Hello @roger191. This noncancerous disorder is rare but there is a lot more information about it in the past 20 years so don't lose hope. I was diagnosed with Rosai Dorfman in 2004. I had three enlarged lymph nodes removed above my left breast during that time. I also had a large mass on my spine (L3 and L4) that was pushing up against spinal cord. I was given prednisone 40mg for almost 6 months to shrink the mass. The prednisone shrank the mass to the point where I could walk again without pain but didnt totally resolve it. It took years for the mass to resolve on its own (no meds just monitoring it). I was in "remission" for more than 20 years. Fast forward to 2026. My Rosai Dorfman flared up again. This time I developed a mass in my heart that was the size of a small orange between my left and right ventricle. It was discovered because my doctor did a chest x-ray because I had a pneumonia at the time and had difficulty breathing. I was admitted to the hospital for 2 weeks and the doctors ran test after test to figure out what caused this mass. I had tell them that I had Rosai Dorfman 20 years ago and it may have flared up again. I was prescribed prednisone again (60 mg this time) and have been taking it for 6 months. The prednisone shrank the mass by 50% (and all my lymph nodes) but it did not shrink it anymore than that. Now I am starting Cotellic 20mg this week and will be gradually increasing my dosage to 60mg this month. I am praying Cotellic will work. I have read studies that Cotellic has worked for Rosai Dorfman symptoms (enlarged lymph nodes) but I havent seen any studies about its effects on tumors or masses caused by Rosai Dorfman. I have been living with RD for years. I've learned it flares up during very stressful times in my life. Im debating if I need to retire or change jobs now because my workplace is stressful. I have lived through my first RD diagnosis and I will live through this one again. If you have been diagnosed with it dont lose hope. There are more treatments for it and more studies about it. I'm living testament that you can overcome the symptoms and manage it for 20 years.