Table 1 Classification of Waldenström’s macroglobulinemia and related disorders.

From: Diagnostics in Waldenström’s macroglobulinemia: a consensus statement of the European Consortium for Waldenström’s Macroglobulinemia

 

IgM monoclonal proteina

Bone marrow infiltrationb

Symptoms attributable to IgM

Symptoms due to tumor infiltrationc

Symptomatic WM

+

+

+d

+d

Asymptomatic WM

+

+

−

−

IgM-related disorderse

+

−

+

−

IgM-MGUS

+

−

−

−

  1. IgM-MGUS IgM monoclonal gammopathy of uncertain significance, WM Waldenström’s macroglobulinemia.
  2. aThe panel considered to be inappropriate to define an IgM concentration to distinguish MGUS from WM. However, it should be noted that IgM concentration rarely, if ever, exceeds 30 g/dl in MGUS.
  3. bPatients with unequivocal BM infiltration by lymphoplasmacytic lymphoma will be considered to have WM, while patients without evidence of infiltration will be considered to have MGUS. However, it is acknowledged that in some patients, equivocal evidence of BM infiltration is demonstrable. This may be manifested in several ways including the presence of clonal B-cells by flow cytometry or PCR in the absence of morphological evidence of BM infiltration. Alternatively, patients may have equivocal bone marrow infiltrates without confirmatory phenotypic studies. It is considered that these patients should be classified as MGUS until further data become available. According to the 2016 WHO classification, bone marrow lymphoplasmacytic infiltration is <10% in IgM-MGUS.
  4. cSymptoms attributable to tumor infiltration will include any of the following manifestations: constitutional symptoms, cytopenia(s), or organomegaly.
  5. dIt is required the presence of one or both groups of symptoms.
  6. eIt is well recognized that a population of patients exist who have symptoms attributable to the IgM monoclonal protein but no overt evidence of lymphoma. Such patients may present with symptomatic cryoglobulinemia, amyloidosis, or autoimmune phenomena such as peripheral and cold agglutinin disease. It is appropriate to consider these patients as a clinically distinct group and the term “IgM-related disorders” is proposed. Adapted from Owen et al. [1].
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