a blocked pore. That opening connects to the cyst wall inside. These cysts are filled with keratin and oily debris, a thick, cheese-like substance that has a distinct foul smell if it’s ever expressed. That dense filling is what gives the cyst its firmness.
The size ranges widely. Some cysts are barely noticeable, feeling like a small bead under the skin. Others grow to the size of a golf ball or larger over months or years. Growth is usually very slow, and the cyst may stay the same size for a long time before gradually enlarging.
How It Changes When Inflamed or Infected
An uninflamed cyst is usually painless. You might not even know it’s there until you happen to run your fingers over it. But when a cyst becomes inflamed or infected, the experience changes dramatically.
An inflamed cyst swells, becomes tender or painful to the touch, and feels warm compared to the surrounding skin. The area around it may turn red, or on darker skin tones, it can appear darker or develop a purplish hue. The lump also becomes more fixed in place, losing some of that easy mobility it had before. At this stage, an inflamed cyst can closely mimic a boil.
If the cyst becomes truly infected, you may notice drainage of pus or foul-smelling fluid, increasing pain even without touching it, and spreading redness. A cyst that ruptures under the skin can trigger a strong inflammatory reaction, and the area may feel hot and swollen over a wider region than the original lump.
Cysts in Different Locations Feel Different
Not all cysts feel the same, partly because different body areas produce different types.
Scalp: Pilar cysts are the most common type found on the head. They tend to feel smoother and firmer than epidermoid cysts elsewhere on the body. You’ll usually discover one while washing or combing your hair, noticing a round, flesh-colored bump that slides under your fingertips. Pilar cysts can grow quite large and often feel harder than cysts on the torso or limbs because of their denser keratin filling.
Wrists, hands, and feet: Ganglion cysts form near joints and tendons rather than from skin glands. They feel like firm, round or oval lumps filled with a thick, jelly-like fluid. A ganglion cyst may change size over time, often swelling with repeated joint movement and shrinking with rest. While many are painless, a ganglion cyst pressing on a nearby nerve can cause tingling, numbness, or a dull ache that radiates outward. Some ganglion cysts are so small you can feel them only when pressing firmly into the area.
Cyst vs. Lipoma: How to Tell Them Apart
The other common lump people find under the skin is a lipoma, which is a benign fatty growth. The two feel noticeably different. A cyst is firm and somewhat compressible, like pressing a small rubber ball. A lipoma feels soft and doughy, more like pressing a piece of clay or a small pillow. Lipomas also tend to move very easily when you push on them, sliding under your finger with minimal pressure, while a cyst is anchored to the skin above it and moves with the skin rather than independently beneath it.
Lipomas are rarely tender. Cysts can become tender even without infection. And lipomas never have that central punctum or pore that epidermoid cysts sometimes show.
Signs a Lump May Not Be a Cyst
Most lumps under the skin turn out to be harmless cysts or lipomas. But certain features warrant closer attention. A lump that grows rapidly over weeks rather than months, feels very hard and immovable (as if attached to the tissue beneath), or has an irregular shape rather than a smooth round border is less typical of a simple cyst.
Other features that set a potentially concerning lump apart from a cyst: the skin over it looks ulcerated or won’t heal, the lump keeps growing without any signs of infection, or it’s painless but rock-hard. A cyst, by contrast, is smooth, round, and moves at least somewhat when you press on it. Skin cancers like basal cell carcinoma can appear as a bump that looks skin-colored or pink on lighter skin, or brown to glossy black on darker skin, often with a rolled or raised border.
If a lump doesn’t have the classic cyst characteristics, firm but compressible, round, mobile over deeper layers, possibly with a visible punctum, getting it examined gives you a clear answer. A doctor can often distinguish a cyst from other lumps through a simple physical exam, and in uncertain cases, an ultrasound or biopsy settles it quickly.