- Basal cell cancer, also called rodent ulcer, is caused by exposure to the sun.
- The most common form present as a raised, round lesion with small blood vessels concentrated around it and may often a have central ulceration.
- Treatment is by scraping the tumour out, liquid nitrogen, full surgical excision, radiation or imiquimod cream (Aldara).
- After incomplete removal, basal cell cancer can recur in the same place up to 10 years after treatment.
basal cell carcinoma; rodent ulcer; Jacobi's ulcer
Basal cell cancer (BCC) is a type of skin cancer caused by exposure to the sun. It is also called a rodent ulcer. It is a locally invasive type of cancer that, if treated early, is generally easily managed and causes very few long-term problems.
It usually consists of a single lesion on sun-exposed skin. These cancers are usually seen in patients in older age groups, however, they have been observed in younger patients in recent years.
Sun exposure is the single most important cause of this skin cancer. It is therefore more common in people with lighter complexions. The most common site for development of BCC is the face, particularly the nose.
However, basal cell cancer can also arise in areas of skin with chronic scarring or X-ray damage.
Symptoms and signs
BCC can appear in many forms.
The most common type of BCC is a raised, round lesion with transparent borders. There may be ulceration in the centre and small blood vessels that appear to lead away from the lesion. Recurrent crusting and bleeding are common, and the lesion may continue to enlarge slowly.
Superficial BCC can look like chronic eczema – red and scaly with a sharply demarcated border.
Pigmented BCC can have a smooth, relatively transparent border with deep pigmentation. This sometimes looks like, and is mistaken for, malignant melanoma (another type of pigmented skin tumour).
Another form of BCC may appear as a yellowish to white lesion with a collection of small capillaries visible around the lesion. This and another type, the ‘wartlike’ BCC tend to be aggressive tumours that infiltrate surrounding tissues.
Diagnosis is made based on the appearance of the lesion, but is then confirmed by taking a sample of the tumour (biopsy) and looking at it under the microscope. This is the only way in which a definitive diagnosis can be made. Sometimes, a doctor may biopsy a lesion suspected to be a BCC, and it may turn out to be something benign.
Lessening exposure to the sun will help prevent any skin cancer, including BCC. Using sunblock and wearing a wide-brimmed hat may provide some protection. Regularly checking your skin, or having someone else check your skin may allow for early detection. If you have had pervious BCC, or other skin cancer, or have sun damage, your skin should be regularly checked by a doctor.
The type of BCC, its size, the site and the clinical appearance will determine the choice of treatment.
Sometimes, the initial tissue sample taken for diagnosis under the microscope will be sufficient to treat a small, early BCC. The area should then be carefully monitored for recurrence for many years afterwards.
Sometimes the doctor will be so convinced just by looking at the tumor that it is a BCC that they will try to take it out completely when taking the initial sample to be looked at under the microscope.
If the lesion is very superficial, it may be treated with liquid nitrogen. In this case careful follow up is particularly important.
In some cases, a topical preparation applied to the lesion can be used to treat superficial BCC. This product is called imiquimod (Aldara). This should be carefully supervised by a doctor.
The tumour may be curetted out – effectively scraped off the surface of the skin. It may then be dried out using electrodesiccation or cautery – destruction with electricity.
Surgical excision is used for larger and more aggressive tumours. Occasionally, radiation therapy is used.
Recurrent tumours are treated by excising the tissue under a microscope so that all the tissue, including the edges, is removed. This is called Moh’s surgery.
Some of the worst complications of BCC arise when treatment is neglected, and a patient presents with a large lesion that is difficult to treat. These cancers are relatively simple to treat when they are small, but may require more invasive treatment if allowed to grow and invade locally, therefore go and see your doctor sooner rather than later!
BCC can recur up to 10 years after treatment, and there is a higher incidence of other non-melanoma skin cancers in people who have had BCC than in those who have not (this includes BCC and another type of skin cancer, squamous cell carcinoma). Therefore, long-term follow-up examination of the skin is important.
BCC can recur within scar tissue, at the edge of a scar or skin graft, or as a mass under a scar or skin transplant.
The natural history of BCC is of a slow-growing and locally invasive cancer. It rarely spreads to other areas of the body (metastases). Metastases occur in less than 0.5% of cases.
When to call the doctor
Any kind of skin lesion which starts to change shape or colour, bleed or grow in size should be seen by a doctor as soon as possible. Any chronic nodule, ulcer or patch of abnormal skin should be checked by a doctor.
Previously reviewed by Prof H.F. Jordaan, MBChB, MMed (Derm)
Updated by Dr B M Tod, MBBh (Wits), dermatologist, May, 2011