Skin Cancer (cont.)
Alan Rockoff, MD
Alan Rockoff, MD
Dr. Rockoff received his undergraduate degree from Yeshiva College with the distinction of Summa Cum Laude. He received his medical degree from the Albert Einstein College of Medicine. His internship and two years of Pediatric residency were at the Bronx Municipal Hospital Center, followed by training in Dermatology at the combined residency program at Tufts and Boston Universities. Dr. Rockoff is certified by both the American Board of Dermatology and the American Board of Pediatrics.
William C. Shiel Jr., MD, FACP, FACR
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
Squamous cell carcinoma
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What is squamous cell carcinoma?
Squamous cell carcinoma is cancer that begins in the squamous cells, which are thin, flat cells that look like fish scales under the microscope. The word squamous came from the Latin squama, meaning "the scale of a fish or serpent" because of the appearance of the cells.
Squamous cells are found in the tissue that forms the surface of the skin, the lining of the hollow organs of the body, and the passages of the respiratory and digestive tracts. Thus, squamous cell carcinomas can actually arise in any of these tissues.
Squamous cell carcinoma of the skin occurs roughly one-quarter as often as basal cell carcinoma. Light-colored skin and a history of sun exposure are even more important in predisposing to this kind of cancer than to basal cell carcinoma. Men are affected more often than women. Patterns of dress and hairstyle may play a role. Women, whose hair generally covers their ears, develop squamous cell carcinomas far less often in this location than do men.
Actinic (or solar) keratosis is a precancerous condition. Up to 10 % of these keratoses may become squamous cell carcinomas. They are also markers that indicate an patient is at risk of developing any kind of cancer. Actinic keratoses appear as rough, red bumps on the scalp, face, ears, and backs of the hands. They often appear against a background of mottled, sun-damaged skin. They can be quite sore and tender, out of proportion to their appearance. An actinic keratosis that becomes thicker and more painful raises the concern that it may have transformed into a squamous cell carcinoma.
A rapidly-growing form of squamous cell carcinoma that forms a mound with a central crater is called a keratoacanthoma. While some consider this not a true cancer but instead a condition that takes care of itself, most pathologists consider it to be a form of squamous cell cancer and clinicians treat is accordingly.
Other forms of squamous cell carcinoma that have not yet invaded deeper into the skin include
What are risk factors for developing squamous cell carcinoma?
The single most important factor in producing squamous cell carcinomas is sun exposure. Many such growths can develop from precancerous spots, called actinic or solar keratoses. These lesions appear after years of sun damage on parts of the body like the forehead and cheeks, as well as the backs of the hands. Sun damage takes many years to promote skin cancer. It is therefore common for people who stopped being "sun worshipers" in their 20s to develop precancerous or cancerous spots decades later.
Several rather uncommon factors may predispose to squamous cell carcinoma. These include exposure to arsenic, hydrocarbons, heat, or X-rays. Some squamous cell carcinomas arise in scar tissue. Suppression of the immune system by infection or drugs may also promote such growths. Some strains of HPV (the human papillomavirus responsible for causing genital warts) can promote development of squamous cell carcinoma in the anogenital region.
Can squamous cell carcinoma of the skin spread (metastasize)?
Yes. Unlike basal cell carcinomas, squamous cell carcinomas can metastasize, or spread to other parts of the body. These tumors usually begin as firm, skin-colored or red nodules. Squamous cell cancers that start out within solar keratoses or on sun-damaged skin are easier to cure and metastasize less often than those that develop in traumatic or radiation scars. One location particularly prone to metastatic spread is the lower lip. A proper diagnosis in this location is, therefore, especially important.
How is squamous cell carcinoma diagnosed?
As with basal cell carcinoma, doctors usually perform a biopsy to make a proper diagnosis. This involves taking a sample by injecting local anesthesia and punching out a small piece of skin using a circular punch blade. Usually the method used referred to as a punch biopsy. The skin that is removed is then examined under a microscope to check for cancer cells.
How is squamous cell carcinoma treated?
Techniques for treating squamous cell carcinoma are similar to those for basal cell carcinoma (for detailed descriptions, see above under treatment of basal cell carcinoma):
The possibility of metastasis makes it especially important to diagnose squamous cell carcinomas early and treat them adequately.
How is squamous cell carcinoma prevented?
Even more so than is the case with basal cell carcinoma, the key principles of prevention are minimizing sun exposure and getting regular checkups.
Common-sense preventive techniques are the same as for basal cell carcinoma and include
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