In the first criteria set, patients must have ≥10% bone marrow clonal plasma cells plus ≥1 of the CRAB criteria; in the second criteria set, patients must have ≥10 bone marrow clonal plasma cells plus ≥1 of the following findings, ≥60% bone marrow clonal plasma cells, a free κ/λ or λ/κ light chain ratio in serum of ≥100 (the involved clonal light chain concentration must be ≥100 milligrams/liter), and/or >1 focal bone lesion on magnetic resonance imaging. The 5 year medium survival of patients with multiple myeloma treated with currently used treatment regiments is 48.5%. Light chain multiple myeloma
Light chain multiple myeloma is diagnosed in patients who have: a) the criteria for diagnosis of multiple myeloma except having a serum free light chain ratio outside the normal range of 0.26 to 1.65 without evidence of an intact immunoglobulin or free heavy chain; or b) an extreme free light chain ratio, i.e. outside the range of 0.02 to 100 (with the light chain having the lower concentration being present at >10 milligrams/liter) regardless of the stage of their plasma cell dyscrasia. At the time of diagnosis, 30% to 50% of light chain multiple myeloma patients have severe renal dysfunction or kidney failure due to light chain myeloma cast nephropathy or the nephrotoxic effects of free light chains on renal tubular cells.
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.