Hi  Thanks for your query You seem to have developed skin pigmentation due to tanning. I would like to tell you that this does not have any relation to blood donation. Topical medications can definitely be of help to you in reducing the pigmentation to some extent. I would advice that you should use a lightening agent like kojic acid and vitamin c combination over the affected areas. This is a simple, harmless lightening agent which can be used for as long the blackish pigmentation is there. Also ,try not to touch the area too much.  Also ,try not to touch the area too much  Use proper sunscreen (spf 26) before going out in the sun so that the lesion doesn t darken any further  Take a diet rich in vitamin C and antioxidants like Citrus fruits and lots of salads  If after all the above measures, the pigmentation tend to persist, then i would advise that you should see a dermatologist as there are various other measures for the treatment of pigmented skin like the use of chemical peels, dermabrasion etc which a dermatologist can decide according to the type of scars..  Hope it helps  Wishing you speedy recovery  Dr Geetika Paul