Actinic purpura results from extravasation of blood into the dermis. This phenomenon is due to the skin atrophy and the fragility of the blood vessels in elderly individuals, which is exacerbated by chronic sun exposure. Actinic purpura lesions are located on sun-exposed areas, like the arms, face, and neck.
Skin atrophy in dermatoporosis is due to an alteration of collagen, similar to that which is seen in osteoporosis. This pronounced skin atrophy caused by the photo-aging makes the dermal vascular network very sensitive to the slightest trauma or shearing force.