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)

Reference:

• 1. Kyle RA et al. Clinical course and prognosis of smoldering (asymptomatic) multiple myeloma. N Engl J Med. 2007;356(25):2582-90.
• 2. Palumbo A, Anderson K.Multiple myeloma. N Engl J Med. 2011;364(11):1046-60.
• 3. Palumbo A et al. International Myeloma Working Group guidelines for the management of multiple myeloma patients ineligible for standard high-dose chemotherapy with autologous stem cell transplantation. Leukemia. 2009;23(10):1716-30.
• 4. International Myeloma Working Group.Criteria for the classification of monoclonal gammopathies, multiple myeloma and related disorders: a report of the International Myeloma Working Group. Br J Haematol. 2003;121(5):749-57.