Squamous Cell Carcinoma

What is squamous cell carcinoma?

After basal cell carcinoma, squamous cell carcinoma (SCC) is the next most frequent skin cancer. It arises from keratinocytes, which make up most of the skin's outer layer. Unlike basal cell carcinoma, SCC has a small but real risk of spreading to the lymph nodes or other parts of the body, so prompt diagnosis and management are important.

Who gets it?

SCC is most common in older people with fair skin and a history of significant sun exposure, including outdoor workers and people who have lived in sunny climates. Some rare conditions, for example albinism and xeroderma pigmentosum, raise the risk considerably. People with a weakened immune system, particularly organ transplant recipients, have a much higher risk and can develop many SCCs, which may behave more aggressively.

What causes it?

The main cause is cumulative ultraviolet (UV) exposure over a lifetime, from the sun or sunbeds. Further risk factors are: fair skin that burns readily; outdoor jobs or pastimes; many actinic keratoses or patches of Bowen's disease; weakened immunity; past radiotherapy or PUVA; smoking, especially for SCC on the lip; old wounds, ulcers or scars; some long-standing inflammatory conditions of genital skin, for example lichen planus or lichen sclerosus; and some types of human papillomavirus infection, mainly around the genitals and anus.

Is it hereditary or contagious?

SCC is not usually inherited, although the skin type that increases the risk runs in families. It is not contagious.

What does it look and feel like?

SCC usually appears on sun-exposed skin, such as the scalp, particularly in men with thinning hair, the face, ears, lips, backs of the hands, forearms and lower legs. It can also occur in non-sun-exposed sites, such as the genitals.

It typically appears as a firm, scaly or crusted lump that grows over weeks to months. It may have a hard, horn-like surface, may be tender or painful, and can bleed or form an ulcer that does not heal. On the lip, it may appear as a persistent sore, scaly patch or lump.

Keratoacanthoma is a fast-growing lump on sun-exposed skin that develops over a few weeks into a firm, dome-shaped lump with a central crater, like a volcano. It is considered benign and can shrink away on its own, usually leaving a scar, but because it can look almost identical to SCC, it needs to be assessed and is often examined under the microscope.

How is it diagnosed?

A suspected SCC is examined with a dermatoscope and the diagnosis is confirmed by examining the tissue under the microscope, either after a biopsy or after the whole lesion has been removed. The pathology report describes features such as size, depth and how the cancer cells look, which help determine the risk of the cancer coming back or spreading. Your doctor may also examine the nearby lymph nodes.

What is the outlook?

Most SCCs are low risk and can be cured, especially when found early. A minority can spread, mainly those that are larger, deeper or recurrent, or that occur in people with weakened immunity. People who have had an SCC have a higher chance of developing further skin cancers, so regular skin checks and sun protection are important.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/squamous-cell-carcinoma

British Association of Dermatologists patient leaflet on Bowen's disease: https://www.bad.org.uk/pils/squamous-cell-carcinoma-in-situ

British Association of Dermatologists patient leaflet on keratoacanthoma: https://www.bad.org.uk/pils/keratoacanthoma

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.