Thanks for writing in.
The problem can be acanthosis nigricans
Without actual visualisation of the skin it is not possible to comment on nature of pigmentation.
Sun protection is most important for any cosmetic treatment.
Use good quality sunscreen.
Avoid sun exposure.
Use brevoxyl face wash.
Apply Kojivit cream at night over dark spots.
Take lot of vitamin C
Glycolic peels is ideal treatment for this you can continue the sessions.5-6 sessions would be required
for good results.
Hope this helps.