Brown patches on the skin may be hyperpigmentation, lichen planus, flat warts and so on. 1. Hyperpigmentation: such as chloasma, mostly yellow-brown or dark brown patches, usually distributed symmetrically on the cheeks and cheeks, and may also involve the forehead, nose, perioral area and other parts. 2. lichen planus: the initial stage of light brown, white and other spots, with the development of the disease, the skin lesions fusion into a large and deepening pigmentation, can form a brown plaque. 3. flat warts: manifested as small rice grains to soybean size, round or oval flat protruding skin papules, light brown or normal skin color. It is recommended that people who have brown patches on their skin go to the hospital in time to get a clear picture of the cause, and if they need to be treated, they should be standardized under the guidance of the doctor.