Rosie O'Donnell is standing by fiancee Michelle Rounds for the biggest challenge of her life.
On Friday, the 50-year-old comedian and talk show host revealed on her blog that, after months of unexplained pain and "medical mystery," Rounds has been diagnosed with desmoid tumors, an extremely rare, cancer-like disease.
Rounds -- whom O'Donnell calls "Mish" -- awoke on Mother's Day to "morning pain that won't let up."
As doctors struggled to diagnose Rounds' condition, "We wander thru the maze of medical mystery confused – scared . . .undiagnosed – again and again, her pain grew worse," O'Donnell explains. "It seemed impossible no one knew what was wrong."
Finally, doctors diagnosed rounds with desmoid tumors, which O'Donnell calls "odd and curious beasts . . . a non cancer that acts cancerous."
According to the website for the Desmoid Tumor Research Foundation, the extremely rare disease, also known as aggressive fibromatoses, arises from connective tissue, with approximately 900 new cases occurring each year in the U.S.. Although desmoid tumors cannot metastasize like more well-known cancers, they can destroy "adjacent normal tissues," including bone, and can be fatally destructive.
Rounds is "recovering from surgery in June, getting stronger every day," writes O'Donnell.
As a result of the diagnosis, the couple -- who got engaged in late December -- have delayed their wedding to summer 2013. In lieu of gifts, they ask for donations to be made to the Desmoid Tumor Research Foundation.
"Good thoughts, wishes, prayers all welcomed," O'Donnell wrote.
Prior to the discovery of Rounds' disease, she had been seeing a fertility doctor in the hopes of conceiving a child. O'Donnell revealed back in January that Rounds was "trying to get pregnant."
Their nuptials had been planned to take place in Long Island, where O'Donnell grew up.
This article originally appeared on Usmagazine.com: Rosie O'Donnell's Fiancee Michelle Rounds Diagnosed With Rare Tumors