Wade Arnott said the 19-year-old Kessel, the fifth pick in this year's NHL draft, had surgery Monday at Massachusetts General Hospital, according to The Boston Globe's website. "He got thrown a curveball," Arnott told the Globe, without specifying the kind of cancer. "But he's holding up pretty well."
The condition was identified "very recently" after Kessel felt minor symptoms, Arnott said. "He's resting in Boston and on the road to recovery."
Arnott did not immediately return a call from The Associated Press.
Kessel missed Monday's practice. The club did not say how long he would be sidelined, starting with Tuesday night's game in Montreal.
The Bruins issued a statement Monday from his family saying Kessel was being treated for a health issue that wasn't hockey related but gave no details on his condition.
The speedy Kessel has five goals and four assists in 27 games.