Madonna: Katy Perry Joins Mommie Dearest in Concert

Madonna rocked The Forum in L.A. Tuesday night, and there was a revelation during the concert ... Katy Perry has mother issues.

Katy joined Madonna, as a bunch of stars cheered them on, including AJ McLean, Rondell Sheridan, Joe Walsh, Sean Hayes, Ashton Kutcher, Mila Kunis, Liberty Ross, Kathy Griffin, Fergie and Queen Latifah.

57 ... pretty impressive.