Disease associations with monoclonal gammopathy of undetermined significance: a population-based study of 17,398 patients

The clinical value of monoclonal protein in ANCA-associated vasculitis with renal involvement

PURPOSE

The value of monoclonal protein (M-protein) in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients with renal involvement has not been investigated.

METHODS

We analyzed AAV patients with renal involvement from 2013 to 2019 in our center. Patients with immunofixation electrophoresis were divided into M-protein positive group and M-protein negative group. The clinicopathological features and outcomes of the two groups were compared.

RESULTS

Ninety-one AAV patients with renal involvement were enrolled for analysis, and 16 patients (17.6%) had a positive test for M-protein. Compared with M-protein negative patients, M-protein positive patients had lower hemoglobin (77.6 vs 88.4 g/L, p = 0.016), mean corpuscular hemoglobin concentration (313 vs 323 g/L, p = 0.002),serum albumin (29.4 vs 32.5 g/L, p = 0.026) and complement 3 (C3) (0.66 vs 0.81 g/L, p = 0.047), while higher platelets (252 vs 201 109/L, p = 0.048) and incidence of pulmonary infection (62.5% vs 33.3%, p = 0.029). However, renal pathological features between the two groups had no significant difference. In addition, during a median follow-up of 33 months, Kaplan-Meier survival analysis showed that, compared with M-protein negative patients, M-protein positive patients had a higher risk of all-cause mortality (log-rank test, p = 0.028), especially for patients who were not dialysis-dependent at the time of admission (log-rank test, p = 0.012).

CONCLUSION

Our results indicate that M-protein is associated with different clinicopathological features and increased all-cause mortality in AAV patients with renal involvement. Testing M-protein and rigorous diagnosing of the significance of the presence of M-protein may be helpful for assessing the survival of AAV patients with renal involvement.

Monoclonal Gammopathy of Undetermined Significance

Monoclonal gammopathy of undetermined significance (MGUS) is of considerable clinical importance to primary care physicians given its high prevalence in the general population. MGUS has a variable but lifelong risk for progression to hematologic cancer, such as multiple myeloma, Waldenström macroglobulinemia, or light-chain amyloidosis. In addition, MGUS has been associated with several nonmalignant yet symptomatic disorders that require therapy directed toward eliminating the monoclonal gammopathy. Thus, it is important not only to understand the essentials of diagnosing and monitoring patients with MGUS but also to recognize when to refer patients with MGUS to a specialist.

Monoclonal gammopathy of undetermined significance and COVID-19: a population-based cohort study

Multiple myeloma (MM) patients have increased risk of severe coronavirus disease 2019 (COVID-19) when infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Monoclonal gammopathy of undetermined significance (MGUS), the precursor of MM has been associated with immune dysfunction which may lead to severe COVID-19. No systematic data have been published on COVID-19 in individuals with MGUS. We conducted a large population-based cohort study evaluating the risk of SARS-CoV-2 infection and severe COVID-19 among individuals with MGUS. We included 75,422 Icelanders born before 1976, who had been screened for MGUS in the Iceland Screens Treats or Prevents Multiple Myeloma study (iStopMM). Data on SARS-CoV-2 testing and COVID-19 severity were acquired from the Icelandic COVID-19 Study Group. Using a test-negative study design, we included 32,047 iStopMM participants who had been tested for SARS-CoV-2, of whom 1754 had MGUS. Among these participants, 1100 participants, tested positive, 65 of whom had MGUS. Severe COVID-19 developed in 230 participants, including 16 with MGUS. MGUS was not associated with SARS-CoV-2 infection (Odds ratio (OR): 1.05; 95% confidence interval (CI): 0.81–1.36; p = 0.72) or severe COVID-19 (OR: 0.99; 95%CI: 0.52–1.91; p = 0.99). These findings indicate that MGUS does not affect the susceptibility to SARS-CoV-2 or the severity of COVID-19.

The evaluation and management of monoclonal gammopathy of renal significance and monoclonal gammopathy of neurological significance

Despite the benign nature of monoclonal gammopathy of undetermined significance (MGUS), mounting data are associating MGUS with the development of organ dysfunction, specifically monoclonal gammopathy of renal significance (MGRS) and monoclonal gammopathy of neurological significance (MGNS), which could be associated with substantial morbidity. Emerging evidence suggests that patients with MGRS and MGNS could benefit from treatments used for myeloma, Waldenström macroglobulinemia, or chronic lymphocytic leukemia, depending on the underlying pathology. However, the treatment of MGRS and MGNS is not standardized, and potentially effective therapies might not be reimbursed because these conditions do not formally meet the criteria for malignant processes. The present review aims at establishing standards for the evaluation and management of MGRS and MGNS, which can facilitate the diagnosis of and provide therapeutic options for treating practitioners and patients affected by these conditions. The careful design and execution of clinical trials for patients with MGRS and MGNS are positively encouraged.

Clinical Presentation, Renal Histopathological Findings, and Outcome in Patients with Monoclonal Gammopathy and Kidney Disease

Monoclonal gammopathies are associated with acute and chronic kidney injury. Nephrotoxicity of the secreted monoclonal (M)-protein is related to its biological properties and blood concentration. Little is known about epidemiology, clinical manifestations, and outcome of monoclonal gammopathies in patients with kidney disease. We retrospectively collected data about demographics, clinical manifestations, and renal histological lesions of all patients (n = 1334) who underwent kidney biopsy between January 2000 and March 2017. Monoclonal gammopathy was detected in 174 (13%) patients with a mean age of 66.4 ± 13.1 years. The spectrum of monoclonal gammopathies comprised monoclonal gammopathy of undetermined significate (MGUS) (52.8%), multiple myeloma (MM) (25.2%), primary amyloidosis (AL) (9.1%), smoldering MM (SMM) (4%), non-Hodgkin lymphoma (NHL) (6.8%), and Hodgkin lymphoma (HL) (1.7%). Monoclonal gammopathy of renal significance (MGRS) accounted for 6.5% in patients with MGUS and 14.2% in patients with SMM. Evaluation of kidney biopsy revealed that M-protein was directly involved in causing kidney injury in MM (93.1%). MM was the only gammopathy significantly associated with an increased risk of kidney injury (odds ratio [OR] = 47.5, CI 95%, 13.7–164.9; P ≤ 0.001). While there were no significant differences in the progression toward end-stage renal disease or dialysis (P = 0.776), monoclonal gammopathies were associated with a different risk of death (P = 0.047) at the end of the follow-up. In conclusion, monoclonal gammopathy was a frequent finding (13%) in patients who underwent kidney biopsy. M-protein was secreted by both premalignant (56.8%) and malignant (43.2%) lymphoproliferative clones. Kidney biopsy had a key role in identifying MGRS in patients with MGUS (6.5%) and SMM (14.2%). Among monoclonal gammopathies, only MM was significantly associated with biopsy-proven kidney injury. The rate of end-stage renal disease or dialysis was similar among monoclonal gammopathies, whereas NHL, MM, and SMM showed a higher rate of deaths.

