Melanosis is the benign pigmentation of the mucosal surface of the vulva.
The areas are multiple, flat, and stable. Biopsy, if performed, will show clusters of melanocytes with a benign appearance.
The cause is unknown but genetics presumably plays a role. Left alone, they will remain stable for long periods of time, but may fade following childbirth.
As they do not pose a threat and are not a cosmetic issue, no treatment is necessary.
Suspicious areas or areas that are rapidly changing should be biopsied.