Olivia Munn is opening up about a health diagnosis.

The 43-year-old shared she has been diagnosed with breast cancer, noting that she was diagnosed two months after she took a genetic test that came back negative.

"In the past ten months, I've had four surgeries," she wrote in a March 13 Instagram post, "so many days spent in bed I can't even count and learned more about cancer, cancer treatment and hormones than I could ever have imagined. Surprisingly, I only cried twice. I guess I felt like there was time to cry. My focus narrowed and I tabled any emotions that I felt would interfere with my ability to stay clearheaded."

As the actress, who shares 2-year-old son Malcolm with John Mulaney, went on to explain, "I've tended to let people see me when I have energy when I can get dressed and get out of the house, when I can take my baby boy to the park. I've kept the diagnosis and the worry and recovery and the medicine and the paper gowns private. I needed to catch my breath and get through some of the hardest parts before sharing."