Brown spots on the body may be caused by age spots, flat warts, lichen planus and other factors. 1. Age spots: may be related to sunlight damage, natural aging, genetic factors, etc., the skin localization can appear yellowish or brown spots, but there are no other clinical symptoms, will not cause too much impact, usually do not need to be treated. 2. flat warts: usually caused by human papilloma virus infection, mostly in the face, limbs and other skin parts, usually light brown or normal skin color pimples, smooth surface, hard texture, usually no self-conscious symptoms, some patients may feel a mild itching. 3. lichen planus: it may be related to fungal infection and environmental factors, which may lead to infection of the cuticle of the skin, and may make the affected skin appear brown, reddish, yellowish spots, presenting a round shape, and the area will gradually increase, accompanied by obvious itching. Brown spots with discomfort are recommended to go to the dermatology department of the hospital to avoid delaying the condition.