A dollar-sized nevus on baby’s arm needs to be examined first. If it is a benign nevus, it usually does not need to be treated, if it is not aesthetically pleasing enough, it can be removed by surgical treatment or physical treatment, if it is a melanoma, it needs to be treated by surgery. 1. Benign nevus: Most benign nevi do not need treatment. If they feel that they affect the aesthetics, parents can choose to remove the localized nevus by surgical or physical means, so as to improve the aesthetics. 2. Melanoma: Melanoma has a higher degree of malignancy, if you find a dollar-sized nevus on baby’s arm is melanoma, you need to have it removed by surgery in time, most of the early melanoma can be cured by surgery. Most early melanomas can be cured by surgery. After surgery, it can be treated with targeted drug therapy and chemotherapy to improve the curative effect. If you find a dollar-sized mole on your baby’s arm, it is recommended that you take your child to a doctor for a relevant examination and choose the appropriate way to deal with it.