I Have A Type Of Dermatitis On My Legs And

I have a type of dermatitis on my legs and arms that appear as round red spots. They do not itch unless I inflame them. I have tried weeks of two cortisone RX creams and lot lots of moisturizers. Had this for about 3 years. If I scratch, there is scaly skin underneath and they will bleed. I am 74 - not had this as a younger person. Tried years with 4 dermatologists.Begin as round elevated red round spots