Pederson, during a tense back-and-forth with the media, said that it's an injury that has "evolved over time" and will not require surgery.
Wentz was listed as doubtful for Sunday's game. Pederson had said earlier Friday that he would be listed as questionable and would travel with the team to Los Angeles. However, given the estimated three-month recovery time, it seems unlikely Wentz will play the rest of the season.
Super Bowl MVP Nick Foles will start if Wentz can't go.
Wentz was listed on the injury report as a limited participant with a back injury on consecutive Wednesdays in late October. Asked if the stress fracture was related to that injury, Pederson raised his voice.
"He has a stress injury, evolved over time and it requires no surgery," Pederson said. "[I'm not] answering any more questions about it. We're playing the Rams in two days, if you guys haven't figured this out."
The questions persisted for about 10 more minutes, though, and Pederson went on to offer more details. He said he anticipates a full recovery for Wentz.
The fracture was discovered as a result of a scan on Tuesday, according to Pederson.
"Until you do a scan, you don't know," he said, but added "we do a lot of testing each week on a lot of players."
Pederson explained why he had no concern about having Wentz play while this injury was presumably getting worse.
"There were no symptoms," Pederson said. "He was 100 percent, he practiced. He was not on the injury report for this. So yeah, I had no issue with that."
Pederson does not anticipate any long-term issues for Wentz as a result of this injury.
"The fact that he doesn't need surgery on this is the best news that you could possibly have on anybody that has a stress fracture or a stress injury in this case," he said. "As long as we take the proper steps to make sure that all our players are 100 percent, then [there's no concern]."