New York Rangers left wing Chris Kreider sets before a...

New York Rangers left wing Chris Kreider sets before a face-off against the Vancouver Canucks in the first period of an NHL hockey game at Madison Square Garden on Sunday, Nov. 26, 2017. Credit: Kathleen Malone-Van Dyke

In a sudden and disturbing turn of events, the Rangers will be without power forward Chris Kreider indefinitely because of a blood clot in his right arm that was discovered in hospital tests after he left Wednesday’s game against the Capitals.

Kreider, 26 and in his sixth season with the Blueshirts, was undergoing further examination on Thursday to determine treatment.

The team could not provide a timetable, but given the circumstances, Kreider, who scored 28 goals last season, could be placed on long-term injured reserve. That means that a player must miss a minimum of 10 games or 24 days, and potentially longer.

“Just before the first period he felt some swelling in his arm, the docs checked him out and didn’t see anything out of the ordinary,” said coach Alain Vigneault. “Then in between the first and second, it got to a point where this was out of the ordinary so they sent him to the hospital [Manhattan’s Hospital for Special Surgery]. He’s going through some other tests today.”

Teammates of the Boxford, Mass. native and Boston College alum were shaken. “Most importantly, he is a good friend,” Mika Zibanejad said. “I hope for a speedy recovery and for everything to work out.” Said veteran Marc Staal: “It’s a hard thing to see a teammate go through. Hopefully he gets it right and comes back healthy.”

In recent years, several NHL players have been diagnosed with blood clots, and after treatment have returned to play.

Tampa Bay’s Steven Stamkos had a clot near his right collarbone, part of a vascular thoracic outlet syndrome (TOS) called effort thrombosis, and underwent surgery in early April 2016. He was prescribed blood thinners and missed seven weeks. Earlier that season, Lightning goalie Andrei Vasilevskiy had a clot removed from near his left collarbone, and returned two months later. Other older players, such as Philadelphia’s Kimmo Timonen, Florida’s Tomas Fleischmann, Nashville/Florida goalie Tomas Vokoun, and Pittsburgh’s Pascal Dupuis, some of whom had blood clots in the legs and near the lungs, retired.

Before the team left for Friday’s game in Detroit, right wing Vinni Lettieri, 22, who almost made the roster out of training camp, was recalled from AHL Hartford and practiced on the fourth line and the second power-play unit.

“Everybody remembers the skill set and the speed from camp,” said Vigneault, who likes the combination of a right-hander — with 12 goals and 21 points in 31 games — and a youngster who will fire away. “We’ve got a lot of guys who think pass-first . . . in Vinni’s case, he’s got a shoot-first mentality.”

“It’s the best Christmas present,” said Lettieri, who played with defenseman Brady Skjei at the University of Minnesota. “I’ll just keep doing what I was doing in Hartford, keep shooting the puck . . . you’ve got to have a nose for the net and keep digging.”

The Rangers (20-13-4, 44 points and in a wild-card spot) also are missing Jesper Fast, who will be sidelined for a third game with a quad strain, leaving 12 healthy forwards. Another player could be summoned from the AHL as a spare if Fast cannot make the four-day, two-game trip to Arizona and Las Vegas that begins Jan. 4.

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