Renal lesions in multiple myeloma: their relationship to associated protein abnormalities

Multiple Facets of Multiple Myeloma in Kidney Biopsy: A Multicenter Retrospective Study

Introduction

Multiple myeloma is a type of plasma cell dyscrasia, which causes clonal proliferation of plasma cells and deposition in various organ systems. At presentation, 50% of patients with multiple myeloma have kidney dysfunction, which is considered a poor prognostic indicator. Data on the histopathological manifestations of multiple myeloma are sparse.

Objective

To look at the kidney histopathological lesions in patients with the clinical diagnosis of multiple myeloma.

Materials and Methods

A retrospective analysis of all kidney biopsies in patients with the clinical diagnosis of multiple myeloma was performed from June 1, 2020 to May 30, 2022, from three tertiary care nephrology referral centers.

Results

A total of 61 patients with multiple myeloma and biopsy-proven kidney involvement were included in the study. The mean age at presentation was 55.39 ± 11.91 years, with male predominance (male to female ratio -1.6:1). The most common lesion on kidney biopsy was myeloma cast nephropathy (72.1%), followed by light chain deposition disease (21.3%) and AL amyloidosis (18%). About 26% of patients had dual lesions on kidney biopsy, 3% had three types of lesions on kidney biopsy In 48% of patients, the diagnosis of multiple myeloma was made only after the kidney biopsy.

Conclusion

Patients with multiple myeloma and kidney involvement should be biopsied as the type of histopathological lesion influences the treatment options and prognosis.

Tubular basement membrane amyloid deposition: is it an indicator of renal progression in light chain amyloidosis?

In light chain amyloidosis (LA), the massive glomerular and vascular amyloid deposition leading to interstitial fibrosis/tubular atrophy (IFTA) is thought to be responsible for renal failure. The amyloid deposition in the interstitium and the tubular basement membrane (TBM) has received less attention in the study of LA. We, therefore, collected clinical and laboratory data on patients diagnosed with LA in our Nephrology Department and studied amyloid deposition in the TBM. Twelve LA patients were diagnosed by renal biopsy during a seven-year period. In 4 of the 12, amyloid deposition could also be detected in the TBM. In our first case of a patient with diabetes mellitus, non-amyloid fibrils resembling 'diabetic fibrillosis' were also seen by electron microscopy. Despite the double damage, IFTA was negligible, blood vessels were unaffected, and the glomerular deposition was segmental. In the other three cases, significant (>50%) IFTA and a severely reduced estimated glomerular filtration rate were already detected at the time of diagnosis and amyloid deposition was also observed in the blood vessels. These findings indicate the importance of TBM amyloid deposition in the progression of renal disease. This may represent a late-stage presentation of the disease with a heavy LC burden.

Light chain deposition disease presenting as an atrial mass: a case report and review of literature

Light chain deposition disease (LCDD) also known as nonamyloidotic immunoglobulin deposition disease is a rare systemic disorder due to the abnormal deposition of immunoglobulin in multiple organs caused by the clonal proliferation of B lymphocytes and plasma cells. Renal involvement is the most common with cardiac manifestations being the most common extra renal presentation of the disease. Renal involvement is not always associated with LCDD. Isolated cardiac involvement can manifest in a wide variety of ways: heart failure, cardiomyopathy, arrhythmias, angina, myocardial infarction, etc. We hereby present an unusual case of 59-year-old female who presented to clinic for routine follow up. A murmur on physical exam was evaluated with echocardiogram which led to the discovery of an incidental right atrial mass. Cardiac magnetic resonance imaging was completed 6 months later for follow up which showed increasing size of the mass. The mass was excised and found to be consistent with LCDD. To the best of our knowledge, this is the first reported case of LCDD manifesting as an atrial mass. Through this case report and review of literature we would like to generate awareness among our fellow pathologists and clinicians to maintain a high level of suspicion for LCDD as it can manifest in many unusual ways, with or without kidney involvement.

Two kinds of rare light chain cast nephropathy caused by multiple myeloma: case reports and literature review

BACKGROUND

Light chain cast nephropathy (LCCN) is the most common renal disease caused by multiple myeloma (MM). In addition to ordinary light chain protein casts, there are a few rare casts with unique shapes, including light chain amyloid casts (LCAC) and light chain crystal casts (LCCC).

CASE PRESENTATIONS

Here, we report two patients. Patient 1 is a 72-year-old man who was clinically diagnosed with MM and acute kidney injury (AKI). Pathological examination of a renal biopsy revealed that there were many amyloid casts in the distal tubules that had a lightly-stained central area and a deeply-stained burr-like edge. The marginal zone of the cast was positive for Congo red staining and contained numerous amyloid fibers, as observed by electron microscopy. No systemic amyloidosis was found. The patient received 4 courses of bortezomib-based chemotherapy, and then, his MM achieved partial remission. Patient 2 is a 57-year-old man who was also clinically diagnosed with MM and AKI. Pathological examination of a renal biopsy showed that there were many crystalline casts in the distal tubules that were fully or partially composed of crystals with different shapes, including rhomboid, needle, triangle, rectangle and other geometric shapes. Congo red staining was negative. Crystals were also detected in the urine of this patient. After 9 courses of treatment with a bortezomib-based regimen, his MM obtained complete remission and his renal function returned to normal.