Transient Pleural Fluid Infiltration by Clonal Plasma Cells Associated with Pulmonary Tuberculosis

Pleural effusion is a rare presentation of plasma cell myeloma, occurring in around 6% of patients during the course of their disease, most commonly as a consequence of a concurrent disease process like heart failure secondary to amyloid deposition. Direct infiltration of the pleural fluid by malignant cells leading to myelomatous pleural effusion is a rare mechanism occurring in less than 1% of patients with plasma cell myeloma, and it is associated with a worse prognosis. There are few case reports of myelomatous pleural effusion as an initial presentation of multiple myeloma. Pleural fluid infiltration by monoclonal plasma cells in the absence of an underlying plasma cell myeloma was not reported before in the literature. Tuberculosis is a known cause of polyclonal gammaglobulinemia, however few case reports described the coexistence of monoclonal gammopathy of undetermined significance and tuberculosis. Here we present an interesting case of pleural fluid infiltration by an abnormal looking clonal plasma cells associated with active pulmonary tuberculosis and parapneumonic effusion in a patient with a background of acute myeloid leukemia. Interestingly, the clonal plasma cell proliferation was confined to the pleural fluid without any evidence of an underlying plasma cell neoplasms (including monoclonal gammopathy of undetermined significance and plasmacytomas). Since our patient had an underlying meyloid neoplasm, we though about the possibility of secondary malignancy. However, in almost all patients with coexisting myeloid and plasma cell neoplasms, myeloid neoplasms developed following chemotherapeutic treatment of plasma cell neoplasms not the other way around. Given that, one must conclude localized extramedullary (pleural) plasma cell proliferation probably represents a transient reactive process to pulmonary tuberculosis which is an extremely rare phenomenon and not described before.

Monoclonal Gammopathy of Undetermined Significance (MGUS)-Not So Asymptomatic after All

Monoclonal Gammopathy of Undetermined Significance (MGUS) is considered to be a benign precursor condition that may progress to a lymphoproliferative disease or multiple myeloma. Most patients do not progress to an overt condition, but nevertheless, MGUS is associated with a shortened life expectancy and, in a minority of cases, a number of co-morbid conditions that include an increased fracture risk, renal impairment, peripheral neuropathy, secondary immunodeficiency, and cardiovascular disease. This review aims to consolidate current evidence for the significance of these co-morbidities before considering how best to approach these symptoms and signs, which are often encountered in primary care or within a number of specialties in secondary care.

Analysis of the Targets and Glycosylation of Monoclonal IgAs From MGUS and Myeloma Patients

Previous studies showed that monoclonal immunoglobulins G (IgGs) of “monoclonal gammopathy of undetermined significance” (MGUS) and myeloma were hyposialylated, thus presumably pro-inflammatory, and for about half of patients, the target of the monoclonal IgG was either a virus—Epstein–Barr virus (EBV), other herpes viruses, hepatitis C virus (HCV)—or a glucolipid, lysoglucosylceramide (LGL1), suggesting antigen-driven disease in these patients. In the present study, we show that monoclonal IgAs share these characteristics. We collected 35 sera of patients with a monoclonal IgA (6 MGUS, 29 myeloma), and we were able to purify 25 of the 35 monoclonal IgAs (6 MGUS, 19 myeloma). Monoclonal IgAs from MGUS and myeloma patients were significantly less sialylated than IgAs from healthy volunteers. When purified monoclonal IgAs were tested against infectious pathogens and LGL1, five myeloma patients had a monoclonal IgA that specifically recognized viral proteins: the core protein of HCV in one case, EBV nuclear antigen 1 (EBNA-1) in four cases (21.1% of IgA myeloma). Monoclonal IgAs from three myeloma patients reacted against LGL1. In summary, monoclonal IgAs are hyposialylated and as described for IgG myeloma, significant subsets (8/19, or 42%) of patients with IgA myeloma may have viral or self (LGL1) antigen-driven disease.

Hematological Diseases and Osteoporosis

Secondary osteoporosis is a common clinical problem faced by bone specialists, with a higher frequency in men than in women. One of several causes of secondary osteoporosis is hematological disease. There are numerous hematological diseases that can have a deleterious impact on bone health. In the literature, there is an abundance of evidence of bone involvement in patients affected by multiple myeloma, systemic mastocytosis, thalassemia, and hemophilia; some skeletal disorders are also reported in sickle cell disease. Recently, monoclonal gammopathy of undetermined significance appears to increase fracture risk, predominantly in male subjects. The pathogenetic mechanisms responsible for these bone loss effects have not yet been completely clarified. Many soluble factors, in particular cytokines that regulate bone metabolism, appear to play an important role. An integrated approach to these hematological diseases, with the help of a bone specialist, could reduce the bone fracture rate and improve the quality of life of these patients.

Identifying monoclonal gammopathy of undetermined significance in electronic health data

PURPOSE

Monoclonal gammopathy of undetermined significance (MGUS) is a prevalent yet largely asymptomatic precursor to multiple myeloma. Patients with MGUS must undergo regular surveillance and testing, with few known predictors of progression. We developed an algorithm to identify MGUS patients in electronic health data to facilitate large-scale, population-based studies of this premalignant condition.

METHODS

We developed a four-step algorithm using electronic health record and health claims data from men and women aged 50 years or older receiving care from a large, multispecialty medical group between 2007 and 2015. The case definition required patients to have at least two MGUS ICD-9 diagnosis codes within 12 months, at least one serum and/or urine protein electrophoresis and one immunofixation test, and at least one in-office hematology/oncology visit. Medical charts for selected cases were abstracted then adjudicated independently by two physicians. We assessed algorithm validity by positive predictive value (PPV).

RESULTS

We identified 833 people with at least two MGUS diagnosis codes; 429 (52%) met all four algorithm criteria. We randomly selected 252 charts for review, including 206 from patients meeting all four algorithm criteria. The PPV for the 206 algorithm-identified charts was 76% (95% CI, 70%-82%). Among the 49 cases deemed to be false positives (24%), 33 were judged to have multiple myeloma or another lymphoproliferative condition, such as lymphoma.

CONCLUSIONS

We developed a simple algorithm that identified MGUS cases in electronic health data with reasonable accuracy. Inclusion of additional steps to eliminate cases with malignant disease may improve algorithm performance.

Immunogenicity And Safety Of The 13-Valent Pneumococcal Conjugate Vaccine In Patients With Monoclonal Gammopathy Of Undetermined Significance - Relationship With Selected Immune And Clinical Parameters

Purpose

Patients with monoclonal gammopathy of undetermined significance (MGUS) have an increased risk of developing infections. Streptococcus pneumoniae vaccinations are recommended for immunocompromised patients, including patients with lymphoproliferative disorders such as MGUS. The objective of the study was to assess the immune response to the 13-valent pneumococcal conjugate vaccine (PCV13) in treatment-naive MGUS patients versus healthy subjects. All study groups were evaluated for the levels of specific pneumococcal antibodies, the levels of IgG and IgG subclasses, and selected peripheral blood lymphocyte subpopulations, including the proportion of plasmablasts before and after immunization.

Patients and methods

A total of 22 previously untreated patients with MGUS and 15 healthy age- and sex-matched volunteers were included in the study. All participants were immunized with PCV13 Prevenar13 (Pfizer). The following parameters were assessed: 1) serum-specific pneumococcal antibody titers before and 30 days after vaccination, 2) percentage of plasmablasts, defined as CD19+/IgD-/CD27++, before and 7 days after vaccination, 3) serum total IgG and IgG1, IgG2, IgG3, IgG4 levels before and 30 days after vaccination.

Results and conclusion

PCV13 vaccination in MGUS patients is safe and effectively protects against S. pneumoniae infection. In unvaccinated individuals, vaccination should be carried out as soon as possible after diagnosis. It can protect patients against serious infectious complications, which can contribute to extending the time to progression and transformation into more aggressive diseases. PCV13 vaccination is more effective in MGUS patients with a lower concentration of M protein. Serum M protein concentration in patients diagnosed with MGUS may be a useful predictor of the effectiveness of vaccination.

