Light brown patches on the skin may be hyperpigmentation, lichen planus, chloasma and so on. 1. Hyperpigmentation: If the light brown patches on the skin are secondary to localized eczema or dermatitis, they may be simple hyperpigmentation, and will usually recover gradually over time. 2. lichen planus: it is a chronic superficial fungal infection caused by malassezia invading the stratum corneum of the skin, which is related to several factors such as environmental factors and bad habits. The patient’s skin may appear light brown plaques of different sizes, which are fused with each other. 3. Chloasma: Mostly occurring in young and middle-aged women, endocrine abnormalities, sun exposure, genetic factors, etc., may cause chloasma. The patient’s facial skin has brown plaques, which are symmetrically distributed. In addition, it should be noted that some coffee-colored spots may be the manifestation of neurofibromatosis. Therefore, if light brown patches appear on the skin, the patient should consult the doctor in time to clarify the cause and carry out treatment under the doctor’s guidance.