Cleveland State took permanent control with a 12-0 run in which Illinois-Chicago went scoreless for 5:53. Lee's 3-pointer ignited the surge, and Devon Long added five points.
Long's three-point play with 13:58 remaining gave the Vikings a 46-28 lead, and the Flames got no closer than seven points the rest of the way.
Mason was 8 of 12 from the field and added six rebounds. Lee finished with 10 assists.
Mike Brey is looking at former Notre Dame players to fill two assistant jobs that have opened up with the departures of Martin Ingelsby and Anthony Solomon.
Purdue's 2016-17 prospects got a jolt Wednesday when forward Caleb Swanigan announced he will return for his sophomore season.
Clemson's Jaron Blossomgame says he is withdrawing from the NBA draft and returning to school for a final season.