Gammapatía monoclonal de significado incierto / Monoclonal gammopathy of uncertain significance

La gammapatía monoclonal de significado incierto es una neoplasia de células plasmáticas premaligna, con una elevada prevalencia en la población mayor de 50 años, y un riesgo anual de progresión del 1%. Numerosos estudios recientes han permitido un avance en la compresión de la patogenia de estos trastornos y su riesgo de progresión a otras enfermedades. Los pacientes requieren un seguimiento de por vida, siendo fundamental un enfoque multidisciplinar y adaptado al riesgo. En los últimos años, cada vez se reconocen más entidades asociadas a la presencia de una paraproteína, conocidas como gammapatías monoclonales de significado clínico (AU)

Monoclonal gammopathy of uncertain significance is a premalignant plasma cell neoplasm with a high prevalence in the population over 50 years of age and an annual risk of progression of 1%. Multiple recent studies have led to advances in understanding both the pathogenesis of these disorders and their risk of progression to other diseases. Patients require lifelong follow-up, and a multidisciplinary and risk-adapted approach is essential. In recent years, an increasing number of entities associated with a paraprotein, known as clinically significant monoclonal gammopathies, have been recognized (AU)

Efficacy of Antiviral Treatment in Hepatitis C Virus (HCV)-Driven Monoclonal Gammopathies Including Myeloma.

Multiple myeloma (MM) remains an incurable plasma cell malignancy. While its origin is enigmatic, an association with infectious pathogens including hepatitis C virus (HCV) has been suggested. Here we report nine patients with monoclonal gammopathy of undetermined significance (MGUS) or MM with previous HCV infection, six of whom received antiviral treatment. We studied the evolution of the gammopathy disease, according to anti-HCV treatment and antigen specificity of purified monoclonal immunoglobulin, determined using the INNO-LIA™ HCV Score assay, dot-blot assays, and a multiplex infectious antigen microarray. The monoclonal immunoglobulin from 6/9 patients reacted against HCV. Four of these patients received antiviral treatment and had a better evolution than untreated patients. Following antiviral treatment, one patient with MM in third relapse achieved complete remission with minimal residual disease negativity. For two patients who did not receive antiviral treatment, disease progressed. For the two patients whose monoclonal immunoglobulin did not react against HCV, antiviral treatment was not effective for MGUS or MM disease. Our results suggest a causal relationship between HCV infection and MGUS and MM progression. When HCV was eliminated, chronic antigen-stimulation disappeared, allowing control of clonal plasma cells. This opens new possibilities of treatment for MGUS and myeloma.

Immunoglobulin light-chain toxicity in a mouse model of monoclonal immunoglobulin light-chain deposition disease.

Light chain (LC) deposition disease (LCDD) is a rare disorder characterized by glomerular and peritubular amorphous deposits of a monoclonal immunoglobulin LC, leading to nodular glomerulosclerosis and nephrotic syndrome. We developed a transgenic model using site-directed insertion of the variable domain of a pathogenic human LC gene into the mouse immunoglobulin κ locus, ensuring its production by all plasma cells (PCs). High free LC levels were achieved after backcrossing with mice presenting increased PC differentiation and no immunoglobulin heavy chain production. Our mouse model recapitulates the characteristic features of LCDD, including progressive glomerulosclerosis, nephrotic-range proteinuria, and finally kidney failure. The variable domain of the LC bears alone the structural properties involved in its pathogenicity. RNA sequencing conducted on PCs demonstrated that LCDD LC induces endoplasmic reticulum stress, likely accounting for the high efficiency of proteasome inhibitor-based therapy. Accordingly, reduction of circulating pathogenic LC was efficiently achieved and not only preserved renal function but also partially reversed kidney lesions. Finally, transcriptome analysis of presclerotic glomeruli revealed that proliferation and extracellular matrix remodeling represented the first steps of glomerulosclerosis, paving the way for future therapeutic strategies in LCDD and other kidney diseases featuring diffuse glomerulosclerosis, particularly diabetic nephropathy.

A case of proliferative glomerulonephritis with immunoglobulin A1-lambda deposits successfully treated by chemotherapy.

A 74-year-old man presented with nephrotic syndrome and kidney insufficiency. Laboratory tests revealed monoclonal gammopathy of immunoglobulin A-lambda. Renal biopsy revealed diffuse mesangial proliferation and double-contoured basement membranes. Immunofluorescent analyses showed granular deposition of immunoglobulin A and C3 at the capillary walls and mesangial regions. Immunohistochemistry suggested monoclonal deposition of immunoglobulin A1-lambda. Electron microscopic analyses showed finely granular electron-dense deposits at mesangial and subendothelial areas. These findings suggested immunoglobulin A-type proliferative glomerulonephritis with monoclonal immunoglobulin deposits. Based on the results of bone marrow aspiration, multiple myeloma was diagnosed. Because the renal manifestation was considered to be affected by monoclonal gammopathy, chemotherapy was initiated rather than immunomodulatory therapy. Although bortezomib and dexamethasone proved ineffective, second chemotherapy with elotuzumab, lenalidomide, and dexamethasone was successful, and kidney function recovered. Effective treatments for proliferative glomerulonephritis with monoclonal immunoglobulin deposits have not been established. This represents the first description of a patient successfully treated for proliferative glomerulonephritis with monoclonal immunoglobulin deposits by chemotherapy using elotuzumab.

