A Scab That Won't Heal: When It's Skin Cancer

A scab is dried blood and serum forming a protective crust over a wound while new skin grows underneath. A typical scab from a scratch, shave nick, picked spot, or minor cut goes through clear stages: it forms, it tightens and may itch as healing proceeds, then it separates to reveal pink new skin within roughly 1-3 weeks depending on the size and location.

The key feature of normal healing is forward progress. Each week the wound is smaller and closer to closed. Even if you accidentally knock a scab off early, it reforms and the wound continues toward closing. A normal scab is a phase, not a permanent fixture.

Basal cell carcinoma (BCC) is the most common culprit. It often appears as a pearly or translucent pink bump, sometimes with tiny visible blood vessels across the surface, and a central depression that scabs, bleeds, and crusts repeatedly. It is most common on sun-exposed skin: face, nose, ears, scalp, and neck.

Squamous cell carcinoma (SCC) often appears as a scaly, crusted, or wart-like patch or a firm sore, sometimes tender, that may have a raised rolled border. It also favours sun-exposed sites and can grow faster than BCC.

Both share the signature behaviour: a sore that will not heal. It scabs, partially closes, then opens and bleeds again, never fully resolving, sometimes over months.

Normal scab: gone or nearly gone by 3 weeks. If a wound has a clear cause and is steadily shrinking, time will close it.

Skin cancer: a sore or scab that is still present at 4 weeks, with no steady progress toward healing, is the classic flag. The single most useful question to ask is: 'Is this clearly better than it was two weeks ago?' If the honest answer is no, it needs to be looked at.

Normal scab: scabs once, then heals. It does not return to the same spot.

Skin cancer: scabs, looks like it is healing, then breaks down and bleeds from the same place again — and again. This repeating cycle, often described as 'a sore that keeps coming back,' is one of the most reliable signs of BCC and SCC. A spot you have re-scabbed three or four times over a couple of months is not a normal wound.

Normal scab: sits on otherwise normal skin and shrinks toward a clean closed scar.

Skin cancer: look for a pearly, shiny, or rolled border, a translucent quality, tiny spider-web blood vessels (BCC), or persistent rough scale and crust on a firm base (SCC). The lesion sits on a slightly raised or indurated (firm) area rather than flat healthy skin. These structural features distinguish a tumour from a simple wound.

Normal scab: started with an identifiable injury — a scratch, a shave, a picked pimple, a knock.

Skin cancer: often there was no injury at all, or only a minor one that 'should have healed by now.' A scab that appeared on its own, on sun-exposed skin, in an adult over 50, and refuses to close is suspicious. The absence of a real wound behind a persistent scab is itself a clue.

See a dermatologist if a scab or sore: has not healed within 4 weeks; scabs and re-bleeds in repeated cycles; has a pearly, rolled, or translucent border; sits on a firm or raised base; appeared without an injury on sun-exposed skin; or is in someone over 50 or with significant sun exposure or prior skin cancer.

Book sooner (within 1-2 weeks) if the lesion is rapidly growing, increasingly tender, or persistently bleeding. Diagnosis is a quick shave or punch biopsy under local anaesthetic. BCC and SCC caught early are curable in well over 90% of cases by simple excision, and acting early keeps the procedure small and the scar minimal.