Plasmocytoma: Classification

Symptomatic multiple myeloma (plasmocytoma) is defined by the revised IMWG criteria as follows: Presence of monoclonal plasma cells in bone marrow ≥ 10% or biopsy-confirmed plasmacytoma of bone or extramedullary manifestation and any of the following “myeloma-defining events.”

CRAB criteria for the diagnosis of multiple myeloma (see below Laboratory Diagnostics).

Hypercalcemia (calcium excess) C (hypercalcaemia) Serum calcium > 0.25 mmol/L above the upper normal range or > 2.75 mmol/L (> 11 mg/dL)
Renal insufficiency(renal dysfunction) R (renal failure) GFR (glomerular filtration rate) <40 mL/min or serum creatinine >177 µmol/L.
Anemia (anemia) A (anemina) > 2.0 g/dL below the lower normal range or < 10 g/dL
Bone lesions(osteolysis and/or osteoporosis). B (bone lesions) ≥ 1 lesion by radiography, CT, or PET-CT.

Biomarker

  • Clonal plasma cells in bone marrow ≥ 60%.
  • Involved/non-involved free light chain (FLC) ratio ≥ 100
  • > 1 focal lesion on magnetic resonance imaging (MRI) > 5 mm.

Staging according to Durie and Salmon (staging according to the International Staging System (ISS) is preferable: see below).

Stage Criteria
I (A/B)
  • Hb > 10 g/dl and
  • Serum Ca normal and
  • Normal bone structure on X-ray/a solitary focal point and
  • IgG < 50 g/l/IgA < 30 g/l/, Bence-Jones protein in urine < 4 g/24 h
II (A/B) Counting neither to I nor to III
III (A/B)
  • Hb <8.5 g/dl and/or
  • Serum Ca elevated and/or
  • Advanced bone lesions in the Rö and/or
  • IgG > 70 g/l/IgA > 50 g/l/, Bence-Jones protein in urine > 12 g/24 h

Legend

  • A: renal function normal
  • B: renal function limited
  • Hb: hemoglobin (blood pigment)
  • Ca: calcium
  • IgG: immunoglobulin G
  • IgA: immunoglobulin A

Staging according to the international staging system (ISS).

Stage Criteria 5-year survival
I
  • Β 2-microglobulin ≤3.5 mg/l
  • Albumin ≥3.5 g/dl
  • LDH normal
  • Cytogenetic standard risk
 82
II
  • Neither stage I nor III
 62
III
  • Β 2-microglobulin ≥5.5 mg/l
  • LDH elevated

Or

  • Cytogenetic high risk
 40

Legend: LDH: lactate dehydrogenaseThe International Myeloma Working Group (IMWG) proposes a new prognostic staging system that takes into account the previous “international staging system” (ISS), chromosomal aberrations (CA) detected in interphase fluorescence in situ hybridization after CD138 plasma cell enrichment, and serum levels of lactate dehydrogenase (LDH):

Stage Criteria
I
  • SS2-microglobulin < 3.5 mg/l and albumin > 35 g/l
  • Non-high-risk CA such as del(17p) and/or t(4;14) and/or t(14;16).
  • And normal LDH levels (below the upper limit of the normal range).
II
  • SS2-microglobulin > 5.5 mg/l
  • High-risk CA or
  • High LDH levels
III
  • All other possible combinations of ISS, CA, and LDH.

After a median observation period of 46 months, the 5-year survival rate was:

  • Initial R-ISS I at 82%.
  • R-ISS II at 62 %
  • R-ISS III at 40

The rates of progression-free survival (survival without cancer progression) in the three prognosis groups were 55%, 36%, and 24%.