Light chain deposition disease with renal involvement: clinical characteristics and prognostic factors

Translocation (11;14) is a common cytogenetic abnormality in clonal plasma cells in monoclonal immunoglobulin deposition disease

Monoclonal Immunoglobulin deposition disease (MIDD) is characterised by deposits of intact monoclonal light chains in the kidney leading to renal dysfunction. In this study, we retrospectively investigated the underlying plasma cell cytogenetic abnormalities in MIDD. CyclinD1 (11;14) translocation was identified in 12/27 (45%) patients. Among the patients without translocation, del13q and hyperdiploidy were the most common abnormalities. Patients in the non-t (11;14) group had a higher baseline light-chain ratio, higher proteinuria and lower eGFR as compared to patients with t (11;14). Haematological VGPR or higher was seen in 58% of t (11;14), and 30% without t (11;14), possibly related to higher use of Daratumumab-based therapy in the t (11;14) group. With a median follow-up of 750 days, 30% (8/24) progressed to end stage renal disease (ESRD). eGFR <20 mL/min (HR 25, 95% CI 2.09-298, p = 0.01) and 24 urine protein >3 g/24 h (HR 9, 95% CI 1.27-63.90, p = 0.02) at diagnosis were significantly associated with progression to ESRD. Renal survival was better in t (11;14) as compared to the non-t (11;14) group (HR 0.11, p = 0.06). Translocation (11;14) is a common abnormality in MIDD and affects the presentation and outcomes. Identification of this abnormality should lead to exploration of BCL2 inhibitors in this disease.

Light chain deposition disease: pathogenesis, clinical characteristics and treatment strategies

Light chain deposition disease (LCDD) is a rare hematologic disorder characterized by the deposition of non-amyloid monoclonal light chains in several organs. Together with renal impairment is being the primary morbidity associated with this disease. Due to its rarity, randomized clinical trials lack to explore treatment strategies and there are no approved or universally accepted standard of care treatment options. We aimed to provide a systematic summary of histological and clinical aspects of LCDD and treatment options of available literature therapies strategies. Currently, drugs used to treat multiple myeloma are recommended when LCDD patients also presented multiple myeloma. Anyway, in patients with LCDD that is not associated to multiple myeloma, haematopoietic stem cell transplantation (ASCT) and chemotherapy with thalidomide, dexamethasone, bortezomib are also recommended. In eligible patients, bortezomib-based chemotherapy followed by ASCT appears to be an effective treatment option with durable hematologic remission and organ responses. Although it appears that the patients undergoing ASCT seem to achieve deeper and durable hematologic remissions and organ responses, no statistically significant superiority can be demonstrated over non-transplant or standard chemotherapy-based approaches. As retrieved by our review, bortezomib-based therapy appears to be favorable strategy as long as no dose modification is required for renal impairment, and early hematologic responses as a recovery of renal function. Encouraging data were also demonstrated by treatment lenalidomide or melpalan based. Moreover, new myeloma treatment strategies, as monoclonal antibody Daratumumab, seem to be effective in LCDD. Instead, renal allograft is not recommended, due to high incidence of relapse.

Multimodal Imaging of Bilateral Retinal Pigment Epithelial Immunoglobulin Light Chain Deposition in Patients with Systemic Immunoglobulin Light Chain Deposition

OBJECTIVE

To describe multimodal imaging of peculiar bilateral globular subretinal deposits and acquired serous retinal detachment in patients with systemic immunoglobulin light chain deposition.

DESIGN

A retrospective observational case series.

PARTICIPANTS

We examined 6 eyes in 3 patients (1 with multiple myeloma, 1 with membranous nephropathy, and 1 with immunoglobulin A nephropathy) at the Eye and ENT Hospital of Fudan University. The patients presented with peculiar globular subretinal deposits along the retinal pigment epithelium (RPE)‒Bruch's membrane complex and acquired serous retinal detachment.

METHODS

Fundus appearance was documented with multimodal imaging, which included fundus photography, fundus autofluorescence, spectral domain OCT, swept-source OCT (SS-OCT), en face OCT, and SS-OCT angiography. Additional evaluations included serum protein electrophoreses, positron emission tomography computed tomography, and renal and bone biopsies to assess the primary diseases.

MAIN OUTCOME MEASURES

Multimodal imaging, course, and prognosis of bilateral RPE immunoglobulin light chain deposition in patients with systemic immunoglobulin light chain deposition.

RESULTS

Bilateral, multiple, speckled, or patchy RPE changes in the posterior fundus that corresponded to striking multifocal hyperautofluorescence on fundus autofluorescence and lumpy, globular hyperreflective deposits along the RPE‒Bruch's membrane complex were identified as characteristic features of bilateral RPE light chain deposition. These features may be accompanied by dense light chain deposits in the choriocapillaris and choroid vessels, diffuse choroidal thickening, and "angiographically silent" serous retinal detachment in patients with systemic immunoglobulin light chain deposition.

CONCLUSIONS

We have documented the characteristic features, clinical course, and prognosis of bilateral RPE immunoglobulin light chain deposition in patients with systemic immunoglobulin light chain deposition. Appropriate evaluations, including serum protein electrophoresis and hematologic consultation, are recommended to manage patients with this fundus abnormality.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Light chain only variant of proliferative glomerulonephritis with monoclonal immunoglobulin deposits: a clinicopathological study of three cases

AIMS

To explore the clinical and pathological features of light chain only variant of proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID-LC).

METHODS

From January 2010 to December 2022, patients who were diagnosed with PGNMID-LC were selected, and their clinical and pathological features were retrospectively analysed.

RESULTS

Three males aged 42-61 years old were enrolled. Hypertension was present in three patients, oedema in three patients, anaemia in two patients, proteinuria in three patients, nephrotic syndrome in one patient, microscopic haematuria in three patients, renal insufficiency in two patients and hypocomplementaemia of C3 in one patient. Elevated serum-free LC ratios and plasmacytosis on bone marrow smears were observed in three patients, and κ was identified by serum protein immunofixation electrophoresis in one patient. Renal biopsy showed membranoproliferative glomerulonephritis in two patients and endocapillary proliferative glomerulonephritis in one patient on light microscopy. Immunofluorescence indicated restricted κ LC and C3 distributed in glomeruli. By electron microscopy, electron-dense deposits without substructure were identified predominantly in the mesangial and subendothelial regions and were variable in the subepithelial region. Two patients were treated with plasma cell-directed chemotherapy and achieved haematological complete response or very good partial response, and one of them achieved a renal status of complete remission. One patient treated with immunosuppressive therapy only did not achieve haematological or renal remission.

CONCLUSIONS

PGNMID-LC is a rare and uniform disease with a high frequency of a detectable pathogenic plasma cell clone and is characterised by glomerular deposition of restricted LC and C3 in renal pathology. Plasma cell-directed chemotherapy may improve haematological and renal prognosis.

