What should you know about a cyst outside the skin?

An epidermoid cyst can contain keratin, a skin protein, inside a lining. It may feel smooth, firm or slightly mobile, and it can have a small central opening. Some cysts remain quiet; others become tender, red, swollen or warm when irritated or inflamed. A lump can have other causes, so a clinician may examine its position, texture and surface before naming it.

A cyst is different from an abscess, although an inflamed cyst can resemble one. A clinician can distinguish these possibilities and check whether the lump needs treatment.

Keep the area clean, avoid rubbing it, and use a warm compress for comfort if the skin is closed and not severely painful. Do not puncture, lance or repeatedly press the lump at home. If it is growing, recurrent, bothersome or catching on clothing, arrange a skin assessment. Options may include observation, an injection to calm inflammation, drainage when infection is suspected, or removal of the cyst and its lining; the appropriate choice depends on the examination.

Seek prompt medical care if redness spreads, pain is escalating, the area feels hot, pus is draining, or you feel feverish or unwell. Arrange an assessment for a lump that changes quickly, bleeds, becomes fixed, or does not settle. Urgent attention is sensible when swelling near the eye, mouth or airway affects vision, swallowing or breathing.

Ask whether the lump appears to be a cyst, whether inflammation or infection is present, and whether monitoring is reasonable. You can also ask what treatment would address the cyst lining, how wound care would work, and what changes should prompt a return visit.