Doctors ruled Letang, who has not played since Jan. 27, is well enough to return after not practicing with the Penguins in six weeks. Bylsma said the team knew there was a chance he could return to practice at this point, but the 2013 Norris Trophy finalist "still has some other things to go through."
Bylsma said the date of Letang's full return is to be determined.
"He's been working out. He's been skating on his own, doing quite a bit on his own," Bylsma said. "It's not a complete surprise."
Letang, who was on blood thinners over the six-week time frame, suffered a stroke while preparing to travel on the Penguins' West Coast road trip in late January. His wife found him lying on the floor, and his mother-in-law, who is a nurse, treated him.
He participated in a Penguins morning skate before their game against the Los Angeles Kings on Jan. 30 but was ruled out for the game with an undisclosed illness. The extent of Letang's condition was not revealed until the weekend when Pittsburgh was in Arizona for a game against the Phoenix Coyotes.
A small hole in Letang's heart that was caused by a birth defect was detected and could have been the cause of his stroke. Letang has said he will not look into surgery to mend the hole.
Letang said Feb. 27 his condition has been "mentally a little tough." He said he was not contemplating a return date, but instead was "targeting day by day."
"Right now, I would like to step on the ice and play," Letang said. "But there are many things that won't let me do that."
Letang, 26, has 18 points (eight goals) in 34 games this season with a minus-6 rating, the second lowest of his career. He has missed 33 games due to three injuries.
The Penguins lost back-to-back games to the Philadelphia Flyers this weekend, 4-0 Saturday and 4-3 Sunday.