Classification of plasma cell neoplasms

The plasma cell neoplasms are clonal proliferations of immunoglobulin (Ig)-producing plasma cells or lymphoplasmacytic cells that make and secrete a single class of Ig or a polypeptide subunit of Ig that is usually detectable as a monoclonal protein (M protein) in serum or urine. The plasma cell neoplasms range from asymptomatic disorders that may never develop clinical disease (monoclonal gammopathy of undetermined significance) to more aggressive diseases with significant morbidity and mortality (plasma cell myeloma). The classification of plasma cell neoplasms is based on a combination of clinical and pathological parameters that takes into account the extent of disease (clonal plasma cell burden and level of M-protein) and evidence of end organ damage/dysfunction.