Mac Miller has worked with some true hip-hop heavies, among them Lil Wayne and Cam'ron -- both guests on his Macadelic mixtape -- but there was something extra special about his recent team-up with Bobby Stewart, aka Yung Ka.

Hailing from Fox Chapel, Penn., a suburb of Miller's native Pittsburgh, the 18-year-old rapper suffers from T-cell lymphoma, a life-threatening cancer that informs many of his lyrics. On Monday (May 14), Stewart visited Miller's ID Labs studios, where he had the opportunity to collaborate with the hometown rap star.

"To be with Mac is a blessing," Stewart told WTAE TV. "His lyrics are amazing. Hip-hop is my passion. To be able to be with Mac Miller ... he is a Pittsburgh legend."

Miller met Stewart last year, when he donated $50,000 to the Make-A-Wish Foundation. The "Loud" MC had kind words for his young disciple, praising him on his unique point of view.

"He has something real to say, and it's different, and it's cool," Miller told the local TV station.

For Stewart, the trip to ID Labs was equal parts music making and music therapy.

"It gives me something to look forward to, and it's a moment that's timeless," he said. "You can turn a song on and remember right back to that moment."

Watch Mac Miller's "Knock Knock" Video
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