Sunlight exposure and immunosuppression are risk factors for SCC of the skin, with chronic sun exposure being the strongest environmental risk factor. There is a risk of metastasis starting more than 10 years after diagnosable appearance of squamous cell carcinoma, but the risk is low, though much higher than with basal-cell carcinoma. Squamous cell cancers of the lip and ears have high rates of local recurrence and distant metastasis. In a recent study, it has also been shown that the deletion or severe down-regulation of a gene titled Tpl2 (tumor progression locus 2) may be involved in the progression of normal keratinocytes into becoming squamous cell carcinoma.SCCs represent about 20% of the non-melanoma skin cancers, but 80-90% of those with metastatic potential are located on the head and neck.Tobacco smoking also increases the risk for cutaneous squamous cell carcinoma.The vast majority of SCCs are those of the skin, and are often the result of ultraviolet exposure. SCCs usually occur on portions of the body commonly exposed to the Sun; the face, ears, neck, hands, or arm. The main symptom is a growing bump that may have a rough, scaly surface and flat reddish patches. Unlike basal-cell carcinomas, SCCs carry a higher risk of metastasis, and may spread to the regional lymph nodes,Erythroplasia of Queyrat (SCC in situ of the glans or prepuce in males, M: 733 : 656  or the vulvae in females.) may be induced by human papilloma virus. It is reported to occur in the corneoscleral limbus.
Later stages of invasion are characterized by the formation of nests of atypical tumor cells in the dermis, often with a corresponding inflammatory infiltrate. Degree of differentiation
Prevention
Appropriate sun-protective clothing, use of broad-spectrum (UVA/UVB) sunscreen with at least SPF 50, and avoidance of intense sun exposure may prevent skin cancer. A 2016 review of sunscreen for preventing squamous cell skin cancer found insufficient evidence to demonstrate whether it was effective. Management
Most squamous cell carcinomas are removed with surgery. A few selected cases are treated with topical medication. Surgical excision with a free margin of healthy tissue is a frequent treatment modality. Radiotherapy, given as external beam radiotherapy or as brachytherapy (internal radiotherapy), can also be used to treat squamous cell carcinomas. There is little evidence comparing the effectiveness of different treatments for non-metastatic SCC of the skin.Mohs surgery is frequently utilized; considered the treatment of choice for squamous cell carcinoma of the skin, physicians have also utilized the method for the treatment of squamous cell carcinoma of the mouth, throat, and neck. An equivalent method of the CCPDMA standards can be utilized by a pathologist in the absence of a Mohs-trained physician. Radiation therapy is often used afterward in high risk cancer or patient types. Radiation or radiotherapy can also be a standalone option in treating SCCs. As a non invasive option brachytherapy serves a painless possibility to treat in particular but not only difficult to operate areas like the earlobes or genitals.