However, Bruins general manager Peter Chiarelli would not confirm on Tuesday a report from a Boston television station that said the 19-year-old had testicular cancer. He said the surgery was performed on Monday.
"At the beginning of this week, Phil had cancer-related surgery," Chiarelli said. "He's progressing well and we'll have follow-up information upon the wishes of the family.
"I spoke to him. He's in very good spirits."
Kessel's family issued a statement on Monday that said the rookie centre was absent from the team with a "health issue" and asked that their privacy on the matter be respected.
Agent Wade Arnott told the Boston Globe that Kessel had unspecified cancer surgery at Massachusetts General Hospital and that he was "resting in Boston and on the road to recovery."
Arnott said the cancer was detected recently.
Chiarelli could give no timeline on how long Kessel will be out of action. He missed his first game Tuesday night against the Montreal Canadiens.
Chiarelli said coach Dave Lewis has addressed Kessel's injury with the other players.
"Dave's had a series of meetings and some of the guys have talked to Phil," he said. "They handled it internally.
"They're a good bunch of guys. Each team has their own way of handling it, but these guys have done a good job of it, as has Phil."
Kessel, a native of Madison, Wis., is a quick, highly-skilled centre who has been used mainly on the fourth line and on the second power-play unit in his first NHL season. He has five goals and four assists in 27 games.
If detected and treated early, testicular cancer has a cure rate of more than 90 per cent, according to the American Cancer Society. It has become the most common form of cancer for males between 15 and 35.
It also has some encouraging success stories.
Lance Armstrong returned to win the Tour de France after a difficult battle with testicular cancer. His case was diagnosed late and had spread to other parts of his body.
Last summer, 40-year-old golfer Billy Mayfair played in - and briefly led - the PGA championship only two weeks after testicular cancer surgery.