My Husband Has A Dark Purple Spotty Rash On His

my husband has a dark purple spotty rash on his left lower leg that almost goes all the way around his leg. it is about 5 inches above his ankle. he is 56 years old. only medical history is cardiomegaly. it is not raised, and does not itch. he will not go to the doctor to get it looked at so I am trying to get an idea of what it could be.