Light chain deposition disease presenting with gastrointestinal disorder as primary manifestation: report of two cases and literature review

Light chain deposition disease (LCDD) is an under-recognized condition characterized by deposition of abnormal monoclonal light chains in tissues, leading to organ dysfunction. LCDD involving the gastrointestinal tract is very uncommon, and its diagnosis is challenging. We herein report two cases of LCDD that manifested as inflammatory bowel disease-like symptoms and protein-losing gastroenteropathy. Both patients were women in their early 60s. Tissue biopsies from the gastrointestinal mucosa demonstrated extracellular deposits, which were negative by Congo red staining but positive for κ-light chain by immunohistochemistry. The recent literature on LCDD was reviewed. When patients unexpectedly show extracellular deposits in gastrointestinal biopsy specimens, evaluation of immunoglobulin chains is recommended for diagnosis of LCDD after systemic amyloidosis has been excluded.

Monoclonal Gammopathy of Renal Significance with Deposits of Infrequent Morphology: Two Case Reports of Light and Heavy Chain Deposition Disease with Atypical Presentation and Literature Review

BACKGROUND

Monoclonal immunoglobulin deposition disease (MIDD) includes three entities: light chain deposition disease (LCDD), heavy chain deposition disease (HCDD) and light and heavy chain deposition disease (LHCDD). The renal presentation can manifest with varying degrees of proteinuria and/or nephrotic syndrome, microhematuria, and often leads to end-stage renal disease. Given the rarity of LHCDD, therapeutic approaches for this condition remain inconclusive, as clinical trials are limited.

CASE PRESENTATION

We report two male patients with underlying monoclonal gammopathy of renal significance (MGRS) associated with LHCDD lesions. Both cases had non-nephrotic proteinuria, moderately impaired renal function, and normal levels of C3 and C4. Light microscopy of the renal biopsies in both patients did not show lesions of nodular glomerulosclerosis. Immunofluorescence showed a staining pattern with interrupted linear IgA-κ in patient #1 and IgA-λ in patient #2 only along the glomerular basement membrane (GBM). Electron microscopy of patient #1 revealed electrodense deposits in the subendothelial and mesangial areas only along the GBM.

DISCUSSION

In this case series, we discuss the clinical, analytical, and histopathological findings of two rare cases of LHCDD. Both patients exhibited IgA monoclonality and were diagnosed with monoclonal gammopathy of undetermined significance (MGUS) by the hematology department at the time of renal biopsy. Treatment with steroids and cytotoxic agents targeting the clone cells responsible for the deposition disease resulted in a favorable renal and hematologic response.

Lymphangioleiomyomatosis and Other Cystic Lung Diseases

Cysts and cavities in the lung are commonly encountered on chest imaging. It is necessary to distinguish thin-walled lung cysts (≤2 mm) from cavities and characterize their distribution as focal or multifocal versus diffuse. Focal cavitary lesions are often caused by inflammatory, infectious, or neoplastic processes in contrast to diffuse cystic lung diseases. An algorithmic approach to diffuse cystic lung disease can help narrow the differential diagnosis, and additional testing such as skin biopsy, serum biomarkers, and genetic testing can be confirmatory. An accurate diagnosis is essential for the management and disease surveillance of extrapulmonary complications.

Plasma cell myeloma initially diagnosed as light-chain deposition disease on liver biopsy: A case report and literature review

RATIONALE

Light-chain deposition disease (LCDD) is a rare condition characterized by the abnormal deposition of monoclonal light chains (LCs) in multiple organs, leading to progressive organ dysfunction. Herein, we report a case of plasma cell myeloma initially diagnosed as LCDD on liver biopsy performed for prominent cholestatic hepatitis.

PATIENT CONCERNS

A 55-year-old Korean man complained of dyspepsia as the main symptom. On abdominal computed tomography performed at another hospital, the liver showed mildly decreased and heterogeneous attenuation with mild periportal edema. Preliminary liver function tests revealed abnormal results. The patient was treated for an unspecified liver disease; however, his jaundice gradually worsened, prompting him to visit our outpatient hepatology clinic for further evaluation. Magnetic resonance cholangiography revealed liver cirrhosis with severe hepatomegaly of unknown cause. A liver biopsy was performed for the diagnosis. Hematoxylin and eosin staining revealed diffuse extracellular amorphous deposits in perisinusoidal spaces with compressed hepatocytes. The deposits, which morphologically resembled amyloids, were not stained by Congo red but stained strongly positive for kappa LCs and weakly positive for lambda LCs.

DIAGNOSES

Therefore, the patient was diagnosed with LCDD. Further systemic examination revealed a plasma cell myeloma.

INTERVENTIONS

Fluorescence in situ hybridization, cytogenetics, and next-generation sequencing tested in bone marrow showed no abnormalities. The patient initially received bortezomib/lenalidomide/dexamethasone as the treatment regimen for plasma cell myeloma.

OUTCOMES

However, he died shortly thereafter because of coronavirus disease 2019 complications.

LESSONS

This case demonstrates that LCDD may present with sudden cholestatic hepatitis and hepatomegaly, and may be fatal if patients do not receive appropriate and timely treatment because of delayed diagnosis. Liver biopsy is useful for the diagnosis of patients with liver disease of unknown etiology.

Monoclonal gammopathy of renal significance: Multidisciplinary approach to diagnosis and treatment

Monoclonal gammopathy of renal significance (MGRS) is a hemato-nephrological term referring to a heterogeneous group of kidney disorders characterized by direct or indirect kidney injury caused by a monoclonal immunoglobulin (MIg) produced by a B cell or plasma cell clone that does not meet current hematologic criteria for therapy. MGRS-associated kidney diseases are diverse and can result in the development of end stage kidney disease (ESKD). The diagnosis is typically made by nephrologists through a kidney biopsy. Many distinct pathologies have been identified and they are classified based on the site or composition of the deposited Mig, or according to histological and ultrastructural findings. Therapy is directed towards the identified underlying clonal population and treatment decisions should be coordinated between hematologists and nephrologists in a multidisciplinary fashion, depend on the type of MGRS, the degree of kidney function impairment and the risk of progression to ESKD.

A Case of Light Chain Deposition Disease Leading to Acute Liver Failure and Review of Literature

Light chain deposition disease (LCDD) is a monoclonal immunoglobulin deposition disease characterized by light chain deposition in soft tissues and viscera, causing systemic organ dysfunction with an underlying lymphoproliferative disorder. While the kidney is the most affected organ, cardiac and hepatic involvement is also seen with LCDD. Hepatic manifestation can range from mild hepatic injury to fulminant liver failure. Herein, we are presenting a case of an 83-year-old woman with a monoclonal gammopathy of undetermined significance (MGUS), who presented to our institution with acute liver failure progressing to circulatory shock and multiorgan failure. After an extensive workup, a diagnosis of hepatic LCDD was determined. In conjunction with the hematology and oncology department, chemotherapy options were discussed, but given her poor prognosis, the family decided to pursue a palliative route. Though establishing a prompt diagnosis is important for any acute condition, the rarity of this condition, along with paucity of data, makes timely diagnosis and treatment challenging. The available literature shows variable rates of success with chemotherapy for systemic LCDD. Despite chemotherapeutic advances, liver failure in LCDD indicates a dismal prognosis, where further clinical trials are difficult owing to the low prevalence of the condition. In our article, we will also be reviewing previous case reports on this disease.

