Monoclonal gammopathy of undetermined significance (MGUS)

Proposed Terminology and Classification of Pre-Malignant Neoplastic Conditions: A Consensus Proposal

Cancer evolution is a step-wise non-linear process that may start early in life or later in adulthood, and includes pre-malignant (indolent) and malignant phases. Early somatic changes may not be detectable or are found by chance in apparently healthy individuals. The same lesions may be detected in pre-malignant clonal conditions. In some patients, these lesions may never become relevant clinically whereas in others, they act together with additional pro-oncogenic hits and thereby contribute to the formation of an overt malignancy. Although some pre-malignant stages of a malignancy have been characterized, no global system to define and to classify these conditions is available. To discuss open issues related to pre-malignant phases of neoplastic disorders, a working conference was organized in Vienna in August 2015. The outcomes of this conference are summarized herein and include a basic proposal for a nomenclature and classification of pre-malignant conditions. This proposal should assist in the communication among patients, physicians and scientists, which is critical as genome-sequencing will soon be offered widely for early cancer-detection.

A first Czech analysis of 1887 cases with monoclonal gammopathy of undetermined significance

INTRODUCTION

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant condition with a risk of malignant conversion.

PATIENTS AND METHODS

With the aim to estimate the cumulative risk MGUS progression to hematologic malignancies, we analyzed a nationwide population-based cohort of 1887 MGUS patients from the Czech Registry of Monoclonal Gammopathies (RMG) between 2007 and 2013.

RESULTS

During the follow-up period (median 4 years; range 0.6-34.8), progression to hematologic malignancies was observed in 8.6% (162 of 1887) of patients. Factors associated with progression were as follows: M-protein concentration ≥1.5 g/dL, pathological sFLC (<0.26 or >1.65) ratio, bone marrow plasma cells (BMPCs) in cytology >5%, immunoparesis, age ≥69 years, and the level of serum hemoglobin at baseline <12.0 g/dL. Combining these factors, we propose a new risk model (CMG model). The risk of progression at 10 years was 1.6%, 16.9%, 22.9%, 39.4%, and 52.3%, respectively, if 0 (reference group), one, two, three, or four to five risk factors are present (P<.001) with HR 63 times higher compared to the reference MGUS group.

CONCLUSION

The new CMG model was established with an advantage for better identification of MGUS patients at low risk.

Incidence of gammopathies in long-term plasmapheresis donors at Canadian Blood Services

BACKGROUND

To investigate the long-term consequences of repeated plasmapheresis on donor health, their donation histories and demographic data were reviewed to determine the frequency of development of monoclonal (Mc) gammopathies or other gamma globulin abnormalities (OGGAs).

STUDY DESIGN AND METHODS

Samples from apheresis plasma donors collected at Canadian Blood Services were tested initially and every 4 months for total protein (TP) followed by serum protein electrophoresis (SPE). Out-of-range samples or those showing abnormal band patterns were forwarded to a hospital laboratory for additional investigation.

RESULTS

Of 52,972 donors who donated 471,446 apheresis plasmas over 9 years, 89,490 samples were sent for TP and SPE testing. Of 3005 samples forwarded for further investigation, abnormal immunofixation electrophoresis (IFE) results were found in 209 (0.4%) donors, 85 from first-time (FT) and 124 from repeat (RPT) plasma donors during participation in the program. There were 167 donors with Mc gammopathies (73 FT, 94 RPT) and 42 with OGGAs (12 FT, 30 RPT). FT or RPT donors with Mc gammopathies or OGGAs were significantly older than those with normal SPEs. RPT donors with Mc gammopathies or OGGAs also had a longer donation period than donors with normal SPEs.

CONCLUSIONS

The incidence of Mc gammopathies (2.41 per 1000 donors) did not significantly increase from 2004 to 2012. Older donors had a higher incidence of Mc gammopathies and longer donation periods than their healthy counterparts. Overall, gammopathy rates were below those reported over the same age range in the general population.

