There are several cases of ringworm on the arms as follows: the first case is the appearance of an erythematous scaly rash on both elbows, where the scales can appear silvery white in color, and after scraping away the scales you can see punctate bleeding and thin film phenomenon, accompanied by a certain amount of itching, mainly the occurrence of psoriasis. In terms of etiology, it is caused by genetics and other factors. The treatment can be oral amineptine tablets and Chinese medicine such as anti-silver granules or Danqing capsules, and topical tacalcitol ointment with hydrocortisone butyrate ointment is applied to the treatment. The second condition is lichen planus. The cause is mainly due to genetics or immune disorders, and treatment can be oral immunosuppressant regimen of tretinoin tablets and topical application of fluticasone propionate cream.