Sudden appearance of brown spots on the chest may be endocrine disorders, but also may be lichen planus, nevus, coffee spot, etc., should be timely consultation to identify the cause of the disease. 1. Endocrine disorders: its cause is more complex, may be related to long-term late night, or long-term spicy and stimulating food, resulting in endocrine dysfunction, often manifested in the face or chest and other parts of the skin color is dark, may cause brown patches on the chest. 2. lichen planus: usually associated with malnutrition, or diabetes, pregnancy and other factors. It is often manifested as a round, dotted rash with brown, or yellowish-brown furfuraceous scales attached to its surface, which may be manifested as brown patches on the chest. 3. Nevus pigmentosus: usually associated with abnormal development of melanocytes, resulting in excessive aggregation of melanocytes locally, often manifested as brown or brown round spots, papules, so there may be brown patches on the chest. 4. Coffee spot: its etiology is still unclear, may be related to heredity, often manifested as brown patches of varying sizes, visible in all parts of the body. If the symptoms of brown spots suddenly appear on the chest, it is recommended to consult a doctor in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor symptomatic treatment.