What should you know about a cyst under the skin of the shoulder?

An epidermoid cyst is a sac beneath the skin that may feel round, firm, or slightly mobile. It can remain quiet or become irritated by pressure from clothing, bags, or shoulder movement. A visible pore, thick material, tenderness, redness, or warmth may occur, but these features are not enough to confirm the diagnosis. Other skin lumps and abscesses can have a similar feel.

A clinician can examine the lump and surrounding skin, ask how it has changed, and decide whether it can be observed or needs treatment. Avoid calling it a sebaceous cyst as a diagnosis until it has been assessed.

Do not squeeze, pierce, or massage the lump. Reduce rubbing from straps or tight clothing and keep the skin clean. Note its size, tenderness, colour, drainage, and whether movement makes it sore. A clinician may discuss observation, an injection into the skin for selected inflammation, drainage when an abscess is present, or cyst removal when the lump is recurring or troublesome.

Arrange prompt assessment if the lump grows quickly, becomes painful, red, hot, soft in the centre, or starts draining. Fever, spreading redness, red streaking, or feeling very unwell needs urgent attention. A stable lump still deserves a routine review if it persists, returns after draining, limits shoulder movement, or causes repeated friction.

Ask whether the lump is consistent with an epidermoid cyst, whether there are signs of an abscess, and whether imaging or another test is needed. Ask which option fits its current state, how to protect the area from rubbing, and whether removal could leave a scar.