What Causes Light Brown Spots on Skin?

Light brown spots on the skin may be café-au-lait spots or nevi, the scientific word for moles, explains Cleveland Clinic. Both are types of pigmented birthmarks. Te spots might also indicate neurofibromatosis.

About 10 percent of people have one or two café-au-lait spots that are not due to any disorder, but the presence of more than six spots that measure over 1/2 centimeter in diameter may indicate a genetic disorder called neurofibromatosis, notes Cleveland Clinic. The spots may have either a smooth or an irregular border.

There are three types of neurofibromatosis: NF1, NF2 and schwannomatosis, explains Mayo Clinic. Café-au-lait spots are associated with NF1, the most common form of neurofibromatosis. The spots do not pose any health risks, although they can be a cosmetic concern. Other symptoms of NF1 are soft bumps, called neurofibromas, either on the surface of the skin or under the skin, bone deformities, learning disabilities, short stature, a larger-than-average head and freckling in the groin area or underarms.

Nevi can appear as either flat or raised, dark or light brown spots, explains Cleveland Clinic. The majority of them are harmless, but some can turn into melanoma, necessitating monitoring of them for abnormal changes or appearances, such as bleeding, crusting, uneven borders, size changes, itching, asymmetry or pain.