Case Report: Monoclonal Gammopathy of Undetermined Significance is Associated with Loa loa Infection

A 63-year-old woman who migrated from Nigeria to the United States was found to have an elevated total serum protein, anemia, and eosinophilia. Serum protein electrophoresis (SPEP) and serum protein immunofixation electrophoresis (SPIFE) demonstrated monoclonal immunoglobulin G (IgG) κ restricted bands (IgG 3,820 mg/dL; κ/λ ratio 4.47), indicative of monoclonal gammopathy of unknown significance (MGUS). A rapid diagnostic test (RDT) for malaria was positive for Plasmodium falciparum (BinaxNOW^®; Alere Scarborough Inc., Scarborough, ME). Giemsa-stained blood smears were negative for malarial parasites, however, Loa loa microfilariae were identified. Reverse transcription polymerase chain reaction for P. falciparum, Plasmodium ovale, Plasmodium malariae, and Plasmodium vivax yielded a negative result. She was treated for loiasis with diethylcarbamazine and received no malaria medication. Treatment resulted in a resolution of the microfilaremia and eosinophilia, a negative RDT for malaria, and marked reduction in the monoclonal gammopathy. This is the first reported human case of MGUS associated with loiasis and its resolution after antiparasitic treatment.

BCOR mutation and TLS-ERG expression in acute myeloid leukemia with monoclonal immunoglobulinemia

Acute myeloid leukemia (AML) originates from the abnormal clonal proliferation of myeloblasts. Immunoglobulin is secreted by B cells. AML with monoclonal antibody often indicates a poor prognosis. Here we report a case of BCOR mutation and TLS-ERG expression in AML with monoclonal immunoglobulinemia. After chemotherapy, the patient achieved bone marrow complete remission. BCOR mutation and TLS-ERG fusion gene in patient's bone marrow were not detected, at the same time, peripheral blood monoclonal immunoglobulin also disappeared. BCOR mutation or TLS-ERG fusion gene expression is associated with poor prognosis, AML with monoclonal immunoglobulin may have the same prognostic significance.

Polyclonal serum free light chain elevation is associated with increased risk of monoclonal gammopathies

Monoclonal gammopathies (MG) constitute a spectrum of disorders starting from a monoclonal gammopathy of undetermined significance (MGUS) to active disease requiring therapy such as multiple myeloma. MG are characterized by proliferation of clonal plasma cells (PC) secreting a monoclonal protein either as intact immunoglobulin or free kappa or lambda free light chains (FLC). We hypothesized that a polyclonal elevation of serum FLC may indicate an inflammatory state that precedes development of MG. We studied 15,630 individuals from Olmsted county, who did not have MGUS based on baseline screening studies. At a median follow-up of 18.1 years, 264 patients had developed a clonal PC disorder; 252 with MGUS, 1 with SMM, 8 with MM, and 3 with amyloidosis, translating to an annual incidence of development of a MG of 0.1%. We examined the baseline polyclonal ΣFLC (kappa + lambda FLC) from the initial screening and grouped them into deciles. The highest decile group had a 2.6-fold (95% CI; 1.8, 3.7) increase in the risk of developing a MG, P < 0.001. We demonstrate for the first time, the increased risk of developing MG in patients with elevated serum FLC, suggesting that an underlying inflammatory state may play an etiologic role.

Fibrogenesis Imperfecta Ossium

Fibrogenesis imperfecta ossium (FIO) is an extremely uncommon fatal bone disorder of poorly understood etiology. The pathogenesis of FIO is not well known. The fundamental skeletal defect appears to be an abnormality in organic matrix of bone characterized by defective mineralization of the abnormal collagen. FIO clinically manifests in middle-aged adults presenting with fracture and bone pain. Elevated serum alkaline phosphatase is the only and the most consistent biochemical abnormality. Although paraproteinemia is observed in one-third of cases, the pathogenic link to the disease process is unclear. Limited information on FIO and its close resemblance to many metabolic bone disorders leads to delayed or missed diagnoses and management. Prednisolone, bisphosphonates, melphalan and steroids have been tried previously with variable success. Recently, a trial of recombinant growth hormone therapy was found to be effective. Further research focused on the pathogenetic mechanisms of FIO is needed to identify and develop targeted therapeutic options.

Association of Monoclonal Gammopathy with Progression to ESKD among US Veterans

BACKGROUND AND OBJECTIVES

Whether patients with monoclonal protein are at a higher risk for progression of kidney disease is not known. The goal of this study was to measure the association of monoclonal protein with progression to ESKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective cohort study of 2,156,317 patients who underwent serum creatinine testing between October 1, 2000 and September 30, 2001 at a Department of Veterans Affairs medical center, among whom 21,898 had paraprotein testing within 1 year before or after cohort entry. Progression to ESKD was measured using linked data from the US Renal Data System.

RESULTS

Overall, 1,741,707 cohort members had an eGFR≥60 ml/min per 1.73 m2, 283,988 had an eGFR of 45-59 ml/min per 1.73 m2, 103,123 had an eGFR of 30-44 ml/min per 1.73 m2 and 27,499 had an eGFR of 15-29 ml/min per 1.73 m2. The crude incidence of ESKD ranged from 0.7 to 80 per 1000 person-years from the highest to lowest eGFR category. Patients with low versus preserved eGFR were more likely to be tested for monoclonal protein but no more likely to have a positive test result. In adjusted analyses, a positive versus negative test result was associated with a higher risk of ESKD among patients with an eGFR≥60 ml/min per 1.73 m2 (hazard ratio, 1.67; 95% confidence interval, 1.22 to 2.29) and those with an eGFR of 15-29 ml/min per 1.73 m2 (hazard ratio, 1.38; 95% confidence interval, 1.07 to 1.77), but not among those with an eGFR of 30-59 ml/min per 1.73 m2. Progression to ESKD was attributed to a monoclonal process in 21 out of 76 versus seven out of 174 patients with monoclonal protein and preserved versus severely reduced eGFR at cohort entry.

CONCLUSIONS

The detection of monoclonal protein provides little information on ESKD risk for most patients with a low eGFR. Further study is required to better understand factors contributing to a positive association of monoclonal protein with ESKD risk in patients with preserved and severely reduced levels of eGFR.

Contributions of the Bone Microenvironment to Monoclonal Gammopathy of Undetermined Significance Pathogenesis

PURPOSE OF REVIEW

MGUS (monoclonal gammopathy of undetermined significance) is a plasma cell disorder characterized by a moderate increase in serum monoclonal protein (≤ 3 g/dL), an increase in bone marrow plasma cell infiltration (≤ 10%) and the absence of any end-organ damage. Although MGUS is considered a benign condition, evidence for clinical consequences is increasing. In this review, we examine the most recent evidence regarding MGUS manifestations and risks and present an overview of MGUS population studies as related to bone disease. Data reveals important MGUS-related bone alterations that may contribute to disease pathogenesis.

RECENT FINDINGS

MGUS patients present a rate of 1% per year risk of progression to the more aggressive multiple myeloma (MM) and therefore research has focused on the study of risk factors and the events leading to this progression. However, the exact health implications of MGUS itself and the mechanisms behind them remain unclear. It is now evident that the bone microenvironment plays a key role in hematologic cancers and other oncogenic processes leading to bone metastasis.

What is the significance of monoclonal gammopathy of undetermined significance?

