Basal cell carcinoma (BCC) is a malignant tumor or cancer of the skin arising from the epidermis, which includes several variations: pigmented, morphea type, keratotic, nodular, ulcerative and superficial or multicentric basal cell carcinoma. BCC is the most common skin cancer worldwide with an incident risk of 30%. It occurs in sun-damaged skin of fair skinned individuals. There is evidence that there is a correlation between ultraviolet (UV)-B exposure and the development of skin cancer. Gene mutations associated with the p53 and Bcl-2 genes have been found. BCCs can also occur on non sun exposed or damaged skin surfaces and may be found in the following conditions of the skin: scars, chickenpox scars, tattoos, hair transplant scars, old skin injuries, skin changes from arsenic ingestion and x-ray exposure. PUVA treatment for psoriasis patients has been reported to result in an increased risk for basal cell carcinoma. Fiberglass dust and dry-cleaning agents have been report to increase the risk of development of BCC. There is also a link between basal cell carcinoma and smoking in young women only. The Human Papilloma Virus (HPV) oncogenes have been implicated in the development of basal cell carcinoma but it not been proven that it is the actual cause.
Superficial or multicentric basal cell carcinoma basal cell carcinoma arises from skin with sparse hairs, mainly the trunk of the body. Patients with basal cell carcinomas on the trunk are at increased risk for developing multiple basal cell carcinomas. Superficial consists of small tumor foci either attached to or within the superficial dermis of the skin. The tumor nests or basal cells resemble the normal basal cells of the skin epidermis or superficial layer of the skin. The belief is that these cells are derived from the primitive cells of the hair follicle. The nests may develop into nodules of basal cells and become nodular basal cell carcinoma or may regress or disappear. Usually when regression occurs there is associated with it a dense inflammatory response. The dermis of the skin shows sun damage.
The tumor is slow growing, but when left untreated may ulcerate and extend into the fat underneath the skin and into adjacent muscle and bone. Metastases or spread of the cancer to different sites in the body is extremely rare less than 0.5 % and is usually associated with neglect. The risk of its occurrence is dependent upon the size of the tumor. Tumors greater than 3 cm have a 2% risk, greater than 5 cm a 25% risk and greater than 10 cm a 50% risk. Immnocompromised patients who have deficit immune system and who have such tumors in the head and neck area are also at increased risk for metastatic disease.
Primary treatment of the cancer is by surgical excision, scraping or curettage and dissication or irradiation. These treatments are usually curative, however, the variant of superficial basal cell carcinoma tends to have a higher recurrence rate than the other types. Recurrences can be treated with radiation or surgical excision. If surgical excision is used the margins of excision can be checked at the time of surgery by submitting the tissue for a frozen or quick section and reviewed by the pathologist to ensure that the tumor is completely excised. Immumodulation therapy with the drug Imiquimod is beginning to be used as a monotherapy drug to elicit an inflammatory response to eradicate the tumor. These types of drugs may be used more in the future to eliminate tissue loss and scarring of surgical therapy.