Compare · Conditions

Epidermal Inclusion Cyst vs Abscess

An epidermoid cyst is a firm lump under the skin, lined with the same cells as the skin surface and slowly filling with keratin. It is harmless and often sits quietly for years. The trouble starts when the wall ruptures, which is why squeezing one is the worst thing you can do to it. A localised pocket of pus within or under the skin.

Research updated 2026-10-23
A smooth, dome-shaped lump about two centimetres across on the upper back on pale skin, with a tiny dark pore at its center and faintly pink skin over it.AI-generated educational illustration: A small dome-shaped localized tender-looking red swollen bump on adult upper arm beneath intact skin; no incision or large open wound.
Key differencesWhat is it?What it looks likeDiagramsWhen it startsTriggersDaily CareTreatmentOutlookComplicationsWhen to get helpQuestions

Key differences

The same eight facts on every condition comparison.

Usual age
Adults
Any age
Where
Face, neck, trunk
Armpits, groin, buttocks; anywhere
Main sign
Firm, movable lump with a pore
A tender, swollen pocket of pus
Itch or pain
Painless unless inflamed
Painful
Contagious
No
The bacteria can spread
Long term
Stays until the sac is removed
Clears once drained
Scars
Removal leaves a scar
Can leave a small scar
Who gets it
Adults; more in men
Anyone; more with diabetes or friction

What is it?

Epidermal Inclusion Cyst
Abscess
What is it?
  • It is a keratin-filled sac.
    The cyst is a usually benign sac lined by skin-like cells and filled with keratin.
  • It grows slowly.
    It often appears as a slowly growing lump with a central opening.
  • "Sebaceous cyst" is a misnomer.
    It is commonly called a sebaceous cyst, but its contents are not simply trapped oil.
  • Unusual lumps need examining.
    A new, changing, hard, fixed or uncertain lump should be checked rather than assumed to be a cyst.
  • What it is
    A localised pocket of pus within or under the skin.

What it looks like

Epidermal Inclusion Cyst

Representative image of quiet cyst. It illustrates a visible feature or experience and is not a diagnostic reference.

Round lump Smooth and movable under skin.

Representative image of cyst punctum. It is not a diagnostic reference or an exact depiction of every subtype, stage or location.

Central opening A small dark pore on top.

A small red swollen dome-shaped cyst with a tiny central punctum on the side of the neck.

Inflamed cyst Red, swollen and tender.

Abscess

An upper arm with a rounded red bump and a pale-yellow central point.

Abscess A red swelling rises above the surrounding upper-arm skin.

Skin tones
A smooth, dome-shaped lump about two centimetres across on the upper back on pale skin, with a tiny dark pore at its center and faintly pink skin over it.
A smooth, dome-shaped lump on the upper back on medium olive skin, with only a faint central pore and skin over it the same color as the skin around it.
A smooth, dome-shaped lump on the upper back on mid-brown skin, with a small central pore and skin over it very slightly darker than the skin around it.
A smooth, dome-shaped lump on the upper back on deep brown skin, with a small dark central pore and even-toned skin over it.
a localized raised abscess on light skin.
a localized raised abscess on medium skin.
a localized raised abscess on brown skin.
a localized raised abscess on deep skin.
Diagram
Epidermal Inclusion Cyst mechanism diagram. A lining forms: Skin-like cells line a sac beneath the surface. Keratin collects: The lining sheds skin protein into the sac. Rupture can inflame it: Escaped keratin irritates surrounding tissue.
In the skin

A sac lined by skin-like cells forms beneath the surface and fills with shed keratin. If the lining ruptures, escaped keratin can provoke inflammation in the surrounding tissue.

An infection can lead to a localized collection of pus within tissue. The surrounding inflammatory response creates a tender, swollen cavity rather than diffuse inflammation alone.

When it usually starts

010203040506070+

Epidermal Inclusion Cyst. Most often develops in adults, though it can occur at other ages.

Abscess. Can occur at any age.

Causes and triggers

Causes

An epidermal inclusion cyst forms when surface skin cells get trapped under the skin and keep making keratin.