Monoclonal gammopathy of undetermined significance (MGUS) is characterised by the presence of a monoclonal paraprotein in the blood, without the characteristic end organ damage seen in multiple myeloma. MGUS is more common in older age groups and has a risk of progression to myeloma of 1% per year. Population screening is not currently recommended, but retrospective studies have suggested improvements in myeloma outcomes in those under MGUS follow-up; in addition, MGUS has associated complications, including fracture, osteoporosis, renal disease and infection, which can be treated. Given this increasing evidence of disease related directly to MGUS, strategies for early identification might be needed. In this review, we discuss the complications of MGUS and whether MGUS fulfils the criteria needed to implement a screening programme. We also highlight areas where more evidence is needed, including identification of a higher risk population to make screening more practical and economically viable.

Abnormal Plasma Cell Disorders in Refinery Waste Workers

A monoclonal gammopathy of undetermined significance (MGUS) may develop into a multiple myeloma or a correlated lymphoproliferative malignancy with a progress rate of 1% per year. The immune status, occupational-environmental risk factors, and hereditary factors may influence the risk of developing MGUS. We investigated the prevalence of MGUS in 77 refinery waste workers. They were all males, averagely aged 36, with a mean working history of 18.5 years and working in the dump for about 4.2 years. After analyzing the results of standard serum electrophoresis migrations, 16% of cases (n = 12) showed levels beyond the normal ranges. In all 12 samples we observed an increase of gamma component: 67%, IgG; 17%, IgM; 8%, IgA; 8%, oligoclonal. Workers were exposed to hazardous refinery waste. After the biological monitoring of urine samples for metals and t,t-muconic acid, no extra-range values were observed. The multivariate analysis shows, however, that cigarette smoking and residence near industrial sites are significantly (p < 0.001) associated with a high risk of MGUS development; while no association was found with occupational exposure. Additional attention might be paid in particular to these conditions in epidemiological studies and further larger, prospective, population-based researches appear warranted to evaluate the strength of any positive association.

Association of Monoclonal Gammopathy of Undetermined Significance with Behcet's Disease: A Review of Shared Common Disease Pathogenetic Mechanisms

An association between a number of chronic inflammatory rheumatic diseases and Monoclonal Gammopathy of Undetermined Significance (MGUS) has been reported. To date no cases of Behcet’s disease (BD) and MGUS have been documented. BD sits at the interphase of auto-inflammatory and chronic auto-immune disease spectrums. Alterations in the cellular and cytokine microenvironments can promote a pro-inflammatory state in which persistent antigenic stimulation and cellular proliferation can progressively induce cytogenetic abnormalities which could perturbate plasma cell functions such as seen in MGUS. Herein, we present a rare case of a woman presenting with BD who subsequently developed MGUS. Pathogenetic mechanisms that could potentially contribute to development of both conditions, are reviewed and demonstrate that this disease association is not coincidental but is an evolutionary association driven by shared common disease pathogenetic mechanisms.

How I manage monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is, in many ways, a unique hematologic entity. Unlike most hematologic conditions in which the diagnosis is intentional and credited to hematologists, the discovery of MGUS is most often incidental and made by nonhematologists. MGUS is considered an obligate precursor to several lymphoplasmacytic malignancies, including immunoglobulin light-chain amyloidosis, multiple myeloma, and Waldenström macroglobulinemia. Therefore, long-term follow-up is generally recommended. Despite its high prevalence, there is surprisingly limited evidence to inform best clinical practice both at the time of diagnosis and during follow-up. We present 7 vignettes to illustrate common clinical management questions that arise during the course of MGUS. Where evidence is present, we provide a concise summary of the literature and clear recommendations on management. Where evidence is lacking, we describe how we practice and provide a rationale for our approach. We also discuss the potential harms associated with MGUS diagnosis, a topic that is rarely, if ever, broached between patients and providers, or even considered in academic debate.

Monoclonal gammopathy of undetermined significance and bone health outcomes: a systematic review and exploratory meta-analysis

Monoclonal gammopathy of undetermined significance (MGUS) is a common condition in the elderly. A number of studies have investigated the relationship between MGUS and bone health outcomes including bone mineral density (BMD), osteoporosis and fractures, but no meta-analysis exists. We conducted a systematic review and exploratory meta-analysis comparing bone health outcomes in patients with MGUS. Two independent authors searched PubMed and Scopus from inception until 19 October 2016. A meta-analysis of cross-sectional and longitudinal studies investigating fractures and BMD was conducted. Standardised mean differences (SMD) ± 95% confidence intervals (CIs) were calculated for BMD, and risk ratios (RRs) were calculated for prevalent and incident fractures. Of 174 initial hits, 10 studies of moderate methodological quality were eligible, including 8711 individuals with MGUS vs. 52,865 controls. Compared to controls, subjects with MGUS showed significantly lower values for radial cortical volumetric BMD (1 study; SMD = -5.45, 95% CI: -7.24 to -3.66), but not at the lumbar spine, femoral neck or hip. The incidence of fractures was higher in people with MGUS (n = 7466) vs. controls (n = 52,304) (RR = 1.36, 95% CI 1.28-1.44, I ² = 0%) over a median of 12.5-year follow-up. The incidence of vertebral fractures was particularly elevated (RR = 2.50, 95% CI 1.53-4.06) although limited to two studies. In conclusion, although with limitations, our preliminary meta-analysis suggests that patients with MGUS are at higher risk of fractures despite evidence for differences in BMD being equivocal. Future longitudinal research is required to confirm our findings and determine if fracture prevention interventions are warranted in people with MGUS.

Bone disease in monoclonal gammopathy of undetermined significance: results from a screened population-based study

Previous studies have shown that individuals with monoclonal gammopathy of undetermined significance (MGUS) have an increased risk of fractures, although the underlying mechanisms remain unknown. Our aim was to analyze bone mineral density (BMD), bone volume, and risk of fractures among individuals with MGUS. We performed a screening using the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study cohort, consisting of 5764 elderly individuals, identifying 300 individuals with MGUS, and 275 with light-chain MGUS. Quantitative computerized tomography was performed in the lumbar spine and hip to evaluate BMD and bone geometry. Analysis of variance and the Tukey honest significance test were used to compare the groups. Hospital records were used to record fractures, with a mean follow-up of 6.9 years. Cox proportional hazard was used to compare fracture risk. No difference was found in BMD between subjects with MGUS and others in the spine (P = .34) or in total hip (P = .30). Individuals with MGUS had a significant increase in bone volume compared with others in the spine (P < .001) and total hip (P < .001). Overall, the risk of fractures was not significantly increased in individuals with MGUS (hazard ratio [HR], 1.19; 95% confidence interval [CI], 0.94-1.50). Men with MGUS had a significantly increased fracture risk, compared with other men (HR, 1.46; 95% CI, 1.03-2.08). Our results show that although individuals with MGUS do not have decreased BMD, bone volume is increased, and MGUS men have a 50% increased fracture risk. These results indicate that bone disease and fractures in MGUS differ from processes known from osteoporosis.

A case report of paraproteinemia-associated pauci-immune glomerulonephritis - a new form of monoclonal gammopathy of renal significance?

Background: Renal disease associated with paraproteinemias is classically predicated upon pathologic paraprotein deposition in the kidney. However, growing evidence suggests that paraproteins may be able to systemically activate complement or neutrophils to drive renal damage. This may provide an alternative pathologic mechanism for renal injury in rare cases. Case report: We report a case of a patient with crescentic pauci-immune glomerulonephritis presenting with rapidly progressive renal failure, polyarthropathy, and a purpuric rash in association with a monoclonal immunoglobulin G κ-light-chain producing multiple myeloma. Serum anti-neutrophil cytoplasmic antibodies were not detected. Kidney biopsy, including with Pronase digestion, did not reveal pathologic paraprotein deposition. Two previously published similar case reports are also discussed. Conclusion: We propose a novel pathologic mechanism involving monoclonal proteins as a trigger for pauci-immune glomerulonephritis, potentially via complement dysregulation and/or neutrophil activation. This requires further epidemiologic and mechanistic study.

