You are having purpura.Melanoma
has no relation with purpura.
You should be investigated to find out some cause.
It may infection,allergy ,connective tissue
diseases or some internal or blood diseases.
For perfect diagnosis you consult dermatologist
Oral vitamin C
and K may improve the lesions.
Local thrombophob oint. would be helpful.
I hope you got my answer.
Dr. Ilyas Patel MD