Melanin deposits on the neck may be caused by frequent exposure to ultraviolet rays resulting in sunburn, or it may be acanthosis nigricans. 1. Sunburn: mostly seen in people who work outdoors for a long time, the neck area is exposed to sunlight for a long time, and localized melanin deposits can appear. It can be improved by applying sunscreen, wearing sun-protective clothing and reducing outdoor working hours. Melanin deposits caused by sunburns generally have no adverse effects. 2. Acanthosis nigricans: mostly related to heredity, obesity, diabetes, taking hormone drugs. Benign acanthosis nigricans can be relieved after puberty, obese acanthosis nigricans lesions in the skin folds, manifested as hyperpigmentation and skin tags. Malignant acanthosis nigricans is almost always associated with visceral tumors, except for neck hyperpigmentation. Acanthosis nigricans can be based on the cause of the disease, take different treatment measures, including etiological treatment, drug treatment and symptomatic treatment, obese people need to control diet, strengthen exercise, correct obesity. Those who are obese need to control diet, strengthen exercise, and correct obesity. Those who are caused by drugs need to stop taking them. Local skin lesions can be treated with laser and surgery, while malignant acanthosis nigricans requires radiotherapy and chemotherapy, and for patients with visceral tumors, timely surgical treatment. If there is black pigmentation on the neck, it is recommended to consult a doctor in time to clarify whether it is caused by acanthosis nigricans, as well as to standardize the treatment as early as possible.