Monoclonal Gammopathy-Associated Peripheral Neuropathy: Diagnosis and Management

Monoclonal gammopathies comprise a spectrum of clonal plasma cell disorders that include monoclonal gammopathy of undetermined significance, multiple myeloma, and Waldenström macroglobulinemia. In this review, we outline the epidemiology, etiology, classification, diagnosis, and treatment of monoclonal gammopathy-associated peripheral neuropathy. Monoclonal gammopathy of undetermined significance is relatively common in the general population, with a prevalence of 3% to 4% among individuals older than age 50 years. Therefore, the presence of M protein in a patient with neuropathy does not automatically indicate a causal relationship. Monoclonal gammopathy-associated peripheral neuropathy is often a difficult diagnosis with limited treatment options. Studies addressing the optimal approach to diagnosis and management of this entity are limited. In addition to a review of the literature, we present a diagnostic approach to patients with monoclonal gammopathy-associated peripheral neuropathy and discuss available data and options for treatment.

The Incidence of Senile Cataract and Glaucoma is Increased in Patients with Plasma Cell Dyscrasias: Etiologic Implications

Plasma cell dyscrasias, including monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma (MM), Waldenström macroglobulinemia (WM) and light chain AL amyloidosis, are characterized by clonal expansion of plasma cells which produce a vast amount of an immunoglobulin-derived M-protein. We noted that MGUS diagnosis often coincided with diagnoses of senile cataract and glaucoma and tested the associations of MGUS, MM, WM and AL amyloidosis with subsequent eye diseases identified from the Swedish patient registers between 1997 and 2012. Standardized incidence ratios (SIRs) for senile cataract was significantly increased to 1.80 after MGUS, 1.70 after MM, 1.85 after WM and 2.31 after AL amyloidosis. The SIR for glaucoma was 1.60 after MGUS, 1.76 after WM and 2.18 after AL amyloidosis. All SIRs decreased systematically from age below 60 years to over 79 years, but most risks were also significant in age group over 79 years. The M-protein and the related increase in blood viscosity could be a novel etiologic discovery for these common eye diseases. As MGUS prevalence is around 3% at 60 years and close to 10% at age over 80 years, its contribution to the eye disease burden is expected to be remarkably high.

Management of endocrine disease: Secondary osteoporosis: pathophysiology and management

Osteoporosis is a skeletal disorder characterized by decreased mass and compromised bone strength predisposing to an increased risk of fractures. Although idiopathic osteoporosis is the most common form of osteoporosis, secondary factors may contribute to the bone loss and increased fracture risk in patients presenting with fragility fractures or osteoporosis. Several medical conditions and medications significantly increase the risk for bone loss and skeletal fragility. This review focuses on some of the common causes of osteoporosis, addressing the underlying mechanisms, diagnostic approach and treatment of low bone mass in the presence of these conditions.

Factors associated with an increased risk of vertebral fracture in monoclonal gammopathies of undetermined significance

Monoclonal gammopathies of undetermined significance (MGUS) have been shown to be associated with an increased risk of fractures. This study describes prospectively the bone status of MGUS patients and determines the factors associated with vertebral fracture. We included prospectively 201 patients with MGUS, incidentally discovered, and with no known history of osteoporosis: mean age 66.6±12.5 years, 48.3% women, 51.7% immunoglobulin G (IgG), 33.3% IgM and 10.4% IgA. Light chain was kappa in 64.2% patients. All patients had spinal radiographs and bone mineral density measurement in addition to gammopathy assessment. At least one prevalent non-traumatic vertebral fracture was discovered in 18.4% patients and equally distributed between men and women. Fractured patients were older, had a lower bone density and had also more frequently a lambda light chain isotype. Compared with patients with κ light chain, the odds ratio of being fractured for patients with λ light chain was 4.32 (95% confidence interval 1.80-11.16; P=0.002). These results suggest a high prevalence of non-traumatic vertebral fractures in MGUS associated with lambda light chain isotype and not only explained by low bone density.

Neoplastic and non-neoplastic complications of solid organ transplantation in patients with preexisting monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) occurs in 3-7% of the elderly population, with higher prevalence in renal failure patients, and is associated with a 25-fold increased lifetime risk for plasma cell myeloma (PCM), also known as multiple myeloma. Using the California State Inpatient, Emergency Department, and Ambulatory Surgery Databases components of the Healthcare Cost and Utilization Project (HCUP), we sought to determine whether patients with MGUS who undergo solid organ allograft (n = 22,062) are at increased adjusted relative risk (aRR) for hematologic malignancy and other complications. Among solid organ transplant patients, patients with preexisting MGUS had higher aRR of PCM (aRR 19.46; 95% CI 7.05, 53.73; p < 0.001), venous thromboembolic events (aRR 1.66; 95% CI 1.15, 2.41; p = 0.007), and infection (aRR 1.24; 95% CI 1.06, 1.45; p = 0.007). However, when comparing MGUS patients with and without solid organ transplant, there was decreased aRR for PCM with transplant (aRR 0.34; 95% CI 0.13, 0.88; p = 0.027), and increased venous thromboembolic events (aRR 2.33; 95% CI 1.58, 3.44; p < 0.001) and infectious risks (aRR 1.44; 95% CI 1.23, 1.70; p < 0.001). While MGUS increased the risk of PCM overall following solid organ transplantation, there was lower risk of PCM development compared to MGUS patients who did not receive a transplant. MGUS should not preclude solid organ transplant.

unveiling skeletal fragility in patients diagnosed with MGUS: no longer a condition of undetermined significance?

Monoclonal gammopathy of undetermined significance (MGUS) is a common finding in clinical practice, affecting greater than 3% of adults aged 50 years and older. As originally described, the term MGUS reflected the inherent clinical uncertainty of distinguishing patients with a benign stable monoclonal plasma cell disorder from subjects destined to progress to malignancy. There is now clear epidemiologic evidence, however, that patients with MGUS suffer from a significantly increased fracture risk and that the prevalence of MGUS is increased in patients with osteoporosis. Despite this relationship, no clinical care guidelines exist for the routine evaluation or treatment of the skeletal health of patients with MGUS. Recent work has demonstrated that circulating levels of at least two cytokines (CCL3/MIP-1α and DKK1) with well-recognized roles in bone disease in the related monoclonal gammopathy multiple myeloma are also increased in patients with MGUS. Further, recent imaging studies using high-resolution peripheral quantitative CT have documented that patients with MGUS have substantial skeletal microarchitectural deterioration and deficits in biomechanical bone strength that likely underlie the increased skeletal fragility in these patients. Accordingly, this Perspective provides evidence that the "undetermined significance" portion of the MGUS acronym may be best replaced in favor of the term "monoclonal gammopathy of skeletal significance" (MGSS) in order to more accurately reflect the enhanced skeletal risks inherent in this condition.