Post-transplant Monoclonal Gammopathy of Renal Significance: A Case Series.

Monoclonal gammopathy of renal significance (MGRS) is a new concept with evolving evidence for treatment. MGRS in the transplant kidney is a rare cause of renal transplant dysfunction that can lead to graft loss. Most cases of post-transplant MGRS are due to recurrent disease. Clone-specific chemotherapy is required to target the underlying clone, and this may improve graft survival; however, this can be challenging, as most patients are elderly with age-related comorbidities and may have complications associated with increasing immunosuppression. Here, we report 3 cases of renal allograft MGRS, and each case highlights different challenges in the diagnosis and management of this condition.

Hypercarotenemia / Hipercarotenemia

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An update to the pathogenesis for monoclonal gammopathy of renal significance.

Monoclonal gammopathy of renal significance (MGRS) is characterized by the nephrotoxic monoclonal immunoglobulin secreted by an otherwise asymptomatic or indolent B cell or plasma cell clone, without hematologic criteria for treatment. These MGRS-associated diseases can involve one or more renal compartments, including glomeruli, tubules, and vessels. Hydrophobic residue replacement, N-glycosylated, increase in isoelectric point in monoclonal immunoglobulin (MIg) causes it to transform from soluble form to tissue deposition, and consequently resulting in glomerular damage. In addition to MIg deposition, complement deposition is also found in C3 glomerulopathy with monoclonal glomerulopathy, which is caused by an abnormality of the alternative pathway and may involve multiple factors including complement component 3 nephritic factor, anti-complement factor auto-antibodies, or MIg which directly cleaves C3. Furthermore, inflammatory factors, growth factors, and virus infection may also participate in the development of the diseases. In this review, for the first time, we discussed current highlights in the mechanism of MGRS-related lesions.

A Multicenter Cross-Sectional Study and Systematic Review of Necrobiotic Xanthogranuloma With Proposed Diagnostic Criteria.

Importance: Necrobiotic xanthogranuloma (NXG) is a non-Langerhans cell histiocytosis classically associated with paraproteinemia attributable to plasma-cell dyscrasias or lymphoproliferative disorders. Despite the morbidity of NXG, the literature is limited to case reports and small studies, and diagnostic criteria are lacking. Objective: To evaluate the characteristics of NXG and propose diagnostic criteria. Design, Setting, and Participants: This multicenter cross-sectional study was conducted at tertiary academic referral centers and followed by a systematic review and a consensus exercise. The multicenter cohort included patients with NXG diagnosed at the Brigham and Women's and Massachusetts General Hospitals (2000-2018), the University of Iowa Hospitals and Clinics (2000-2018), and the University of Pennsylvania Health System (2008-2018). The systematic review was conducted in 2018 and included patients with NXG identified in the Cochrane, Ovid EMBASE, PubMed, and Web of Science databases. The consensus exercise was conducted by 8 board-certified dermatologists to identify diagnostic criteria. Main Outcomes and Measures: Demographic factors, comorbidities, clinical features, and treatment response. Results: Of 235 included patients with NXG (34 from the multicenter cohort and 201 from the systematic review results), the mean (SD) age at presentation was 61.6 (14.2) years; 147 (62.6%) were female. Paraproteinemia was detected in 193 patients (82.1%), most often IgG-κ (117 patients [50.0%]). A malignant condition was detected in 59 patients (25.1%), most often multiple myeloma (33 patients [14.0%]). The overall rate of paraproteinemia and/or a malignant condition was 83.8% (197 patients). In the multicenter cohort, evolution of paraproteinemia into multiple myeloma was observed up to 5.7 years (median [range], 2.4 [0.1-5.7] years) after NXG presentation. Cutaneous lesions consisted of papules, plaques, and/or nodules, typically yellow or orange in color (113 of 187 [60.4%]) with a periorbital distribution (130 of 219 [59.3%]). The eye was the leading site of extracutaneous involvement (34 of 235 [14.5%]). In the multicenter cohort, intravenous immunoglobulin had the best treatment response rate (9 of 9 patients [100%]), followed by antimalarial drugs (4 of 5 patients [80%]), intralesional triamcinolone (6 of 8 patients [75%]), surgery (3 of 4 patients [75%]), chemotherapy (8 of 12 patients [67%]), and lenalidomide or thalidomide (5 of 8 patients [63%]). The consensus exercise yielded 2 major criteria, which were (1) clinical and (2) histopathological features consistent with NXG, and 2 minor criteria, consisting of (1) paraproteinemia, plasma-cell dyscrasia, and/or other associated lymphoproliferative disorder and (2) periorbital distribution of cutaneous lesions. In the absence of foreign body, infection, or another identifiable cause, fulfillment of both major and at least 1 minor criterion were proposed to establish the diagnosis of NXG. Conclusions and Relevance: Necrobiotic xanthogranuloma is a multisystem disorder associated with paraproteinemia and malignant conditions. The proposed diagnostic criteria may advance clinical research and should be validated.

