Abdomen cysts/hernias?

[BigJohn97]

Last month, my female theraphosa stirmi molted and when she came out she had a massive bump on her abdomen. I've been told by another hobbyist that it's a "cyst" and it'll ultimately kill her. I don't know what to do, is there anything I can do for her so she can survive her next molt?
I'm also seeing what looks like the beginnings of a cyst on my a. seemanni (she molted in August). Is there anything I can do to reverse it?

 

[Dave Jay]

Cyst is a very ambiguous term, I guess it really means a lump with something inside. I've only kept tarantulas for about a year but this is the first time I've come across it mentioned in relation to tarantulas so it can't be terribly common. To have two tarantulas in the one household with it is very unusual I'd say.
Parasites can cause a cyst, an egg is laid and skin grows around it. Depending on the parasite a larva may emerge and drop into the substrate or more horribly burrow into the flesh.
Cysts can also form around a "splinter" or just an irritated area, often they are just full of fluid, perhaps with a foreign object inside.
In reptiles the substrate is the first thing to be looked at, both the type and the level of moisture. Too much moisture is often blamed for cysts on a reptiles belly, cysts form around an irritated or inflected area.
I would certainly look at changing your substrate as a first action to take and if you usually keep it very moist I would back off on the moisture level and have dry areas. Changing the substrate will decrease the population of any parasites or bacteria present at least, it can't hurt.
I'm sorry I can't really help you, I simply don't have the experience with tarantulas and it's not something I've read about.
There are plenty of experienced keepers on the forum so hopefully someone will have some better feedback for you.