I'd think it means that:
the "cellularity" is still normal - in other words, the marrow is not yet filled with scar tissue aka fibrosis, instead it still has lots of cells present
they know it is B-cell lymphoma but haven't tested the type, and so refer to his previous diagnosis of Follicular Lymphona
for the 5%, I'd guess that means 5% of cells are lymphoma
altogether I'd say that indicates that although the lymphoma has gotten into the marrow, it's not taken over the marrow much so far. I'd further guess that therefore your husband's CBC is still normal. Once a cancer takes over marrow, it will eventually crowd out the good and normal cells that produce blood cells: white cells, red cells and platelets.
Thank you. No one could explain it in laymans terms to us. Unfortunately, he needs a liver transplant so we are linited in what they can do to stop the lymphoma.
I'd imagine they certainly would analyze the cells from the biopsy. If they are (still) Follicular Lymphoma and not transformed to some other type, then oftentimes the strategy is just to "watch and wait" because Follicular is usually very slow growing.
Besides merely waiting, Rituxan is a very mild treatment.