Hard sebaceous cyst: what to know

The term sebaceous cyst is commonly used for an epidermoid cyst, a sac under the skin containing keratin rather than liquid sebum. It may feel smooth, round, and firm, sometimes with a small opening at the surface. Inflammation can make it harder, sore, warm, or red. A ruptured cyst can leak thick material and may resemble an abscess. Other skin lumps can look similar, so a new, unusual, or changing lump should not be labelled at home.

Do not squeeze, lance, or try to empty the cyst. Keep the skin clean, avoid friction, and use a warm compress if it provides comfort. A clinician may monitor a quiet cyst, treat inflammation, drain an abscess, or perform cyst removal when the cyst repeatedly troubles you. Drainage can relieve pressure but may not remove the cyst wall, so ask what outcome each option is intended to provide.

Arrange prompt assessment for increasing redness, warmth, pain, swelling, pus, unpleasant drainage, or fever. Seek urgent help if redness spreads quickly, you feel faint or very unwell, or swelling is near the eye. A cyst that repeatedly returns, bleeds, ulcerates, or changes should be examined even if it is painless.

Ask whether this is an epidermoid cyst, whether inflammation or infection is present, and whether observation, steroid injection, abscess drainage, or cyst removal fits your situation. Ask about wound care and recurrence after any procedure.