A Case of Type I Cryoglobulinemia Associated with a Monoclonal Gammopathy of Undetermined Significance (MGUS)

A 79-year-old Japanese male who had been suffering from renal insufficiency of unknown causes visited us with reddish papules and purpura on both forearms of a month's duration. A skin biopsy was performed from the right forearm, and the histopathology showed an obstruction of superficial blood vessels with eosinophilic amorphous materials suggesting cryoglobulins. Although further investigations revealed the presence of monoclonal immunoglobulin (Ig) G-kappa type I cryoglobulin, a bone marrow biopsy demonstrated that there was 7.6% proliferation of plasmacytoid cells, and the serum level of Ig G was less than 3 g/dl. The diagnosis was type I cryoglobulinemia associated with monoclonal gammopathy of undetermined significance as the possible cause of chronic renal failure. Therefore, purpuric changes on extremities of the elderly, especially those complaining of renal failure should, be taken seriously and not regarded simply as an age-related phenomenon.

Monoclonal gammopathy in a tertiary referral hospital

OBJECTIVE

Monoclonal gammopathies reflect conditions of plasma B-cell disorders. Our objective was to identify the prevalence and types of these gammopathies in our population.

METHODS

A 10year retrospective study was conducted. Serum and/or urine protein electrophoresis were performed on 6624 samples. Positive bands were further tested by immunofixation (IFE).

RESULTS

Homogenous bands were detected in 7% of the patients. IFE method confirmed 6.3% in which 59% were males and 41% were females. The mean age was 64.7 for females and 66.5 for males. The sensitivity and specificity were 91% and 99% respectively. The most common protein was IgG kappa 41%, followed by IgG lambda 19%. Sixty-eight percent of these patients had monoclonal gammopathy of undetermined significance and 14.6% had multiple myeloma.

CONCLUSION

The majority of the studied population had MGUS. This observation is in concord with other western populations. The sensitivity and specificity of protein electrophoresis is diagnostically and reasonably acceptable.

Autologous bone marrow transplanation for extramedullary plasmacytoma presenting as adrenal incidentaloma

Extramedullary adrenal plasmacytoma (EMP) involving the adrenal glands is rarely encountered clinically. We report a A 47-year-old male who presented with bilateral adrenal incidentalomas. After confirming EMP, the patient received two consecutive autologous hematopoietic stem cell transplants (HSCT) using high-dose melphalan. Following HSCT, a serial follow-up helical CT revealed a substantial decrease in the size of both adrenal masses. Serial periodic serum protein and urine electrophoresis and immunofixation showed abrogation of a previously noted monoclonal band. At 50 months follow-up the patient was alive and well. Our patient is the first with EMP to have received an autologous HSCT, which may prove to have a role in therapy due to the immunological effect of the infused donor marrow T-lymphocytes against the clonal proliferation of abnormal plasma cells in extrammedullary sites.This case indicates that an EMP should be added to the differential diagnosis of adrenal incidentalomas.

Prevalence of monoclonal gammopathy of undetermined significance: study of 52,802 persons in Nagasaki City, Japan

OBJECTIVE

To assess the prevalence of monoclonal gammopathy of undetermined significance (MGUS) in a large Japanese population.

PARTICIPANTS AND METHODS

From October 1, 1988, to March 31, 2004, a total of 52,802 (of 71,675) Japanese survivors of the atomic bomb explosion in Nagasaki City, Japan, were screened for M protein. The youngest participant was 42.3 years as of October 1, 1988. A 2-step screening was performed with a serum protein electrophoresis followed by immunoelectrophoresis and a quantitative determination of serum concentration of immunoglobulins. Twenty-one patients who were diagnosed for the first time at the time of screening as having multiple myeloma and Waldenström macroglobulinemia were excluded from analyses. Age- and sex-specific prevalence rates of MGUS were calculated.

