Skin Cancer: Squamous Cell Carcinoma Diagnosis

  • Diagnosis

    Squamous cell carcinoma is a common skin cancer that usually appears on sun-exposed areas of the body. In the vast majority of cases it is completely curable. Skin cancer is the most common cancer in the US. Squamous cell carcinoma (SCC) is the second most common skin cancer, following basal cell carcinoma. It can occur on all areas of the body, including the mucous membranes in the mouth and genitals; however, it most commonly arises on sun-exposed areas such as the face, arms, ears, hands, lips, neck, and scalp. More and more people develop skin cancer every year, possibly due to more people living longer, as well as greater populations residing in the sun belt.

    The cancer develops in the outer layer of the skin (epidermis) in cells called squamous cells. Squamous cell carcinoma usually remains confined to the upper skin layers for some time, where it is relatively harmless. It can, however, penetrate deeper into the skin and occasionally spread (metastasize) to distant tissues and organs, significantly reducing the chance of a cure.

    When squamous cell cancer is left untreated, it can expand laterally along the skin surface, penetrate deeper into the middle portion of the skin (the dermis), or grow along nerves or blood vessels. In some instances, SCC can spread to distant organs and tissues in the body via the lymphatic, nerve, or circulatory systems. Large SCCs; those on ears, lips, genitals, or backs of hands; and those that have developed over a prolonged period of time, have a greater risk of metastasis. While localized SCC can usually be easily removed, it is much harder to cure once it has spread in this fashion..

    Experts believe that cumulative sun exposure over the years is the most likely cause for SCC, with an estimated 80% of lifetime exposure obtained before the age of 18.

    SCC develops from the squamous cells of the epidermis Figure 01 Table 01. A series of increasingly abnormal changes can develop in the skin’s squamous cells. These changes occur when the cell’s DNA becomes altered (mutated). Subsequent generations of cells that grow from these damaged cells are then damaged themselves. Cell-damaging DNA mutations are usually the result of excessive exposure to sunlight. Other risk factors include radiation, arsenic exposure, burns, and chronic wounds.

    Click to enlarge: Anatomy of the skin

    Figure 01. Anatomy of the skin

    The most common culprit for SCC is sun exposure, or more specifically, ultraviolet (UV) radiation. Damaging ultraviolet radiation occurs in two types: ultraviolet A (UVA) and ultraviolet B (UVB). UVB is the type of radiation primarily responsible for sunburn, and mainly affects the outer skin layers. UVA penetrates more deeply. Both have been implicated in the development of skin cancer.

    The appearance of both SCC and its precursors can vary in color and size. SCC is often crusty or scaly, and may occasionally bleed Figure 02. Actinic, or “solar” keratosis is a precancerous condition that may eventually develop into SCC if left untreated. It is usually less than 1 cm (.4 inches) in diameter, often has a scaly surface, and can vary in color from pink, red, or tan-brown. Because it may be the same color as the skin, it is sometimes noticeable only by its sandpaper-like texture. Sometimes it resembles a wart, and horn-like structures may develop on the surface. Occasionally, SCC can develop and grow rapidly if left untreated.

    Another precencerous lesion is called actinic cheilitis. Actinic cheilitis gives a white, scaly appearance to the lip. It often involves the lower lip, which receives the most sun exposure. This, too, may develop into SCC if left untreated.

    Click to enlarge: Actinic keratosis

    Figure 02. Actinic keratosis

    SCC that remains in the epidermis is known as Bowen’s disease, or squamous cell carcinoma in situ Figure 03. Bowen’s disease may appear as a persistent, reddish-brown, scaly plaque that can resemble psoriasis or eczema, and may occasionally bleed. Although it does not invade deeper into the skin, it is a true skin cancer that requires treatment.

    Click to enlarge: Bowen’s disease

    Figure 03. Bowen’s disease

    More advanced carcinoma that has spread beyond the epidermis is often nodular, and may have open sores.

    SCC can also develop inside the mouth, where it appears as a white, thickened area that may develop non-healing sores.

    Lesions may also appear on the genital and anal regions, where they are often associated with a history of genital warts.

    Table 1.  Symptoms of Squamous Cell Carcinoma

    Color: flesh-colored, pink, red, or brown
    Size: from microscopic to several centimeters in diameter, though usually less than 1 cm (.4 in)
    Sandpaper-like texture
    Scaly
    Crusty
    May grow horn-like structures
    May occasionally bleed
    May form open sores
    On lips: white, scaly
    On mucous membrane (such as in mouth): whitish, thickened patch

    Light-skinned individuals with a cumulative history of prolonged or intense sun exposure are at an increased risk of skin cancer. The incidence of skin cancer and its precursors increase dramatically with age. People who tend to burn rather than tan, those with light skin color, blond or red hair, freckles, and blue eyes are at especially high risk.

    SCC tends to develop on people who have had excessive sun exposure: farmers, lifeguards, construction workers, outdoor enthusiasts, and others with a history of severe or frequent sunburns. Those who live at high altitudes or in areas where the ozone layer has thinned are also at increased risk. Immunocompromised people, including those with organ transplants, have a significantly increased risk of developing skin cancer.

    Various other environmental factors have been implicated in SCC development.

    • Tobacco: smokers have a 50% higher risk than nonsmokers
    • Alcohol
    • Treatment with UV radiation, as for psoriasis
    • Treatment with x-rays
    • Arsenic exposure

    Skin cancer can also develop within burns or other chronic, nonhealing wounds.

