Monoclonal gammopathy (thesaurus synonyms: gammopathy with lymphoplasmocytic dyscrasia; IgG [immunoglobulin G]-paraproteinemia; monoclonal paraproteinemia; POEMS syndrome; secondary paraproteinemia; secondary paraproteinemia in malignant disease; ICD-10-GM D47. 2: Monoclonal gammopathy of undetermined significance [MGUS]) is a disorder associated with an increase in monoclonal immunoglobulins or their parts (light or heavy chains) within the gamma fraction of serum proteins.
The following proteins are produced in increased amounts in monoclonal gammopathy:
- Complete immunoglobulin molecules of one class and type (e.g., kappa-IgG ).
- Free light chains of the κ or λ type, so-called Bence-Jones proteins.
- Combination of immunoglobulin molecules and free light chains.
- Free heavy chains, e.g. γ-, α-, μ-, δ-, ε-chain.
- Different immunoglobulin molecules, e.g., di-, tri-, multiclonal gammopathy.
They result from uncontrolled proliferation of an immunocompetent B lymphocyte.
Monoclonal gammopathy can be a symptom of many diseases (see under “Differential diagnoses”).
Z. E.g., monoclonal gammopathy of uncertain significance (MGUS): precancerous for lymphoproliferative disorders such as multiple myeloma or Waldenström’s disease; paraproteinemia with monoclonal IgM globulins without histologic infiltration of the bone marrow with plasma cells or lymphoma cells (i.e., there is no plasmacytoma/multiple myeloma or Waldenström’s disease).
Sex ratio: Slightly more frequent in men than in women (1.4: 1)
Frequency peak: In the 6th decade of life (Central Europe)
Prevalence (disease incidence) in persons over 25 years of age is 1%.
The incidence (frequency of new cases) is approximately 4 per 100,000 population in industrialized countries.
Monoclonal gammopathy is a common incidental pathologic finding on routine laboratory examination in the elderly.
Course and prognosis: Course and prognosis depend on the cause of the monoclonal gammopathy.
