Sebaceous Cysts Explained: Types, Causes and When to Act

What “Cyst” Actually Means

In medical terms, a cyst is simply an enclosed sac with a distinct wall, containing fluid, semi-solid material or air. The word describes the structure, not the location or the cause — which is why “cyst” can refer to anything from a harmless skin lump to an ovarian cyst on a scan. What defines every true cyst is the wall (also called the capsule or lining): a layer of living cells that produces the contents. That single anatomical fact explains almost everything about cyst behaviour — why they grow, why squeezing them fails, and why removing the whole capsule is the only permanent fix.

The Types of Skin Cyst — and What Each Costs to Remove

Epidermoid cysts — the common “sebaceous cyst”

The type we remove most often at Harley Street. A pocket of surface skin cells becomes trapped under the skin and keeps doing what skin does — shedding keratin — into a closed space. Firm, round, mobile, often with a central dark pore (punctum); commonest on the face, neck, chest and back. Despite the everyday name, most “sebaceous cysts” are epidermoid cysts.

Pilar cysts — the scalp cysts that run in families

Arising from hair-follicle cells, pilar cysts appear almost exclusively on the scalp, are often multiple, and are inherited in about 70% of cases. Surgically they are the good-news cyst: well-formed capsules that shell out cleanly, with low recurrence — and no, we do not shave your head to remove one.

True sebaceous cysts (steatocystoma)

Genuine sebaceous-gland cysts are much rarer and contain sebum (oil) rather than keratin. The distinction matters mainly to the surgeon; assessment and removal work the same way from a patient’s perspective.

The other cysts we treat

• Ganglion cysts — jelly-filled swellings over wrist and hand joints or tendons. Removal at our clinic: £1,000.
• Mucous cysts (mucoceles) — soft, bluish blisters of the lip or inside the mouth, usually after a bitten lip blocks a saliva gland. Removal: £400.
• Digital mucous cysts — small firm cysts at the finger joint near the nail, linked to the joint itself. Removal: £900.
• Dermoid cysts — congenital cysts, typically around the eyebrow or midline, present from birth and often removed in early adulthood for cosmetic reasons. Removal: £1,000.
• Scrotal cysts — common, benign and removed discreetly at the standard £400 fee.

Skin Cysts vs Ovarian and Other Internal Cysts

A quick disambiguation, because the word confuses: this guide — and our clinic — deals with cysts of the skin and just beneath it. Ovarian cysts, breast cysts, kidney cysts and other internal cysts share the same sac structure but are entirely different conditions, investigated with scans and managed by gynaecologists and other specialists. If a scan has found an internal cyst, your GP or the relevant specialist is the right port of call.

Why Cysts Form — and Why Yours Didn’t Appear Overnight

Most skin cysts start with a blocked or damaged hair follicle: minor trauma, friction, a spot that healed over, or simply bad luck traps surface cells beneath the skin, and the sac forms around them. Pilar cysts add genetics — family history is the norm. Acne-prone skin, and conditions like Gardner syndrome in the rare multiple-cyst patient, raise the odds. Testosterone-era skin (young and middle-aged adults) is the peak time; children rarely form them.

And a pattern we see weekly in clinic: almost every patient says their cyst “appeared suddenly”. On questioning, it has nearly always been there for months or years — it only became noticeable when it enlarged or flared. Cysts grow at the speed of the keratin their lining sheds, which is to say: slowly.

What’s Inside a Cyst

Keratin — the same protein that makes hair and nails — in a soft, wet, cheese-like form, with a smell patients remember. The colour of anything that escapes is a useful signal: white and cheesy is normal contents (smelly or not); yellow-green, thick and foul means infection and needs assessment — the full colour guide is in our infected cyst guide. The sac itself, when removed whole, looks like a small deflated balloon — there is a real photograph in our capsule explainer.

Are Cysts Dangerous?

Almost never. Epidermoid and pilar cysts are benign, do not spread, and malignant change within one is vanishingly rare. The honest caveats are three. First, an untreated cyst can become inflamed or infected — painful, and occasionally serious if ignored. Second, cysts in awkward sites (face, neck, over joints) are easier to remove before they grow. Third — and this is why assessment matters — not every lump called a “cyst” is one: we regularly see lipomas, dermatofibromas, pilomatricomas and occasionally skin cancers referred as cysts. A lump that is growing rapidly, ulcerated, hard or fixed to deep tissue is treated as suspicious, and we refer those to the NHS skin-cancer pathway via your GP rather than removing them privately.