IgD heavy-chain deposition disease: detection by laser microdissection and mass spectrometry

Monoclonal Ig deposition disease (MIDD) is a rare complication of monoclonal gammopathy characterized by deposition of monoclonal Ig light chains and/or heavy chains along the glomerular and tubular basement membranes. Here, we describe a unique case of IgD deposition disease. IgD deposition is difficult to diagnose, because routine immunofluorescence does not detect IgD. A 77-year-old man presented with proteinuria and renal failure, and kidney biopsy analysis showed a nodular sclerosing GN with extensive focal global glomerulosclerosis, tubular atrophy, and interstitial fibrosis. Immunofluorescence was negative for Ig deposits, although electron microscopy showed deposits in the glomeruli and along tubular basement membranes. Laser microdissection of glomeruli and mass spectrometry of extracted peptides showed a large spectra number for IgD, and immunohistochemistry showed intense glomerular and tubular staining for IgD. Together, these findings are consistent with IgD deposition disease. Bone marrow biopsy analysis showed 5% plasma cells, which stained for IgD. The patient was treated with bortezomib and dexamethasone, which resulted in improvement of hematologic parameters but no improvement of renal function. The diagnosis of IgD deposition disease underscores the value of laser microdissection and mass spectrometry in further evaluating renal biopsies when routine assessment fails to reach an accurate diagnosis.

Association between the delta estimated glomerular filtration rate and the prevalence of monoclonal gammopathy of undetermined significance in Korean males

Background. We investigated the association between the reduction in the estimated glomerular filtration rate (eGFR) and the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in Korean males. Methods. We enrolled 723 healthy Korean males. Serum creatinine concentration, serum electrophoresis, serum immunofixation, and the serum free light chain assay were performed. We calculated delta eGFR per year (ΔeGFR/yr). The prevalence of MGUS was compared based on the ΔeGFR/yr and age group. Results. Thirteen (1.8%) of 723 participants exhibited the monoclonal band on serum immunofixation. Prevalence of MGUS by age group was 0.00% (0/172 for 40 years), 1.63% (6/367 for 60 years), and 3.80% (7/184 for >60 years). The median decrease in ΔeGFR/yr was 5.3%. The prevalence of MGUS in participants in their 50s with >5.3% decline in ΔeGFR/yr was significantly higher than those with <5.3% decrease in ΔeGFR/yr (3.16% versus 0.00%; P = 0.049). The prevalence of MGUS in participants in their 50s with >5.3% decrease in ΔeGFR/yr was similar to that of healthy males in their 60s. Conclusion. Using the rate of reduction in ΔeGFR/yr in healthy Korean males who had their serum creatinine level checked regularly may increase the MGUS detection rate in clinical practice.

The clinical relevance and management of monoclonal gammopathy of undetermined significance and related disorders: recommendations from the European Myeloma Network

Monoclonal gammopathy of undetermined significance is one of the most common pre-malignant disorders. IgG and IgA monoclonal gammopathy of undetermined significance are precursor conditions of multiple myeloma; light-chain monoclonal gammopathy of undetermined significance of light-chain multiple myeloma; and IgM monoclonal gammopathy of undetermined significance of Waldenström's macroglobulinemia and other lymphoproliferative disorders. Clonal burden, as determined by bone marrow plasma cell percentage or M-protein level, as well as biological characteristics, including heavy chain isotype and light chain production, are helpful in predicting risk of progression of monoclonal gammopathy of undetermined significance to symptomatic disease. Furthermore, alterations in the bone marrow microenvironment of monoclonal gammopathy of undetermined significance patients result in an increased risk of venous and arterial thrombosis, infections, osteoporosis, and bone fractures. In addition, the small clone may occasionally be responsible for severe organ damage through the production of a monoclonal protein that has autoantibody activity or deposits in tissues. These disorders are rare and often require therapy directed at eradication of the underlying plasma cell or lymphoplasmacytic clone. In this review, we provide an overview of the clinical relevance of monoclonal gammopathy of undetermined significance. We also give general recommendations of how to diagnose and manage patients with monoclonal gammopathy of undetermined significance.

Precursors to lymphoproliferative malignancies

We review monoclonal B-cell lymphocytosis (MBL) as a precursor to chronic lymphocytic leukemia and monoclonal gammopathy of undetermined significance (MGUS) as a precursor to plasma cell disorders. These conditions are present in the general population and increase with age. These precursors aggregate with lymphoproliferative malignancies in families suggesting shared inheritance. MBL and MGUS may share some of the same risk factors as their related malignancies but data are limited. Although these conditions are characterized by enhanced risk for the associated malignancy, the majority of individuals with these conditions do not progress to malignancy. A key focus for current work is to identify markers that predict progression to malignancy.

Common community-acquired infections and subsequent risk of multiple myeloma: a population-based study

The role of bacteria and viruses as aetiological agents in the pathogenesis of cancer has been well established for several sites, including a number of haematological malignancies. Less clear is the impact of such exposures on the subsequent development of multiple myeloma (MM). Using the population-based U.S. Surveillance Epidemiology and End Results-Medicare dataset, 15,318 elderly MM and 200,000 controls were identified to investigate the impact of 14 common community-acquired infections and risk of MM. Odds ratios (ORs) and associated 95% confidence intervals (CIs) were adjusted for sex, age and calendar year of selection. The 13-month period prior to diagnosis/selection was excluded. Risk of MM was increased by 5-39% following Medicare claims for eight of the investigated infections. Positive associations were observed for several infections including bronchitis (adjusted OR 1.14, 95% CI 1.09-1.18), sinusitis (OR 1.15, 95% CI 1.10-1.20) pneumonia (OR 1.27, 95% CI 1.21-1.33), herpes zoster (OR 1.39, 95% CI 1.29-1.49) and cystitis (OR 1.09, 95% CI 1.05-1.14). Each of these infections remained significantly elevated following the exclusion of more than 6 years of claims data. Exposure to infectious antigens may therefore play a role in the development of MM. Alternatively, the observed associations may be a manifestation of an underlying immune disturbance present several years prior to MM diagnosis and thereby part of the natural history of disease progression.

Polyclonal gammopathy related to renal bleeding in a peritoneal dialysis patient

Polyclonal gammopathy represents the diffuse activation of B cells and is usually related to inflammation or immune-related diseases. However, the mechanisms leading to polyclonal gammopathy are essentially speculative. Generally, infectious, inflammatory, or various other reactive processes may be indicated by the presence of a broad-based peak or band in the gamma region on serum protein electrophoresis results. A 15-year-old girl, who had been receiving peritoneal dialysis, presented with polyclonal gammopathy and massive gross hematuria. Renal artery embolization was performed, after which the continuous bleeding subsided and albumin-globulin dissociation resolved. This is a rare case of polyclonal gammopathy related to renal bleeding.

Schnitzler syndrome: an under-diagnosed clinical entity

Schnitzler syndrome is considered to be a rare disorder characterized by a monoclonal IgM protein and chronic urticaria that is associated with considerable morbidity. We hypothesized that the syndrome may be under-recognized and patients may be deprived of highly effective therapy in the form of anakinra. We performed a retrospective search of the dysproteinemia database at Mayo Clinic as well as the medical records of all patients with chronic urticaria to determine the true incidence of the disease. We compared patients with the diagnosis of Schnitzler syndrome and those who met the criteria but in whom the syndrome was not recognized. Comparisons between groups were performed and survival curves determined. We identified 16 patients with diagnosed Schnitzler syndrome and an additional 46 patients who met diagnostic criteria. The monoclonal protein was IgMκ in 94% of patients. Therapy with anakinra in 4 patients led to rapid and complete resolution of symptoms. The median overall survival for this syndrome is over 12.8 years. Progression to lymphoma was only observed in 8% of patients; this is lower than previous reports. Schnitzler syndrome may be present in up to 1.5% of patients with a monoclonal IgM in their serum and likely under-recognized as a clinical syndrome.