Schnitzler's syndrome: A female elderly case presenting intractable non-pruritic febrile urticarial rush.

Schnitzler's syndrome is an acquired autoinflammatory disease characterized by chronic urticarial rash and monoclonal gammopathy (predominantly IgM type). A 75-year-old Japanese woman complained of high fever and non-pruritic urticarial rash appearing almost every day for 3 years. Her abnormal laboratory data included leukocytosis and neutrophilia with elevated erythrocyte sedimentation rate and C-reactive protein level. Hyperglobulinemia of IgA and IgM was also noted. Histological analysis revealed perivascular and interstitial neutrophilic infiltration without any signs of vasculitis. Immunofixation analysis confirmed IgM-kappa-type monoclonal gammopathy. Oral prednisolone initially improved her symptoms, but recurrence was observed upon its tapering. The addition of colchicine successfully controlled her symptoms and allowed a reduction in the dose of systemic steroid.

Henoch-Schönlein purpura nephritis associated with monoclonal gammopathy of renal significance: a case report.

Monoclonal gammopathy of renal significance (MGRS) can present with different morphologic features and lead to kidney failure. The Henoch-Schönlein purpura nephritis (HSPN) that cannot be relieved by treatment with glucocorticoid and immunosuppressive agents suggests the presence of monoclonal gammopathy in adult patients. The present study reports on a single case of HSPN associated with IgA-κMGRS. The patient who suffered from recurrent skin purpura for 6 months and nephrotic syndrome for 2 months was admitted to our hospital. Bone marrow biopsy showed monoclonal gammopathy of undetermined significance. Kidney biopsy indicated a Henoch-Schönlein purpura nephritis (HSPN, ISKDC classified as type III) with positive staining with κ-light chain in the glomeruli and renal tubular epithelial cells. Furthermore, skin biopsy showed leukocytoclastic vasculitis and negative staining for Congo red and light chain. Given both the renal and cutaneous involvement, the patient was considered to have HSPN associated with IgA-κMGRS. The patient experienced an exacerbation in his purpura-like lesions and clinical status after treatment with glucocorticoid and immunosuppressive agents. Consequently, the patient was put on a regimen that included dexamethasone (20 mg on the 1st, 4th, 8th, and 11th days of each month, iv) and bortezomib (2.4 mg on the 1st, 4th, 8th, and 11th days of each month, iv). Eight weeks after treatment, he had complete resolution of his cutaneous purpura and his biochemical parameters improved. The latent presence of MGRS in cases of HSPN should be considered in adult patients. Increased cognizance and correct treatment options could improve patient outcomes.

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.

Epstein-Barr Virus and Monoclonal Gammopathy of Clinical Significance in Autologous Stem Cell Transplantation for Multiple Sclerosis.

INTRODUCTION: Autologous hematopoietic stem cell transplantation (AHSCT) with anti-thymocyte globulin (ATG) conditioning as treatment of active multiple sclerosis (MS) is rapidly increasing across Europe (EBMT registry data 2017). Clinically significant Epstein-Barr virus reactivation (EBV-R) following AHSCT with ATG for severe autoimmune conditions is an underrecognized complication relative to T-cell deplete transplants performed for hematological diseases. This retrospective study reports EBV-R associated significant clinical sequelae in MS patients undergoing AHSCT with rabbit ATG. METHODS: Retrospective data were analyzed for 36 consecutive MS-AHSCT patients at Kings College Hospital, London. All patients routinely underwent weekly EBV DNA polymerase chain reaction monitoring and serum electrophoresis for monoclonal gammopathy (MG or M-protein). EBV-R with rising Epstein-Barr viral load, M-protein, and associated clinical sequelae were captured from clinical records. RESULTS: All patients had evidence of rising EBV DNA-emia, including 7 who were lost to long-term follow-up, with a number of them developing high EBV viral load and associated lymphoproliferative disorder (LPD). Nearly 72% (n = 18/29) developed de novo MG, some with significant neurological consequences with high M-protein and EBV-R. Six patients required anti-CD20 therapy (rituximab) with complete resolution of EBV related symptoms. Receiver operating characteristics estimated a peak EBV viremia of >500 000 DNA copies/mL correlated with high sensitivity (85.5%) and specificity (82.5%) (area under the curve: 0.87; P = .004) in predicting EBV-R related significant clinical events. CONCLUSION: Symptomatic EBV reactivation increases risk of neurological sequelae and LPD in MS-AHSCT. We recommend regular monitoring for EBV and serum electrophoresis for MG in MS patients in the first 3 months post-AHSCT.