When to Act — the Case for Early Removal

There is no medical law that a quiet cyst must be removed. But two patterns from hundreds of removals a year are worth knowing. Small cysts are the best cysts to remove: quicker surgery, an easier dissection and a smaller scar. And once a cyst has flared once, it tends to flare again — each episode adds scar tissue that makes the eventual excision harder and the scar larger. The most expensive cyst we see is the one that waited for its second infection. If yours has already announced itself, the quiet spell afterwards is the ideal window to plan removal.

Treatment Options at a Glance

Every option, honestly ranked, lives in its own guide — this is the map:

• Do nothing: legitimate for a small, quiet cyst — but it will not shrink itself. See what actually shrinks a cyst (and what doesn’t).
• Steroid injection (£150): the fast, temporary option for an inflamed cyst — typically visible in 2–5 days; about half still need excision later.
• Drainage: same-day relief for a collecting, painful cyst — but the sac stays. The full comparison: drainage vs surgical removal.
• Complete excision (£400; additional cysts £250): the permanent fix — whole capsule out, ~3% recurrence across ~600 removals a year. Same-day “see and treat” for most cysts: the complete London guide.
• Afterwards: showers from day one, stitches out at 7–9 or 14–18 days, silicone tape from week three — the whole protocol is in our aftercare guide.

Frequently Asked Questions

What is a sebaceous cyst?

A benign, closed sac just under the skin — usually an epidermoid or pilar cyst — whose living lining slowly fills it with keratin, a soft cheese-like protein. It feels firm, round and mobile, often shows a small central pore, and grows slowly over months to years.

What does “cyst” actually mean?

Any enclosed sac with its own wall containing fluid, semi-solid material or air. The word describes a structure, not a disease — which is why skin cysts, ovarian cysts and kidney cysts are entirely different conditions sharing one name.

Are sebaceous cysts dangerous?

No — they are benign and malignant change is extremely rare. The practical risks are infection and inflammation if left, and misdiagnosis: some lumps referred as “cysts” turn out to be lipomas or, rarely, skin cancers, which is why a rapidly growing, hard or ulcerated lump needs proper assessment.

Why do I keep getting cysts?

Usually a combination of skin type, follicle blockages and genetics — pilar cysts in particular run in families. Acne-prone skin raises the odds. Frequent new cysts are worth a consultation to confirm the diagnosis and, rarely, to exclude syndromic causes.

Do sebaceous cysts go away on their own?

Rarely and seldom permanently. The sac is self-sustaining: even if a cyst drains or flattens, the lining remains and typically refills it. The only permanent resolution is removal of the whole capsule.

What is the white stuff inside a cyst?

Keratin — the protein of hair and nails — in a soft, wet form, often with a strong smell. White, cheesy material is normal cyst content; thick yellow-green, foul-smelling discharge suggests infection and needs assessment.

Is a skin cyst related to ovarian cysts?

Only by name. Both are enclosed sacs, but ovarian cysts are an internal, gynaecological condition managed by different specialists with different investigations. Having one does not make the other more likely.

Which doctor removes skin cysts?

GPs with minor-surgery services, some dermatologists, and plastic surgeons all remove cysts; the practical difference is surgical volume and scar planning. At London Skin Clinic every cyst is removed by a GMC-registered Consultant Plastic Surgeon — the reasoning is set out in our removal guide.

Cyst Identity Crises, Courtesy of Reddit

“Reddit diagnosed my lump as a cyst / lipoma / ‘go to the ER’. Who do I believe?”

Nobody, respectfully — including the confident commenter with the anatomy diagram. Cyst vs lipoma is a genuinely useful question (firm + punctum + surface-attached vs soft + deep + no pore), but photographs cannot feel mobility or depth, and those two findings decide the diagnosis. Use the thread for reassurance; use an examination for an answer.

“Why do I get cysts when my friends never do?”

Mostly the follicle lottery, partly your parents. Skin type and acne history load the dice, and pilar cysts are frankly hereditary — patients often remember a parent with the same scalp bumps. It is not hygiene, and nothing you washed or ate caused it.

“Can I prevent the next one?”

Honestly: not reliably. No cream or diet stops follicles trapping keratin. What you can prevent is the expensive version of the story — the infected, twice-flared, scarred cyst — by not squeezing them and by removing the troublemakers while they are small and quiet.