genuinely his/her enthusiasm with biomedical research (being necessary for becoming a leader in medicine) and ambitious to be a leader in medicine. Top 15 (probably 20) especially top 10 medical schools are aimed at educating/training leaders in medicine not just a physician though they know most of their students might not be a leader eventually.
Also, don't show or indicate his/her intention to be matched in the highly competitive resideny programs such as dermatology, plastic surgery and Ophthalmology
Good luck
