Dense small bumps on the small arms, consider periosteal keratosis, small spiny tinea, hairy erythema, etc., according to the specific cause, choose the appropriate treatment. 1. Keratosis pilaris: Keratosis pilaris is prevalent in the upper arm and thigh extensor, mainly follicular papules, you can apply urea cream, retinoic acid cream or salicylic acid ointment for treatment, and if the symptoms are more serious, you can choose glucocorticosteroid preparation, such as fluoxetine, hydrocortisone butyrate. 2. Echinocereus vulgaris: Echinocereus vulgaris is mainly characterized by clusters of follicular papules, which can be treated with oral vitamin A and vitamin E, and topical use of benzylphenol ointment, salicylic acid ointment, and retinoic acid ointment. 3. Hairy erythema: Hairy erythema, mainly reddish-brown or orange-red lesions, the size of a needle tip, you can take oral vitamin A, vitamin E isotretinoin to alleviate the symptoms, the local can be coated with urea ointment, cod liver oil ointment. Small arm long dense small bumps, should be to go to the hospital, under the guidance of the doctor’s correct treatment, if you need to use drugs to follow the doctor’s instructions to use, can not blindly use their own.