Dyspnea and cough in a 68-year-old female with light chain deposition disease

Light chain deposition disease (LCDD) is a rare hematologic disorder characterized by non-amyloid monoclonal immunoglobulin light chain deposition in multiple organs. Pulmonary LCDD (PLCDD) is an uncommon manifestation of LCDD usually seen in middle-aged patients presenting with radiologic cystic and nodular findings. We report the case of a 68-year-old female who presented with shortness of breath and atypical chest pain. Chest computerized tomography (CT) scan revealed numerous diffuse but basilar predominant pulmonary cysts and mild bronchiectasis without nodular disease. Given concomitant abnormal renal function and hepatic laboratory indices, she underwent biopsy of both organs confirming the presence of LCDD. Directed chemotherapy was initiated and stabilized renal and hepatic progression, but on follow-up imaging, pulmonary disease appeared worse. While therapeutic options targeting other organ involvement are available, their directed efficacy for progressive lung disease is not well known.

Clinicopathologic characteristics and prognostic analysis of monoclonal gammopathy of renal significance (MGRS) in patients with IgM monoclonal gammopathy: a case series

Monoclonal gammopathy has emerged as an important cause of renal injury. Since the clinicopathologic features related to monotypic monoclonal gammopathy of renal significance with IgM monoclonal gammopathy (IgM-MGRS) are poorly described and it is uncertain if intervention improves renal survival and mortality, we report a series of such patients, characterizing their clinicopathologic spectrum and outcomes. We retrospectively analyzed 38 patients referred to one medical center between 2009 and 2019 with detectable serum monoclonal IgM by immunofixation, performance of a bone marrow biopsy and kidney biopsy-proven MGRS. Of the 38 patients identified, about half patients were amyloidosis, followed by cryoglobulinemic glomerulonephritis. Patients were divided into two groups on the basis of their kidney pathology: amyloid and non-amyloid. Patients with non-amyloidosis were more likely to have renal dysfunction, hematuria, anemia and hypocomplementemia and κ light chain was predominant in this sub-group. Amyloid patients were more often treated with chemotherapy than the non-amyloid patients (P = 0.002). There were no significant differences between amyloid and non-amyloid patients in mortality (48% vs 29%, P = 0.467) and incidence of ESRD (19% vs 59%, P = 0.103). The incidence of ESRD was lower in patients treated with chemotherapy and/or ASCT, compared to those without chemotherapy (25% vs 57%, P = 0.049), and it was also lower in the hematologic responders than non-responders (10% vs 40%, P = 0.047). Our study confirmed a diverse variety of clinicopathological features and outcomes in patients with IgM-MGRS. Chemotherapy and/or ASCT and deep hematologic responses might improve renal prognosis.

Monoclonal gammopathy of renal significance (MGRS): Real-world data on outcomes and prognostic factors

Monoclonal gammopathy of renal significance (MGRS) is a recognized clinical entity. Literature regarding treatment and its outcomes in MGRS is sparse due to the rarity and misdiagnosis of MGRS. We retrospectively analyzed 280 adults with an MGRS diagnosis from 2003 to 2020 across 19 clinical centers from 12 countries. All cases required renal biopsy for the pathological diagnosis of MGRS. Amyloidosis‐related to MGRS (MGRS‐A) was present in 180 patients; nonamyloidosis MGRS (MGRS‐NA), including a broad spectrum of renal pathologies, was diagnosed in 100 patients. The median overall survival in the studied cohort was 121.0 months (95% CI: 105.0–121.0). Patients with MGRS‐A had a shorter overall survival than patients with MGRS‐NA (HR = 0.41, 95%CI: 0.25–0.69; p = 0.0007). Both hematologic and renal responses were associated with longer survival. Achievement of ≥VGPR was generally predictive of a renal response (OR = 8.03 95%CI: 4.04–115.96; p < 0.0001), one‐fourth of patients with ≥VGPR were renal nonresponders. In MGRS‐A, factors associated with poor prognosis included elevated levels of creatinine, beta‐2‐microglobulin, and hemodialysis at diagnosis. In MGRS‐NA, only age >65 years was associated with increased risk of death. Treatments provided similar hematologic response rates in both types of MGRS. Autologous stem cell transplantation led to better response than other treatments. This multicenter and international effort is currently the largest report on MGRS.

Light Chain Deposition Disease: A Morphological Case Report

Light chain deposition disease (LCDD) is a rare condition associated with the overproduction and deposition of monoclonal light chain immunoglobulins. The kidneys are universally affected in LCDD, with the development of renal failure with nephrotic syndrome, microscopic hematuria, and proteinuria. Most cases are associated with a plasma cell neoplasm (multiple myeloma or plasmacytoma) or other lymphoproliferative disorders, with a reasonable number of cases also being idiopathic. Other organs can be affected in rare cases, without producing significant symptoms, predominantly the liver and heart. In this report, we discuss a case of a 72-year-old female presenting with the aforementioned symptoms. Percutaneous ultrasound-guided kidney biopsy revealed nodular sclerosis with periodic acid-Schiff stain (PAS)-positive, Congo red-negative, silver impregnation weakly-positive, and Masson's trichrome-positive (red reaction) deposits with ribbon-like changes together with light chain deposits in the tubular basement membranes. As LCDD was diagnosed, the patient was subjected to further tests, with multiple myeloma of the thoracic vertebrae also being diagnosed. The patient was started on myeloma treatment; however, she subsequently developed a severe lower limb infection that required amputation, after which she developed sepsis and expired.

Light chain deposition disease masquerading as smoking-associated nodular glomerulosclerosis with deposits identified by electron microscopy only

Light chain deposition disease (LCDD) is a form of monoclonal gammopathy of renal significance. The diagnosis is based on the immunofluorescence (IF) findings of linear monoclonal light chain staining of basement membranes throughout the kidney, which appear as non-organized, granular punctate to powdery electron dense deposits by electron microscopy (EM). Although "LCDD by IF only" without EM deposits has been well-described, LCDD identified by EM with negative IF is very rare and hardly mentioned in the literature. Herein we describe a case of lambda-type LCDD that appeared negative by IF and showed light microscopic findings of nodular glomerulosclerosis, which was initially attributed to the patient's history of significant tobacco use and uncontrolled hypertension. However, EM later showed powdery electron dense material in focal glomerular and tubular basement membranes and mesangium. Subsequent bone marrow analysis revealed greater than 60% lambda-restricted plasma cells. We report this case to illustrate that within the differential diagnosis of nodular sclerosis, monoclonal immunoglobulin deposition disease (MIDD) should remain in the differential even if immunofluorescence appears negative as EM can prove to be crucial in identifying cases of MIDD.

