"We're discussing options with our doctor. Surgery is a possibility," Bylsma told reporters. "I'm not sure if there is a rehab possibility."
Malkin injured his right knee Friday night against Buffalo. He had missed the previous five games with a left knee injury and a sinus infection. Malkin won the Art Ross and Conn Smythe trophies in the 2008-09 season as the League's regular season scoring leader and playoff MVP, but has been slowed in each of the past two campaigns by injuries.
He has 15 goals and 37 points in 43 games this season for Pittsburgh. The Penguins have the second-most points in the Eastern Conference and sit one back of rival Philadelphia for the top spot.
"This is a difficult injury for him," Bylsma said. "It was kind of a fluke situation going into the boards with a guy. That's a tough injury for Geno. We have dealt with games without him. We've managed to find our way without him. That's what we're going to have to look at now."
Pittsburgh has won five straight games despite being without Malkin and captain Sidney Crosby since he suffered a concussion early last month. Mark Lestestu is also out for at least a month after knee surgery, so the Penguins are without three of their top four centers.