Spot is divided into white and black two colors, specific as follows: 1, chest long spot is white, and white spot surface is not smooth covered with white scales, itchy symptoms, consider the skin superficial fungal infection caused by sweat spot, more in the summer, with a lot of sweating has a direct relationship with the use of ketoconazole ointment, clotrimazole ointment wipe the affected area, oral fluconazole capsule, diligent bathing, diligent change of clothes, to keep the skin dry, clean. 2, chest long spot is black or brown, not higher than normal skin, no pain, no itch, consider is caused by melanin deposition, and ultraviolet radiation, long stay up late, often drink strong tea, endocrine disorders, etc., leading to an increase in melanin at the base of the skin, and the formation of black plaques, to change the bad habits, go out and wear a sunscreen clothing, to reduce ultraviolet stimulation of skin, can effectively prevent this disease. The disease can be effectively prevented by wearing sun protection clothing when going out and reducing the stimulation of the skin by ultraviolet rays.