The appearance of dark patches on the skin may be caused by post-inflammatory hyperpigmentation, sun spots, acanthosis nigricans and other skin diseases.
1. Post-inflammatory hyperpigmentation: if the patient suffers from localized eczema, prickly heat, dermatitis and other inflammatory diseases, during the recovery of these diseases, due to the stimulation of inflammation, it will proliferate the localized melanocytes, thus triggering the melanin deposition and causing the patient to develop dark patches on the skin.
2. Sun spots: if the patients are exposed to ultraviolet rays for a long time, it will activate the tyrosinase in local cells, which will lead to the formation of melanin and massive precipitation in the local area, resulting in the appearance of dark patches on the skin.
3. Acanthosis nigricans: If patients usually stay up late for a long time, or have irregular diet, it will cause excessive secretion of androgens in the body, which will stimulate the synthesis of melanin cells and make patients develop acanthosis nigricans, causing the appearance of dark patches on the skin.
When the skin appears black plaque, should go to the hospital in time to improve the examination, and cooperate with the doctor to give targeted treatment.