Criteria of the International Myeloma Working Group for Solitary Plasmacytoma

A solitary plasmacytoma requires all of the following:

(1) single biopsy proven lesion of bone or soft tissue composed of clonal plasma cells

(2) no other skeletal lesions seen in imaging studies (MRI or CT) of the spine or pelvis

(3) absence of end-organ damage (CRAB findings of hypercalcemia, renal insufficiency, anemia, bone lesions) associated with the plasma cell disorder

(4) clonal bone marrow plasma cells less than 10%

If no clonal plasma cells are seen in the bone marrow, then the diagnosis is solitary plasmacytoma.

If clonal plasma cells are seen in the bone marrow, then the diagnosis is solitary plasmacytoma with minimal marrow involvement.