Monoclonal Gammopathy of Undetermined Significance (MGUS) - Summary Framework Hematologic disorder characterized by the presence of either abnormal intact monoclonal immunoglobulins or their corresponding light-chain fragments. Epidemiology: • It is present in more than 3% of patients 50 years or older • Prevalence M > F MGUS can be categorized into 3 sub-types based on the hematologic cancer for which they carry the greatest future risk. IgM MGUS: • Serum IgM monoclonal protein level <3 g/dL • Bone marrow lymphoplasmacytic infiltration <10% • No evidence of anemia, constitutional symptoms, hyperviscosity, lymphadenopathy, or hepatosplenomegaly • 1.5% risk per year for progression to Waldenström macroglobulinemia • Rarely, patients can progress to IgM multiple myeloma Non-IgM MGUS: • Serum monoclonal protein level (non-IgM type) < 3 g/dL • Clonal bone marrow plasma cells < 10% • Monoclonal immunoglobulin is an IgA or IgG isotype (rarely IgD or IgE) • Absence of end-organ damage, such as hyperCalcemia, Renal insufficiency, Anemia, and Bone lesions (CRAB) • 1% risk per year for progression to multiple myeloma, AL amyloidosis, or a related disorder Light-Chain MGUS: • Abnormal FLC ratio (<0.26 or >1.65) • Increased level of the appropriate involved light chain (increased kappa FLC in patients with ratio >1.65 and increased lambda FLC in patients with ratio <0.26) • No immunoglobulin heavy-chain expression on immunofixation • Absence of end-organ damage that can be attributed to the plasma cell proliferative disorder • Clonal bone marrow plasma cells < 10% • Urinary monoclonal protein level < 500 mg/24 h • Risk for progression to light-chain myeloma and AL amyloidosis • Rate of progression not defined #MGUS #Monoclonal #Gammopathy #Undetermined #Significance #hematology #diagnosis #oncology