Cast nephropathy associated with monoclonal immunoglobulin M-secreting mucosa-associated lymphoid tissue B-cell lymphoma
.

The kidney is among the various anatomical sites involved in mucosa-associated lymphoid tissue (MALT) lymphoma. A variety of renal pathological types, including membranous glomerulopathy, membranoproliferative glomerulonephritis, crescentic IgA nephropathy, minimal change disease, and cryoglobulinemic glomerulopathy, have been reported in MALT lymphoma patients. However, cast nephropathy is extremely rare in MALT lymphoma. Herein, we describe the case of a patient with a history of MALT lymphoma of the stomach and small intestine 7 years before presenting with acute kidney failure 1 year after chemotherapy cessation. Monoclonal IgM-λ was detected in the serum, and kidney biopsy showed λ light chain deposition-based cast nephropathy. In addition, MALT recurrence was discovered in the stomach rather than intestinal tissue by gastrointestinal endoscope, and no lymphoplasmacytic infiltration was found in bone marrow. After 1 year of chemotherapy, renal function was partially restored, and the level of serum λ chain, serum IgM, and 24-hour urine protein all decreased. Our case illustrates that MALT lymphoma is prone to recurrence and grows slowly, moreover, with the characteristic of monoclonal immunoglobulin production and kidney infiltration.

Tres casos de gammapatía monoclonal de significado renal postrasplante renal: nefropatía c3 de novo / Three cases of monoclonal gammopathy of renal significance after kidney transplantation. De novo C3 glomerulopathy

La gammapatía monoclonal de significado renal incluye todas las enfermedades renales causadas por una inmunoglobulina monoclonal secretada por un clon de célula B no maligno. Por definición, los pacientes con gammapatía monoclonal de significado renal no cumplen criterios de mieloma múltiple y la alteración hematológica es generalmente considerada gammapatía monoclonal de significado incierto. No obstante, la dolencia que pueden causar a nivel renal puede ser importante, requiriendo un tratamiento específico. El espectro de la gammapatía monoclonal de significado renal es amplio, incluyendo una entidad reciente como la nefropatía C3. El desarrollo de una nefropatía C3 en el contexto de una gammapatía monoclonal de significado renal tras el trasplante renal no es frecuente y hasta el momento ha sido poco descrita. A continuación presentamos 3 casos de nefropatía C3 asociados a una gammapatía monoclonal de aparición de novo tras el trasplante renal

Monoclonal gammopathy of renal significance includes all renal disorders caused by a monoclonal immunoglobulin secreted by a non-malignant B-cell clone. Patients with MGRS do not, by definition, meet criteria for multiple myeloma, with haematological disorders generally considered to be monoclonal gammopathy of undetermined significance. Nevertheless, the renal involvement can be serious and require specific treatment. Monoclonal gammopathy of renal significance is associated with a wide spectrum of disorders, including the recently discovered C3 glomerulopathy. Development of C3 glomerulopathy in the context of monoclonal gammopathy of renal significance after kidney transplantation is uncommon and very few cases have been published to date. We report on three cases of C3 glomerulopathy in the context of de novo monoclonal gammopathy after kidney transplantation

[Free light chains assay: Indications and methods]. / Dosage des chaînes légères libres : indications et méthodes.

Serum free light chains (sFLC) assay is an important marker in plasma cell dyscrasia. It is thus recommended for the diagnosis of monoclonal gammopathy, together with serum protein electrophoresis and immunofixation. sFLC assay has also a prognostic value and is a criterion for treatment response and relapse of some monoclonal gammopathies. Three assays are currently available in France, the gold standard being the Freelite® assay, the two others requiring further validation. These three assays are not interchangeable during patient's follow-up. The Freelite® assay is integrated in the myeloma diagnostic criteria from the International Myeloma Working Group 2014, and has a higher sensitivity than Bence Jones protein test for diagnosis, treatment response and follow-up of light chain myeloma. The Freelite® assay is the main marker of therapeutic response in light chain amyloidosis and allows to stratify the risk for progression in monoclonal gammopathy of undetermined significance. Some studies have also shown its value in diagnosis of multiple sclerosis and in screening for monoclonal gammopathy in the cases of acute renal failure. The Freelite® assay is then currently essential in myeloma or amyloidosis, and could be soon extended to the management of autoimmune diseases.