RESULTS

Monoclonal gammopathy of undetermined significance was identified in 1088 of the 52,781 study participants. The overall prevalence of MGUS was 2.1% (95% confidence interval [CI], 1.9%-2.2%) in the total population screened and 2.4% (95% CI, 2.0%-2.6%) in those 50 years or older. The prevalence was significantly higher in men than in women (2.8% vs 1.6%; age-adjusted odds ratio, 2.0; 95% CI, 1.8-2.3; P less than .001). In both sexes, the prevalence rose with increasing age from 1.0% in participants aged 42 to 49 years, 1.9% in those 50 to 59 years, 2.6% in those 60 to 69 years, and 3.0% in those 70 to 79 years, to 4.4% in those 80 years and older. The heavy chain isotypes of immunoglobulin were IgG in 73.6% of patients, IgA in 17.7%, IgM in 7.5%, and oligoclonal gammopathies in 1.1%.

CONCLUSION

The prevalence of MGUS is lower in this Japanese population than that reported in Western countries among people older than 60 years, especially among women.

Monoclonal gammopathies and malignancies in patients with chronic urticaria

BACKGROUND

Monoclonal gammopathy of undetermined significance (MGUS) has been described in association with chronic urticaria (CU) in patients with Schnitzler syndrome. Chronic urticaria may be a manifestation of hematologic malignancies.

METHODS

This study was conducted to evaluate the frequency and characteristics of MGUS or malignancy in patients with CU. The Mayo Clinic electronic database was reviewed to identify patients with the diagnosis of CU.

RESULTS

Of the 1639 patients presenting with CU between 1994 and 2001, 797 (49%) underwent laboratory evaluation for the presence of a coexisting monoclonal protein. Forty-seven CU patients had MGUS, 142 had a malignancy, and 24 had both. Fifteen percent of CU patients with MGUS had a hematologic malignancy compared with 0.9% of CU patients without MGUS (P < 0.001). Patients presenting with a new diagnosis of CU at an older age (> 56 years) were more likely to have associated underlying MGUS. The occurrence of MGUS in this group was higher than the reported incidence of MGUS in the general population.

CONCLUSIONS

Patients with CU younger than 43 years were unlikely to have associated MGUS or malignancy. A higher percentage of patients with CU and MGUS had an associated diagnosis of hematologic malignancy.

Conventional diagnostics in multiple myeloma

This paper reviews the most relevant laboratory techniques currently used for the evaluation of patients with multiple myeloma (MM) and other monoclonal gammopathies. Although the bone marrow morphological examination and electrophoretic analysis of the monoclonal paraprotein still remain the 'gold standard' techniques for fast, accurate and cost-effective diagnosis, other assays such as immunophenotyping, DNA cell content and cell cycle analysis measured by flow cytometry may contribute to a better assessment of myeloma patients. Here, we will discuss not only the contribution of each technique to differential diagnosis of monoclonal gammopathies, but also the value of each parameter as prognostic factor and for monitoring treatment efficacy. In addition, possible technical pitfalls inherent to each technique will be analysed.

Characterization of bone marrow T cells in monoclonal gammopathy of undetermined significance, multiple myeloma, and plasma cell leukemia demonstrates increased infiltration by cytotoxic/Th1 T cells demonstrating a squed TCR-Vβ repertoire

BACKGROUND

The majority of studies published to date regarding the role of the bone marrow (BM) microenvironment in the pathogenesis of monoclonal gammopathies (MG) have focused on the interaction between stroma cells and plasma cells, whereas information concerning the lymphocytes infiltrating the tumor microenvironment is scanty.

METHODS

The authors measured the distribution, TCR-Vbeta repertoire, immunophenotype, and functional characteristics of different subsets of BM T lymphocytes from 61 nontreated patients with MG (30 patients with MG of undetermined significance [MGUS], 27 patients with multiple myeloma [MM], and 4 patients with plasma cell leukemia [PCL]).

RESULTS

The authors found a significantly increased rate of BM infiltration by T cells in all patient groups, at the expense of CD4+CD8- and CD4-CD8- T lymphocytes and both CD4+CD28- and CD8+CD28- cytotoxic/effector T cell subsets, and associated with TCR-Vbeta expansions in both CD4+ and CD8+ BM T cells in the majority of patients with MGUS, MM, and PCL. Moreover, the percentage of T cells secreting interferon (IFN)-gamma was found to be increased (P < or = 0.05) both in CD4+ and CD8+ T cells in MGUS and MM patients, and a higher plasma concentration of IFN-gamma was found in patients with MM. It is interesting to note that a positive correlation was noted between the proportion of CD28- and both the percentage of IFN-gamma-secreting cells and the proportion of expanded TCR-Vbeta lymphocytes within the total BM CD4+ T cells.

