Vatican museum - leave and re-enter?

There are restaurants and cafeterias within the Vatican Museums for tourists to eat lunch.

sorry, this doesn't really answer your question but maybe it will help. First thing in the morning, we toured the museum and the Sistene. Then we grabbed lunch at a place nearby. Then we toured St. Peter's and climbed to the top. It was a natural break for us having spent the morning in the museum. Also there is a cafeteria there, but the only thing we got there was a coffee - it is there if you need something quick.
There are folks handing out all kinds of flyers for lunch places nearby. We took one and headed in it's direction - but when we got to it, another place nearby caught our eye that was down further. Nice lunch. My only point being is if you walk a block or two away - there are all kinds of places you can find.
I would be interested to know if you can leave and re-enter. My hunch is no since there is a line to get into the place at any given moment during the day. I don't imagine that they have a seperate entrance for re-enters.

If you don't get an answer here, ask when you arrive in Rome. I would think that it will be possible. Ask a guard where to eat. Or visit the Tourist Information Office in Rome to ask.