Case Report: Lenalidomide as a Second-Line Treatment for Bortezomib-Ineffective Nephrotic Syndrome Caused by LCDD: 2 Case Reports and a Literature Review

Background: Light-chain deposition disease (LCDD) is a rare systemic disorder characterized by the deposition of monoclonal light chains in organs. The kidney is a prominent target of light-chain deposition, with a median time to end-stage renal disease (ESRD) of 2.7 years and 5-year ESRD-free survival of 37%. The therapeutic management of LCDD remains ill-defined. In addition to bortezomib-based therapy as first-line therapy, the effect of lenalidomide on LCDD is rarely reported.

Case Presentation: This study describes two male LCDD patients in their 60s with nephrotic syndrome and moderately impaired renal function. One patient had monoclonal IgGλ with underlying MGRS, and another had monoclonal IgGκ with underlying monoclonal gammopathy that developed into symptomatic MM during follow-up. The hallmarks of this disease were consistent with previous reports. Both patients initially received BCD therapy, but no hematological response was observed. Consequently, the nephrotic syndrome was refractory. Sequential Rd therapy was initiated, and partial hematological response and nephrotic remission were observed in the IgGλ patient but absent in the IgGκ patient.

Conclusion: Limited reports have demonstrated the effect of lenalidomide in LCDD. We report the outcome of lenalidomide in two cases of bortezomib-resistant LCDD. This treatment might be a beneficial supplement for those unresponsive or intolerant to bortezomib in LCDD, but the effect should be prospectively investigated.

Light Chain Glomerulopathy Causing Kidney Failure in Renal Cell Carcinoma

Light chain deposition disease (LCDD) is a rare cause of kidney failure. It is associated with multiple myeloma and is diagnosed by the evaluation of serum and urine free light chains. Patients who are diagnosed with this disease often develop rapidly progressive renal failure. To our knowledge, it does not have any association with other malignancies aside from multiple myeloma. We present a case that highlights a novel association between renal cell carcinoma and light chain-mediated renal disease. Our patient was admitted due to acute renal failure and underwent a comprehensive diagnostic evaluation with an eventual diagnosis of light chain glomerulopathy in the setting of metastatic renal cell carcinoma.

Autologous Stem Cell Transplantation in the Treatment of Pulmonary Light Chain Deposition Disease

Light chain deposition disease is a rare condition that results in the deposition of light chains in organs and their subsequent dysfunction. It is often the consequence of unchecked light chain production by a plasma cell clone. Rarely does it manifest with solely pulmonary involvement, especially in the young otherwise healthy patient. This article highlights the presentation and diagnosis of pulmonary light chain deposition disease in an active duty solider, the discovery of a plasma cell clone responsible for his symptoms, and the therapy targeted at the plasma cell clone-inducing pulmonary disease. This therapy included a novel successful treatment with an autologous stem cell transplantation. To date, it is among the first such documented successful bone marrow transplantations in treatment of isolated pulmonary light chain deposition disease.

Clinicopathological features and outcomes of coexistent light chain cast nephropathy and light chain deposition disease in patients with newly diagnosed multiple myeloma

AIMS

A varying proportion of patients with multiple myeloma suffer from more than one type of kidney disease simultaneously, of which the most common pattern is coexistent light chain cast nephropathy and light chain deposition disease (LCCN+LCDD). We investigated clinicopathological characteristics and outcomes of LCCN+LCDD in comparison with pure LCCN and pure LCDD.

METHODS

We retrospectively analysed 45 newly diagnosed multiple myeloma patients with pure LCCN (n=26), LCCN +LCDD (n=9) and pure LCDD (n=10) between 2000 and 2019 at Peking University First Hospital.

RESULTS

Pathologically, patients with LCCN+LCDD were more likely to have λ light chain isotype and presented atypical features of LCDD including less nodular glomerulosclerosis and less deposit distribution than patients with pure LCDD. In clinical characteristics, patients with LCCN +LCDD and patients with pure LCCN shared similar features. The death-censored renal survival in patients with LCCN +LCDD was similar to patients with pure LCCN but worse than patients with pure LCDD, but the overall survival was much better than patients with LCCN alone and similar to patients with pure LCDD. For patients with pure LCCN, the independent predictor of death-censored renal survival was lactate dehydrogenase, and the independent predictors of overall survival were the mean number of casts and serum albumin.

CONCLUSIONS

Patients with LCCN+LCDD had similar renal outcome compared with patients with pure LCCN but the overall survival is much better. Thus, for patients with LCCN, especially those with λ restriction, pathologists should carefully evaluate the kidney specimens to exclude the possibility of combined LCDD.

Randall-Type Monoclonal Immunoglobulin Deposition Disease: New Insights into the Pathogenesis, Diagnosis and Management

Randall-type monoclonal immunoglobulin deposition disease (MIDD) is a rare disease that belongs to the spectrum of monoclonal gammopathy of renal significance (MGRS). Renal involvement is prominent in MIDD, but extra-renal manifestations can be present and may affect global prognosis. Recent data highlighted the central role of molecular characteristics of nephrotoxic monoclonal immunoglobulins in the pathophysiology of MIDD, and the importance of serum free light chain monitoring in the diagnosis and follow-up disease. Clone-targeted therapy is required to improve the overall and renal survival, and the achievement of a rapid and deep hematological response is the goal of therapy. This review will focus on the recent progress in the pathogenesis and management of this rare disease.

Light chain deposition disease involving kidney and liver in a patient with IgD myeloma

Background

IgD multiple myeloma (MM) is a rare subtype of MM and light chain deposition disease (LCDD) outside the kidney is also a rare and has scarcely been reported. We report herein the details of the first reported case of LCDD involving the kidney and liver co-occurring with IgD myeloma.

Case presentation

A 66-year-old female with IgD MM presented with rapidly progressive acute renal failure, ascites and pleural effusion. Immunofluorescent study of revealed the characteristic linear deposition of Igκ light chain along the glomerular and tubular basement membrane in kidney. Electron microscopy showed the powdery electron-dense deposits along the tubular and glomerular basement membrane consistent with the diagnosis of LCDD. Laser microdissection followed by mass spectrometry identified only Igκ light chain with more than 95% probability confirm the diagnosis of κ-LCDD but not heavy/light chain deposition disease. Liver biopsy with immunofluorescence study revealed the linear deposition of Igκ chain along the perisinusoidal space indicating the hepatic involvement of κ-LCDD. The patient was successfully treated with combination therapy with bortezomib, cyclophosphamide, dexamethasone, and daratumumab.

Conclusions

This report emphasizes that prompt biopsy of affected organs and initiation of clone directed therapy led to the correct diagnosis and favorable outcome in patient with LCDD who has extrarenal involvement.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02246-9.