CONCLUSIONS

The results of the current study demonstrated an increased infiltration of BM by T cells associated with frequent TCR-Vbeta expansions and a more prominent cytotoxic/Th1 phenotype in all the patient groups studied.

A data base for 3000 monoclonal immunoglobulin cases and a new classification

Data from monoclonal immunoglobulin cases screened in our laboratory for 40 years were used to assemble a cohort of 3094 cases selected according to immunoelectrophoresis and immunofixation interpretation and clinical data availability. Molecular distribution and original classification were used to establish five categories of cases: multiple myeloma (MM) and Waldenstrom macroglobulinemia (WM), other lymphoproliferative diseases, cases associated with heavy immunological diseases or other tumors, and benign cases. Free light chain (FLC) cases comprise 7% of the cohort, pluriclonal Ig, 6%. More than 50% of 1335 cases with identified diagnoses are not malignant hemopathies. Male/female ratio is less than 1 for MM cases and close to 1 for benign and other lymphoproliferative cases. Males are a majority in MW and associated cases. Follow-up periods range from 5 to 30 years for 263 cases. The main characteristics of this data base have been defined and the benefit of the original classification is highlighted. Future studies will investigate improvements resulting from immunofixation and current urinary analysis practices, as well as long-term follow-up, pluriclonal Ig cases, cryoglobulins, the meaning of the presence of FLC and malignant transformation.

Clonal plasma cells from monoclonal gammopathy of undetermined significance, multiple myeloma and plasma cell leukemia show different expression profiles of molecules involved in the interaction with the immunological bone marrow microenvironment

The immunological bone marrow (BM) microenvironment plays a major role in controlling growth and survival of clonal plasma cells (PC); this might translate into different patterns of expression of molecules involved in immune responses on PC from different types of monoclonal gammopathies (MG). We have studied the expression of a group of nine such molecules on both BMPC and the plasma of 61 newly diagnosed MG patients (30 MG of undetermined significance (MGUS), 27 multiple myeloma (MM) and four plasma cell leukemia (PCL)) and five normal individuals. Clonal PC from all MG displayed significantly increased levels of CD56, CD86 and CD126, and decreased amounts of CD38 (P<0.001). Additionally, HLA-I and beta2-microglobulin were abnormally highly expressed in MGUS, while CD40 expression was decreased in MM and PCL (P<0.05). Interestingly, a progressive increase in the soluble levels of beta2-microglobulin was found from MGUS to MM and PCL patients (P=0.03). In contrast, all groups showed similar surface and soluble amounts of CD126, CD130 and CD95, except for increased soluble levels of CD95 observed in PCL. Overall, those phenotypic differences are consistent with increased antigen presentation and costimulatory capacities in MGUS, which progressively deteriorate in malignant MG (MM and PCL).

Gammapathies monoclonales en Tunisie : analyse épidémiologique, immunochimique et étiologique d'une série de 288 cas

From July 1992 to December 2000, 288 cases of monoclonal gammapathy (MG) were collected at the university hospital of Sfax. The middle age of the patients at the time of the diagnosis was 62 years and 7 months with extremes to 18 months and 99 years and median to 64 years. One hundred and eighty-two patients were men and 106 women. Among the 270 observations for which aetiology has been established, 73 were classified MG of undetermined significance (MGUS), 160 myeloma (or plasmocytoma) and 37 other malignant MG (Waldenstrom's macroglobulinemia: 13, lymphoma: 9, alpha heavy chains disease: 6, primary amyloidosis: 5, chronic lymphocytic leukaemia: 4). Rheumatological affections (19.2%), infections and renal failure (10% each), haematological and autoimmune diseases (9.6% each) were pathologies most often associated with MGUS. Agarose gel electrophoresis did not show a monoclonal peak in 16% of the cases. In the 242 patients with a peak on electrophoresis, the peak was in the beta zone in 22% of cases and in the gamma zone in 78% of cases. The IgG isotype represents more than the half of the cases of our set (51.7%). IgG is even more predominant in the MGUS group (65.8%). The IgA isotype counts for 20.8% of the cases in our set and the free light chains (kappa or lambda) for 13.6% of the cases whereas the IgM represents 8.7% only of the 288 cases of our set which involves three cases of IgD myeloma and six cases of biclonal gammapathy.

