What causes skin lumps?

An epidermoid cyst is a sac beneath the skin that may contain keratin and can become tender or inflamed. A lipoma is a soft lump formed from fatty tissue, while a dermatofibroma is usually a firm, small growth within the skin. Keloid scars are raised areas that extend beyond an original wound. Boils are painful, inflamed lumps linked to infection around a hair follicle. Basal cell carcinoma can present as a persistent shiny, scaly or bleeding spot or a sore that does not heal.

A lump's depth, firmness, mobility, colour, tenderness and rate of change help a clinician decide whether observation, imaging or a sample is needed. A symptom alone cannot establish the diagnosis.

Do not squeeze, pierce or repeatedly press a lump, because this can inflame it or introduce infection. Note when it appeared, whether it changes and whether there is drainage. Photographing it beside a familiar object can help track change. Keep any opening clean and covered, and avoid friction from tight clothing or equipment.

Book an assessment for a new, persistent or changing lump, especially one that bleeds, crusts, ulcerates, becomes fixed, or differs from nearby skin. Seek prompt care for rapid enlargement, severe pain, spreading redness, pus or fever. A painful fluctuant lump may need professional drainage rather than home treatment.

Ask what type of tissue the lump seems to involve, whether it needs monitoring or removal, and which warning changes should bring you back sooner.