Abnormal pigmentation?

my aunt has a problem that has not been diagnosed yet. the doctor said that the melanin formed was falling on the dermis through the basal layer of the epidermis and in the process leaving gaps in the epidermis.when the sun rays fall in the melanin it reflects the rays giving the skin a dark greyish hue instead of the brown as in tanning. she has tried everything, Vitamin A pills, hydrolic peel etc but of no avail.she even went for skin graft but the problem recurred. could you please help? what is the problem,in medical terms please,i am a med student.