DNA Methylation Profiles of Lymphoid and Hematopoietic Malignancies

PURPOSE

Aberrant methylation of the 5' gene promoter regions is an epigenetic phenomenon that is the major mechanism for silencing of tumor suppressor genes in many cancer types. The aims of our study were (a) to compare the methylation profiles of the major forms of hematological malignancies and (b) to determine the methylation profile of monoclonal gammopathy of undetermined significance (MGUS) and compare it with that of multiple myeloma (MM).

EXPERIMENTAL DESIGN

We compared the aberrant promoter methylation profile of 14 known or suspected tumor suppressor genes in leukemias (n = 48), lymphomas (n = 42), and MMs (n = 40). We also examined the methylation profile of MGUS (n = 20), a premalignant plasma cell dyscrasia. The genes studied represent five of the six "hallmarks of cancer."

RESULTS

Peripheral blood lymphocytes (n = 14) from healthy volunteers were negative for methylation of all genes, and methylation percentages in 41 nonmalignant tissues (peripheral blood mononuclear cells, bone marrows, and lymph nodes) from hematological patients were low (0-9%) for all 14 genes, confirming that methylation was tumor specific. Ten of the genes were methylated at frequencies of 29-68% in one or more tumor types, and the methylation indices (an indicator of overall methylation) varied from 0.25 to 0.34. With two exceptions, the methylation patterns of leukemias and lymphomas were similar. However, the pattern of MMs varied from the other tumor types for six genes. In general, the methylation pattern of MGUS was similar to that of MM, although the methylation frequencies were lower (the methylation index of MGUS was 0.15, and that of MM was 0.3). However, the methylation frequencies of six genes were significantly higher in MGUS than in control tissues. The relatively high frequencies of methylation in MGUS are consistent with it being a premalignant condition.

CONCLUSIONS

The three major forms of lymphoid/hematopoietic malignancies show overlapping but individual patterns of methylation.

Genomic abnormalities in monoclonal gammopathy of undetermined significance

Translocations involving immunoglobulin (Ig) loci and chromosome 13 monosomy (Δ13) are frequent cytogenetic findings in multiple myeloma (MM). Similar chromosomal aberrations have been identified in the monoclonal gammopathy of undetermined significance (MGUS), but their prevalence and significance remain uncertain. Bone marrow from 72 patients with MGUS (n = 62) and smoldering MM (n = 10) was evaluated for translocations between the Ig heavy chain (IgH) and chromosomes 4, 11, and 16, translocations involving Ig light chain–lambda (IgL-λ, and Δ13. Fluorescence in situ hybridization (FISH) analysis was done on clonal plasma cells (PCs) detected by immunofluorescence (cIg-FISH) of the cytoplasmic light chain. We also studied cells for cyclin D1 and FGFR3 up-regulation by immunohistochemistry and immunofluorescence, respectively. Twenty-seven (46%) of 59 patients had IgH translocations, and 4 (11%) of 37 had an IgL-λ translocation. A t(11;14)(q13;q32) was found in 15 (25%) of 59 patients, a t(4;14)(p16.3;q32) in 9% of patients, and a t(14;16)(q32;q23) in 5% of patients. All patients with t(4;14)(p16.3;q32) tested (n = 3) had intense cytoplasmic fluorescence with an anti-FGFR3 antibody. PC nuclear staining of cyclin D1 was only observed in patients with t(11;14)(q13;q32); Δ13 was detected in the clonal PCs in 50% of patients. The percentage of abnormal PCs varied with any given abnormality. No obvious clinical or biologic correlations were associated with these chromosome abnormalities. Similar translocations are found in both MGUS and MM, including t(4;14)(p16.3;q32) and t(14;16)(q32;q23). Moreover, Δ13 is common in MGUS and unlikely to play a predominant role in the evolution of MGUS to MM.

