What type of skin lesion is considered a precursor for squamous cell carcinoma?

The correct answer, actinic keratosis, is recognized as a significant precursor to squamous cell carcinoma (SCC). Actinic keratosis arises from prolonged sun exposure, leading to changes in the skin. These lesions typically appear as rough, scaly patches on sun-exposed areas of the skin, especially on the face, ears, neck, scalp, or back of the hands. The changes in the keratinocytes of the epidermis can potentially progress to SCC if left untreated.

In contrast, basal cell carcinoma is a type of skin cancer that originates from basal cells in the epidermis but is not considered a precursor to squamous cell carcinoma. Melanoma is a distinct and more aggressive form of skin cancer primarily originating from melanocytes, not squamous cells. While atopic dermatitis is a chronic inflammatory skin condition, it does not have precancerous potential like actinic keratosis does. Therefore, it’s important to monitor actinic keratosis for changes given its association with the development of squamous cell carcinoma.