I never had a cyst that was particularly painful, but on 2 occasions I had 2 cysts that developed piggy-backed and made for a visible lump in my boob. The first time was pre-kid and they were drained...they drained probably 1.5oz. fluid -- golfball sized blob. Same dumb cysts refilled when I was nursing, so my doc chose not to do anything with them, for risk of introducing bacteria and giving me mastitis. They resolved on their own.

Which reminds me, I'm like 6 months overdue for my own mammo.