But last week, Joe said, scans showed that a troublesome tumor in 1-year-old Gianna's brain shrank significantly after rounds and rounds of surgeries and chemotherapy, to the point where it's "basically gone."

The tot's stunning reversal of fortune - which came after a dire diagnosis from her doctors - led one family friend to call Gianna's encounter with the pontiff "the Miracle on Market Street."

That same friend, Donny Asper, was the sympathetic FBI agent who tipped off the family that Pope Francis would pass the James A. Byrne U.S. Courthouse on Market Street near 7th when leaving Independence Hall after his Sept. 26 address there.

Her parents knew she needed help: Gianna, whose first birthday was in September, was ailing with a rare brain tumor and had already gone through several chemotherapy sessions.

Initially, doctors were skeptical that anything could be done: They said the tumor was inoperable.

"They said go home, enjoy the last weeks, maybe months, that you have with her," said Joe, 37, a St. Joseph's University grad.

But Kristen had dreamed of Gianna meeting the pope weeks before it was announced he would arrive in Philly.

"She was just dead-set," Joe said. "I'm the dad who didn't want to see the pope."

He was worried about the effect a hectic day in public would have on his daughter's immune system, already weakened by the radiation. So they left it up to their doctor, who encouraged them to head down there.

They made it to the city in 40 minutes from Warrington, a record drive time for them, and held Gianna out as far as they could by the courthouse, while officers from the Philadelphia Police Department waved the Popemobile over.

"He just caught our eye... it's like God told him," Joe Masciantonio, who also has a 4-year-old son, Dominic, told the Daily News last night.

Gianna is named after St. Gianna Beretta Molla, a modern-day saint and an Italian pediatrician canonized in 2004. St. Cyril church arranged for Gianna and the family to meet her namesake saint's daughter.

Domenico Giani, a mash-up of the Masciantonio children's names and the head of security for Vatican City, brought Gianna over to Pope Francis, who kissed her on the head, right where her tumor was.

"It was truly blessed," Joe said. "God really let her know he heard her prayers."

Uniformed law enforcement and military were cheering for Gianna after the convoy whisked the Holy Father away to his next engagement. Some teared up. Others wanted to meet her.

"She must have taken, like, 50 selfies," Joe said.

The family then joined hands in prayer with several FBI agents and the bureau's chaplain in Philly, Monsignor Mike Mannion.

"Sometimes coincidence is God's way of remaining anonymous," Mannion said. "The fact that they were literally able to flag the pope down, he stopped and blessed the baby... it's very special."

"I don't even know how to describe that feeling," Joe said. "The miracle is all the people who prayed. The pope is just the messenger that God heard."