An Unusual Case of Cholestatic Hepatitis due to Light-Chain Deposition Disease

Light-chain deposition disease (LCDD) is a rare paraproteinaemia characterized by the deposition of monoclonal immunoglobulins with a non-fibrillar structure and hence Congo red negative deposits. Kidney disease is the more frequent manifestation, but other organs may also be involved. A 70-year-old man with hypertension and mild chronic renal failure showed a hepatomegaly without splenomegaly. His renal and liver test rapidly got worse. A serum electrophoresis and immunofixation isolated monoclonal kappa light-chain gammopathy, with serum free kappa light chain excess. The bone marrow biopsy showed the presence of interstitial infiltration of plasma cells like multiple myeloma type at initial phase. Periumbilical fat biopsy was negative. Echocardiography demonstrated an infiltrative cardiac disease. The biopsies of the duodenum small intestine mucosa showed flaps with eosinophil material (Masson's staining) with atrophic crypts and chronic inflammation at chorion level. Amyloid substance was negative. There was a strong positivity for light chains kappa compatible with LCDD. A liver biopsy confirmed this finding. Therapy with dexamethasone and bortezomib improved clinical state and hepatic and renal laboratory tests. Chemotherapy based on novel anti-myeloma agents should be rapidly considered in LCDD patients with severe organ involvement.

Rate and Predictors of Finding Monoclonal Gammopathy of Renal Significance (MGRS) Lesions on Kidney Biopsy in Patients with Monoclonal Gammopathy

BACKGROUND

Little is known about the rate and predictors of finding lesions of monoclonal gammopathy (MG) of renal significance (MGRS) on kidney biopsy specimens among patients with MG.

METHODS

We reviewed the medical records from 2013 to 2018 at the Mayo Clinic in Rochester, Minnesota, to identify patients with MG and whether they had undergone a kidney biopsy. In a more select group of patients with MG from 2017 to 2018, we conducted a review of records to determine how many had underlying CKD, which of those with CKD had undergone a kidney biopsy, and reasons for deferring a kidney biopsy.

RESULTS

Between 2013 and 2018, we identified 6300 patients who had MG, 160 (2.5%) of whom had undergone a kidney biopsy. Of the 160 patients, 64 (40%) had an MGRS lesion; amyloid light chain amyloidosis, the most common finding, accounted for nearly half of these lesions. In the non-MGRS group comprising 96 patients, 23 had arteriosclerosis, the most common finding. In multivariate analysis, strong predictors of finding an MGRS lesion included the presence of an elevated free light chain ratio, proteinuria, and hematuria. Among 596 patients with CKD and MG from 2017 to 2018, 62 (10.4%) underwent a kidney biopsy. Kidney biopsy was deferred for 70 patients (20%); for 62 of the 70, the diagnosis was already known, and eight were not candidates for therapy. Younger age and higher proteinuria and serum creatinine levels increased the likelihood that the patient would undergo a kidney biopsy.

CONCLUSIONS

Proteinuria ≥1.5 g/d, hematuria, and an elevated free light chain ratio increase the likelihood of finding MGRS, and a kidney biopsy should be highly considered in such patients.

Pathophysiology and management of monoclonal gammopathy of renal significance

Recent years have witnessed a rapid growth in our understanding of the pathogenic property of monoclonal proteins. It is evident that some of these small monoclonal proteins are capable of inducing end-organ damage as a result of their intrinsic physicochemical properties. Hence, an umbrella term, monoclonal gammopathy of clinical significance (MGCS), has been coined to include myriad conditions attributed to these pathogenic proteins. Because kidneys are the most commonly affected organ (but skin, peripheral nerves, and heart can also be involved), we discuss MGRS exclusively in this review. Mechanisms of renal damage may involve direct or indirect effects. Renal biopsy is mandatory and demonstration of monoclonal immunoglobulin in kidney, along with the corresponding immunoglobulin in serum or urine, is key to establish the diagnosis. Pitfalls exist at each diagnostic step, and a high degree of clinical suspicion is required to diagnose MGRS. Recognition of MGRS by hematologists and nephrologists is important, because timely clone-directed therapy improves renal outcomes. Autologous stem cell transplant may benefit selected patients.

Current opinions in nephrology and hypertension: kidney transplantation in patients with plasma cell dyscrasias

PURPOSE OF REVIEW

Plasma cell dyscrasias encompass a group of hematological disorders characterized by increased production of immunoglobulins by clonal B cells. Kidney involvement is common. Significant advances in the treatment of plasma cell dyscrasias have resulted in improved survival and may permit kidney transplantation in candidates previously denied transplantation. Treatments may also have effects on kidney transplant recipients who develop plasma cell dyscrasias post transplantation.

RECENT FINDING

The available evidence suggests that transplantation of candidates with nonmultiple myeloma plasma cell dyscrasias provides good outcome with low recurrence rates, so long as the disease has been treated with a complete or good partial response prior to transplantation. Candidates with a history untreated MGRS or a history of multiple myeloma have a high rate of recurrence posttransplant. Kidney transplant recipients who develop plasma cell dyscrasias post transplantation have an increased risk of death and thalidomide-based regimens may increase the risk of rejection.

SUMMARY

Transplant candidates with a history of plasma cell dyscrasia who are in remission should not be excluded from transplantation. Individuals with multiple myeloma have a high rate of recurrence and myeloma post kidney transplant must be managed carefully.

The clinical implication of monoclonal gammopathies: monoclonal gammopathy of undetermined significance and of renal significance

Monoclonal gammopathy of renal significance (MGRS) has introduced a new perspective to several well-known disease entities impacting nephrology, haematology and pathology. Given the constantly changing disease spectrum of these entities, it is clinically imperative to establish diagnostic and treatment pathways supported by evidence-based medicine. MGRS is a disease of the kidney, secondary to plasma cell clonal proliferation or immune dysfunction, requiring therapeutic intervention to eradicate the offending clone. To fully understand the disease(s), it is prerequisite to determine the significance of the findings. The diagnostic work up should be extensive due to the wide heterogeneity of clinical presentation, ultimately necessitating kidney biopsy. Particular patient profiles such as AL amyloidosis, which may be diagnosed through biopsies of other tissues/organs, may be an exception. Treatment decisions should be formulated by multi-disciplinary consensus: nephrologists, haematologists and pathologists. The ultimate goal in managing MGRS is eradication of the offending plasma cell clone which requires targeted chemotherapy and, in eligible cases, haematopoietic stem cell transplantation. We present a review of diagnostic procedures, treatment options and advances in the last few years in the management of MGRS in an effort to acquaint specialists with this new face of several older diseases.

The Role of Kidney Transplantation in Monoclonal Ig Deposition Disease

Introduction

Monoclonal Ig deposition disease (MIDD) frequently leads to kidney failure, and a large proportion of these patients would greatly benefit from kidney transplantation. However, data on kidney transplantation outcomes in MIDD are limited.

Methods

This was a retrospective analysis of long-term renal outcomes of 23 patients with MIDD, including 6 patients who underwent kidney transplantation.

