The Pittsburgh Penguins tweeted the news Thursday afternoon.
The 20-year-old was skating Nov. 11 for the first time since his surgery. He skated with the team at practice today.
Maatta told the media Thursday that he believes he'll return soon.
The results aren't a surprise, but his quick recovery from his Nov. 4 surgery has been impressive.
Team doctor Dharmesh Vyas said before the surgery that there was an 85 per cent chance that the tumour was cancerous.
He was expected to miss at least four weeks. He's only been out of the lineup for one.
Coach Mike Johnston said Maatta was ahead of schedule to return to game action.
"The way it looks right now, he'll definitely be back before the four-week window," Johnston said. "I would expect if he reacts positively to the skate today and the doctors take a look at him over the next day or so, he can be back any time in the next five, six days."