An infection can create a walled-off collection of pus.

Risk factors
Acne, Skin injury, Adults aged 20 to 40
Skin breaks, Bacterial colonisation, Diabetes or immune suppression
Trigger
● Epidermal Inclusion Cyst
● Abscess
Blocked hair follicles
Strong link
Not listed
Skin injury or surgery
Strong link
Not listed
Squeezing the cyst
Well established
Not listed
Skin injury
Not listed
Can contribute
Friction
Not listed
Can contribute

Daily Care

Epidermal Inclusion Cyst
Abscess
Daily care

Habits that help

  • Warm compresses
    Ease discomfort and help it come to a head.
  • Reduce friction over it
    Adjust a strap, move a backpack.
  • Treat underlying acne
    Fewer new cysts where heavy acne is controlled.

Avoid

  • Avoid: Squeezing it
    Pressure tears the sac from inside.
  • Avoid: Picking at the central dot
    Widens the opening, invites bacteria.
  • Avoid: Lancing it at home
    Infection risk, a scar, and the lining stays.
  • Avoid: Friction and pressure over it
    Straps and waistbands set a stable cyst flaring.
  • Avoid: Shaving over it
    A nick is a straight route to inflammation.
  • Avoid: Drawing salves and home remedies
    Nothing surface-applied dissolves a sac.
  • Avoid: Waiting for a flare to remove it
    The sac tears instead of lifting out.
  • Avoid: Having only the contents drained
    The lining stays, so it refills.
  • Avoid: Repeated flares over years
    Each lays down scar tissue that tethers the sac.
  • Avoid: A midline lump on a baby
    Identify it first - a few connect to deeper structures.

Habits that help

  • Keep the area gently clean and cover any drainage
    Use a clean non-stick dressing and replace it when wet, dirty or as instructed.
  • Wash hands before and after dressing changes
    Dispose of used dressings safely and clean surfaces contaminated by drainage.
  • Keep towels, washcloths and razors for your own use
    Launder items that touch the affected area and let them dry fully.
  • Reduce pressure and rubbing over the lump
    Choose loose clothing and avoid shaving across inflamed skin.
  • Follow the wound-care plan after professional drainage
    Keep dressing and follow-up appointments; do not remove packing unless told to do so.

Avoid

  • Avoid: Squeezing, lancing or piercing the lump at home
    This can spread infection; a collection of pus may need professional drainage.
  • Avoid: Delaying assessment for spreading redness, fever or worsening pain
    Home care does not replace drainage or antibiotics when they are needed.

Treatment differences

Evidence labels come from each condition’s own treatment list.

Treatment
● Epidermal Inclusion Cyst
● Abscess
Prescription pills
None listed

Antibiotics

Listed

Spreading infection, systemic illness or individual risk factors may require antibiotics alongside source control.

Injections
Editorial illustration for Cortisone Injection, based on the entry’s treatment or equipment reference.

Cortisone Injection

Limited evidence

A small injection of steroid into an inflamed cyst early in a flare, which settles the swelling and pain over a few days. It is for the flare, not the cyst — the sac and its lining are still there afterwards. It works best in the first day or two, before the lump has come to a head.

None listed
Procedures
Editorial illustration for Cyst Removal, based on the entry’s treatment or equipment reference.

Cyst Removal

Strong evidence

The only thing that ends a cyst, because it takes out the sac wall as well as the contents. It is a single minor procedure under local anesthetic, done through a small cut that is usually placed along a natural skin crease. Done on a quiet cyst it lifts out whole and leaves a thin line; done on an inflamed one it tears, fragments get left behind, and it is more likely to come back.

Editorial illustration for Incision and Drainage, based on the entry’s treatment or equipment reference.

Incision and Drainage

Moderate evidence

Incision and drainage. A small cut to let out the contents of a large, painful, inflamed cyst. The relief is immediate and it is exactly the right thing to do for an abscess. It is not a cure: the lining stays behind and keeps making keratin, so it usually refills over weeks to months. The usual plan is to settle things this way, then remove the sac properly a month or two later.

