HealthInfo Canterbury
Epidermoid & pilar cysts
A cyst is a sac-like pocket of tissue that contains fluid or a semi-solid substance. It's made up of a lining and the contents of the sac.
Epidermoid cysts and pilar cysts (also called sebaceous or trichilemmal cysts) are common, non-cancerous (benign), smooth lumps that appear under your skin.
The difference between an epidermoid cyst and a pilar cyst is the lining – the lining of an epidermoid cyst is made up of cells from the outer layers of your skin (the epidermis), while the lining of a pillar cyst is made up of cells from hair roots.
Both types of cyst are usually surrounded by a fibrous capsule under your skin. Inside the capsule is a thick, cheese-like substance. This is soggy keratin. Keratin is made up of skin cells and is what hair is made of.
Read more about epidermoid cysts here and pilar cysts here.
Epidermoid cysts most commonly occur when you're young or middle-aged and men get them more than women.
Pilar cysts occur in middle age and affect women more than men.
Symptoms of epidermoid and pilar cysts
Both epidermoid and pilar cysts are slow growing, smooth, round lumps just under your skin.
Epidermoid cysts can affect any part of your body but mostly appear on your face, neck, chest and upper back. Sometimes they can occur on your scrotum.
Pilar cysts usually appear on your scalp. Sometimes several form on your scalp.
Occasionally either cyst can rupture under your skin and become infected where they are red, inflamed and painful.
Diagnosing epidermoid and pilar cysts
Usually your GP can diagnose an epidermoid or pilar cyst by examining the lump under your skin but you may need a biopsy.
Treating epidermoid and pilar cysts
Most cysts don't cause problems so you don't need any treatment. But if they're causing you problems such as being unsightly or interfering with your everyday life, they can be removed through a minor operation using a local anaesthetic.
If you have an infected cyst you may need antibiotics and the cyst may need to be drained.
Getting help for epidermoid and pilar cysts
If you have any doubts about a lump under your skin, get your GP to have a look.
While cysts don't usually need to be removed you can pay to have them removed – talk to your GP about this.
HealthInfo recommends the following pages
- DermNet NZ
- Cutaneous cysts and pseudocysts
An explanation of the different types of cysts, which ones need to be treated and which ones can be left alone.
- Epidermoid cyst
Information about epidermoid cysts and how they're treated.
- Trichilemmal cyst
Information about trichilemmal (pilar) cysts and how they're treated.
- Cutaneous cysts and pseudocysts
Written by HealthInfo clinical advisers. Last reviewed August 2021.
SourcesReview key: HISEC-125440
