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

Actinic keratosis is considered a precursor to squamous cell carcinoma due to its association with prolonged sun exposure and the potential for malignant transformation. This skin condition manifests as rough, scaly patches on sun-exposed areas of the skin, indicating that the keratinocytes are undergoing atypical changes. While the majority of actinic keratoses do not progress to cancer, they are recognized as lesions that can develop into squamous cell carcinoma if left untreated, making them a key focus in dermatological screening and intervention.

In contrast, basal cell carcinoma, although it is a non-melanoma skin cancer that arises from basal cells, is not a precursor to squamous cell carcinoma but instead represents a different type of malignancy. Melanoma, which originates from melanocytes, does not relate to squamous cell carcinoma as a precursor. Squamous papilloma, while it is a benign neoplasm consisting of squamous cells, does not carry the same risk for malignant transformation into squamous cell carcinoma as actinic keratosis does.