- Actinic Keratoses (AKs) are pre-malignant neoplasms of keratinocytes confined to the epidermis, caused by life-long sun exposure that manifest as characteristic erythematous scaling papules and plaques.
- The primary risk factor for AKs is life-long sun exposure, especially in light-skinned individuals. AKs typically develop later in life and once seen, continue to develop in new locations as previous lesions are treated. Given the role of sun-exposure AKs develop in sun-exposed skin, especially the head, neck, forearms, and dorsal hands.
- Gross Morphology
- AKs are characteristically poorly-demarcated, erythematous papules and plaques with scale. Classically, these lesions are more easily felt by their rough texture, rather than seen by the naked eye.
- Histological Morphology
- AKs are characterized by keratinocyte atypia in the lower levels of the epidermis. Hyperkeratosis and parakeratosis are responsible for the lesion's scale and a dermal lymphocytic infiltrate is frequently found beneath.
- Although considered pre-malignant, the relationship between AKs and Skin Squamous Cell Carcinoma is unclear. It is estimated that 2-5% of AKs may harbor or develop into SCCs.
- AKs are typically treated by freezing with liquid nitrogen. Some patients harbor so many AKs that individual freezing of lesions is unacceptable. In these patients topical therapy with anti-neoplastics or immune modulators is effective.