Fact - With that score and being an IMG...NOT GONNA HAPPEN...235 these days is low even for a less competitive field like internal medicine..so if u think that ur lack of visa requirement is gonna get u dermatology, u r mistaken. Your chances might increase if u end up getting a 260+ in CK but at this moment, NOPE.
Shahzaib is right. In the case of dermatology, the truth is that they filter IMGs because they have a huge pool of american applicants with 250+ graduating from top US schools. So nope, not gonna happen. I can sit here and tell you to not loose hope, but reality is reality. Other spots that are almost impossible for IMGs are ENT, orthopedics and maybe radiology.
That said, if you would still like to take the leap, shoot for 260+ on CK and get ridiculous amounts of research (at good institutions) under your belt.
according to NRMP report, in 2012 , only 9 positions were offered for dermatology nation wide! No false hopes, no chance at all! Be realistic and enjoy life. Your step 1 score is very decent and you have many other specialties to shoot for. Good luck