Skin lumps are any abnormal bumps or swellings on or under the skin.

Most lumps and swellings are benign (not cancerous) and are harmless, especially the kind that feel soft and roll easily under the fingers (such as lipomas and cysts).

A lump or swelling that appears suddenly (over 24 to 48 hours) and is painful is usually caused by an injury or an infection.

Common causes of skin lumps include:

• Lipomas, which are fatty lumps under the skin
• Enlarged lymph glands, usually in the armpits, neck, and groin
• Cysts, a closed sac in or under the skin that is lined with skin tissue and contains fluid or semisolid material
• Benign skin growths such as seborrheic keratoses, skin tags, or neurofibromas
• Boils, painful, red bumps usually involving an infected hair follicle or group of follicles
• Corns or calluses, caused by skin thickening in response to continued pressure (for example, from shoes) and usually occurring on a toe or foot
• Warts, caused by a virus that develops a rough, hard bump, usually appearing on a hand or foot and often with tiny black dots in the bump
• Moles, skin-colored, tan, or brown bumps on the skin
• Abscesses, infected fluid and pus trapped in a closed space from which it cannot escape
• Cancer of the skin (colored or pigmented spot that bleeds easily, changes size or shape, or crusts and does not heal)

Skin lumps from an injury can be treated with rest, ice, compression, and elevation. Most other lumps should be looked at by your health care provider before you try any home treatments.

Call your provider if you have an unexplained lump or swelling.

Your provider will perform a physical exam and ask about your symptoms, including:

• Where is the lump?
• When did you first notice it?
• Is it painful or growing larger?
• Is it bleeding or draining?
• Is there more than one lump?
• Is it painful?
• What does the lump look like?
• What other symptoms do you have?

Your provider may prescribe antibiotics if you have an infection. If cancer is suspected or the provider cannot make a diagnosis by looking at the lump, a biopsy or an imaging test may be done.

James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM. Dermal and subcutaneous tumors. In: James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM, eds. Andrews' Diseases of the Skin: Clinical Dermatology. 13th ed. Philadelphia, PA: Elsevier; 2020:chap 28.

Seller RH, Symons AB. Skin problems. In: Seller RH, Symons AB, eds. Differential Diagnosis of Common Complaints. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 29.