Which type of skin cancer is often associated with chronic sun exposure and presents as a scaly red plaque?

Squamous cell carcinoma (SCC) is a type of skin cancer that is commonly associated with chronic sun exposure. It typically arises from the keratinocytes in the epidermis. One of its classic presentations is as a scaly red plaque or a firm, crusted nodule that can be tender to touch. This characteristic appearance is due to the uncontrolled growth of squamous cells, often as a result of ultraviolet damage from prolonged sun exposure.

Chronic sun exposure leads to cumulative DNA damage in the skin cells, which can trigger mutations that contribute to the development of cancer. SCC can also present in areas that previously had actinic keratosis, an early form of sun-induced skin damage characterized by rough, scaly patches.

In contrast, basal cell carcinoma usually appears as a pearly nodule and is less likely to be found in a scaly plaque form. Lentigo maligna represents a pre-invasive form of melanoma often seen in sun-exposed areas but typically appears as a flat, brown stain rather than a red plaque. Melanoma itself usually presents as an irregularly shaped, dark lesion and is associated with more aggressive behavior compared to SCC. Thus, the description of a scaly red plaque aligns best with squamous cell carcinoma.