Large sebaceous cyst: what to know

The term sebaceous cyst is commonly used for an epidermoid cyst, a sac containing keratin rather than ordinary liquid. It may feel smooth, round, and mobile under the skin, and some have a small central pore. A cyst can remain quiet for a long time, then become swollen, tender, or foul-smelling if its contents escape or bacteria are present. Other skin lumps can look similar, so an enlarging or uncertain lump deserves an examination rather than home treatment.

Do not squeeze, lance, or repeatedly massage the cyst; these actions can cause inflammation, infection, and scarring. Keep the skin clean and protect it from rubbing. A clinician may discuss observation, an intralesional steroid injection for selected inflammation, drainage when an abscess is present, or cyst removal. Drainage can relieve pressure but may not remove the cyst wall, so recurrence remains possible. Removal is planned around the cyst’s condition and location.

Seek prompt assessment for rapid enlargement, increasing pain, heat, spreading redness, pus, fever, or difficulty moving the nearby body part. Urgent care is appropriate for facial swelling near the eye, severe illness, or rapidly spreading infection. Arrange a routine appointment for any persistent, changing, repeatedly inflamed, or uncertain lump.

Ask whether the lump appears to be a cyst, whether it is inflamed or infected, and which option fits its size and site. Discuss wound care, possible scarring, whether the cyst wall will be removed, and what changes should prompt review.