You can use multiple select items in nested queries.
1> create table t1(c1 int, c2 int) 2> go 1> create table t2(c1 int, c2 int) 2> go 1> select * from t1 where exists (select c1, c2 from t2) 2> go
1> select * from t1 where exists (select t2.*, c1 from t2) 2> go
Msg 102, Level 15, State 1: Line 1: Incorrect syntax near ','.