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Sebaceous cyst

What is a sebaceous cyst?

Asebaceous cyst is a small, dome-shaped cyst or sac that develops in the skin. It is filled with a thick, greasy, cream-cheese like substance (called sebaceous material) that slowly fills up the cyst over many years. It can be seen as a pale lump just beneath the skin. Sometimes a small, dark dot can be seen in the centre of the cyst – this is a narrow pore connecting the cyst to the outside of the skin.

Where are they located?

Sebaceous cysts are very common and can occur in any area of hair-bearing skin, but mostly on the scalp. They are also found on the face, neck, trunk (especially on the back) and scrotum.
What are the signs and symptoms? The cyst is dome-shaped and looks like a hemisphere on the skin.It is whitish or skincoloured. Cysts usually vary in size from 1cm to 4cm in diameter.
They occur singly or in groups. The cysts are usually painless but may become red and painful if infected.

What is the cause of a sebaceous cyst?

It arises in a hair follicle, which has a small duct opening onto the surface of the skin. The duct becomes plugged with a sticky material and the secretions from the cyst gradually build up and cause it to expand.

Who gets sebaceous cysts?

They can develop at any age but are usually first noticed in adult life.

What happens to them?

Most people with small cysts that cause no symptoms are happy to live with them. The cysts may stay the same size and cause no problems. Occasionally they may grow to be large and unsightly or become infected – these require attention. Cysts in the scalp can be a nuisance and people may choose to have them removed.

What is the risk?

They are usually harmless, but the main risk is infection by bacteria. This causes the cyst to become enlarged, red, inflamed and tender. It may eventually burst and release a foul-smelling pus. However, it usually resolves but can become reinfected later.

What is the treatment?

An obtrusive or unsightly cyst can be removed by a simple operation for which you will be given a local anaesthetic. A simple incision is made in the skin overlying the cyst, the sac is removed and the wound is closed with stitches. If a small part of the cyst is left behind – as is sometimes unavoidably the case – it can recur. If a cyst becomes infected, a course of antibiotics may be needed.