Dominik Kahun has a concussion and will be out indefinitely for the Pittsburgh Penguins.
The forward was injured in the second period of a 4-3 win against the Boston Bruins on Sunday. He has 27 points (10 goals, 17 assists) in 48 games this season, his second in the NHL.
The Penguins play at the Philadelphia Flyers on Tuesday (7:30 p.m. ET; NBCSN, ATTSN-PT, NHL.TV), their final game before the League-mandated, five-day break. They won't play again until Jan. 31.
Penguins forward Dominik Simon sustained a lower-body injury against the Bruins but practiced with the team Monday, and coach Mike Sullivan said he will play against the Flyers.
"I feel way better," Simon said. "Unfortunately, I had to leave the game. Tried to go back, but it wasn't good. So yeah, I feel good today."
Defenseman Justin Schultz practiced Monday in a regular jersey and didn't rule out a return against the Flyers. Schultz, who has eight points (two goals, six assists) in 27 games, has not played since sustaining a lower-body injury Dec. 17.
"I was full out today," Schultz said. "We'll see. Obviously, I want to play, but you want to be smart with these things."
Sullivan said he's looking forward to Schultz's return to the lineup.
"It would be a huge boost. He's a real good player," Sullivan said. "He's played a lot of good minutes for us. He's been banged up a fair amount of this year. So when we do get him back, it's going to be a big boost for the team."
NHL.com independent correspondent Wes Crosby contributed to this report