Shoulders have a piece of skin brown also very itchy and painful may be due to solar dermatitis, lichen planus and other reasons. 1. solar dermatitis: mainly caused by strong sun exposure, the sunburned skin will have a burning sensation, tingling, etc., in the erythema subsides, there will be patches of darker brown spots, you can take cetirizine tablets orally under the guidance of a doctor, topical glycerine lotion or glucocorticosteroids and other medications for treatment. 2. Tinea versicolor: Tinea versicolor is a skin disease caused by Malassezia infection, which is mostly seen in people who sweat a lot. It can be treated with selenium disulfide lotion, biphenylbenzazole cream, ketoconazole lotion and other medicines under the guidance of doctor. It is recommended to go to the hospital for examination, the doctor will make a judgment according to the clinical symptoms, give symptomatic treatment, the specific use of drugs need to follow the doctor’s instructions.