Dark skin that does not wash off like dirt may be a normal phenomenon caused by heredity, or it may be caused by diseases such as acanthosis nigricans and melioidosis.
1. Heredity: If the patient’s parents have dark skin, it may lead to genetic inheritance, and the patient will have the phenomenon of dark skin that cannot be washed off like dirt, which is a normal phenomenon.
2. Acanthosis nigricans: the cause of acanthosis nigricans is not yet clear, and it is considered to be caused by heredity, obesity and other factors. The main symptom of patients is that the skin color becomes gray, brownish yellow, black, and there will be dry skin, roughness, itchy skin and other symptoms.
3. Melanosis: the pathogenesis of melanosis is not yet clear, and it is considered to be related to factors such as colonic melanosis, long-term constipation, as well as age and chemotherapeutic drugs. Patients will have skin pigmentation plaques, abdominal pain, constipation and other symptoms, but also skin itching, weight loss, emaciation and other symptoms.
There are other reasons (such as sun exposure, friction) for patients to have dark skin like dirt, and if it is caused by heredity, there is no need for special treatment. If it is caused by disease, patients should consult a doctor in time and follow the doctor’s instructions.