Results

The 1-, 5-, and 10-year overall survival (OS) from diagnosis were 95%, 78%, and 65%, respectively. Approximately half of the patients (n = 12) progressed to end-stage renal disease (ESRD) with a median time from diagnosis to ESRD of 3.4 years. The 1-, 5-, and 10-year renal survival from diagnosis were 77%, 48%, and 29% respectively. Renal response was observed only in 5 patients (22%), all of them after achieving hematologic complete response. Median OS from diagnosis was significantly better for those who underwent kidney transplantation versus those who remained on dialysis (19.8 years vs. 8.3 years, P = 0.016). Among patients who underwent kidney transplantation, the shortest survival from MIDD diagnosis was 13.7 years and the longest was 27.8 years. Of the 3 patients with kidney transplants who died, the time from the first kidney transplantation to death was 7.4, 18.8, and 20.4 years. Graft loss due to disease recurrence occurred at 4 months and 3.8 years after kidney transplantation in 2 patients who either were not treated or did not respond to treatment.

Conclusion

As treatments for MIDD have dramatically improved, more patients are achieving sustained hematologic responses with longer patient and graft survival after kidney transplantation.

Pulmonary nodular and cystic light chain deposition disease: A retrospective review of 10 cases

INTRODUCTION

Light chain deposition disease (LCDD) rarely involves the lungs. We report clinical and radiologic findings of pulmonary LCDD.

METHODS

We retrospectively identified patients with biopsy-proven pulmonary LCDD seen at Mayo Clinic (Rochester, Minnesota) from January 1997 through December 2018. Demographic, clinical, and imaging features were analyzed.

RESULTS

We identified 10 patients with pulmonary LCDD (median age at diagnosis, 55 years; range, 39-77 years). Eight patients were women and 7 were never-smokers. Dyspnea (n = 3) and chest pain (n = 3) were the most common respiratory symptoms. Associated conditions included Sjögren syndrome (n = 6), sarcoidosis (n = 1), and limited scleroderma (n = 1). Eight patients had mucosa-associated lymphoid tissue (MALT) lymphoma. Among the 9 patients with chest computed tomography (CT) images, 8 (89%) had cysts. Cysts were predominantly distributed in the lower lung and were round or oval. All patients had multiple cysts (5 patients had 1-5 cysts, 3 had >20 cysts). The median diameter of the largest cyst was 18 mm (range, 5-68 mm). All 9 patients had solid nodules (3 had >10 nodules). Five patients had subsolid nodules. The median diameter of the largest solid nodules was 13 mm (range, 6-26 mm). Positron emission tomography-CT images were available for 8 patients. The median maximum standardized uptake value of the most avid pulmonary nodule was 2.2 (range, 1.9-6.0). Two patients died during a median follow-up of 2.3 years (range, 0.5-9.9 years).

CONCLUSIONS

Pulmonary LCDD is characterized by cysts and nodules. The disease is associated with MALT lymphoma, especially in the setting of Sjögren syndrome.

The prevalence and significance of monoclonal gammopathy of undetermined significance in acute medical admissions

Monoclonal gammopathy of undetermined significance (MGUS) affects 3·2% of adults aged >50 years. MGUS carries a life-long risk of progression to multiple myeloma and causes complications including infection and renal impairment; common causes of hospital admission. This study aimed to assess MGUS prevalence in emergency medical hospital admissions. Patients were recruited from unselected emergency medical admissions in a hospital in the United Kingdom. Serum protein electrophoresis was performed, with immunofixation of abnormal results. Reason for admission and routine test results were recorded. After education about MGUS and myeloma, patients chose whether they wished to be informed of new diagnoses. A total of 660 patients were tested and 35 had a paraprotein suggestive of MGUS. The overall rate of MGUS was 5·3%. MGUS prevalence in those aged >50 years was 6·94%, higher than the previously published rate of 3·2% (P < 0·0005). There were higher rates in those with chronic kidney disease (13·75% vs. 4·14%, P = 0·002), heart failure (14% vs. 4·59%, P = 0·012), anaemia (8·96% vs. 3·41%, P = 0·003) or leucocytosis (9·33% vs. 3·04%, P = 0·002). In all, 96% of patients wished to be informed of their screening results. The prevalence of MGUS in emergency hospital admissions is higher than expected based on previous population-based rates. This may suggest a selected population for screening.

Outcomes of autologous stem cell transplant for cardiac AL-amyloidosis and cardiac light chain deposition disease

INTRODUCTION

Cardiac amyloidosis and light chain deposition disease (LCDD) are the most common cause of death in AL amyloidosis or LCDD.

METHODS

Our multiple myeloma database identified 50 patients with cardiac amyloidosis or LCDD between January 2004 and January 2013. Descriptive analyses were performed on available data for patient characteristics, disease course, and outcomes.

RESULTS

The median age at diagnosis was 61 years for those who received autologous hematopoietic stem cell transplant (ASCT) and 71 years for those who received only bortezomib-based chemotherapy; 62.5% (n = 30) of patients had elevated levels of NT-proBNP ≥323 ng/L, and 29.2% (n = 14) of patients had an elevated cTnT ≥0.1 µg/L. Echocardiogram findings showed a speckled appearance in 18% (n = 9) of patients, and 60% (n = 30) of patients had an increased diastolic intra-ventricular septum (IVSD) thickness measuring ≥1.3 cm; 64.3% (n = 18) of patients who underwent cardiac MRI showed subendocardial enhancement. Out of 48 patients who received treatment, 37 patients were diagnosed with cardiac amyloidosis and 11 patients were diagnosed with cardiac LCDD. Twenty-eight patients (75.7%) with cardiac amyloidosis received ASCT, compared to 34.3% (n = 9) patients who were ineligible for ASCT and received chemotherapy only. Patients who underwent ASCT had a median OS of 4.48 years compared to 1.82 years (p = 0.69) for those receiving chemotherapy alone.

CONCLUSION

Our single institution experience shows that ASCT is feasible for cardiac amyloidosis and/or cardiac LCDD. However, careful selection of proper patients and diligent supportive care are vital to decreasing transplant-related mortality.

The evaluation of monoclonal gammopathy of renal significance: a consensus report of the International Kidney and Monoclonal Gammopathy Research Group

The term monoclonal gammopathy of renal significance (MGRS) was introduced by the International Kidney and Monoclonal Gammopathy Research Group (IKMG) in 2012. The IKMG met in April 2017 to refine the definition of MGRS and to update the diagnostic criteria for MGRS-related diseases. Accordingly, in this Expert Consensus Document, the IKMG redefines MGRS as a clonal proliferative disorder that produces a nephrotoxic monoclonal immunoglobulin and does not meet previously defined haematological criteria for treatment of a specific malignancy. The diagnosis of MGRS-related disease is established by kidney biopsy and immunofluorescence studies to identify the monotypic immunoglobulin deposits (although these deposits are minimal in patients with either C3 glomerulopathy or thrombotic microangiopathy). Accordingly, the IKMG recommends a kidney biopsy in patients suspected of having MGRS to maximize the chance of correct diagnosis. Serum and urine protein electrophoresis and immunofixation, as well as analyses of serum free light chains, should also be performed to identify the monoclonal immunoglobulin, which helps to establish the diagnosis of MGRS and might also be useful for assessing responses to treatment. Finally, bone marrow aspiration and biopsy should be conducted to identify the lymphoproliferative clone. Flow cytometry can be helpful in identifying small clones. Additional genetic tests and fluorescent in situ hybridization studies are helpful for clonal identification and for generating treatment recommendations. Treatment of MGRS was not addressed at the 2017 IKMG meeting; consequently, this Expert Consensus Document does not include any recommendations for the treatment of patients with MGRS.

