Anesthesiologist in Hyères, Côte d'azur, France, I work in a Burn
Rehabilitation Unit but we also manage cutaneous wounds including cutaneous
envenomation by Pelagia noctiluca.
You're right : there's a lot of variability in the individual response to
the Pelagia sting.
A previous sting ( by Pelagia but probably by any cnidarian) and / or a
history of allergy and / or an idequate first management of the
envenomation is a worsening factor for the severity of the wound.

You describe a necrotizing envenomation that I consider and first treat
like a superficial to mid-superficial thickness burn (topical dressing :
silver-sulfadiazine then betamethasone).
The hyperchromic scar could remain some years.

I have seen (and photograph) some impressive cases. But no one was
life-threatening.

Best Regards

Dr Philippe QUERUEL ippe QUERUEL