Sebaceous cyst: what it is, treatment and removal

BAD says small cysts that give no trouble can be left alone. Removal may be recommended if a cyst causes problems in everyday life, for example by catching on a comb, or becomes repeatedly infected. To remove a cyst completely, the whole sac and its contents are taken out in a minor operation under local anaesthetic, which lowers the chance of it coming back. Removal leaves a scar and does not stop new cysts forming elsewhere.

A simpler option for a sore cyst is lancing: a small cut to drain the contents, with the wound packed so it heals from the inside out. Because the sac is not removed, the cyst can return. NHS Scotland guidance says treatment is not usually indicated and symptomatic cysts may be removed in primary care where this service is offered, and that benign lesions are not removed in hospital for cosmetic reasons alone.

A cyst is a closed sac with a lining and liquid or semi-solid contents. The BAD leaflet explains that epidermoid cysts have a lining made of cells from the outer layer of skin, while pilar cysts have a lining like the cells at the root of a hair. Both contain a thick, cheesy-like substance, rather like white toothpaste, which is keratin, the material that makes up hair and the outer skin.

Because the true source is not a sebaceous gland, dermatologists prefer the terms epidermoid and pilar. NHS Scotland's Right Decisions guidance still lists them as epidermoid (sebaceous) cysts, which is how many people will have heard them described.

They are round, sometimes dome-shaped lumps lying just under the skin surface, and they usually grow slowly. They can look yellow, pale or skin-coloured, and vary from smaller than a pea to several centimetres across. Some have a punctum, a central opening connecting the cyst to the skin. Right Decisions describes an epidermoid cyst as a smooth, mobile, flesh-coloured nodule within and fixed to the overlying skin, with a punctum helping to confirm the diagnosis.

Cysts on the scalp can catch on a comb, which BAD gives as one reason people ask for them to be removed.

• A smooth, dome-shaped lump that moves slightly under the skin.

• Sometimes a tiny dark central pore (punctum).

• Usually painless unless infected.

• Often on the face, neck, chest, upper back or scalp.

BAD says cysts can form without a clear cause, and that they are not linked to hygiene. They can occur after the skin has been damaged or irritated, when cells from the skin surface or hair follicles move deeper into the skin and keep multiplying to form a cyst.

Epidermoid cysts typically affect adults in their thirties and forties. Pilar cysts affect women more than men and tend to appear in middle age. BAD says epidermoid and pilar cysts by themselves are not usually inherited, although pilar cysts run strongly in some families and may be passed down as a dominant trait, with each child of an affected parent having a 1 in 2 chance of inheriting it.

The British Association of Dermatologists says some cysts become infected, which can make them red, sore and enlarged, with discharge of cheesy, foul-smelling contents. Your doctor may give you an antibiotic if the cyst becomes infected. It also lists a cyst that becomes repeatedly infected as a reason removal may be recommended.

The NHS cellulitis page describes skin that is painful, hot and swollen as a reason to ask for an urgent GP appointment or call NHS 111, so a cyst that becomes hot, painful and swollen should be assessed promptly rather than squeezed at home. The British Association of Dermatologists notes that lancing, which drains the contents through a small cut, does not remove the sac, so the cyst can return.

BAD says the diagnosis is made from the appearance of the lump. If there is any doubt, the cyst can be removed surgically and checked under the microscope. The leaflet stresses that cysts are not dangerous, but a healthcare professional should check any lump in the skin to make sure the diagnosis is right. NHS Scotland guidance says to refer to dermatology if there is diagnostic doubt and to be cautious about lesions with an atypical history or appearance, as they could be a malignancy.

Because other skin lumps can look similar, a healthcare professional should check any new lump in the skin. NHS Scotland’s Right Decisions dermatology guidance describes how the common benign lesions present.

The British Association of Dermatologists says that if you find any sort of lump in your skin you should consult a healthcare professional, because although epidermoid and pilar cysts are not dangerous, they should be checked to make sure the diagnosis is right.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if your skin is painful, hot and swollen, which can be a sign of cellulitis, because early treatment with antibiotics can stop it becoming more serious. It says to call 999 or go to A&E if cellulitis comes with a very high temperature or feeling hot, cold or shivery, a fast heartbeat or fast breathing, confusion, dizziness or faintness, or cold, clammy or pale skin.

NHS Scotland’s guidance says referral to dermatology may be appropriate if there is diagnostic doubt, a significant risk of a growth that is not benign, the lesion causes functional problems or significant disfigurement, or the lesion is prone to recurrent infection.

NHS Scotland’s guidance says that treatment of an epidermal (sebaceous) cyst is not usually indicated, that symptomatic cysts may be removed in primary care where this service is offered, and that a benign skin lesion will not be removed in secondary care for cosmetic reasons alone. The guidance itself says removal is offered only where the service exists, so ask your GP what is available in your area.

Private dermatology and minor surgery services can also remove cysts. The British Association of Dermatologists says removal is done by a trained surgical practitioner under local anaesthetic and leaves a scar. Ask whether the whole sac will be removed, what the scar will look like and whether the tissue will be sent for laboratory checking.