@cmayer03
Welcome to Mayo Clinic’s Connect. I had never heard of Gray Zone Lymphoma and hoped that there has been some discussion here about it, but my search of Connect yielded no results. It appears that it is rare indeed. It must be a stressful time for your family. I’m so sorry.
There is data cited in Mayo Clinic’s work with Gray Zone patients that covers a decade+ and it references six patients.
I found this informational, but I hope there will be patients or their families who can contribute to the discussion.
https://www.mayoclinicproceedings.org/article/S0025-6196(11)00023-1/pdf
It’s encouraging that your nephew is now responding to chemo. Have the chemo treatments side effects been manageable?