Teammates Sidney Crosby and Beau Bennett were diagnosed with mumps in the last week. Crosby missed three games but returned for Thursday night's overtime win against Colorado. Bennett tested positive on Monday and remains out indefinitely with a lower-body injury.
Maatta is already out because of an upper-body issue. The 20-year-old missed two weeks this season after surgery to remove a cancerous thyroid tumor.
The mumps is spread through infected saliva and causes facial swelling and fatigue. There's no specific treatment for the virus, with symptoms lasting up to two weeks.
The Penguins host Florida on Saturday night.