If you have a sebaceous cyst, should it drain by itself once it got too big?

Possible but remove: It is always easier to remove this under controlled situation rather than while infected. Seek evaluation by a plastic surgeon, dermatologist, general surgeon, or physician skilled with removal.

Not necessarily: Sebaceous cyst don't necessarily drain spontaneously when they get to a certain size. Usually the only time they drain on their own is if they become infected. When this happens they may recur. It is harder to remove a cyst that has scar tissue and been previously infected. In general the larger the cyst the longer the scar will be to remove it.