How to determine if temporary table exists

[mos]

How can I determine if a temporary table exists? Normally I use something like:

create temporary table Tablex like Table1;
show tables like "Tablex";

but the Show Tables never displays any rows for a temporary table even 
though the temporary Tablex exists. (All in same thread).

So is there a better way to determine if a temporary table exists?
TIA
Mike