This Expert Consensus Document from the International Kidney and Monoclonal Gammopathy Research Group includes an updated definition of monoclonal gammopathy of renal significance (MGRS) and recommendations for the use of kidney biopsy and other modalities for evaluating suspected MGRS

The pathogenesis of renal injury and treatment in light chain deposition disease

Light chain deposition disease (LCDD) is a rare clinical disorder. The deposition of light chain immunoglobulins mainly affects the kidneys, which have different characteristics than other tissues. To date, the therapeutic approach for the treatment of LCDD has no evidence-based consensus, and clinical experience of reported cases guides current disease management strategies. The present systematic review investigates and summarizes the pathological mechanisms of renal injury and the subsequent treatments for LCDD.

Acute kidney injury on chronic kidney disease: from congestive heart failure to light chain deposition disease and cast nephropathy in multiple myeloma

Acute on chronic renal failure is a common but notably broad diagnosis. We present a 64-year-old man with a history of diastolic heart failure and chronic kidney disease, admitted for an elevated creatinine. History and physical examination were suggestive of decompensated heart failure; however, the careful interpretation of urinalysis rendered the diagnosis of multiple myeloma. On renal biopsy, the patient was found to have light chain deposition disease with cast nephropathy. Combination lesions in multiple myeloma are rare and require diligent histopathology for detection, including light microscopy, immunofluorescence and electron microscopy. These patients portray different demographics, renal manifestations, oncologic characteristics and outcomes, and hence, further studies isolating these combined lesions are warranted.

Abbreviations: CKD: chronic kidney disease; CN: cast nephropathy; CT: computerized tomography; EDD: electron-dense deposits; EM: electron microscopy; IF: immunofluorescence; FLC: free light chain; LC: light chain; LCDD: light chain deposition disease; MIDD: monoclonal immunoglobulin deposition disease; MM: multiple myeloma; LM: light microscopy; NGS: nodular glomerulosclerosis; κ: kappa; λ: lambda.

Renal pathologic spectrum and clinical outcome of monoclonal gammopathy of renal significance: A large retrospective case series study from a single institute in China

OBJECTIVES

To analysis the pathological spectrum and prognosis of monoclonal gammopathy of renal significance (MGRS) patients.

METHODS

Patients with renal biopsy-proven MGRS from 1999 to 2017 in Peking University First Hospital were included, clinical data, renal pathology type, treatment and prognosis were collected.

RESULTS

One hundred and eighty-seven patients were enrolled, accounting for 0.7% of renal biopsies. Seventy-seven per cent of the MGRS patients were amyloidosis. Eighteen patients (9.6%) were monoclonal immunoglobulin deposition disease. Others included 10 patients (5.3%) with proliferative glomerulonephritis with monoclonal immunoglobulin (G) deposits, seven patients (3.7%) with cryoglobulinaemic glomerulonephritis, five patients (2.6%) with light chain proximal tubulopathy, two patients (1.1%) with fibrillary disease and one patient (0.5%) with C3 glomerulonephritis. Sixty-three per cent were treated with chemotherapy and/or stem cell transplantation. The mean follow-up time was 27 ± 32 months. One patient developed multiple myeloma at 17-month during follow-up. At the end of follow-up, 61 patients (33%) died, and 47 patients (25%) reached end-stage renal disease (ESRD). For the 144 amyloid patients, low estimated glomerular filtration rate (eGFR), decreased blood pressure, presence of cardiac involvement and absence of chemotherapy or high-dose melphalan/autologous peripheral blood stem cell transplantation were identified as independent risk factors for death. Low eGFR, decreased blood pressure, and presence of cardiac involvement were identified as independent risk factors for ESRD. For the 43 non-amyloid patients, no factor was identified for the risk of death. Low eGFR was identified as independent risk factor for ESRD.

CONCLUSION

MGRS was an uncommon form of hematologic disorder related renal injury with a wide spectrum of pathologic lesions, and amyloidosis was the most common type. Treatment with chemotherapy and/or high-dose melphalan/autologous peripheral blood stem cell transplantation improved amyloid patients' survival.

Bortezomib-Based Chemotherapy with Autologous Stem Cell Transplantation for Monoclonal Gammopathy of Renal Significance: A Case Report and Literature Review

BACKGROUND/AIMS

The term monoclonal gammopathy of renal significance (MGRS) was introduced in 2012 to emphasize kidney lesions in monoclonal gammopathy patients. Bortezomib-based chemotherapy has become the first-line treatment for MGRS.

OBJECTIVES

The objective of this study was to investigate whether the strategy of combining chemotherapy with autologous stem cell transplantation (ASCT) could improve prognosis and decrease functional kidney impairment in patients with MGRS.

METHODS

We reported the case of a 44-year-old Asian patient who was diagnosed with MGRS and received 5 cycles of Velcade® (a trade name for bortezomib), thalidomide, and dexamethasone therapy (VTD therapy), and subsequently underwent ASCT. In addition, we performed a literature review and summarized the latest advances in the characterization, treatment, and prognosis of MGRS.

RESULTS

The patient was diagnosed with light chain deposition disease by renal biopsy. After 5 cycles of VTD therapy, the patient had a very good partial response characterized by the resolution of M-protein (20.2% before treatment vs. 2.5% after treatment), remission of the level of serum free lambda (FLAM; over 80% decline), and normalization of the serum free light chain (sFLC) ratio (κ to λ). He also had a renal response characterized by a decreased serum creatinine level (1.61 vs.1.34 mg/dL) and less severe proteinuria (6.77 g/24 h vs.1.264 g/24 h) after chemotherapy. Importantly, after ASCT, the patient achieved a complete response (CR) characterized by a negative serum immunofixation electrophoresis (IFE) result and a dramatic decrement in FLAM (over 90%). Furthermore, 6 months after ASCT, the patient still remained in stable condition with a negative IFE result, normal sFLC ratio, and low level of serum creatinine (1.31 mg/dL) and proteinuria (0.339 g/24 h). In our retrospective literature analysis, we found that MGRS patient survival time and renal outcome had been markedly improved by current therapies due to the popularization of bortezomib-based chemotherapy and ASCT.

