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Squamous Cell Carcinoma

Squamous cell carcinomas are less common than basal cell carcinomas and occur
predominantly on areas of the skin that have been exposed to the sun. Chronic exposure to
sunlight appears to be more significant in the etiology of squamous cell carcinomas than in
that of basal cell carcinomas.

Primary squamous cell carcinoma of the skin appears as a red, firm nodule, which gradually
forms a shallow ulcer that is surrounded by an indurated border. These lesions are commonly
located on the scalp, the ears, the back of the hands, and the
Histopathologic examination shows irregular masses of proliferating epidermal cells that
invade the dermis. Keratinization in the form of horn pearls may be seen.
Tumors are graded I to IV, according to their degree of differentiation, that is, keratinization
and depth of

Cutaneous squamous cell carcinoma may have a higher incidence of metastasis than had
previously been assumed.28 Three varieties, each with a different incidence of metastasis,
must be distinguished: primary cutaneous (three percent), mucocutaneous (11 percent), and
cutaneous squamous cell carcinoma secondary to inflammatory and degenerative processes
(10 to 30 percent). Secondary squamous cell carcinomas, which have the poorest prognosis,
include tumors that develop in burn scars, in sites of radiation damage, and in sites of
chronic inflammation such as osteomyelitic foci and, at times, chronic leg ulcers. Such
carcinomas and those arising on mucous membranes of the lip or genitalia may be rapidly
invasive and are often metastatic, with involvement of regional nodes and fatal progression.
In addition to the anatomic site, other important prognostic factors are duration and size of
tumor at the time of diagnosis. A lymph node examination is mandatory in all patients with
squamous cell carcinoma and should be repeated at follow-up. Biopsy of any suspicious
node should be, skin cancer, sqamous

Modalities used in the treatment of squamous cell carcinoma include complete surgical
excision, radiation therapy, and Mohs’ microscopic controlled surgery. Invasive actinic

Various retinoids, including b-carotene, isotretinoin, and etretinate, have been investigated
for their possible cancer prevention properties. A clinical trial of b-carotene, a plant-derived
previtamin A (retinol), was conducted in 1,805 patients with a history of recent nonmelanoma
skin cancer. Patients were randomized to receive either 50 mg of b-carotene or placebo daily.
After five years of follow-up, no difference was observed in the rate of occurrence of