Losing Fear Immunity

If I have an active Draconic Malice Spell taking away the fear immunity of all creatures around me, and say I inflict the Panicked condition for 20 rounds on an undead in my aura. The undead then turns tail and runs. What happens to that condition? Is it cured entirely, or just suppressed. If they are mindless will they take one step away, then turn back and re-engage next turn? If it just suppressed will they instantly become panicked again when re-entering my aura?