In 1985 a 13-year-old boy with an infectious smile, responded to a flyer distributed throughout local grade schools inviting kids to try out for a new TV show. “No Experience Necessary”.
That show turned out to be Degrassi High and would change his life forever.
Pat started his acting career thinking his role on Degrassi would be a summer job - a few months at the most. Six seasons later, however, Pat found himself on the highest rated show in Canada, syndicated in over 60 countries (including Showtime and PBS in the U.S.), in dozens of languages. In the span of six seasons, the critically acclaimed Degrassi Junior High, and its successor Degrassi High, won several awards including an 'International Emmy for Children's Television' in 1988. That same year, Pat received Canada's highest acting honour: the Gemini for "Outstanding Acting in a Continuing Dramatic Role".
In 1991, the Degrassi series came to a close. The two-hour series finale, School's Out, brought the CBC (Canadian Broadcasting Corporation) its highest ratings to date
In late 2001 Pat made a special return appearance on the much anticipated new drama Degrassi: The Next Generation on CTV television. He reprised his role as Joey Jeremiah for the one hour reunion episode, then returned for 5 more seasons.
In 2007, ET Canada included Mastroianni's character of Joey in a list of the top 25 Canadian television characters of all time.
Upcoming roles in 2011 are a leading role in the independent film “Unlucky” produced by Avion Films Recurring role on the family channel series “Conner Undercover” Special Guest Role in the Disney film "Sharpay's Fabulous Adventure” Guest Appearing "Rookie Blue" Season 3 episode 1 (2012) Guest Appearing "Saving Hope" NBC series (2012)