"He looked like someone with acromegaly," says Turtz, who was at first reluctant to approach the young man.
Then he noticed Kisielewski speaking to surgical technician Renee Bekier. Her son Bill is the young man's best friend.
So Turtz asked for an introduction.
"It was a very unusual way to get started on a case," observes the 53-year-old Cherry Hill resident, who informally examined Kisielewski's hands and head and asked a number of questions.
"I think, somehow, God put the three of us all together," says Bekier, who is 49 and lives in Bellmawr. "It was meant to be. Dr. Turtz is an expert on pituitary tumors."
It's not unusual for acromegaly - which ultimately damages the heart, eyes and other organs - to go undetected for years.
In Kisielewski's case, the growth of the tumor coincided with the growth spurt of puberty. And while he grew taller than his parents and his older brother, Mike, 23, his paternal grandfather had been tall.
"He would ask me, 'Why am I so tall?' and I would just tell him, 'You got the gene,' " says his mother, Dolores, a 51-year-old Navy employee.
I'm sitting in the big, bright kitchen of the Kisielewski home with Matthew, a typical 20-year-old, except for being 6-foot-5. Family members bustle in and out as we chat.
"I had always been really little, and my junior year I think I grew a foot and a half," he says. "Everybody at my high school thought I was on steroids. At the gym, everybody would look at me."
An increase in strength - he could bench-press 350 pounds - also was accompanied by less salutary changes, including excessive sweating and snoring.
As the growth hormones gradually reached three times the normal level, Kisielewski's personality also changed. He became moody and antisocial. "I got (angry) easily," he says.
"He became the Tasmanian devil," says his father, Mike, a 52-year-old labor union agent. "Now he's Bambi. Dr. Turtz gave my son back to me."
After the hallway encounter, Turtz suggested Kisielewski undergo blood tests, which showed elevated growth hormone levels. Brain scans revealed a large tumor, and surgery was scheduled for May 10.
The tumor was benign; Kisielewski's recovery was relatively painless, uneventful - and rapid. Almost immediately, his face lost its swollen appearance.
"I can notice now that I'm littler than I was," he says.
Turtz, and the Cooper staff, were "awesome," Kisielewski adds. "I love Dr. Turtz to death."
Says Turtz, "Thank God everything worked out for him. But even though everything is normal, he will have to be followed forever."
Meanwhile, Kisielewski has a new job, as a helper in the tile setters' union.
He's enjoying life on a more even emotional keel.
"Everything turned for him," his father says.
For a young man who can now stop growing, it looks like the sky's the limit.
Contact staff writer Kevin Riordan at 856-779-3845, firstname.lastname@example.org, or @inqkriordan on Twitter. Read the metro columnists' blog, "Blinq," at http://www.philly.com/blinq.