It may be due to pigmentation caused by various reasons, such as more fat and folds in the neck of obese patients, which are not cleaned up in time after sweat generation and formed by combining with dust in the environment after accumulation. In addition, it may also be caused by diseases. There are different treatment means for this symptom caused by different diseases: 1. Pigmented skin diseases: common such as pigmentation, freckles, coffee spots, melanosis, etc. When these diseases do not affect the quality of life, they can be relieved by oral vitamins and local application of vitamin A acid cream, hydroquinone cream and other drugs. For pigmentation serious, or a large area of pigmented dermatosis, can also choose laser removal or liquid nitrogen freezing removal under the guidance of a doctor; 2, metabolic dermatosis: commonly known as acanthosis nigricans, can also lead to deepening of the skin color of the patient’s neck, light gray, light brown or dark brown dry, rough and hypertrophic, and touch the surface, can feel a lot of tiny papillary elevation like velvet, soft to the touch. Benign acanthosis nigricans generally does not affect health, so weight control, endocrine adjustment, and topical application of keratolytic agents or bamboo leaf resin and isotretinoin gel are sufficient to address the cause. Malignant acanthosis nigricans may be related to the occurrence of malignant tumors in the body, which cannot be treated by itself and requires prompt medical attention and targeted treatment of the primary cause.