Welcome to the forum. I'm not sure if you will get an answer for your question on this forum as most of us here are Lymhoma/Leukemia survivors or caregivers and not physicians. I personally have never even heard of NRBC, but perhaps someone else here does know (Ken)? You might have better luck posting your question over on the doctor forums. That said, it may be a good idea to get a second opinion if your current hematologist isn't giving you any answers. May I ask why the bone marrow extraction was unsuccessful?
Mocha's question to you was a good one and the answer could have been a big clue as to why the nRBCs are there.
Mocha, it turns out that it's called a "dry tap" bone aspiration. (An aspiration uses a thinner needle to get 'liquid narrow', while a BMB uses a bigger needle and gets a string of tissue.) They could/should have done a BMB after the dry tap, in order to see what was wrong in the marrow.
I'll post these for the record:
"An Illustrated Guide to Performing the Bone Marrow Aspiration and Biopsy"
"Dry tap bone marrow aspiration: clinical significance"
"The presence of peripheral blood nucleated red blood cells, thrombocytopenia, and elevation of the serum lactate dehydrogenase were frequent findings in patients who experienced dry taps."
A dry tap could be from faulty technique. But the presence of the nucleated RBCs tends to indicate that's not the case. "Extramedullary hematopoiesis" (blood cells abnormally being produced outside the marrow) can result because the marrow is damaged and that in turn can produce nRBCs. An enlarged spleen or liver would be a clue.
Sorry to say, there are associations with a dry tap and malignancies in the marrow. But another possibility is that the marrow was poisoned by some medication.
I'm thinking I must have had a dry tap and a BMB as it was a two step procedure, much how you described, but I thought the whole two step procedure was called a BMB. See...I'm still learning stuff about this cancer years later.
Elsaria: Did they do a BMB on you...where they used a larger bore needle that takes a piece of your marrow? If not, you may need to inquire about that with your doctor.
The sense that I get, Mocha, is that when lymphoma is suspected then both aspiration and the biopsy are both typically done.