He lay in a hospital bed at the University of Arkansas, stricken with a rare disease. His blood platelet count was so low that even a slight bump to his body could trigger a lethal brain bleed. A doctor told him to write his living will on a piece of paper.

Fajgenbaum was rushed to a CT scan. Tears streamed down his face and fell on his hospital gown. He thought about the first patient who’d died under his care in medical school, and how her brain had bled in a similar way from a stroke.

He didn’t believe he’d live out the scan.