Welcome to Healthcare Magic
Hi dear, Has this pigmentation come off acutely. You need to first get tested for diseases which can cause this like Addison's disease. There are a lot of good skin bleach creams containing Hydroquinone
which can whiten skin but do get checked up from your Doctor first, if you have weakness, dizziness
on standing up, back pain
etc. Consult a Dermatologist
about these skin bleaching creams.