Malkin left Friday's game against the Buffalo Sabres with what appeared to be a right leg injury after a second-period collision with Sabres defenseman Tyler Myers.
Malkin got tied up racing for a loose puck in the corner with Myers in the first few seconds of the period. Myers, a 6-foot-8 defenseman, appeared to fall on Malkin's right leg, which crumpled underneath him. Malkin remained on the ice for some time, then skated off to the dressing room with some assistance.
According to the Penguins' official Twitter feed, Malkin suffered what the team is calling a lower-body injury and will not return.
Malkin returned to the lineup Friday after missing five games with a left knee injury and a sinus infection. The 24-year old has 15 goals and 27 assists in 43 games this season.
The Penguins were playing their 12th game without captain Sidney Crosby, who's out with a concussion. They are also without rookie centre Mark Letestu, who was hurt in the morning skate on Tuesday and is expected to miss up to six weeks with a knee injury.