Honestly, a case report will do nothing for you. It's kind of like a poster presentation. Sure, it is always great to get a first author pub on you CV/application, but it does not demonstrate your skill or prowess as an investigative dermatologist. t's not like an interviewer will ask you about your case report or be impressed by it. Rather, if you get a first author basic science or clinical research pub in a reputable journal (JAAD, JID, and especially Science or Nature), then you got something to discuss, but such work takes a time and effort.
However, your greatest obstacle is the fact that your are a FMG. Realistically, you have no chance coming straight out of an international institution. If you are truly serious about derm, I would suggest doing a 2 year fellowship, not necessarily at a top academic institution (NYU, UCSF, Stanford), but rather at a program where they historically take fellows such as UCI, Emory, Case Western, etc. I am sure I will get slammed for being harsh, but honestly, if someone on this board tells you otherwise, he or she is full of **** and is unrealisticaly optimistic.
Applicants going in to derm are superstars at U.S. schools. Many are MD/PhDs, top of their classes, or have done fellowships/years of research. Look at the current match list. It is good that you are starting somewhat early, but you have a long road ahead of you. Approx. 1/3 of applicants do not match 1st time round (ie many of the aforementioned superstars) so don't give up if this is what you truly want. Derm is a fantastic field and definitely worth the fight.
best of luck
oh and by the way, being class rep will not help you at all so if it gets in the way of pursuing research or making derm contacts, drop it like a bad habit. Extracurriculars that would help are true leadership roles like pres. of a medical society or founder/pres. of a volunteer organization.