The tumour was discovered during a preseason physical. Maatta underwent further tests before team doctors came to a diagnosis. He is scheduled to miss four weeks but is cleared to play until the surgery.
"I feel fine," Maatta said. "The only thing that's different is now I know that I have a cancer. It's tough news but I really don't think it has affected me much."
Team doctor Dharmesh Vyas said there is an "85 per cent chance" the tumour is cancerous but added the 20-year-old from Finland will not need to undergo chemotherapy or radiation. He is expected to make a full recovery.
Maatta called the diagnosis "a bit of a surprise" but kept the news from most his teammates when he learned of his condition three weeks ago.
"I've been talking to doc a lot, to trainers, finding out everything I can about the cancer," he said. "But I know I'm going to be fine and I really haven't been that worried about it because I know we have a great medical staff here and I know they're going to take care of me."
Maatta has one goal and four assists in seven games this season for the Penguins, who host New Jersey on Tuesday.
"It's kind of news that catches your breath a little bit," Johnston said. "''His mindset is he's a strong athlete mentally ... and we're very confident he's going to be able to rebound from this fine."
Maatta will be forced to rest for seven to 10 days following the surgery. Barring any setbacks, he'll be cleared to return to skating and eventually work his way back into the lineup. Vyas said any additional procedures would be done following the season if any are required at all.