I am writing this for my mother. She is 72 year old. She is diabetic. Last year she started developing some dark pigmentation on her face. Now it is like her whole face has become not dark but black. We consulted a dermatologist and he said it can be due to sun, diabetes or allergy due to hair dye. But the treatment is not very effective and it is increasing day by day. Now it has come to a stage where my mother is so very depressed. Can you please help me with the exact cause of it and what is its effective remedy? Please send you reply to YYYY@YYYY