What reason is the skin of neck below ear blackens

There are many causes of skin darkening under the ears and neck in dermatology, such as pigmentation after tears, etc., but the most common cause is called melanosis of the hair follicles of the face and neck. The main manifestation of this disease is that the bilateral ears and neck and jaw show this reddish brown patch, with this dense keratinization of hair follicles and a hard and prickly feeling to the touch. This disease has no effect on health, only affects the appearance, if you want to treat, you can also carry out some laser treatment, you can improve the color, or use some topical vitamin A acids, etc. These ointments, or some moisturizing treatments, can temporarily improve symptoms, but it has no effect on health.