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Haematological Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
The elegant term monoclonal gammopathy of undetermined significance (MGUS) is applied to the finding of a low-level paraprotein alone (e.g. IgG paraprotein <20 g/L), without increased plasma cells in the marrow or any symptoms, signs or investigational findings suggesting myeloma activity. It is a very common finding in patients over 65 years and might be found in up to 1% of individuals over 80 years. Patients have a small annual risk of progressing to multiple myeloma and require annual follow-up.
Multiple myeloma
Published in Anju Sahdev, Sarah J. Vinnicombe, Husband & Reznek's Imaging in Oncology, 2020
The disease is characterized by uncontrolled proliferation of monoclonal plasma cells. It evolves from a clinically silent premalignant stage termed monoclonal gammopathy of undetermined significance (MGUS), which carries a risk of progression to malignancy of ∼1% per year through an intermediate stage termed smouldering multiple myeloma (SMM) (∼10% risk per year) (5–8). Both are typically asymptomatic and are differentiated from each other based on the level of the secreted monoclonal protein and/or the extent of clonal plasma cell involvement on bone marrow examination (9).
Familial Multiple Myeloma
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Multiple myeloma is a fatal B-cell malignancy characterized by clonal proliferation of malignant plasma cells in the bone marrow, bones, and other tissues and production of monoclonal protein in the blood or urine, leading to lytic bony lesions, fractures, anemia, renal failure, hypercalcemia, and immune dysfunction. Multiple myeloma is usually preceded by a precursor condition known as monoclonal gammopathy of undetermined significance (MGUS) followed by an intermediate stage called smoldering multiple myeloma (SMM). MGUS is asymptomatic and present in 3% of the general population over the age of 50 years, with potential to progress at a rate of 1%–2% per year. SMM is also asymptomatic and carries a higher risk of progression at 10% a year for the first 5 years, 3% per year for the next 5 years, and 1% per year thereafter [1].
Monoclonal glomerulopathy with features of cryoglobulinemic glomerulopathy in murine multiple myeloma model
Published in Ultrastructural Pathology, 2020
Ping L. Zhang, Guillermo A. Herrera, Bei Liu
Multiple myeloma is a malignant proliferation of monoclonal plasma cells in the bone marrow, which causes 1% of cancer deaths and results in high morbidity from renal dysfunction due to the monoclonal immunoglobulin light chain deposition.1,2 Myeloma occurs mainly in the elderly. The mean ages for men and women to develop myeloma are 67 and 70 years old, respectively, without gender difference. Approximately 3% to 5% of individuals older than 50 have a monoclonal gammopathy of undetermined significance (MGUS) in absence of clinical evidence of myeloma. Some may progress and deposit monoclonal immunoglobulins in the kidney causing significant injury to glomeruli, renal tubules and/or renal vessels, so-called monoclonal gammopathy of renal significance.3–5 Good animal models are needed to investigate the etiology, disease progressions, and treatment effects in approximately 10 variants of the para-protein-related renal diseases.
IgG4 plasma cell myeloma without clinical evidence of IgG4-related disease: a report of two cases
Published in Hematology, 2020
Deonne Thaddeus V. Gauiran, Krista M. Marcon, Mari L. DeMarco, Angela W. S. Fung, Grace van der Gugten, Andre Mattman, Mollie N. Carruthers, Kevin W. Song, Luke Y. C. Chen
IgG4 myeloma is a rare subtype of IgG plasma cell myeloma; in historical studies, its prevalence is thought to parallel the normal distribution of IgG4 subclass among healthy subjects (3-6% of IgG) and patients with plasma cell neoplasms (2-8% of IgG-positive cases) [20,21]. Neither of the two patients in this report had clinical or radiologic features of IgG4-related disease such as autoimmune pancreatitis, sialadenitis, orbital pseudotumor, retroperitoneal fibrosis or tubulointerstitial nephritis, despite presenting with very high levels of monoclonal IgG4. Both patients had a partial response to standard first-line myeloma therapy at the time of publication. In the second patient, the monoclonal band was present for at least 2 years before diagnosis of myeloma, presumably in the form of IgG4 monoclonal gammopathy of undetermined significance (MGUS). These cases suggest that elevated monoclonal serum IgG4 in isolation is not pathogenic for IgG4-related disease.
Amyloid transthyretin cardiac amyloidosis: diagnosis and management
Published in Expert Review of Cardiovascular Therapy, 2019
Bennett Di Giovanni, Dakota Gustafson, Diego Hernan Delgado
Ruling out monoclonal proliferation helps support the diagnosis of ATTR amyloidosis as opposed to the more common AL amyloidosis. However, monoclonal gammopathy of undetermined significance (MGUS) is more prevalent with advanced age, occurring in roughly 5% of all individuals 65 and older [20]. One of the most sensitive ways to diagnose monoclonal gammopathy is through laboratory testing of serum and urine protein immunofixation electrophoresis (IFE) in combination with serum-free light chains (SFLC) [20]. Using serum IFE and SFLC in patients with abnormal urinary results identified 99.5% of monoclonal gammopathy [20]. However, in patients with evidence of amyloid deposition, these tests are insufficient to confirm AL amyloidosis as ATTR amyloidosis patients can have MGUS or concomitant plasma cell dyscrasias [22]. Physicians must evaluate patient risk factors and determine whether more invasive diagnostic testing, such as bone marrow biopsy, is needed. If these investigations suggest a more sinister diagnosis than MGUS, a cardiac biopsy with amyloid subtyping via mass spectrometry is essential [22].