It's the same leg on which a cancerous lesion confined her to a wheelchair earlier this year.
Mayor Richard Daley and their daughters accompanied Maggie Daley to Washington, D.C., where she was scheduled to receive a Leadership Award from the Kuwait-America Foundation to benefit the Susan G. Komen for the Cure organization, the mayor's press office said in a statement.
She was unable to personally accept the award.
“She was experiencing some bone discomfort that we felt was significant enough to warrant an immediate evaluation,” her primary physician, Northwestern Memorial Hospital oncologist Dr. Steve Rosen said.
Rosen said he's been in contact with doctors at Georgetown University Medical Center.
"They did a reassessment, including all the same imaging studies that we've done here in Chicago just a few weeks ago, that were quite stable, and she's been doing quite well. And all of the X-rays showed similar findings to what we found just a few weeks ago, so there doesn't appear to be a significant change," said Rosen. "She may have a micro-fracture bone, which is something that we can't actually see on an imaging study, but can cause discomfort. It doesn't necessarily reflect a significant change in the disease process and hopefully she'll soon feel a lot better."
Maggie Daley is expected to return to Chicago in the next few days and have another evaluation at Northwestern, Rosen said.
She was first diagnosed with cancer in 2002 and and July 2006 had surgery to remove a tumor in her right breast. A titanium rod was inserted into her leg earlier this year to reduce the risk of fracture.
"It doesn't appear that it's in the same location as the previous fracture that she had had related to the leg and the placement of the rod," Rosen said in a telephone conversation Friday evening.