None listed

Outlook

Long term

Left alone, a cyst sits quietly for years, punctuated by flares. The pattern matters more than any single episode - a cyst that has never flared can come out whenever it suits you, while one that has flared twice is on a trajectory. Plan removal during a quiet spell.

A skin abscess often improves after appropriate drainage; some also need antibiotics. It can recur if a contributor remains, and spreading redness, fever or worsening pain needs prompt review.

Complications

Possible complications
  • Rupture and a painful flare
  • Infection or an abscess
  • Scars and keloids from repeat flares
More details

Rupture and a painful flare
The wall tears and keratin spills into the tissue around it, and the immune system attacks it. The lump becomes hot, swollen and painful over a day or two, and feels bigger and firmer than it did. Most of these are not infections. Squeezing is the single most common reason it happens, so leaving a quiet cyst alone is the best prevention there is.

Infection or an abscess
Sometimes bacteria do get in, and the cyst becomes a genuine abscess. It looks much like an ordinary flare, so the things that point to infection are spreading discoloration, pus, fever and feeling unwell. This is the version where antibiotics belong, and a large abscess usually needs draining as well. A hot, inflamed cyst around the nose, eyes or upper lip is treated more cautiously than one anywhere else.

Scars and keloids from repeat flares
Every rupture and every emergency drainage lays down its own scar, and after a few episodes the area is tethered and marked before anyone has operated. Raised, thickened scars and keloids are more likely on the chest, shoulders, upper back and jawline, and more likely on deeper skin tones. A planned removal on a quiet cyst usually leaves a thin line along a natural skin crease, which is the argument for doing it sooner.

Infection can spread to nearby skin or cause systemic illness.

When to get help

When to get help

Seek assessment if a lump is growing, recurrently inflamed or uncertain. Rapidly increasing pain, redness, drainage or fever may require prompt treatment.

Seek prompt care for a painful pus collection; fever, spreading swelling or feeling unwell increases urgency.

Common questions

Epidermal Inclusion Cyst:Is it dangerous?

Epidermoid cysts are benign. They do not spread and do not turn into cancer. Cancers arising inside a cyst are described but genuinely rare. Have it examined if it grows rapidly, feels hard and fixed rather than mobile, bleeds, or has a sore over it that will not heal - those suggest the lump may not be a cyst.

Epidermal Inclusion Cyst:Why does it smell?

The contents are keratin and broken-down skin cells, sealed in for a long time, and skin bacteria break that material down. The smell comes from the contents, not from infection.

Epidermal Inclusion Cyst:Can I just have it drained?

You can, and for a large, painful, inflamed cyst that is the right thing for relief. But draining empties the contents and leaves the lining, and the lining makes keratin, so it refills over weeks to months. Removing the whole sac is what ends it.

Epidermal Inclusion Cyst:Why will my doctor not remove it while it is inflamed?

Because the result is worse. Inflamed tissue is swollen and fragile, so the sac tears instead of lifting out whole, fragments get left behind, the cyst is more likely to come back, and the scar is wider. Settle the flare first, then remove it a month or two later.

Epidermal Inclusion Cyst:Will it come back after surgery?

Not if the whole lining comes out, which is the goal. Recurrence happens when a fragment is left behind, more likely if the cyst was inflamed or heavily scarred from previous flares. New cysts can form elsewhere - that is a new cyst, not the old one.

Epidermal Inclusion Cyst:Can I stop getting them?

Not reliably, because most people who get one have no identifiable cause. You can reduce flares - do not squeeze them, take pressure and friction off them, and treat significant acne if cysts keep appearing where it was. If you are getting a lot from a young age, mention it, because a few people have an inherited reason.

Abscess:What is Abscess?

A localised pocket of pus within or under the skin.

Abscess:What can I do day to day?

Keep the area clean and covered. Do not squeeze or lance it; do not share towels.

Abscess:When should I get medical advice?

Seek prompt care for a painful pus collection; fever, spreading swelling or feeling unwell increases urgency.

Sources

Sources and further reading

  1. DermNet
  2. Abscess
Dermapedia on YouTube