What should you know about a cyst underneath the skin?

A skin cyst can feel smooth, firm, or slightly movable beneath the surface. An epidermoid cyst commonly contains keratin, a protein from skin cells, and may have a small opening on the skin. It is different from an abscess, which is a collection of infected material and is more likely to be hot, tender, swollen, or associated with feeling unwell.

Do not squeeze, pierce, or repeatedly press the lump. These actions can irritate the surrounding skin, push material deeper, or introduce infection. A clinician can distinguish a cyst from an inflamed follicle, abscess, lipoma, or another skin lump.

Keep the area clean and avoid friction from tight clothing, straps, or repeated shaving. A warm, moist compress may make an irritated lump feel more comfortable, but it does not remove the cyst wall. Arrange a dermatology assessment if it keeps returning, interferes with clothing or movement, or you want it removed.

Depending on the finding, care may involve observation, treatment of inflammation, drainage when infection is present, or a minor procedure that removes the cyst and its wall. See the related guides on [Skin Lumps], [Steroid Injection Into The Skin], [Abscess Drainage], and [Cyst Removal].

Seek prompt medical care if the lump becomes rapidly more painful, hot, red, or swollen; releases foul-smelling material; or is accompanied by fever or spreading redness. An unexplained lump that is hard, fixed, bleeding, ulcerated, or changing in appearance also deserves assessment. Urgent care is appropriate for severe pain, rapidly spreading redness, or feeling significantly unwell.

Could this be a cyst, abscess, or another type of lump? Is examination enough, or is another test needed? If removal is considered, will the cyst wall be addressed to reduce recurrence? What changes should prompt an earlier review?