CONCLUSIONS

The patient successfully achieved CR after VTD therapy followed by ASCT. However, this treatment is controversial, and a standard therapy recommendation for MGRS has not been established. Bortezomib-based chemotherapy combined with ASCT may have prospects for the treatment of MGRS, but the exact effects of ASCT remain unclear and should be thoroughly investigated.

Activin A: a novel urinary biomarker of renal impairment in multiple myeloma

Renal impairment (RI) is a common complication of multiple myeloma (MM) that significantly affects treatment efficacy and mortality. However, no useful biomarkers for early detection of renal damage in MM exist. Reports indicate that activin A, a multifunctional cytokine of the TGF-β superfamily, is involved in the development and progression of various kidney diseases. In the present study, we measured urinary activin A levels in patients with newly diagnosed MM (NDMM) (n=41), smoldering MM (SMM) (n=10), and monoclonal gammopathy of undetermined significance (MGUS) (n=28), including monoclonal gammopathy of renal significance (MGRS), and assessed the correlation between urinary activin A and several clinical parameters. Urinary activin A, undetectable in healthy volunteers, was significantly increased in NDMM patients but not in patients with SMM and MGUS (97.3, 25.0, and 6.61 mg/gCr, respectively, P<0.05). In all patients with NDMM, urinary activin A levels were significantly reduced after initial treatment regardless of the therapy regimen. There was a significant correlation of urinary activin A with spot urinary protein level (P<0.001) and serum M-protein (P=0.029) but not with estimated glomerular filtration rate (eGFR), serum creatinine (Cr), N-acetyl-glucosaminidase (NAG), and serum activin A level. Histological analysis using renal biopsy samples revealed that activin A, which was absent from normal kidneys, was detected in the renal tubular cells of patients with MGRS. These data suggest that urinary activin A reflects tubular injury in MM and might aid the early detection of RI in plasma cell neoplasms.

Randall-type monoclonal immunoglobulin deposition disease: novel insights from a nationwide cohort study

Monoclonal immunoglobulin deposition disease (MIDD) is a rare complication of B-cell clonal disorders, defined by Congo red negative–deposits of monoclonal light chain (LCDD), heavy chain (HCDD), or both (LHCDD). MIDD is a systemic disorder with prominent renal involvement, but little attention has been paid to the description of extrarenal manifestations. Moreover, mechanisms of pathogenic immunoglobulin deposition and factors associated with renal and patient survival are ill defined. We retrospectively studied a nationwide cohort of 255 patients, with biopsy-proven LCDD (n = 212) (including pure LCDD [n = 154], LCDD with cast nephropathy (CN) [n = 58]), HCDD (n = 23), or LHCDD (n = 20). Hematological diagnosis was monoclonal gammopathy of renal significance in 64% and symptomatic myeloma in 34%. Renal presentation was acute kidney injury in patients with LCCD and CN, and chronic glomerular disease in the other types, 35% of whom had symptomatic extrarenal (mostly hepatic and cardiac) involvement. Sequencing of 18 pathogenic LC showed high isoelectric point values of variable domain complementarity determining regions, possibly accounting for tissue deposition. Among 169 patients who received chemotherapy (bortezomib-based in 58%), 67% achieved serum free light chain (FLC) response, including very good partial response (VGPR) or above in 52%. Renal response occurred in 62 patients (36%), all of whom had achieved hematological response. FLC response ≥ VGPR and absence of severe interstitial fibrosis were independent predictors of renal response. This study highlights an unexpected frequency of extrarenal manifestations in MIDD. Rapid diagnosis and achievement of deep FLC response are key factors of prognosis.

Primary idiopathic CNS non-amyloidogenic light chain deposition disease complicated by treatment-resistant focal seizure disorder

Light chain deposition disease (LCDD) is a systemic disorder characterised by the pathologic deposition of immunoglobulin light chains, which is histologically distinguished from amyloidosis by failure to stain with Congo red. Central nervous system (CNS)-restricted LCDD is among the rarest manifestations. We describe a unique case complicated by focal onset epilepsy with impaired awareness for which control with anticonvulsant therapy proved difficult.

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.

Unmasking and successful management of light chain deposition disease of kidney in pregnancy: a complex case, mirroring the complex needs of pregnancy with kidney disease in India

Pregnancy offers a precious window of opportunity to diagnose previously undetected or new onset kidney diseases in emerging countries like India, where access to medical, educational and health care facilities are not equitably distributed across varied sections of society. We report a case of a 33 year-old primi gravida who had a successful pregnancy following what was initially considered to represent preeclampsia at 38 weeks of gestation, in whom a subsequent kidney biopsy for persistence of pregnancy-related acute kidney injury (Pr-AKI) revealed light chain deposition disease (LCDD). The etiological evaluation of LCDD led to the detection of an underlying plasma cell dyscrasia which was treated effectively with chemotherapy and autologous stem cell transplant. In this report, we explore the hitherto uncharted pathophysiological relationship between LCDD and pregnancy-related kidney injury by transmission electron microscopic (TEM) studies of endothelial injury in this setting, and underscore the benefits of medical care in a multidisciplinary environment which yielded gratifying results in preservation of maternal kidney health and fetal outcome.

Acquired Fanconi syndrome secondary to light chain deposition disease associated with monoclonal gammopathy of renal significance: A case report

RATIONALE

Renal Fanconi syndrome (FS) is a rare complication of monoclonal gammopathy. It is characterized by the impairment of renal proximal tubular function leading to normoglycemic glycosuria, aminoaciduria, hypophosphatemia, hypouricemia and proximal renal tubular acidosis. Renal impairment in monoclonal gammopathy, without fulfilling the criteria of multiple myeloma, is categorized as monoclonal gammopathy of renal significance (MGRS).

PATIENT CONCERNS

A 54-year-old male presented with progressively aggravated bone pain and limitation of activity was admitted to our department. A proximal renal tubular damage was suggested by hypophosphatemia, compensated metabolic acidosis, renal glycosuria, aminoaciduria, and hypouricemia. M-protein of IgA kappa was detected by immunofixation electrophoresis. Mildly increased plasma cells were found in bone marrow cytomorphologic examination. Renal biopsy revealed diffuse linear monoclonal IgA-kappa light chain deposits along tubular basement membranes (TBMs), while lambda was negative. Electron microscopy showed granular electron-dense deposits along the outer aspect of TBMs.

DIAGNOSES

The patient was diagnosed as FS induced osteomalacia secondary to monoclonal gammopathy of renal significance (MGRS) (IgA-κ type) and LCDD.

INTERVENTIONS

He was treated with bortezomib, supplementation by phosphate, alkali agents, and active vitamin D. He responded well to the treatment symptomatically.

OUTCOMES

We reported a rare case of adult acquired FS with hypophosphatemic osteomalacia secondary to LCDD associated with MGRS and the patient was successfully treated with bortezomib.

LESSONS

Although few cases of LCDD with isolated symptoms of tubulointerstitial nephropathy, rather than glomerular symptoms have been reported. It still needs to be recognized as a differential diagnosis in monoclonal gammopathy.