Chapter 26: Multiple Myeloma

Epidemiology

Pathology

Monoclonal gammopathy of uncertain significance (MGUS), all criteria must be met

• Serum M-protein level <3 g/dL and bone marrow clonal plasma cells <10%

• Urine monoclonal protein <500 mg/24 hours

• Abnormal sFLC ratio (<0.26 but >0.01 or >1.65 but <100) in light chain MGUS with absolute increase in affected light chain

• No myeloma-defining events (MDE)

• No evidence of other B-lymphoproliferative disorders/AL amyloidosis

• Progression to multiple myeloma (MM) in ~1% per year (0.3%/year in light chain MGUS)

Smoldering (asymptomatic) myeloma

• M-protein in serum ≥3 g/dL and/or

• Urine monoclonal protein ≥500 mg/24 hour and/or

• Abnormal sFLC ratio (<0.26 but >0.01 or >1.65 but <100) and/or

• Bone marrow clonal plasma cells 10–60% and

• No MDE or AL amyloidosis

Progression to MM in 10%/year in first 5 years (5%/year for light chain SMM)

Active (symptomatic) myeloma^†

Requires one or more of the following MDE:

• Evidence of end organ damage (CRAB criteria)

  • Calcium elevation (>11.5 mg/dL [>2.88 mmol/L])

  • Renal insufficiency (creatinine >2 mg/dL [>177 μmol/L])

  • Anemia (hemoglobin <10 g/dL or 2 g less than normal)

  • Bone disease (one or more lytic lesions on x-ray, CT/PET-CT scan, or MRI)

• Presence of biomarker of active disease

  • Clonal BM plasmacytosis ≥60%

  • Affected:unaffected sFLC ratio ≥100 with absolute value of affected sFLC≥100 mg/L

  • >1 focal lesions on MRI imaging

Solitary Plasmacytoma

• Biopsy proven tumor of clonal plasma cells affecting soft tissue (extramedullary) or bone (medullary)

• Normal bone marrow aspirate/biopsy with no evidence of clonal plasma cells

• Normal skeletal survey + MRI/CT spine and pelvis, excluding the plasmacytoma

• Absence of MDE

It represents 3–5% of cases of plasma cell dyscrasia

Progression to MM in ~10% patients within 3 years

Local treatment (radiation therapy and/or surgical excision) is treatment of choice

Solitary plasmacytoma with minimal bone marrow involvement

• Biopsy proven tumor of clonal plasma cells affecting soft tissue (extraosseous) or bone (osseous)

• Clonal BM plasmacytosis <10%^✫

• Normal skeletal survey + MRI/CT spine and pelvis, excluding the plasmacytoma

• Absence of MDE

Progression to MM in ~60% (osseous) and 20% (extraosseous) of patients within 3 years

^✫If more than 10% clonal plasmacytosis, then it is defined as active MM

Rajkumar et al. Lancet Oncol 2014;15:e538–e548

Plasma cell leukemia—defined as primary in the setting of de novo presentation (60% cases), secondary as terminal ...