Sebaceous Cysts

What are they?

Sebaceous cysts are smooth round lumps which you can feel just beneath the skin. They are benign. That is, they do not spread or cause any serious problems. They are very common. They can appear anywhere on the body, but the most common place is the scalp. They vary in size. Commonly they are small (pea size) but can enlarge over many months to become a few centimetres in diameter.

What causes them?

The skin has tiny glands under the surface which makes sebum. This is the 'oil' that makes the skin smooth. If a gland's duct (channel) becomes blocked the sebum is still made. This then fills up the blocked pore to form a cyst. The matter inside the cyst has the appearance of toothpaste.

Are they harmful?

No, they usually do no harm. If they do not bother you then it is best just to leave them alone. Rarely they can become infected and you may then need a course of antibiotics. Sometimes people with a sebaceous cyst requests that it be removed, usually for one of three reasons.

• Cosmetic reasons. For example, the cyst is in an obvious site on the skin.
• They are easy to 'catch' and traumatise. This typically occurs on the scalp when combing hair.
• If it has become infected or irritating.

Removal of sebaceous cysts

Usually they can be removed under local anaesthetic. The surrounding skin is 'numbed' by injecting some local anaesthetic. A small incision (cut) is made over the cyst. Typically, the cyst can be easily pulled out. The wound is then stitched up. A small scar will result. Sometimes after the removal of a sebaceous cyst it gradually regrows in the same site under the scar. This is unusual, but if it occurs it can be removed again.

Removal of sebaceous cysts is one of the most common minor operations now done in general practice surgeries.

© EMIS and PIP 2004   Updated: December 2003   CHIQ Accredited   

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