What should you know about a hard cyst under the skin?

An epidermoid cyst is a closed sac beneath the skin that can contain keratin, a thick skin protein. It may feel round, firm, or rubbery and sometimes has a small central opening. A cyst can remain quiet or become swollen, tender, warm, and red when inflamed. Not every hard lump is a cyst, so its texture and appearance alone cannot confirm the cause. A skin-lump assessment can help distinguish a cyst from other growths or an infection.

Do not squeeze, puncture, or repeatedly press the lump; these actions can irritate the sac and introduce infection. Keep the area clean and note its size, tenderness, colour, and whether it moves under the skin. A clinician may discuss observation, a steroid injection into the skin for selected inflammation, drainage when an abscess is present, or cyst removal when the cyst repeatedly returns or causes problems. Drainage may relieve pressure but does not necessarily remove the cyst wall.

Arrange prompt medical assessment for rapidly increasing swelling, spreading redness, marked warmth, pus, fever, or worsening pain. Seek evaluation for a lump that bleeds, forms a persistent sore, becomes fixed, or changes in appearance. Urgent care is appropriate when severe swelling is accompanied by feeling very unwell. A clinician can decide whether examination alone is enough or whether further assessment is needed.

Ask whether the lump appears to be a cyst, whether inflammation or infection is present, and what changes should trigger review. You can also ask whether observation, steroid injection, abscess drainage, or cyst removal fits its location and symptoms.