Squamous cell carcinoma of the skin pathophysiology
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Differentiating Squamous cell carcinoma of the skin from other Diseases |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aditya Govindavarjhulla, M.B.B.S. [2], Raviteja Guddeti, M.B.B.S. [3]
Overview
Squamous cell carcinoma (SCC) is type of non-melanoma skin cancer. The cancer arises as a result of uncontrolled growth of the squamous cells in the epidermis of the skin. Unlike it's counter part, the basal cell carcinoma which also belongs to the group of non-melanoma cancer, SCC is rapid growing and invasive. SCCs may occur on all areas of the body including the mucous membranes and genitals, but are most common in areas frequently exposed to the sun, such as the rim of the ear, lower lip, face, bald scalp, neck, hands, arms and legs. Wrinkling, changes in pigmentation, and loss of elasticity of the skin are often the telltale signs of sun damage
Pathophysiology
Squamous cell carcinoma is a potentially invasive cancer that arises from the surface epithelium.The development of squamous cell carcinoma is frequently a multistep process. Early lesions tend to be either actinic keratoses, with atypia of the basal keratinocytic layer of the epidermis or squamous cell carcinoma in situ, in which keratinocytic atypia spans the full thickness epidermis.
These precursors are frequently present adjacent to invasive squamous cell carcinomas which invade the dermis as nests, islands, or cords squamous cells with or occasionally as individual cells. Several grading schemes have been developed for squamous cell carcinoma and incorporate the extent of keratinization (a form of differentiation) and nuclear atypia. A widely used scheme divides tumors into well, moderately, or poorly differentiated.
Although poorly differentiated tumors tend to behave more aggressively, well-differentiated tumors can also give rise to metastasis and result in death. Several histologic variants of squamous cell carcinoma have been documented, including verrucous, spindle cell and pseudovascular.
Frequently an actinic keratosis or squamous cell carcinoma overlies the invasive component and the two are focally contiguous. Occasionally squamous tumors arise rapidly, have a crater-form morphology and spontaneously regress. These tumors are known as keratoacanthomas. Some craterform squamous lesions do not regress, but continue to invade and grow and represent invasive squamous cell carcinomas.