Why do you think this cannot be Melasma?
Melasma involves symmetric, centrofacial distribution of light to dark brown patches with irregular borders
History of exacerbation with pregnancy, hormonal therapy such as oral contraceptives, and intense sun exposure.
Treatment of these types of hyperpigmented patches involves Combination approach with strict sun protection, cosmetic camouflage, skin‐lightening agents, chemical peels and laser therapy.
For a detailed scientific article about the different types of hyperpigmented patches on the face, read here
For all types of treatment options, read this excellent article
I would request you to please give a POSITIVE 5 star rating by clicking the stars on the top right corner of your question so that I am compensated for the detailed discussion that we have been having.
I would be able to still answer any more questions that you have, even after you have rated me,