There are some human worlds in the Hive Federation.  It's possible that you could have some kind of pacification action on one of those worlds that might involve Ithklur troops.  Or perhaps there are worlds far to rimward and anti-spinward that were settled during the Rule of Man that are now being absorbed by the Hive Federation.  You could easily have a small pocket empire of colonial worlds that are in the path of some Hiver manipulation. They'd be far enough away from other human polities that their fate would be unknown.

Matt