Basal Cell Carcinoma

basal cell carcinoma

The skin has two layers - the epidermis and the dermis.

The epidermis has three main types of cell:

  • Basal cells. These are the bottom layer of cells in the epidermis.
  • Keratinocytes. These cells are in layers above the basal layer. They make keratin which is a hard wax-like material.
  • Melanocytes. These cells are dotted about at the bottom of the epidermis. They make a pigment called melanin when the skin is exposed to sun. The melanin is passed to the nearby skin cells to protect them from the sun's rays.

What are skin cancer and tumors?

What all types of cancer have in common is that the cancer cells are abnormal and multiply out of control.Skin cancers are divided into:

  • Melanoma ('malignant melanoma'). This type of skin cancer develops from melanocytes.
  • Non-melanoma. These are divided into:
    • Basal cell carcinoma (BCC) - skin cancer which develops from basal cells. This is also sometimes called a rodent ulcer.
    • Squamous cell carcinoma (SCC) - skin cancer which develops from keratinocytes.

Who gets basal cell carcinoma and squamous cell carcinoma of the skin?

BCCs and SCCs become more common with increasing age. BCC is the most common skin cancer in white and fair-skinned people. SCC is the second most common skin cancer in white and fair-skinned people.

What causes basal cell carcinoma and squamous cell carcinoma of the skin?

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear.

Sun damage to skin

A BCC typically develops on a sun-exposed area of the skin such as the head and neck. The main risk factor which damages skin and can lead to a BCC or SCC is sun damage. About 9 in 10 cases of BCC and SCC are thought to be caused by sun damage. It is the ultraviolet (UV) radiation in the sunshine which does the damage.
Children's skin is most vulnerable to damage. Sun exposure in childhood is the most damaging. People who have a history of freckling in childhood, or frequent or severe sunburn in childhood are most at risk of developing skin cancer as adults.

Other risk factors

  • A family history of skin cancer.
  • Using sunbeds or similar tanning machines which emit UV light.
  • If you have a solar keratosis (actinic keratosis).
  • If you have already had a previous skin cancer.
  • A diet high in fat and low in vitamins.
  • Occasionally, a skin cancer can develop on an area of skin previously damaged with a burn, scar, a long-standing sore, persistent inflammation, X-ray exposure, or certain chemicals (such as arsenic or creosote).
  • A weakened immune system.
  • Some rare inherited disorders, such as albinism, xeroderma pigmentosa, Gorlin's syndrome and Bazex syndrome.

Skin cancer symptoms

Basal cell carcinoma (BCC)

A BCC typically develops on a sun-exposed area of the skin such as the head and neck. The first sign is often a small red, pink or pearly lump which appears on previously normal skin. They usually grow very slowly and and it can take many months for one to grow to a centimetre or more.In time, the lump on the skin may crust over, ulcerate or bleed from time to time. A skin ulcer caused by a BCC is sometimes called a rodent ulcer. BCCs very rarely spread to other parts of the body. However, they continue to grow locally and can cause damage to nearby structures.

Squamous cell carcinoma (SCC)

An SCC typically develops on the face - most commonly on or around the ears or lips. But, again, any area of skin can be affected. It typically starts as a small crusted or scaly area of skin with a red or pink base. An SCC may ulcerate or bleed from time to time. However, an early SCC can vary in shape, appearance and colour. As the SCC grows larger and deeper, it damages nearby structures. An SCC may also spread to other areas of the body. However, this is uncommon in the early stages and most are treated before any spread occurs.

How is basal cell carcinoma or squamous cell carcinoma diagnosed?


A biopsy (small sample) of tissue can be taken from a suspicious lump on the skin. This is looked at under the microscope, which can confirm the diagnosis.

Further tests

No further tests are usually needed for a BCC or an SCC which is diagnosed when it is small. If a doctor suspects that there has been some spread from an SCC to other parts of the body, then further tests such as X-rays, blood tests or scans may be advised.

What is the treatment for basal cell carcinoma or squamous cell carcinoma of the skin?

Treatment for small skin cancers

Most cases are diagnosed when the skin cancer is still quite small. Depending on the site, size and depth of the tumor following treatments may be used:

  • A simple operation done under local anaesthetic to cut out the cancer. The edges of the normal skin are then stitched together.
  • Curettage and cautery.
  • Cryosurgery (freezing treatment) with liquid nitrogen which destroys cancer cells.
  • Photodynamic therapy (a special kind of light therapy which kills cancer cells).
  • Chemotherapy creams are sometimes placed on skin cancers to kill cancer cells. These are usually either 5-fluorouracil (5-FU) or imiquimod.
  • Mohs' micrographic surgery is done in some situations. In this technique, the tumour is removed piece by piece. Each piece is looked at under the microscope straightaway for cancer cells. Further pieces are removed until no cancer cells are seen.
  • More extensive surgery is needed in some cases
  • If the skin cancer is larger then a more extensive operation may be required. This may need a general anaesthetic. For example, if a large area of affected skin is cut away you may need plastic surgery to place a skin graft over the wound.
  • If an SCC has spread to the nearby lymph glands then an operation to remove these glands may be advised.

Other treatments

Radiotherapy is sometimes used as an alternative to surgery. For example, if the area covered by the cancer is large, if the site is difficult to operate on, or if an operation cannot be done for any other reason.

If an SCC has spread to lymph nodes or other areas of the body, radiotherapy and/or chemotherapy may be used to treat the secondary cancers.

What is the prognosis

Almost all BCCs can be treated and cured, mostly with a simple operation or other simple technique. They rarely spread. Most SCCs can also be treated and cured, as most are treated before there has been any spread to other parts of the body.

Can skin cancer be prevented?

Most skin cancers (non-melanoma and melanoma skin cancers) are caused by excessive exposure to the sun. We should all limit our sun exposure in the summer months by:

  • Staying indoors or in the shade as much as possible between 11 am and 3 pm.
  • Covering up with clothes and a wide brimmed hat when out in the sunshine.
  • Applying sunscreen of at least sun protection factor (SPF) 15 (SPF 30 for children or people with pale skin) which also has high ultraviolet A (UVA) protection.
  • In particular, children should be protected from the sun.

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