Prognostic factors for malignant transformation in monoclonal gammopathy of undetermined significance and smoldering multiple myeloma

PURPOSE

To evaluate the natural history of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM), identify early predictors of evolution, and assess whether associated conditions correlate with disease progression.

PATIENTS AND METHODS

A total of 1,231 consecutive patients with either MGUS (n = 1,104) or SMM (n = 127) diagnosed from July 1975 to March 1998 were included in the study. Cumulative survival probability and cumulative probability of transformation into lymphoproliferative disease were calculated by means of the Kaplan-Meier estimator. Univariate and multivariate Cox models were used to identify possible predictors of malignant evolution.

RESULTS

Cumulative transformation probability at 10 and 15 years was 14% and 30%, respectively. At a median follow-up of 65 months (range, 12 to 239 months), 64 MGUS cases (5.8%) evolved to multiple myeloma (MM) (n = 43), extramedullary plasmacytoma (n = 1), primary amyloidosis (n = 1), Waldenström's macroglobulinemia (n = 12), non-Hodgkin's lymphoma (n = 6), and B-chronic lymphocytic leukemia (n = 1). At a median follow-up of 72 months (range, 12 to 247 months), 25 SMMs (19.7%) evolved to overt MM. A lower evolution risk was observed in MGUS than in SMM (P <.0001). Greater than 5% marrow plasmacytosis, detectable Bence Jones proteinuria, polyclonal serum immunoglobulin reduction, and high erythrocyte sedimentation rate (ESR) were independent factors influencing MGUS transformation. SMM progression correlated with greater than 10% marrow plasma cells, detectable Bence Jones proteinuria, and immunoglobulin (Ig) A isotype. Neither concomitant diseases nor immunosuppression correlated with progression.

CONCLUSION

Careful evaluation of marrow plasmacytosis, urinary paraprotein, background immunoglobulins, ESR, and paraprotein isotype might help identify at presentation patients with benign monoclonal gammopathies requiring stricter monitoring.

Idiopathic AL amyloidosis and biclonal paraproteinemia: a case report and review of the literature

A case of 79 year-old man suffering from nephrotic syndrome, infiltrative cardiomyopathy and sensitive neuropathy of the lower limbs, associated with biclonal gammopathy (IgG K and IgA A), is described. There was a history of non-insulin dependent diabetes mellitus and of two lung nodules considered as benign lesions on the basis of cytologic, hematologic and instrumental examination. A rectal biopsy positive for amyloid deposition (Congo red histology and immunofluorescence study) led to the diagnosis of AL amyloidosis. Considering that the patient did not fulfill diagnostic criteria for lymphoproliferative diaseases (myeloma, lymphoma or Waldenström's macroglubulinemia), nor for secondary malignant paraproteinemia, a diagnosis of idiopathic AL amyloidosis with biclonal gammopathy was made. Very few cases of idiopathic AL amyloidosis with double component are reported in the literature. Our review suggests that idiopathic AL amyloidosis with biclonal gammopathy is similar to idiopathic AL amyloidosis with monoclonal paraproteinemia in terms of clinical features, response to therapy and prognosis. Further studies, however, are necessary to clarify the true incidence and the clinical features of idopathic AL amyloidosis associated with biclonal gammopathy.

Extramedullary plasmacytoma in the adrenal incidentaloma

High-resolution imaging has led to the increasingly frequent discovery of adrenal incidentalomas. Most are nonfunctioning tumours and adenomas, but it is difficult to distinguish benign from malignant tumours using only morphological and laboratory data, and the diagnosis often remains uncertain without histological examination. Here we report the case of a 52-year-old Japanese man who had a right adrenal incidentaloma 4 cm in diameter. The tumour was removed by laparoscopic adrenalectomy. The pathology specimen revealed the typical histology of plasmacytoma. Extramedullary plasmacytoma is a very rare type of plasma cell proliferative disorder. This is the first documented case of an extramedullary plasmacytoma in the adrenal gland.

