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Squamous Cell Carcinoma

Squamous cell carcinoma is the second most common shin cancer after basal cell carcinoma. Squamous cell carcinomas are often described as enlarging red bumps, sometimes with a rough, scaly, or crusted surface. They may also look like flat reddish patches in the skin that grow slowly. If untreated, they can become ulcerated (open sores). Most squamous cell carcinomas grow slowly. Occasionally, they may occur quite rapidly, particularly in patients who are immunosuppressed.

Squamous cell carcinomas occur most frequently on sun-exposed areas such as the head, neck, ears, lips, back of the hands and forearms.

This cancer rarely metastasizes (spreads to lymph nodes or other organs), although distant spread happens more frequently than in basal cell carcinoma. The squamous cell carcinoma that has metastasized typically is:

  1. greater than 2cm in diameter or greater than 4mm in depth
  2. in a site previously exposed to radiation
  3. in a patient with a history of solid-organ transplantation

When squamous cell carcinoma does metastasize, it most commonly travels to the local lymph nodes.

Squamous cell carcinoma is the most common skin cancer in organ transplant recipients.

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What causes squamous cell carcinoma?
The most common cause of squamous cell carcinoma is ultraviolet (UV) light. The duration and dose of UV exposure determines your risk for squamous cell carcinoma. Although UVB (wavelength 290-320 nm) is mainly responsible, the role of UVA is also important. Indoor tanning, fair-skin complexion, prior radiation exposure and immunosuppression are other significant risks factors.

UV light damages DNA. Normally, skin cells have ways to protect DNA or to repair DNA that is damaged by UV light. However, when these protective mechanisms fail, DNA damage can ultimately affect the genes that regulate cell division, causing tumors to form.

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How can I protect myself from developing a squamous cell carcinoma?
The key of preventative therapy is sun protection. Sun protection has three components:

  1. Sun avoidance during peak sun times from 10am to 3pm.
  2. Sun protective clothing (long sleeve shirts, long pants, hats with broad brims, and sunglasses.
  3. Daily sunblock with a Sun Protection Factor (SPF) = 30

Examine your skin once a month for any suspicious changes. The single most important feature that may signal the presence of a skin cancer is a new, changing, enlarging skin growth that persists. Sores that won't heal may also indicate cancerous or precancerous conditions of the skin that need attention. Early treatment is critical.


What should I do if I suspect I have a squamous cell carcinoma?
Contact your primary care physician or a local dermatologist so they may examine the skin lesion that you are concerned with. If your doctor suspects that the lesion may be cancerous, he/she might perform a skin biopsy.

If the diagnosis of squamous cell carcinoma is confirmed, treatment often involves out-patient surgery. Contact your dermatologist to discuss the full range of treatment options.

What should I do if I have had squamous cell carcinoma?
Once you've had one squamous cell carcinoma, you are at higher risk for developing additional squamous cell carcinomas in the future. You are also at higher risk for developing other types of skin cancer including basal cell carcinoma and melanoma.

Most patients with a history of squamous cell carcinoma should see their dermatologist for a full skin evaluation at least once a year. In some cases, the dermatologist may recommend more frequent skin examinations.

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Images (click on an image for a larger view)

Squamous cell carcinoma of the chin This cancer developed over three months and looked like a scaly horn.   squamous

Squamous cell carcinoma in situ This cancer developed on a patient's back as a broad, flat, red lesion with superficial scaling. The diameter of this skin lesion was 2 cm.   squamous

Squamous cell carcinoma of the posterior ear lobe This cancer was firm, ulcerated in the center, and covered with brown crust.   squamous

Squamous cell carcinoma of the hand This cancer was firm, ulcerated in the center and developed on sun damaged skin. Notice the nearby actinic keratoses.   squamous

Squamous cell carcinoma of the hand When untreated, squamous cell carcinoma may become very large. This cancer covers most of the back of this patient's hand. Again, note the surrounding actinic keratoses.   squamous

Squamous cell carcinoma of the scalp Squamous cell carcinoma with surrounding in transit metastasis.   squamous


Squamous cell carcinoma

Microscopic view of Squamous cell carcinoma

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Last reviewed by UCSF Dermatologists
September 16, 2008

This information is for educational purposes only and is not intended to replace the advice of your doctor or health care provider. We encourage you to discuss with your doctor any questions or concerns you may have.
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