Cancers of the Skin

The Melanoma Book
by Howard L. Kaufman, M.D., FACS

(Page 3 of 5)

When I examine a new patient with a skin growth, also known as a lesion, the first question I always ask is whether it has changed from its usual size or shape. This is a crucial question, because nearly all cancerous lesions will exhibit a change. In fact, such changes are the most common reason why people seek medical attention for a skin growth. If a lesion has been present since childhood and has not changed in any way, the likelihood of a serious cancer is much lower.

The second question I ask is whether the skin lesion is pigmented. Whether or not I see pigment is key because melanin is a clue that the melanocyte is the source of the growth, which raises concern about melanoma. Please note that not all melanoma lesions will have pigment. About five percent of melanomas have no pigment at all and are called amelanotic melanomas. Nonetheless, the first distinction that your dermatologist or pathologist will make is whether the skin growth is pigmented or non-pigmented.

Cancer can develop from almost any cell in the skin (or elsewhere in the body), but certain cells are far more frequent culprits than others. Non-pigmented cells as opposed to pigmented melanocytes are the predominant source of skin cancers.

Non-Pigmented Skin Cancer

The two most common non-pigmented skin cancers are basal cell carcinoma and squamous cell carcinoma, named after the respective cells that cause them. Fortunately, the most common variety of non-pigmented skin cancer is relatively easy to cure (see Table 1-3).

Basal cell carcinoma, the most common human cancer, likely accounts for about one quarter of all cancers in the United States. Parts of the body that are exposed to the sun, such as the face especially the nose and scalp are the most frequent sites of basal cell carcinoma. Most experienced dermatologists will be able to recognize a basal cell carcinoma, although some are trickier to identify. One type that happens to produce pigment, for example, can be confused with a melanoma.

Although fairly common, basal cell carcinoma only spreads (metastasizes) to other parts of the body in fewer than 0.1 percent of cases. But treatment is still required since it can disrupt the surrounding normal tissues. Basal cell carcinomas on the nose, ear, and eyelid are often more prone to recurrence, so it is important to make sure that they are completely removed or treated.

Patients with basal cell carcinoma should be examined at least once a year by a dermatologist. If basal cell carcinomas recur, they usually do so within one to five years but may develop at any time. In addition, patients with one basal cell carcinoma may develop other basal cell carcinomas.

Squamous cell carcinoma occurs when the keratin-producing cells in the skin divide without control. Squamous cell carcinoma is the second most common skin cancer, occurring in about 100,000 people each year in the United States. Those who have difficulty tanning and tend to burn when exposed to the sun for a prolonged period of time appear to be at higher risk for developing squamous cell carcinomas. People with fair complexions and those of Celtic descent also have a higher frequency.

Like basal cell carcinomas, this cancer also occurs most commonly on sun-exposed parts of the body and is slightly more common in men than women. But squamous cell carcinoma is much more serious because it is more aggressive and grows more rapidly, causing local destruction of normal tissues, and it has the potential for metastasizing to other parts of the body.

Squamous cell carcinomas appear on the skin as slightly raised and reddish areas and may grow over a period of several weeks to months. Squamous cell carcinomas that occur on the lips and ear are usually more difficult to control than those occurring elsewhere. The severity of squamous cell carcinomas depends on their size, how deep they are located within the layers of the skin, and on the characteristics of the cells involved. This information can only be obtained by a biopsy and examination under a microscope. Some forms of squamous cell carcinoma are very thin and located only in the epidermis and are usually easier to control.

When squamous cell carcinomas spread, they may send cells to the lymph nodes nearby or to internal organs. Always have the lymph node areas of the body examined if you have a squamous cell carcinoma. In cases where the cancer is very large or the cells are very aggressive, further evaluation of the internal organs may be necessary by obtaining a special X-ray known as a CT or CAT scan.

Since squamous cell carcinoma can recur and because a second squamous cell carcinoma can develop, it is important to see a dermatologist on a regular basis after having a squamous cell carcinoma. A good rule of thumb is to have a full skin and lymph node evaluation every three months for the first year after treatment, then every six months during the second year, and once a year after that.

Rare Forms of Non-Pigmented Skin Cancers

Cancer can occur from any of a number of other specialized cells and structures within the skin. Although these cancers are extremely rare, they can be quite serious, even life threatening. The diagnosis of a rare non-pigmented skin cancer usually requires referral to specialists.

Cancer of the sweat glands is called microcystic adnexal carcinoma. More common in women, it usually occurs in middle age. People who received radiation treatment for acne and thyroid cancer may be prone to this type of cancer. Patients require close monitoring, since there is a high likelihood that the cancer may come back in the same location.

Cancer in the sebaceous glands is sebaceous carcinoma. These cancers occur more frequently in women, are most commonly located on the upper eyelid, and may be associated with exposure to previous radiation. In about 20 percent of the cases the cancer may spread to other sites. Occasionally sebaceous carcinomas have been linked to cancer in other organs, especially the colon and urinary tracts. Because of this relationship, patients with sebaceous carcinoma are evaluated for colon cancer and urinary tract cancers.Atypical fibroxanthoma appears as a nodule on the head and neck region in elderly adults or on the torso, arms, and legs in younger adults. The cells involved have a spindlelike appearance. This cancer has been known to metastasize and should therefore be treated by simple excision.

A specialized cell whose function may relate to the sense of touch or to the endocrine system, the Merkel cell can develop into aggressive cancers known as Merkel cell carcinomas. Found most often on the head in older people, these cancers have a tendency to spread to the lymph nodes and later to internal organs.

In addition to these skin cell cancers, cancers of other parts of the body such as the breast, lung, and colon, may spread to the skin. Sometimes the cancer in the skin is the first sign of the primary cancer.

Table 1-3. Types of non-pigmented skin cancer

Type of Cancer	Characteristics
Basal cell carcinoma	Most common skin cancer; rarely spreads; several methods of effective therapy
Squamous cell carcinoma	Less common but more likely to spread; usually treated by surgery or Mohs procedure
Microcystic adnexal carcinoma	Cancer of the sweat glands; aggressive cancer but unlikely to spread
Sebaceous gland carcinoma	Most often occur on the eyelid and can spread; treatment is surgical excision
Atypical fibroxanthoma	Spindle-shaped cancer cells that appear as nodules; can spread; treated by Mohs procedure
Merkel cell carcinoma	Rare but aggressive cancer arising from Merkel cells; may spread to lymph nodes
Metastatic carcinoma	Cancers from internal organs that spread to the skin; prognosis depends on the type of cancer

Copyright © 2005 Howard L. Kaufman, M.D., FACS

About the Author

Dr. Howard L. Kaufman is founder and Co-Director of the Columbia University Melanoma Center, attending physician at The New York Presbyterian-Columbia University Medical Center, chief of surgical oncology, and associate professor of surgery at Columbia University College of Physicians and Surgeons. He has conducted numerous clinical research trials on vaccines for cancer, lectures widely on cancer treatment and has published more than 100 articles in the field of tumor immunology and immunotherapy. He lives in New York City.