There do not seem to be any physical interactions between the two drugs, but I was glancing over the Accutane FDA medication guide and found out that the medication can cause you to have suicidal thoughts shortly after you stop taking it.
http://www.fda.gov/cder/drug/infopag...ationguide.htm
If you feel depressed or suicidal you may want to refrain from using ecstasy, at least more than occassional as many people feel down the days following the roll.

If you have been taking accutane for a while without any such severe side effects then go for it.