If you want to remove the melanin deposits left behind by back acne, you can follow the doctor’s instructions through medication, physical therapy and other ways to remove it. 1. Drug treatment: patients can follow the doctor’s instructions to use niacinamide, azelaic acid and other topical drugs to inhibit the function of melanocytes, so as to reduce pigmentation and promote the elimination of melanin deposits left behind by back acne. 2. Physical therapy: patients with back acne melanin deposits can follow the doctor’s instructions for laser treatment, using selective photothermal effect on the melanin deposits irradiation, destruction of local pigmentation. Back acne melanin deposits generally do not need treatment, if it affects the aesthetic appearance, want to remove it, it is recommended to go to the hospital to follow the doctor’s instructions for treatment.