Actinic keratosis
- Definition: UV-induced precancerous skin lesion that may progress to skin cancer.
- Epidemiology: occurs especially in individuals with light skin who are over the age of 50
- Etiology: sun exposure (e.g., from working outdoors)
- Lesion
- Occurs on areas of sun-exposed skin
- Initially: small lesion (papule or plaque) with rough surface (sandpaper-like texture)
- Later: Lesions grow and become brown or erythematous and scaly.
- Hyperkeratosis in such lesions may become prominent and form cutaneous horns.
- Pathology
- Parakeratosis: Retention of nuclei in the stratum corneum. t
- Atypical keratinocytes: Confined to the basal layer of the epidermis (partial thickness dysplasia).
- Note: If full-thickness dysplasia → Squamous Cell Carcinoma in situ (Bowen disease).
- Solar elastosis (blue-gray degeneration of collagen) in the dermis.
- Prognosis