Maatta, 20, will continue to take the ice for the Penguins in the lead-up to surgery in November, despite there being an 85 per cent chance the tumour is a form of thyroid cancer.
Team doctor Dharmesh Vyas revealed Maatta was likely to miss up to a month of competitive action following the procedure to remove the tumour, with the first 7-10 days following reserved for rest.
Rutherford was amazed by Maatta's matter-of-fact response to his diagnosis.
"I will say that this news came out about three weeks ago, when Olli was first made aware of it," Rutherford said.
"And to watch a young man continue his life and play the way he's played has been absolutely amazing. It's amazing that he can still concentrate and continue on. He's kept this to himself.
"I know a couple of his team-mates knew about it, but at the same time, I can't say enough about Olli, about how he's handled this news."
The Finn said having the tumour had not changed his outlook, and added he felt no ill effects from it.
"I didn't feel any different," Maatta said.
"I felt the same as I did before and right now, I don't feel any different than I did a year ago.
"Anything hasn't really changed. I haven't really been that worried.
"I've been talking to the doctor a lot, the trainers, and trying to find out everything I can about the cancer, but you know what? I know I'm going to be fine and I haven't been that worried about it because I know we have a great medical staff here and they're going to take care of me."