Is early melanoma really curable? if a person has a lesion for several months & it turns out to be melanoma, will it be too late? can mel be white?

Maybe, Maybe, Yes: Nobody watches their skin so closely that they can be certain how long a lesion has been present. Many melanomas stay at the junction between dermis and epidermis for at least months before they invade and have the power to kill. "amelanotic" melanomas are various shades of cream / white. The key is to get the suspicious lesion off and examined.

Depends on stage: Early stage melanoma is highly treatable. Stage is dependent on the depth of the melanoma and whether the melanoma has spread to other locations.