The darkening of the skin on the back without pain or itching may be caused by physiological factors such as sunlight exposure, or it may be caused by post-inflammatory hyperpigmentation, acanthosis nigricans, melioidosis and other diseases.
1. Physiological factors: If the back is exposed to sunlight for a long time, the ultraviolet rays in sunlight will stimulate the synthesis of melanocytes in human skin, which will lead to localized darkening of the skin without pain, itching and other symptoms.
2. Post-inflammatory hyperpigmentation: it is caused by acute or chronic inflammation of the skin. The patient’s back skin has suffered from eczema and other diseases, when the inflammation fades, the back skin may appear black but not painful and itchy.
3. Acanthosis nigricans: the cause of the disease is still unclear, mostly related to genetics, obesity and other factors, the symptoms include deepening of skin color, dryness, roughness and so on. Patients suffering from acanthosis nigricans may have darkened skin on the back.
4. Acanthosis nigricans: Skin-type acanthosis nigricans is mainly related to photosensitive substance exposure, malnutrition, friction, endocrine disorders and so on. Clinically, it is mainly manifested as gray-purple grid-like pigmentation plaques, covered with dust-like skin debris, surrounded by follicular keratinization, capillary dilatation and other symptoms. There will also be darkening of the skin on the back without pain or itching.
There are many reasons for the darkening of the skin on the back without pain and itchiness, in addition to excluding physiological factors, it is recommended that the patient go to a regular hospital for examination, and cooperate with the doctor to clarify the cause of the disease.