system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
An 18-year-old man presents to the office, complaining of an itchy patch on his torso that appeared one week ago. The patient is on the college wrestling team and is concerned he will not be able to compete if it gets infected. He has no significant medical history, and his vital signs are within normal limits. On examination, there is an erythematous, scaly plaque with central clearing at approximately the level of rib 6 on the left side of his torso. What diagnostic test would be most appropriate at this time?
assistant
KOH preparation