Necrotic Cyst, Death, and the Undead

[Doctor Despair]

The Mother Cyst feat enables you to cast the Necrotic Cyst spell, which enables you to plant a cyst in a living creature. However, the spell does not provide any provisions for what happens to the cyst after the creature dies. Presumably the cyst would remain in the body, given that there's no text that describes it vanishing or excising; the spell is instantaneous, not permanent, and the effect is to make the cyst, so it's not a magical effect on the creature. Therefore, if the body were to be raised as an undead, the cyst would still be in the body.

Spoiler: Three Cyst Effects

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* Whenever the victim is subject to a spell or effect from the school of necromancy, she makes saving throws to resist at a -2 penalty.

* Whenever the subject is dealt damage by the natural weapon of an undead (claw, bite, or other attack form), she takes an additional 1d6 points of damage.

* Once a necrotic cyst is implanted, spells that manipulate the cyst and its bearer are no longer thwarted by protection from evil.

Although you clearly could not put a cyst in an undead target, if an undead inhabits a body with a cyst in it, would the undead creature still be subject to the effects of the cyst? I'm torn because the spell creates the cyst, so I think the cyst would persist, but the text for the first two effects references "the victim" or "the subject," which makes me wonder whether the cyst would have any effect on the creature.

I do feel like the last effect is more clear, however, that it would still function in the undead creature, providing the cyst persisted after the original subject's death. In that case, Necrotic Awareness and Necrotic Scrying, being the only other cyst spells that do not specify a living target, should still function as normal, allowing you to at least use undead cyst-bearers as spies, scouts, or envoys after a fashon, and that these uses would not be thwarted by protection from evil.

What do you guys think? Would the cyst persist, and if it does, would any of the effects still be functional in an undead creature raised from the cyst-infested body?