Repeated sun exposure, cutaneous skin ageing, hormonal diseases, post inflammatory hyperpigmentation (PIH) or drugs induced photosensitivity, including the appearance of different types of brown spots:

Repeated sun exposure, cutaneous skin ageing, hormonal diseases, post inflammatory hyperpigmentation (PIH) or drugs induced photosensitivity, including the appearance of different types of brown spots:
Chloasma/melasma
Due to drugs or hormonal imbalances (pregnancy mask) and linked to sun exposure