Mortality and causes of death in patients with monoclonal gammopathy of undetermined significance

To evaluate the mortality and causes of death in monoclonal gammopathy of undetermined significance (MGUS), we identified 1324 cases of MGUS in the period 1978-93 in North Jutland County, Denmark. Data on mortality were obtained by record linkage to the Danish Death Registry. There were 868 deaths in the MGUS cohort during 7785 years of follow-up vs. 409.6 expected, giving a standardized mortality ratio (SMR) of 2.1 (95% confidence interval 2.0-2.3). Malignant transformation was the cause of death in 97 patients vs. 4.9 expected, yielding a SMR of 20.0 (16.2-24.4), which explained about 20% of the excess mortality in the cohort. The mortality was increased for several other malignant and non-malignant causes of death during the first 4 years of follow-up. For late follow-up, 5-18 years after detection of the M-component, the overall SMR was 1.7 (1.5-1.9), and malignant transformation was the only cause of death with a substantial increase of SMR. Although malignant transformation is an important cause of death in MGUS patients, it did not entirely explain the increased mortality. MGUS patients often suffer from coexisting clinical conditions that increase the mortality, especially during the first years after detection of the M-component.

Immunophenotypic Aberrations, DNA Content, and Cell Cycle Analysis of Plasma Cells in Patients with Myeloma and Monoclonal Gammopathies

We describe the immunophenotypic and gross DNA defects in 55 patients with myeloma and 50 patients with monoclonal gammopathy and review the literature on this subject (MedLine, 1994-2000). Our data confirmed previous reports indicating that in myeloma nearly all marrow plasma cells are abnormal (98.7 +/- 8.1%). In monoclonal gammopathy the fraction of abnormal plasma cells was 35.0 +/- 32.8%. In both myeloma and monoclonal gammopathy, the most frequent aberrant phenotypic features consisted of absence of expression of CD19, strong expression of CD56, and decreased intensity of expression of CD38; aberrant expression of CD10, CD20, CD22, or CD28 was observed in less than one-third of myeloma cases. The vast majority of cases had two or more phenotypic aberrations. In the DNA studies, 7% of myeloma cases were biclonal and 93% of cases were monoclonal. In those studies with only one plasma cell mitotic cycle, 37% had normal DNA content and 63% were aneuploid (hyperploid, 61%; hypoploid, 2%). The mean percentages of plasma cells in S- and G2M phases were 4.9 +/- 8.5 and 4.4 +/- 6.9%, respectively. Thirty-eight percent of cases had more than 3% of plasma cells in S phase. In monoclonal gammopathy, the DNA index of abnormal plasma cells ranged from 0.89 to 1.30 and the percentage of diploid (31%) and aneuploid (69%) cases was not different from the results found in myeloma. The differences in percentage of abnormal plasma cells in S- (7.4 +/- 8.6%) and G2M-phases (2.4 +/- 1.7%) in patients with monoclonal gammopathy were not statistically significant.

Long-term clinical and neurophysiological follow-up of patients with peripheral, neuropathy associated with benign monoclonal gammopathy

The incidence of hematological malignancy in patients with monoclonal gammopathy of undetermined significance (MGUS) has been assessed as 17% to 25%. To ascertain whether this is true of neuropathy associated with MGUS, a long-term (5-42 years) retrospective clinical and neurophysiological follow-up was conducted in 50 cases (immunoglobulin M [IgM], n = 38; IgG, n = 11; IgA, n = 1). Only three patients developed hematological malignancy. Of 25 survivors with IgM paraproteinemia, 7 had myelin-associated glycoprotein antibodies with typical clinical features. Evoked distal muscle amplitudes were significantly smaller than for the other paraprotein classes. Preferential distal demyelination manifested by relative prolongation of distal motor latency was not apparent in the cases of long duration. Two patients with IgM antidisialosyl antibodies and cold agglutinating activity had a large fiber neuropathy with intermittent oculofacial involvement. Both responded to intravenous immunoglobulin. Findings in the remaining patients were varied. Recognition of IgM subgroups is important both for prognosis and possible response to treatment.

