My husband had a stem cell transplant in sept 2012 for leukemia (aml). just told he has fully relapsed and has leukemia in his cns? still treatable?

Yes, but...: There are treatments that can be tried, but not knowing his prior treatment history and current condition i cannot say how likely such treatment will be successful. His doctors should have an honest discussion with you & your husband about options, risks and chances of success so you can make an informed decision. As you know, though, this is a bad situation.

Difficult, but yes: I am so sorry. Given how quickly he relapsed after transplant, there is a low, but not zero, chance of getting him in remission again. It depends on what drugs his leukemia has seen. A 2nd transplant is possible. There are a number of promising drugs in clinical trials for relapsed aml: http://www.Cancer.Gov/clinicaltrials/search/results?Protocolsearchid=6288957&vers=2 i wish you the best of luck.