What are the IMWG diagnostic criteria for solitary plasmacytoma?

Updated: Mar 10, 2021
  • Author: Suzanne R Fanning, DO; Chief Editor: Emmanuel C Besa, MD  more...
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For a diagnosis of SP, the International Myeloma Working Group (IMWG) requires all four of the following criteria be met [1] :

  • Biopsy-proven solitary lesion of bone or soft tissue with evidence of clonal plasma cells
  • Normal bone marrow with no evidence of clonal plasma cells
  • Normal skeletal survey and MRI (or CT) of the spine and pelvis, except for the primary solitary lesion 
  • Absence of end-organ damage, such as CRAB (hypercalcemia, renal failure, anemia, and osteolytic bone lesions), that can be attributed to a lympho-plasma cell proliferative disorder

Patients with an apparent SP who have less than 10% clonal marrow involvement are considered to have SP with minimal marrow involvement. SP with 10% or greater clonal plasma is diagnosed as multiple myeloma.

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