Cancer risk in patients with monoclonal gammopathy of undetermined significance

To assess the cancer risk of monoclonal gammopathy of undetermined significance (MGUS) we identified 1229 cases of MGUS in the period 1978 to 1993. Data on cancer occurrence in the MGUS cohort were obtained from the Danish Cancer Registry. The expected numbers of cancer cases were calculated from age-, sex-, county-, and period-specific cancer incidence rates. In the MGUS cohort 64 new cancers with a known association with M-components were diagnosed versus 5.0 expected giving a standardized incidence ratio (SIR) of 12.9 (95% confidence interval, 9.9-16.5). The relative risks of developing multiple myeloma (SIR 34.3), Waldenström's macroglobulinemia (SIR 63.8), and non-Hodgkin's lymphoma (SIR 5.9) were significantly increased and independent of time passed from detection of the M-component. The relative risk of chronic lymphocytic leukemia was not significantly increased, SIR 2.7 (0.5-7. 7). Among cancer sites without known association with M-components 141 cases were observed versus 94.6 expected giving a SIR of 1.5 (1. 3-1.8). This enhanced risk was seen for several non-hematological cancer sites but for most cancer sites the risk was dependent on time passed from detection of the M-component, indicating a bias rather than a causal role of MGUS.

Simultaneous analysis of serum immunoglobulins in patients with M protein using cellulose acetate membrane isoelectric focusing

We developed a method for the simultaneous analysis of microheterogeneity of human serum IgG, IgA, IgM, IgD, and IgE, and serum protein pattern using cellulose acetate membrane isoelectric focusing, and analyzed in 11 healthy subjects and 67 patients with M protein (17 cases of multiple myeloma [MM] and 50 cases of monoclonal gammopathy of undetermined significance [MGUS]). Using this method, bands indicating the microheterogeneity of each immunoglobulin could clearly be detected.Among healthy subjects, the detected IgG, IgA, and IgM bands did not vary, but the detected IgE and IgD bands did vary. Therefore, IgA, IgM, and IgG were selected for comparison of serum immunoglobulins in MM and in MGUS. In the IgA-type M protein group, normal IgM and IgG bands were decreased in MM patients compared to MGUS patients, while the M band and other bands were increased in MM patients compared to MGUS patients, but the differences between the two groups were not significant. In the IgG-type M protein group, normal IgM, IgA, and IgG were significantly decreased in MM patients compared to MGUS patients. We examined the changes in electrophoretic pattern in six MM patients and eight MGUS patients with IgA-type M protein after neuraminidase treatment. The width of the M band in MM patients with IgA-type M protein decreased with neuraminidase treatment. On the other hand, the width of the M band in MGUS patients with IgA-type M protein increased with neuraminidase treatment. We concluded that the decrease of the normal immunoglobulins in MM patients with IgG type M protein could be detected by this method, and IgA type of M protein binding sugar chain were different between MM and MGUS patients.

The risk of bacteremia in patients with monoclonal gammopathy of undetermined significance

We estimated the risk of bacteremia in patients with monoclonal gammopathy of undetermined significance (MGUS) compared with the general population; 1237 cases of MGUS were identified by linking information on detected monoclonal components in the North Jutland County with the Danish Cancer Registry. We evaluated the risk of bacteremia in the MGUS cohort during the 13-yr period from 1981 to 1993 by linkage to the Bacteremia Registry in the County. Follow-up for the occurrence of bacteremia started 30 d after detection of the M-component and continued until malignant transformation, death or until 31 December 1993, whichever came first. The expected numbers of bacteremia was based upon county, age, sex and period-specific incidence rates. The median follow-up period was 3.8 yr. Forty episodes of bacteremia occurred during 5500 person-years versus 18 expected. The crude standardized incidence ratio of bacteremia was 2.2 (95% confidence interval, 1.6-3.0). There was no distinct pattern of bacterial etiology in the MGUS cohort. Although we found an association between MGUS and risk of bacteremia, the overall risk is small and this finding hardly affects the clinical handling of MGUS patients.