Dirty lines on the neck may be long-term sun exposure leading to hyperpigmentation, may also be the manifestation of acanthosis nigricans, may also be the age of the neck lines, need to be analyzed specifically. 1. Long-term sun exposure: long-term direct sunlight on the skin will lead to hyperpigmentation, there will be a dark line on the neck, go out to do a good job of sun protection, eat more coarse grains and vegetables and fruits. 2. Acanthosis nigricans: this is due to genetic, obesity, endocrine diseases and other factors, acanthosis nigricans can be a symptom of hyperpigmentation and hyperkeratosis of the skin, occurring in the neck, armpits and other folds of the skin, manifested as melanin pigmentation of the skin, epidermal roughness. 3. Ageing: Neck lines will appear with ageing, if there is pigmentation at the same time, there will be dirty lines on the neck, you can use skin care products to lighten neck lines to tighten the skin. Patients with dirty lines on the neck should first go to the hospital for examination, if the disease is caused by the need to follow the doctor’s instructions to do symptomatic treatment. Usually to control weight, light diet, pay attention to sunscreen, appropriate massage of the neck skin to relieve neck lines.