International Myeloma Working Group recommendations for the treatment of multiple myeloma-related bone disease

PURPOSE

The aim of the International Myeloma Working Group was to develop practice recommendations for the management of multiple myeloma (MM) -related bone disease.

METHODOLOGY

An interdisciplinary panel of clinical experts on MM and myeloma bone disease developed recommendations based on published data through August 2012. Expert consensus was used to propose additional recommendations in situations where there were insufficient published data. Levels of evidence and grades of recommendations were assigned and approved by panel members.

RECOMMENDATIONS

Bisphosphonates (BPs) should be considered in all patients with MM receiving first-line antimyeloma therapy, regardless of presence of osteolytic bone lesions on conventional radiography. However, it is unknown if BPs offer any advantage in patients with no bone disease assessed by magnetic resonance imaging or positron emission tomography/computed tomography. Intravenous (IV) zoledronic acid (ZOL) or pamidronate (PAM) is recommended for preventing skeletal-related events in patients with MM. ZOL is preferred over oral clodronate in newly diagnosed patients with MM because of its potential antimyeloma effects and survival benefits. BPs should be administered every 3 to 4 weeks IV during initial therapy. ZOL or PAM should be continued in patients with active disease and should be resumed after disease relapse, if discontinued in patients achieving complete or very good partial response. BPs are well tolerated, but preventive strategies must be instituted to avoid renal toxicity or osteonecrosis of the jaw. Kyphoplasty should be considered for symptomatic vertebral compression fractures. Low-dose radiation therapy can be used for palliation of uncontrolled pain, impending pathologic fracture, or spinal cord compression. Orthopedic consultation should be sought for long-bone fractures, spinal cord compression, and vertebral column instability.

Risk of acute leukemia and myelodysplastic syndromes in patients with monoclonal gammopathy of undetermined significance (MGUS): a population-based study of 17 315 patients

The purpose of this study was to determine if there is an increased risk of acute leukemia and myelodysplastic syndromes (MDS) in persons with monoclonal gammopathy of undetermined significance (MGUS). We used a large population-based cohort of individuals systematically screened for the presence or absence of MGUS. MGUS status was then linked to the diagnosis of acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL) and MDS. A total of 17 315 patients age 50 and older (605 MGUS and 16 710 controls) with a cumulative 435 021 person-years of follow-up were studied. MGUS patients had a significantly higher risk of developing MDS compared with controls, hazard ratio 2.4 (95% CI 1.08, 5.32), P=0.031. There was no statistically significant increase in the risk of AML (RR 1.36 P=0.675), and no increased risk of developing ALL.

Monoclonal gammopathy of undetermined significance associated with blue finger syndrome

An 86-year-old Caucasian woman with a medical history of monoclonal gammopathy of undetermined significance (MGUS) was admitted to the hospital with a chief complaint of sudden onset of bluish discolouration of the fifth left hand digit. On a physical examination, cyanosis of the fifth digit of the left hand was noticed with decreased capillary fill but no ulcers. The patient had no tenderness on palpation. Pulses were palpable over the radial arteries bilaterally. Patients with MGUS may be at increased risk of thromboembolic disease. A clear explanation for this association in these patients is not currently known. This case report highlights the association between MGUS and thromboembolic events, particularly blue finger syndrome.

Transient Monoclonal Gammopathy Induced by Disseminated Staphylococcus aureus Infection

Monoclonal gammopathy reflects a serological disorder suggesting a plasma cell dyscrasia or a B-cell abnormality. However, it may occasionally be encountered as a transient manifestation in the course of several diseases including infections. This is the first reported case of a transient monoclonal gammopathy IgG lambda light chain associated with a Staphylococcus aureus infection that was complicated with renal abscess and vertebral spondylodiscitis in a previously healthy 68-year-old male. We observed a complete resolution of the gammopathy within three months of medical treatment before the entire restoration of all clinical and laboratory findings. Many invasive and cost-intensive diagnostic procedures had preceded the exclusion of a malignancy. The clinical significance and the exact pathogenesis of transient monoclonality are poorly understood and remain a matter of speculation.

Clinical interest of bone marrow aspiration in rheumatology: a practice-based observational study of 257 bone marrow aspirations

Bone marrow aspiration (BMA) can be performed by rheumatologists for diagnostic purposes in clinical practice. The aim of the study was to assess professional practices of hospital-based rheumatologists with regard to BMA in order to identify the relevant indications. A retrospective observational study in patients hospitalised in a French university hospital was conducted between 2005 and 2011. All of the patients who had a BMA in the rheumatology department during the study period were included. Clinical indication, number and results of BMA and of bone marrow biopsy (BMB) were collected. Stage and treatment of the haematological disease implemented following the BMA were described. Two hundred fifty-seven BMAs and 79 BMBs were performed during the study period. Of the BMAs, 14.1 % were pathological: myeloma (n = 12), malignant B cell non-Hodgkin's lymphoma (n = 6), myelodysplastic syndrome (n = 6), chronic lymphoid leukaemia (n = 4), Waldenstrom's disease (n = 3), chronic myelomonocytic leukaemia (n = 2), hairy cell leukaemia (n = 1) and acute lymphoblastic leukaemia (n = 1). Eight of the 14 pathological BMBs were associated with normal BMA. BMAs were performed equally for gammaglobulin abnormalities (monoclonal peak = 45 % of indications, hypogammaglobulinemia = 6 %) and for other reasons (haemogram abnormality = 24 %, skeletal osteolysis = 6 %, unexplained inflammatory syndrome = 5 %, lymph node disease = 4 % and others). In clinical rheumatology, BMA may reveal two major types of malignant haematological diseases: myeloma with poor prognostic factors justifying polychemotherapy and autologous grafts and, in contrast, slowly evolving B cell lymphoid haemopathies. Given the additional risk in some types of chronic inflammatory rheumatism, BMB should be performed more frequently in certain specific situations (skeletal or lymph node tumour and unexplained inflammatory syndrome).

Incidental finding of monoclonal gammopathy in blood donors: a follow-up study

BACKGROUND

The incidental finding of monoclonal immunoglobulin in the sera of healthy blood donors is a relatively frequent event and in such cases the subjects are commonly deferred permanently from donating blood. However, no follow-up studies of these cases have been published so far.

MATERIALS AND METHODS

Since 2000, all regular blood donors at Trieste Blood Bank have undergone annual screening by serum protein electrophoresis. Cases presenting with monoclonal gammopathy between January 2000 and December 2008 were registered and follow-up was performed until December 2010.

RESULTS

Out of 8,197 regular blood donors, monoclonal gammopathy was detected in 104 subjects (1.3%). The median age at detection was 53 years, the median monoclonal protein concentration was 0.2 g/dL and the cumulative follow-up of these cases amounted to 763 person/years. In two cases asymptomatic multiple myeloma was diagnosed within 6 months of detection of the gammopathy and in 14 cases, the monoclonal gammopathy was transient. The remaining 88 cases were classified as having monoclonal gammopathy of undetermined significance (MGUS). Out of these, two events related to monoclonal gammopathy were observed during the follow up: one lymphoma and one light chain deposition nephropathy.

DISCUSSION

According to current prognostic staging systems, the majority of blood donors with monoclonal gammopathy were classified as having low-risk MGUS and had a very low incidence of lymphoproliferative diseases. Permanent deferral of blood donors with stable MGUS causes about a 1% loss of potential blood donations and it represents a "precautionary measure" that needs to be substantiated and validated.

