Most cysts appear as small, round, firm lumps just beneath the skin surface. They’re typically flesh-colored or slightly yellowish, range from about 1 to 3 centimeters across, and feel smooth to the touch. But cysts show up in many different places on the body, and each type has its own distinct look. Here’s how to identify what you’re dealing with.
The Most Common Skin Cyst
Epidermoid cysts are by far the most frequently encountered type. They look like a firm, round nodule that matches your skin tone or has a slight yellow tint. The cyst is fixed to the skin surface but moves freely over the deeper tissue underneath, so if you press around it, you’ll feel it shift slightly over muscle and bone.
The signature feature is a tiny dark dot at the center, called a punctum. This looks like a small blackhead plugging a central opening. Not every epidermoid cyst has a visible one, but when it’s there, it’s a strong clue you’re looking at a cyst rather than another type of lump. If the cyst is squeezed or ruptures, a thick, cheese-like substance comes out. This is keratin, a protein your skin naturally produces, and it has a distinctly unpleasant smell.
Cysts on the Scalp
Pilar cysts account for about 90% of cysts found on the head, and they often appear in multiples. Around 70% of people who get them have more than one. They look similar to epidermoid cysts at first glance: round, firm, skin-colored bumps. The key visual difference is that pilar cysts lack the central punctum. There’s no dark dot or visible pore at the surface. They feel like smooth, hard marbles sitting just under the scalp skin and are usually painless unless bumped.
Cysts on the Wrists and Hands
Ganglion cysts develop along tendons or joints, most commonly on the wrists and hands. They look like a small water balloon on a stalk, sitting right over a joint or tendon. The next most common spots are the ankles and feet. These cysts contain a thick, jelly-like fluid similar to the lubricating fluid found naturally in joints. They can range from pea-sized to about an inch across and may change size over time, sometimes swelling with activity and shrinking with rest.
Cysts Behind the Knee
A Baker’s cyst creates a visible bulge in the soft area behind the knee. It’s a fluid-filled growth that causes tightness and swelling, sometimes extending down into the lower leg. The bulge is most noticeable when you’re standing or have been active for a while. Fully straightening or bending the knee can make it more prominent and uncomfortable. Unlike skin cysts, you can’t easily move a Baker’s cyst with your fingers since it sits deep in the joint space.
Tiny Cysts on the Face
Milia are miniature white-to-yellow cysts that appear on the face, most often around the eyes, nose, and cheeks. They’re much smaller than typical skin cysts and look like tiny, hard pearls trapped just under the surface. Unlike a pimple, they don’t have redness around them and won’t pop if squeezed. They’re extremely common in newborns but can appear at any age.
Eyelid Bumps: Stye vs. Chalazion
Two types of cyst-like lumps show up on eyelids, and they look quite different from each other. A stye is a red, painful bump right at the edge of the eyelid, usually at the base of an eyelash. It swells quickly and often makes the entire eyelid puffy. It looks and feels like a small boil.
A chalazion forms farther back on the eyelid, away from the lash line. It starts painlessly, and you might not notice it at first. As it grows, the eyelid may become red and slightly swollen, but it rarely puffs up the whole lid the way a stye does. A chalazion typically looks like a firm, round pea under the eyelid skin.
How a Cyst Differs From a Lipoma
Lipomas are the other common lump people find under their skin, and they have a noticeably different feel. A lipoma sits deeper, feels soft and doughy (almost like a small piece of rubber), and slides easily under your fingertip with light pressure. It feels like it’s sitting underneath normal skin with no visible surface changes.
A cyst, by contrast, feels firmer and more defined, as though you can sense a distinct capsule around it. Cysts tend to be closer to the skin surface and feel tethered or attached to it rather than floating freely underneath. And again, the presence of a central punctum points strongly toward a cyst.
How a Cyst Differs From an Abscess
An abscess is a pocket of pus caused by bacterial infection, and it looks and feels quite different from a cyst. Abscesses are usually pink or red, raised, soft, and painful. They feel warm to the touch and may drain pus if the skin opens. A typical cyst, on the other hand, is firm, matches your skin color, and causes no pain unless it becomes infected or ruptures.
What an Infected Cyst Looks Like
A cyst that was once painless and skin-colored can change dramatically if it gets infected or ruptures. The skin around it becomes red or discolored, and the area swells noticeably. Pain develops where there was none before. If the cyst wall breaks open, it may drain a yellow, foul-smelling fluid. The surrounding skin can feel warm and tender. An infected cyst can sometimes double in size over just a day or two, which is the most obvious visual sign that something has changed.
When a Lump Might Not Be a Cyst
Most skin cysts are completely harmless, but certain visual features suggest a lump may be something else entirely. Be alert to any spot or bump that has irregular or ragged borders, contains multiple colors (brown, black, pink, red, white, or blue mixed together), bleeds or forms a crust that doesn’t heal, or changes noticeably in size, shape, or color over a few weeks.
A pearly or waxy bump can be a sign of basal cell carcinoma. A firm red nodule with scaly, crusted edges may point toward squamous cell carcinoma. And any mole that becomes asymmetrical, develops uneven borders, or grows larger than about 6 millimeters (roughly the size of a pencil eraser) warrants a closer look. The general rule: any new or changing spot on your skin that persists for two weeks or more is worth having evaluated.
Cysts You Can’t See
Internal cysts, like those on the ovaries or kidneys, aren’t visible from the outside and are typically discovered on imaging. On an ultrasound, a simple cyst appears as a well-defined, round, dark area with no solid material inside. Complex cysts may show internal walls, solid areas, or irregular borders. Internal cysts rarely cause symptoms unless they grow large enough to press on surrounding structures or rupture.