Retrospective study of monoclonal gammopathies detected in the clinical laboratory of a Spanish healthcare district: 14-year series

Podocytopathy in patients with monoclonal gammopathy: three patients and literature review

BACKGROUND

Renal manifestations of monoclonal gammopathies are of increasing interest among nephrologists. Typical manifestations include light chain cast nephropathy, amyloidosis or renal damage mediated by monoclonal immunoglobulin deposition. Podocytopathies in the setting of an underlying monoclonal gammopathy constitute a rare manifestation of these diseases and, although being described in the literature, remain a challenge since most data derive from case reports.

METHODS

A retrospective review of the clinical data of Hospital del Mar and Hospital Vall d'Hebron was performed to identify patients with minimal change disease (MCD) or focal and segmental glomerulosclerosis (FSGS) in the setting of neoplasms that produce monoclonal (M) protein. Additionally, a literature review on this topic was performed. This study aims to describe the clinical characteristics and outcomes of these patients.

RESULTS

Three patients were identified to have podocytopathy and monoclonal gammopathy between the years 2013 and 2020. All three were males and  >65 years of age. Two patients were diagnosed with MCD and one patient was diagnosed with FSGS. All patients underwent a kidney biopsy and light and electron microscopic studies were performed. The underlying causes of monoclonal gammopathy were multiple myeloma in two cases and Waldeström macroglobulinemia in one case. Two patients developed nephrotic syndrome during the follow-up. All patients were under active hematological treatment. One patient presented a complete remission of proteinuria whereas the other two presented a partial remission.

CONCLUSIONS

Podocytopathies may infrequently be found in patients with monoclonal gammopathies. Patients with overt glomerular proteinuria and hematological disorders with M protein should undergo a kidney biopsy for prompt diagnosis and to specify a prognosis. In addition, further study on this matter must be done to understand the pathophysiology and treat these patients appropriately.

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.

Epidemiological and immunochemical parameters of monoclonal plasma cell dyscrasias of 2121 cases in Algeria

BACKGROUND

Plasma cell dyscrasias (PCD) are a heterogeneous group of diseases characterized by the expansion of monoclonal bone marrow plasma cells that produce a monoclonal immunoglobulin (M-component).

PURPOSE

This is a retrospective study that describes the epidemiological, immunochemical features and etiology of monoclonal gammopathies diagnosed between 1998 and 2016 in the Teaching Hospital Beni-Messous of Algiers.

PATIENTS AND METHODS

2121 cases of monoclonal gammopathies (MG) were collected during this period. Serum/urine protein electrophoresis, serum/urine immunofixation and serum free light chain measurements were used to demonstrate M protein.

RESULTS

The middle age of the patients at the time of the diagnosis were 62.96 ± 13.19 years with extremes ranging from 07 to 99 years. The study included 1013 (47, 76 %) men and 1108 (52, 23 %) women with a sex ratio 0,91. Isotypes repartition was: IgG (60.91 %), IgA (17.91 %), light chain (10.46 %), IgM (6.6 %), IgD (1.03 %) and IgE (0.09 %) of cases. The most frequent diagnosis was: Multiple Myeloma (55.20 %), followed by monoclonal gammopathy of undetermined significance (34.13 %).

CONCLUSION

In our study, two particularities were noted. There is no male predominance in Algerian PCD patients. Moreover, we observed a higher frequency of light chain multiple myeloma and lower frequency of IgM isotype compared to western studies.

Prevalence, clinical aspects, and natural history of IgM MGUS

BACKGROUND

Waldenström macroglobulinemia (WM) and chronic lymphocytic leukemia (CLL) are related B-cell cancers that share several clinical and biological features. Both WM and CLL have associated precursor conditions: monoclonal gammopathy of undetermined significance (MGUS) of immunoglobulin M (IgM) type and monoclonal B-cell lymphocytosis (MBL), respectively. Recently, a case of MBL with an IgM MGUS was reported, suggesting a close biological relationship between these entities. While much is known about MGUS overall, investigations of IgM MGUS specifically have been fragmentary.

METHODS

In this article, we review data on the prevalence, clinical aspects and natural history of IgM MGUS, and focus on identifying gaps in our understanding of the complex relationships among B-cell malignancies and their precursors.

RESULTS

There appears to be marked heterogeneity in the prevalence of IgM MGUS across populations. However, studies have varied in definition, design, laboratory methods, and endpoints. IgM MGUS differs from non-IgM MGUS in certain respects, including prevalence across racial groups, rate of progression, and pattern of malignant outcomes. There are limited data regarding the coincident occurrence of IgM MGUS and MBL.

CONCLUSIONS

Future studies incorporating both protein electrophoresis and flow cytometry are needed to define the underlying spectrum and causes of precursor development, risk factors for progression, and markers that distinguish low- and high-risk precursor patients.