Correlation 7: Skin cancer

Note the normal thickness of the squamous epithelium of the epidermis with overlying layer of keratin at the left. The cells of the cancer have large, irregular, dark nuclei. The cancer cells are extending (invading) into the dermis.

There are a variety of problems that occur with sun exposure. Sunlight, specifically ultraviolet light, damages the skin. The elastic fibers in the dermis are degraded so that the skin loses its elasticity and wrinkles appear. The cells of the epidermis are damaged to become more prone to give rise to skin cancers. One form of skin cancer is squamous cell carcinoma, so-called because the cells of the cancer mimic, at least somewhat, normal squamous cells.

Sunburn: Excessive exposure to sunlight will produce a sunburn. Some persons are more sensitive than others, based on the amount of melanin pigment and other factors present. The burn causes the outer layer of skin, the epidermis, to die and peel off. The same thing can happen with an accidental burn from fires and hot liquids and can be worse. If the basal layer of cells of the epidermis is left, or there are adnexal structures left (sweat glands and sebaceous glands which have epithelial cells) then the epidermis can regenerate itself and heal. If no epithelial cells are left, then the burned area must have a skin graft placed over it, as is the case with severe burn injuries.