What is skin cancer?

Cancer is the abnormal growth of cells at an uncontrolled and unpredictable rate. The cancer tissue usually grows at the expense of surrounding normal tissue. In the skin, the most common types of cancer are basal cell carcinoma and squamous cell carcinoma. The names reflect the cell within the skin from which the particular type of skin cancer originates. Malignant melanoma or a "cancerous mole" is a rarer type of skin cancer that usually appears as a dark colored spot or bump on your skin and slowly enlarges. In the Mohs surgery unit, we treat basal cell carcinomas, squamous cell carcinomas, malignant melanoma and other unusual skin tumors.

What are basal cell and squamous cell carcinomas?

Both of these cancers behave and are treated similarly. The difference lies in the cell from which it originates within the skin. Often, this can only be distinguished by examining the skin under a microscope. Basal cell carcinoma is the most common cancer of any type with over 1,000,000 new cases a year. Both basal and squamous cell carcinoma most commonly occur on the head and neck. The carcinoma often begins as a small bump that can look like a pimple but will continue to enlarge, often bleeds, and does not heal completely. It may be red, flesh-colored or darker than the surrounding skin. Basal cell carcinoma rarely spreads (metastasizes) to distant parts of the body. Instead, it grows larger and deeper, destroying nearby parts of the body in its path. Squamous cell carcinoma behaves locally like basal cell carcinoma. However, certain tumors can metastasize (spread elsewhere) from the skin. This will be discussed with you prior to surgery.

The abnormal growth (cancer) originates in the uppermost layer of the skin. The cancer then grows downward, forming root and fingerlike projections under the surface of the skin. Unfortunately, at times these roots are so subtle they cannot be seen without the aid of a microscope. Therefore, what you see on your skin is sometimes only a small portion of the total tumor. There are several different types of basal and squamous cell carcinoma. It is important to distinguish these types prior to treatment, as different therapies may be required. For this reason a biopsy is usually performed to treatment.

The most common association with skin cancer is long-term exposure to sunlight. This is why skin cancers develop most often on the face and the arms (sun-exposed body parts). They occur more commonly in fair-skinned people than dark-skinned people, and in the United States they are found most frequently in the southern (sun-belt) areas. Superficial x-rays, which were used many years ago for treatment of certain skin diseases, may result in skin cancer many years later. Trauma (scars), certain chemicals and rare inherited diseases may also contribute to the development of skin cancer.

What about melanoma?

Melanoma is the deadliest skin cancer accounting for two-thirds of all deaths attributed to skin cancers. The standard treatment for melanoma is surgical removal of the melanoma and a wide area of normal appearing skin surrounding the melanoma. There are, however, special cases, especially on the head and neck region, where Mohs micrographic surgery is beneficial in the treatment of melanoma. Many of the melanomas in this region have poorly defined borders making standard excision difficult.

Mohs surgery in the treatment of melanoma is modified. The initial stages done by frozen sectioning is the same as for other skin cancers. At the conclusion of the standard Mohs surgery, however, an additional rim of tissue is removed for additional histological examination that can take a few days to process. This additional step allows for a more precise treatment of the melanoma. Accordingly, the reconstruction will be delayed until this final rim of tissue is cancer free.