I don't think it's possible.
If you really need it, you can always surround the bloc of code with '{' and '}'.
I have never seen it in other code, but one day I've tried it and it compile (ok, I didn't try it into a case statement. By the way, I really rarely use case statements, and they often just call a function, because the code if often reused later)
PS: And I don't think it could become, as there are is way to know the end of the bloc: break statements are not mandatory, so you can say that "case 1:" just imply to run something AND "case 2:".
This is why you probably never see fold in switch cases in an editor made to write C/C++ code.
(some can do, as notepad++ in certain conditions, because it fall on a indent style fold when it don't know the language.)