What I'm seeing is the natural effect of aging and sun damaged skin. The medical term is "Senile Purpura"...a term I actually hate and pronounce "sanili purpura" just to make it sound better for patients. It is simply easy bruising that shows through thin dermis. Many people are taking aspirin or blood thinners that make the capillaries fragile. Couple that with the lack of subcutaneous fat and elasticity that occurs with aging and you have purplish bruises that look positively frightful. These bruises usually appear on the forearms or backs of the hands and shins.
There is no treatment for senile purpura. It is not a marker for any serious disorder. There have been some studies that show over-the-counter arnica montana ointment can help clear the reddish appearance faster.