"Excess pigmentation" is a term used to describe when there is too much color or darkness in a certain area of the skin, hair, or eyes compared to what is normal or desired. Full definition
Vitamin C also inhibits the production of excess pigmentation in our skin, which leads to blotchy pigmentation. (womenshealthandfitness.com.au)
«Sun damage from years of unprotected sun exposure leads to excess pigmentation showing through the thin skin underneath the eyes,» Begoun says. (goodhousekeeping.com)
Certain breeds develop spots of excess pigmentation similar to how humans are born with birthmarks. (dogcare.dailypuppy.com)