    Some people have an inherited predisposition to skin cancer, such as those with the genetic syndromes xeroderma pigmentosum (a hypersensitivity to UV light) and albinism (a deficiency or absence of melanin).

    Skin cancer is diagnosed upon clinical examination and confirmed by biopsy and microscopic examination of suspicious lesions. Most cases of SCC can be diagnosed clinically by a physician. The doctor will suspect either SCC or one of its precursors by the appearance and texture of the lesion. Characteristic microscopic findings of a biopsy of the lesion confirm the diagnosis.

    In some cases, the doctor may biopsy or remove regional lymph nodes to help determine if the cancer has spread.

    It is advisable to have the doctor thoroughly examine the rest of the skin to check for other suspicious lesions.

    Protection from excessive sun exposure--especially though frequent use of sunscreen with SPF 15 or higher, protective clothing, and avoiding the midday sun--is essential to reduce the risk of all types of skin cancer. Light-skinned individuals who burn easily should be especially cautious. The following precautions should be taken by everyone to guard against excessive exposure to UVA and UVB radiation.

    • Try to schedule time outdoors for sports and other recreational activities before 10 AM and after 4 PM. By doing this you will avoid excessive exposure to UVA and UVB radiation. Clouds and haze do not completely block harmful ultraviolet radiation. It is not uncommon for a sunburn to develop on a cloudy day.
    • When outdoors, wear clothes that cover as much skin as possible; such as lightweight, long-sleeved shirts, long pants, and a broad-brimmed hat.
    • Use particular care around reflective surfaces, such as water, sand, concrete and white-painted areas.
    • Everyone over 6 months of age should use a broad-based sunscreen that protects from UVA and UVB rays, and has a skin protection factor (SPF) of at least 15. Apply to exposed skin 20 minutes before exposure and reapply every two hours. More frequent re-application may be necessary with exercise or water-related activities.
    • Zinc oxide and titanium dioxide are two ingredients that offer the best broad-spectrum protection from ultraviolet radiation.
    • Infants should avoid direct sun exposure entirely to minimize risk for sunburn and long-term sun damage.
    • There is no such thing as a “safe” or “healthy” tan. Avoid tanning booths or the use of sunlamps. Even though they emit mostly UVA rays and do not cause sunburn as frequently, they are associated with development of skin cancer, and promote premature aging of the skin.

    Perform a regular skin self-examination in addition to having an annual skin examination by your physician. Experts recommend that individuals conduct a thorough screening of their own skin periodically. Have a partner check your back, or use a hand-held mirror to check your back and other hard-to-see places. Consider drawing a map of your body to indicate the location of moles, areas of discoloration, and other blemishes. Each month, note if a new growth has developed, or if there has been any change in shape, color, or size of lesions. See your doctor if you have any questions or suspicions.

    At your annual checkup, ask your doctor to look at your skin, especially in areas you can’t see. People with major risk factors, such as a history of significant sun exposure, multiple moles, and a fair complexion with a history of burning easily, should be checked at least annually by a dermatologist.

  • Prevention and Screening

    Protection from excessive sun exposure--especially though frequent use of sunscreen with SPF 15 or higher, protective clothing, and avoiding the midday sun--is essential to reduce the risk of all types of skin cancer. Light-skinned individuals who burn easily should be especially cautious. The following precautions should be taken by everyone to guard against excessive exposure to UVA and UVB radiation.

    • Try to schedule time outdoors for sports and other recreational activities before 10 AM and after 4 PM. By doing this you will avoid excessive exposure to UVA and UVB radiation. Clouds and haze do not completely block harmful ultraviolet radiation. It is not uncommon for a sunburn to develop on a cloudy day.
    • When outdoors, wear clothes that cover as much skin as possible; such as lightweight, long-sleeved shirts, long pants, and a broad-brimmed hat.
    • Use particular care around reflective surfaces, such as water, sand, concrete and white-painted areas.
    • Everyone over 6 months of age should use a broad-based sunscreen that protects from UVA and UVB rays, and has a skin protection factor (SPF) of at least 15. Apply to exposed skin 20 minutes before exposure and reapply every two hours. More frequent re-application may be necessary with exercise or water-related activities.
    • Zinc oxide and titanium dioxide are two ingredients that offer the best broad-spectrum protection from ultraviolet radiation.
    • Infants should avoid direct sun exposure entirely to minimize risk for sunburn and long-term sun damage.
    • There is no such thing as a “safe” or “healthy” tan. Avoid tanning booths or the use of sunlamps. Even though they emit mostly UVA rays and do not cause sunburn as frequently, they are associated with development of skin cancer, and promote premature aging of the skin.

    Perform a regular skin self-examination in addition to having an annual skin examination by your physician. Experts recommend that individuals conduct a thorough screening of their own skin periodically. Have a partner check your back, or use a hand-held mirror to check your back and other hard-to-see places. Consider drawing a map of your body to indicate the location of moles, areas of discoloration, and other blemishes. Each month, note if a new growth has developed, or if there has been any change in shape, color, or size of lesions. See your doctor if you have any questions or suspicions.

    At your annual checkup, ask your doctor to look at your skin, especially in areas you can’t see. People with major risk factors, such as a history of significant sun exposure, multiple moles, and a fair complexion with a history of burning easily, should be checked at least annually by a dermatologist.

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