①Endocrine diseases: due to excess melanocyte-stimulating hormone (MSH), adrenocorticotropic hormone (ACTH), such as Addison’s disease, Cushing’s disease, Nelson’s syndrome, ovarian tumors, malignant pheochromocytoma, and long-term treatment with ACTH. Melanosis is also more common during pregnancy, when estrogen and estrogen-containing contraceptives are used to deepen skin pigmentation. ②Metabolic diseases: such as hemochromatosis, various types of porphyrias with photosensitive dermatitis, hepatomegaly, cutaneous amyloidosis, Gaucher disease and other symptoms of melanosis. ③Nutritional diseases: melanosis will have vitamin A deficiency, vitamin B12, vitamin C, folic acid, niacin deficiency, malabsorption syndrome, etc. ④ Chronic infections: such as malaria, black fever, schistosomiasis. ⑤ Tumors: seen in tumors that produce ectopic ACTH and MSH, such as lung cancer, pancreatic cancer, advanced malignant melanoma, and advanced carcinoma malignancy. Melanosis is occasionally seen in Hodgkin’s disease, lymphosarcoma, and chronic lymphocytic leukemia. (6) Connective tissue diseases: seen in rheumatoid arthritis, still disease, pancytopenia, dermatomyositis, systemic lupus erythematosus. (⑦) Pharmacogenic melanosis: seen in long term use of chloroquine or hydroxychloroquine, chlorpromazine, butyl dimethylsulfonate (busulfan), nitrogen mustard, cyclophosphamide, arsenic, bismuth, lead, etc. ⑧ skin lesions melanosis: acute and chronic skin infections, acanthosis nigricans, Riehl’s (Riehl) melanosis, tarry melanosis and reticulopigmented skin heterochromatosis. ⑨ Other: chronic liver disease, hepatic sclerosis, chronic renal insufficiency, Whipple’s disease, and other melanosis.