Letang was injured midway through the first period of Wednesday's game in Dallas when he was hit hard by Dallas' Eric Nystrom. Nystrom was given a two-minute minor for roughing, but will not face supplemental discipline.
Letang missed 21 games earlier this season due to a concussion. In 40 games, he has 9 goals and 31 points.
"I'm certainly concerned for every player," Bylsma told reporters following the Penguins' practice Thursday in Denver. "(Especially with) the significance of the hit, Kris being on the ice. That was the first thing that I thought of in that situation for Kris. Whether you've had one or a couple before, you're concerned for the player and their health. He took a hard hit."
Without Letang the team still has six healthy defenseman, but Bylsma said he will consider recalling an extra blueliner from AHL Wilkes-Barre/Scranton, possibly in time for Saturday's game at the Avalanche.
"We'd be down to six here if Kris was out for an extended period of time -- or longer than just this weekend -- so I think with the number of games that we have left on the schedule, we certainly would consider having one of the players down (in Wilkes-Barre/Scranton) come up," said Bylsma. "Simon (Despres) has been on the power play. He's been 5-on-5 against other team's good guys. So he certainly would be a candidate and a consideration."
Another place Letang's absence would be felt is on the power play, where he quarterbacks the first unit, along with Steve Sullivan. Sullivan also was hurt Wednesday, leaving the game with a lower-body injury that kept him off the ice Thursday.
"Matt Niskanen filled in (Letang's) spot on the ice and in a similar role," said Bylsma. "We had success with Matt there, so Matt will slide into that spot. The bigger question is whether Steve Sullivan can play next game or not and what happens there. (He and Letang are) both point guys. If Steve and Kris aren't playing, we're going to have to put Matt there with Paul Martin, as you saw in (Wednesday's) game. They'll have to play there and possibly Dustin Jeffrey. He's played the point on the power play before and might be used in that similar spot as Sullivan."
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[He's] real confident with the puck now, getting it off his stick quick and no second-guessing. We need that. He's such a good guy in the room. He works so hard. That's the big thing. For not a big man, he just fights for every puck and when he scores, the guys appreciate that even more.
— Winnipeg Jets coach Paul Maurice on Mathieu Perreault, who scored two goals in win against Chicago Blackhawks on Tuesday