What are the aims of this leaflet?
This leaflet has been written to help you understand more about epidermoid and pilar cysts. It tells you what they are, what causes them, what can be done about them, and where you can find out more about them.
What are epidermoid and pilar cysts?
Epidermoid and pilar cysts have previously been referred to as 'sebaceous cysts' however they are not sebaceous cysts because they arise from other cells in the skin, and not sebaceous gland cells.
They appear as smooth lumps just under the surface of the skin.
The definition of a cyst is a closed sac that has two main features:
- A lining
- Contents that are liquid or semi-solid
The lining of the sac distinguishes epidermoid and pilar cysts:
- Epidermoid cyst linings are made up of cells found on the outer layer of the skin (known as the epidermis)
- Pilar cyst linings are made up of cells like those found in the roots of hairs.
Both types of cysts contain a thick substance sometimes described as ‘cheesy-like’ material, looking rather like white toothpaste. This is made of keratin - the material that makes up hair and the outer layer of the skin.
Epidermoid and pilar cysts are common. You cannot pass them on to others, and they are not cancerous.
What causes these cysts?
Epidermoid and pilar cysts can form without a clear cause. They are not linked to hygiene. They can occur after the skin has been damaged or irritated. In these cases, cells found on the skin’s surface (for example, from the outer layer of skin or hair follicles) move deeper into the skin. There, they continue to multiply and form a cyst.
Epidermoid cysts typically affect adults in the third and fourth decade of life. They can appear anywhere on the skin. Most commonly, they develop on the face, neck, chest, upper back and sometimes on the scrotum.
Pilar cysts are most commonly seen on the scalp. They affect women more often than men and tend to come up in middle age. They run strongly in families (see below).
Are cysts hereditary?
Epidermoid and pilar cysts by themselves are not usually inherited. However, they may be part of rare conditions that can cause them.
Pilar cysts run strongly in some families. They may be passed down as an autosomal dominant trait – this means that each child of an affected parent has 1 in 2 (50%) chance of inheriting the condition.
What do cysts feel and look like?
Both types of cysts usually grow slowly. Some become infected, which can make them red, sore and enlarged. They can discharge cheesy, foul-smelling contents.
Cysts found on the scalp can catch on the comb.
Cysts are round, sometimes dome-shaped bumps, lying just under the skin surface. They can appear yellow or pale, and skin coloured. Some cysts may have a punctum – this is a central opening that connects the cyst to the skin surface. Cysts range in size: some can be smaller than a pea, while others can be much larger, reaching several centimetres across.
How are cysts diagnosed?
The diagnosis is made based on the appearance of the bump. If there is any doubt, the cyst can be removed surgically and checked under the microscope.
Can they be cured?
Yes, cysts can be removed safely and easily with a minor operation under local anaesthetic. The local anaesthetic helps numb the pain. However, removal only treats the current cyst. It does not stop new cysts from forming in the future, especially on the scalp or genital skin.
How can epidermoid and pilar cysts be treated?
- Epidermoid and pilar cysts are harmless. Small cysts that give no trouble can safely be left alone.
- Your doctor may give you an antibiotic if your cyst becomes infected.
- If removal is necessary, both types of cysts may require surgical removal under a local anaesthetic. The procedure is done by a trained surgical practitioner. Surgical removals do leave scars.
Removal is not always necessary. However, there are several reasons and/or criteria that your doctor will assess and may recommend for removal. These include:
- If the cyst is causing problems in everyday life - for example, by catching on your comb.
- If the cyst becomes repeatedly infected.
How are cysts removed:
To remove a cyst completely, the entire sac and its contents need to be taken out during a minor surgical procedure. This helps lower the risk of the cyst coming back.
If the cyst is sore or uncomfortable, sometimes a simpler procedure is done. This is called lancing, where a small cut is made to drain the contents of the cyst. The area may then be packed — this means filling the wound with a special sterile dressing (like gauze). Packing helps the wound heal from the inside out and reduces the risk of infection. However, because the sac is not removed during lancing, the cyst can return.
What can I do?
If you find any sort of lump in your skin, you should consult your healthcare professional. Epidermoid and pilar cysts are not dangerous, but your healthcare professional should check them to make sure the diagnosis is right.
Where can I get more information about epidermoid and pilar cysts?
Web links to other relevant sources:
www.dermnetnz.org/topics/trichilemmal-cyst
www.patient.info/doctor/epidermoid-and-pilar-cysts-sebaceous-cysts-pro
www.skinhealthinfo.org.uk/support-resources/jargon-buster/
Please note that the BAD provides web links to additional resources to help people access a range of information about their treatment or skin condition. The views expressed in these external resources may not be shared by the BAD or its members. The BAD has no control of and does not endorse the content of external links.
This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: individual patient circumstances may differ, which might alter both the advice and course of therapy given to you by your doctor.
This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel
BRITISH ASSOCIATION OF DERMATOLOGISTS PATIENT INFORMATION LEAFLET
PRODUCED | SEPTEMBER 2007
UPDATED | NOVEMBER 2010, FEBRUARY 2014, MARCH 2017, APRIL 2025
NEXT REVIEW DATE | APRIL 2028
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