Is a bone marrow biopsy necessary in a patient with a previous tissue diagnosis of plasmacytoma or smoldering multiple myeloma, who now meets criteria for active myeloma?

It depends. If it is a solitary plasmacytoma with no other lesions, a bone marrow biopsy would offer 2 things: (1) if there is bone marrow involvement, you know that systemic therapy is needed and it is not a solitary plasmacytoma and (2) if you can not get a myeloma FISH panel on the plasmacytoma b...