What should you know about dark hard lump under skin?

A firm lump may involve a blocked follicle, an inflamed cyst, a boil, scar tissue, or another skin growth. A [Boils](/conditions/boils/) page can help explain tender infected lumps, but colour and firmness alone cannot identify the cause. A dark surface may reflect dried blood, inflammation, pigment, or a separate lesion.

A lump that is hard, anchored, enlarging, repeatedly crusting, or slow to heal needs a clinician’s assessment. A [Basal Cell Carcinoma](/conditions/basal-cell-carcinoma/) can sometimes resemble a persistent sore or growth, but a lump does not by itself establish that diagnosis.

Do not squeeze, cut, pierce, or repeatedly rub the lump. Keep the area clean, note when it appeared, and record changes in size, colour, tenderness, warmth, drainage, or surface. A clinician may examine the skin and decide whether observation, sampling, removal, or another treatment is appropriate.

For selected inflammatory lumps, a [Steroid Injection Into The Skin](/treatments/injectables/intralesional-steroid-injection/) may be discussed. It is not suitable for every lump and does not replace diagnosis, particularly when a lesion is changing or not healing.

Arrange prompt medical review for rapid growth, increasing pain, spreading redness, warmth, pus, fever, bleeding, repeated crusting, or a wound that does not heal. Seek urgent help if severe swelling affects the eye, mouth, or breathing, or if you feel acutely unwell. A stable lump can still merit routine assessment if its cause is uncertain.

Is the lump in the skin, a follicle, or deeper tissue? Does its colour or firmness require closer examination? Should I avoid pressure or shaving over it? Would an injection help, or would another treatment be safer? What changes should trigger earlier review?