Ask Conall, 6, what he wants to be when he grows up, and he quickly answers, “President of the whole world!” Considering what he’s endured and how cheerful he remains, it’s hard to think of a better person for the job.

On a terrifying day in March 2015, Conall got feverish and then began vomiting. His parents, Christin and John, rushed him to their local emergency room. Alarmingly, the doctors couldn’t find a blood pressure. The doctors said that soon he wouldn’t be able to breath on his own, so a trauma team was called in to intubate him immediately. He was stabilized and transported to The Children's Hospital of Philadelphia in severe septic shock from an unknown cause.

The next morning, CHOP’s doctors had an answer: Conall was diagnosed with acute lymphoblastic leukemia, and the septic shock was caused by a strep infection that he had most likely recently picked up as the cancer suppressed his white blood cell production. “They called it the imperfect storm,” says Christin.

Conall’s initial stay at Children’s Hospital lasted more than two months. After his discharge, he was back at CHOP within 24 hours, and the next months saw frequent overnight stays and trips to CHOP’s Emergency Department.

“We’ve had it all,” Christin says with a sigh. The septic shock caused severe complications, including necrosis to his limbs, requiring the amputation of both legs below the knee and all of the fingers on his right hand. His skin grafts will need to be redone as he grows. He developed an intestinal bacterial infection from taking so many antibiotics as well as a soft tissue infection. Chemotherapy caused hypoglycemia and a seizure. Overall, Conall has had more than 24 surgeries and 30-plus blood transfusions.

The adorable boy who faced one problem after another became a staff favorite. On the Pediatric Intensive Care Unit, “The joke was that you couldn’t get into Conall’s room because there were so many people visiting — neighbors, friends and CHOP employees,” says Christin.

The good news: Conall has been in remission since April 2015, and is now on maintenance chemo, which will continue for more than two years. In February 2016, Conall received prosthetic legs — he calls them his “helper feet.” He spent two months learning to walk with them, and he still goes to physical therapy and occupational therapy every week. Having missed almost all of his kindergarten year, Conall will be entering first grade in September 2016, thanks to his home instruction and tutors.

His family participated in last year’s Parkway Run & Walk, but this year’s event on Sept. 25 will be extra-special for two reasons: Conall will be able to walk the course himself, and he’s serving as a Patient Ambassador for the event. His team, ConallStrong, will be among the thousands running and walking to raise money for pediatric cancer care and research at The Children’s Hospital of Philadelphia’s Cancer Center.