Stages
MGUS stage
Monoclonal gammopathy of undetermined significance (MGUS), is defined as the presence in the blood or urine of a monoclonal antibody, antibody heavy chain, or antibody light chain in a person lacking symptoms or signs of a more serious plasma cell dyscrasia. The condition is typically discovered as an incidental finding when serum protein electrophoresis is done for various reasons unrelated to plasma cell dyscrasias. Protein electrophoresis generally detects one of the following patterns of monoclonal myeloma protein spikes representing: a) intact IgG, IgA, IgE, IgE, or IgM; b) intact IgG, IgA, IgE, IgD, or IgM plus high concentrations of a free (i.e. not bound to a heavy chain) κ or λ light chain; c) a free κ chain in great excess of a λ chain or a free λ chain in great excess of a κ chain; and d) free γ, δ, or μ heavy chains unbound to a light chain (free α and ε heavy chain myeloma protein spikes have not been reported). Among MGUS cases expressing an intact antibody, 70%, 15%, 12%, and 3% express either IgG, IgM, IgA, or two of these M proteins, respectively, with or without excessive levels of a light chain; these cases represent ~80% of all MGUS. About 20% of MGUS cases express either κ or λ light chains. As a group, these MGUS findings occur more commonly in men and are ~2-fold more common in individuals of African descent than Caucasians. MGUS cases expressing free γ, δ, or μ heavy chains are extremely rare.
the CD138+, CD38+, CD19−, CD4+/- phenotype) may be a more sensitive method to enumerate circulating clonal plasma cells and diagnose plasma cell leukemia.There are two forms of plasma cell leukemia: Primary plasma cell leukemia in which patients without a history of multiple myeloma present with diagnostically high levels of circulating plasma cells and Secondary plasma cell leukemia in which patients with multiple myeloma suffer their dyscrasias progression by the expansion of large numbers of their malignant plasma cells into the circulation and distant tissues. Historically, primary plasma cell leukemia was more common than the secondary form but with the increased survival of multiple myeloma patients due to new treatment regiments, more cases of secondary plasma cell leukemia are occurring; currently, the two forms occur in approximately equal numbers. Patients with primary plasma cell leukemia present with clinical findings that are less commonly found in multiple myeloma, e.g. they often have hepatomegaly, splenomegaly, lymphadenopathy, nerve and central nervous system defects, bleeding tendencies secondary to thrombocytopenia, and pleural effusions. They are less likely than multiple myeloma patients to have lytic bone lesions. In several studies of patients with either form of plasma cell leukemia, the disease was associated with clonal IgG in 28% to 56% of cases, IgA in 4% to 7% of cases, and a light chain in 23% to 44% of cases; 0-12% of patients had no myeloma protein. Medium survival for primary and secondary plasma cell dyscrasias have been 7–13 months and 2–7 months, respectively, but appear to be improving with new treatment regimens.