Development of Renal Failure without Proteinuria in a Patient with Monoclonal Gammopathy of Undetermined Significance: An Unusual Presentation of AL Kappa Amyloidosis

AL amyloidosis complicating monoclonal gammopathy of undetermined significance (MGUS) has usually a predominant glomerular deposition of lambda light chain. Heavy proteinuria is one of its cardinal manifestations. A 78-year-old man with a 9-year history of IgG kappa light-chain-MGUS and normal urine protein excretion developed severe renal failure. Serum levels of kappa light chain and serum IgG had been stable while proteinuria was absent throughout the nine-year period. For the first eight years, he had stable stage III chronic kidney disease attributed to bladder outlet obstruction secondary to prostatic malignancy. In the last year, he developed progressive serum creatinine elevation, without any increase in the serum or urine levels of paraproteins or any sign of malignancy. Renal ultrasound and furosemide renogram showed no evidence of urinary obstruction. Renal biopsy revealed AL amyloidosis, with reactivity exclusive for kappa light chains, affecting predominantly the vessels and the interstitium. Glomerular involvement was minimal. Melphalan and prednisone were initiated. However, renal function continues deteriorating. Deposition of AL kappa amyloidosis developing during the course of MGUS predominantly in the wall of the renal vessels and the renal interstitium, while the involvement of the glomeruli is minimal, leads to progressive renal failure and absence of proteinuria. Renal biopsy is required to detect both the presence and the sites of deposition of renal AL kappa light chain amyloidosis.

Monoclonal gammopathy of undetermined significance and risk of infections: a population-based study

No comprehensive evaluation has been made to assess the risk of viral and bacterial infections among patients with monoclonal gammopathy of undetermined significance. Using population-based data from Sweden, we estimated risk of infections among 5,326 monoclonal gammopathy of undetermined significance patients compared to 20,161 matched controls. Patients with monoclonal gammopathy of undetermined significance had a 2-fold increased risk (P<0.05) of developing any infection at 5- and 10-year follow up. More specifically, patients with monoclonal gammopathy of undetermined significance had an increased risk (P<0.05) of bacterial (pneumonia, osteomyelitis, septicemia, pyelonephritis, cellulitis, endocarditis, and meningitis), and viral (influenza and herpes zoster) infections. Patients with monoclonal gammopathy of undetermined significance with M-protein concentrations over 2.5 g/dL at diagnosis had highest risks of infections. However, the risk was also increased (P<0.05) among those with concentrations below 0.5 g/dL. Patients with monoclonal gammopathy of undetermined significance who developed infections had no excess risk of developing multiple myeloma, Waldenström macroglobulinemia or related malignancy. Our findings provide novel insights into the mechanisms behind infections in patients with plasma cell dyscrasias, and may have clinical implications.

Monoclonal Gammopathy of Undetermined Significance (MGUS) in a Man with Fragile X-associated Tremor/Ataxia Syndrome

We report the clinical presentation and laboratory findings of a 69-year-old man with fragile X-associated tremor ataxia syndrome (FXTAS), a progressive neurodegenerative disorder, who was noted to have monoclonal gammopathy of undetermined significance (MGUS), a plasma cell proliferative disorder and a precursor disease of multiple myeloma. Both MGUS and FXTAS are associated with microRNA (miRNA) dysregulation. We speculate that individuals with FXTAS may be predisposed to MGUS and further studies are warranted regarding this association.

Incidence, clinical course, and prognosis of secondary monoclonal gammopathy of undetermined significance in patients with multiple myeloma

During the course of multiple myeloma (MM), new monoclonal proteins of an isotype distinct from the original clone, referred to as secondary monoclonal gammopathy of undetermined significance (MGUS), have been described. We report on the frequency, characteristics, and outcome of secondary MGUS. Of the 1942 patients with MM, 128 (6.6%) developed a secondary MGUS, at a median of 12 months from the diagnosis of MM. The median duration of secondary MGUS was 5.9 months. Secondary MGUS was more common in patients after stem cell transplantation than in those who had not undergone such treatment (22.7% vs 1.6%, P < .001). Overall survival was significantly superior in MM patients who developed secondary MGUS compared with the rest of the cohort (73 vs 38 months, respectively; P < .001). The time of onset and the duration of secondary MGUS, as well as failure to resolve spontaneously, had an effect on overall survival and require further study.

Bone disease in multiple myeloma and precursor disease: novel diagnostic approaches and implications on clinical management

The manifestations of bone involvement in patients with multiple myeloma (MM) can have devastating clinical effects and increase mortality. Recent studies demonstrate that patients with the precursor conditions smoldering MM (SMM) and monoclonal gammopathy of undetermined significance (MGUS) show evidence of bone disease and increased risk of fractures. The understanding of the pathogenesis of bone disease in MM has expanded in recent years. The traditional skeletal survey will probably be replaced by newer and more sensitive imaging techniques, which may have a prognostic impact and change our definition of MGUS and SMM. Bisphosphonates are recommended to prevent skeletal events in patients with MM, and have also been studied in SMM and MGUS. This article summarizes the current knowledge of bone disease in plasma cell disorders, and discusses the current standard and future role of novel imaging techniques, as well as the evidence and current guidelines for bisphosphonates in MM, SMM and MGUS.

Comparative study of immune status to infectious agents in elderly patients with multiple myeloma, Waldenstrom's macroglobulinemia, and monoclonal gammopathy of undetermined significance

Whereas patients with multiple myeloma (MM) have a well-documented susceptibility to infections, this has been less studied in other B-cell disorders, such as Waldenstrom's macroglobulinemia (WM) and monoclonal gammopathy of undetermined significance (MGUS). We investigated the humoral immunity to 24 different pathogens in elderly patients with MM (n = 25), WM (n = 16), and MGUS (n = 18) and in age-matched controls (n = 20). Antibody titers against pneumococci, staphylococcal alpha-toxin, tetanus and diphtheria toxoids, and varicella, mumps, and rubella viruses were most depressed in MM patients, next to lowest in WM and MGUS patients, and highest in the controls. In contrast, levels of antibodies specific for staphylococcal teichoic acid, Moraxella catarrhalis, candida, aspergillus, and measles virus were similarly decreased in MM and MGUS patients. Comparable titers in all study groups were seen against Haemophilus influenzae type b (Hib), borrelia, toxoplasma, and members of the herpesvirus family. Finally, a uniform lack of antibodies was noted against Streptococcus pyogenes, salmonella, yersinia, brucella, francisella, and herpes simplex virus type 2. To conclude, although MM patients displayed the most depressed humoral immunity, significantly decreased antibody levels were also evident in patients with WM and MGUS, particularly against Staphylococcus aureus, pneumococci, and varicella. Conversely, immunity was retained for Hib and certain herpesviruses in all study groups.

The role of bisphosphonates in multiple myeloma: mechanisms, side effects, and the future

Zoledronic acid and pamidronate are two potent anticatabolic nitrogen-containing bisphosphonates (BPs) used extensively in diseases with high bone turnover such as multiple myeloma (MM). In this review we focus on their biology and their current and future use in MM, and highlight some of the most common and emerging side effects. Although the primary target cells for BPs are osteoclasts, new insights suggest other cell types of the bone microenvironment as possible targets, including osteoblasts, endothelial cells, immune cells, and cancer cells. Here, we focus on the current guidelines for the use of BPs in MM and address side effects such as renal toxicity, osteonecrosis of the jaw, and low-energy fractures. Finally, we approach the future of BP use in MM in the context of other bone-targeted agents, evaluating ongoing clinical trials addressing alternate dosing and schedules of BP administration in MM patients.