smouldering myeloma (asymptomatic myeloma)

Last reviewed 08/2021

smouldering myeloma (asymptomatic myeloma)

Smouldering myeloma is defined as an asymptomatic proliferative disorder of plasma cells (1).

  • resembles MGUS (because end organ damage is absent) but the risk of progression to symptomatic or active multiple myeloma or amyloidosis at 20 years is high (78% probability for smouldering multiple myeloma vs. 21% for MGUS)
  • it is the point of transition from MGUS to myeloma (2)

Diagnostic criteria for smouldering myeloma include:

  • monoclonal protein present in the serum, 3 g per 100 ml or higher
  • monoclonal plasma cells 10% or greater present in the bone marrow and/or a tissue biopsy
  • no evidence of end-organ damage attributable to the clonal plasma cell disorder:
    • normal serum calcium, haemoglobin level and serum creatinine
    • no bone lesions on full skeletal X-ray survey and/or other imaging if performed
    • no clinical or laboratory features of amyloidosis or light chain deposition disease

These patients should not be treated. They should be followed up closely since many develop symptomatic myeloma (4)