What is smoldering myeloma?
Smoldering myeloma is an intermediate clinical stage of disease between MGUS and myeloma that has a much higher risk of progression to myeloma than MGUS (10% year or more).
It is defined as a serum monoclonal protein (IgG or IgA) >3g/dL or a urinary monoclonal protein >500 mg/24 h, and/or clonal bone marrow plasma cells between 10% and 60% AND the absence of any CRAB feature.
The early initiation of chemotherapy in this patient group may be considered to reduce the risk of organ damage by progression to myeloma.
4 Interesting Facts of Smoldering Myeloma
- Smoldering (indolent) myeloma has characteristics similar to those of monoclonal gammopathy of undetermined significance but may have more than 10% plasma cells in the bone marrow
- Both criteria must be met:
- Serum monoclonal protein (IgG or IgA) level of 3 g/dL or more or urinary monoclonal protein measurement of 500 mg or more per 24 hours and/or clonal marrow plasma cells 10% to 59%; and
- Absence of myeloma-defining events or amyloidosis
- Obtain skeletal MRI or whole body PET-CT to distinguish multiple myeloma from smoldering myeloma
- Detection of 1 bone marrow lesion larger than 5 mm in diameter changes the status from smoldering myeloma to symptomatic myeloma requiring therapy