What are precancerous skin lesions not caused by sun?

Precancerous skin lesions not caused by sun exposure include actinic keratosis, which is primarily linked to UV radiation, but other types can arise from factors like genetic predisposition or chronic irritation. Conditions such as dysplastic nevi, which are atypical moles, can also be precursors to melanoma. Additionally, lesions like Bowen's disease, a form of squamous cell carcinoma in situ, can develop without direct sun exposure, often linked to HPV or other irritants. Regular dermatological checks are essential for early detection and management.