Don't quote me on this, but DO to Derm is possible depending on the school. For example, VCOM seems to place 3-4 students each year into Derm which is crazy! How? Because they keep setting up their own Derm residencies and they have connections in that sense. Also, I keep trying to see who places into Derm from residency lists but it's nearly impossible because all the students must go through a transitional/traditional year first in order to place.
But for all those who thinks its impossible, it's not.... far from it. There's about 20 PGY-1 positions and 399 PGY-2+ positions for derm. Out of roughly 20,000 U.S. MD graduates means that around 2% match into Derm. As far as DO's go, we currently have around 4,900 graduates (roughly; ACGME and AOA combined) and around 56 AOA Derm positions. This equates to around 1.1% of DO's currently matching into Derm.
Now, how's the merger going to affect the AOA Derm positions, who knows? But seeing as how all the current PD's are DO's specialized in their fields, I doubt they will turn a blind-eye against all DO's. So who knows? But yea hope these numbers help put things into better perspective.