@feruze-- @burcidi gave a good explanation. I just want to add that not every lesion seen in a leukemia patient is leukemia cutis. It's only leukemia cutis when the leukemic cells have infiltrated skin tissue. Otherwise, leukemia patients can have lesions, hyper-pigmentation, and even dermatitis because of the inflammation leukemia causes. Sometimes chemotherapy is also responsible for these lesions.
I just wouldn't want anyone who has leukemia to see that they have a lesion and assume that they are dying soon. You can't know what kind of lesion it is unless your doctor takes a biopsy and tests it.