CONCLUSIONS

LCAC and LCCC nephropathy caused by MM are two rare types of LCCN, and both have their own unique morphological manifestations. LCAC nephropathy may not be accompanied by systemic amyloidosis. The diagnosis of these two unique LCCNs must rely on renal biopsy pathology, and the discovery of urine crystals is of great significance for indicating LCCC nephropathy.

Multiple morphological phenotypes of monoclonal immunoglobulin disease on renal biopsy: Significance of treatment

Plasma cell dyscrasias frequently involve the kidney causing renal dysfunction. Multiple morphologic manifestations of κ light chain disease occurring simultaneously in the same kidney biopsy are uncommon and suggest local microenvironment effects in addition to structural properties of the light chain. A 61-year-old female presented with new onset renal failure and proteinuria. Serological workup revealed monoclonal gammopathy with elevated κ : λ ratio of 1,371. Renal biopsy revealed several paraprotein manifestations including κ light chain deposition disease, monoclonal fibrillary glomerulonephritis, cryocrystalglobulenemia and fibrillar/microtubular cast nephropathy. There was also incidental leukocyte chemotactic factor 2 amyloidosis (ALECT 2), negative for κ light chain and confirmed by immunohistochemistry (IHC). Bone marrow biopsy revealed 10 - 20% κ restricted plasma cells. The patient received 10 cycles of CyBorD (cyclophosphamide, bortezomib, and dexamethasone) chemotherapy. Renal function improved with decreased κ : λ ratio. Repeat bone marrow biopsy showed no evidence of abnormal plasma cells by IHC. The renal recovery demonstrates there may be response to chemotherapy irrespective of the morphologic manifestations of light chain-related injury. Additionally, if amyloid is not demonstrated to be of light chain origin, other amyloid types should be considered.

Intratubular amyloid in light chain cast nephropathy is a risk factor for systemic light chain amyloidosis

Light chain cast nephropathy is the most common form of kidney disease in patients with multiple myeloma. Light chain casts may occasionally show amyloid staining properties, that is, green birefringence after Congo red staining. The frequency and clinical significance of this intratubular amyloid are poorly understood. Here, we retrospectively assessed the clinicopathological features of 60 patients with histologically proven light chain cast nephropathy with a specific emphasis on intratubular amyloid, especially, its association with extrarenal systemic light chain amyloidosis. We found intratubular amyloid in 17 cases (17/60, 28%) and it was more frequent in patients with λ light chain gammopathy (13/17 in the 'intratubular amyloid' group vs 19/43 in the 'no intratubular amyloid' group, P=0.02). Pathological examination of extrarenal specimens showed that intratubular amyloid was significantly associated with the occurrence of systemic light chain amyloidosis (5/13 in the 'intratubular amyloid' group vs 0/30 in the 'no intratubular amyloid' group, P=0.001). Our results indicate that first, intratubular amyloid is not a rare finding in kidney biopsies of patients with light chain cast nephropathy, and, second, it reflects an amyloidogenic capacity of light chains that can manifest as systemic light chain amyloidosis. Thus, intratubular amyloid should be systematically screened for in kidney biopsies from patients with light chain cast nephropathy and, if detected, should prompt a work-up for associated systemic light chain amyloidosis.

Paraprotein-Related Kidney Disease: Evaluation and Treatment of Myeloma Cast Nephropathy

Nearly 50% of patients with multiple myeloma develop renal disease, most commonly from AKI caused by cast nephropathy. Development of AKI is associated with poor 1-year survival and reduces the therapeutic options available to patients. There is a great need for more effective therapies. Cast nephropathy is caused by the interaction and aggregation of filtered free light chains and Tamm-Horsfall protein causing intratubular obstruction and damage. The key to treating cast nephropathy is rapid lowering of free light chains, because this correlates with renal recovery. Newer chemotherapy agents rapidly lower free light chains and have been referred to as renoprotective. There is additional great interest in using extracorporeal therapies to remove serum free light chains. Small trials initially showed benefit of therapeutic plasma exchange to improve renal outcomes in cast nephropathy, but a large randomized trial of therapeutic plasma exchange failed to show benefit. A newer technique is extended high-cutoff hemodialysis. This modality uses a high molecular weight cutoff filter to remove free light chains. To date, trials of high-cutoff hemodialysis use in patients with cast nephropathy have been encouraging. However, there are no randomized trials showing the benefit of high-cutoff hemodialysis when used in addition to newer chemotherapeutic regimens. Until these studies are available, high-cutoff hemodialysis cannot be recommended as standard of care.

Prognostic value of kidney biopsy in myeloma cast nephropathy: a retrospective study of 70 patients

BACKGROUND

Light chain myeloma cast nephropathy (MCN) is the major cause of renal failure in multiple myeloma and strongly impacts patient survival. The role of kidney biopsy in the management of MCN is unclear.

METHODS

Renal pathological findings were retrospectively studied in 70 patients with multiple myeloma and MCN. Patients were categorized according to the achievement or not of renal response, as defined by estimated glomerular filtration rate (eGFR) ≥ 30 mL/min/1.73 m(2) and/or dialysis independence at 3 months.

RESULTS

Thirty-two patients (46%) achieved a renal response. In the whole study population, the following parameters differed significantly between patients with and without renal response, respectively: baseline median eGFR (13.3 versus 9.3 mL/min/1.73 m(2), P = 0.017), Acute Kidney Injury Network Stage 3 (68.8 versus 92.1%, P = 0.019), haematological response rate (94 versus 34%, P < 0.0001), median percentage of free light chain (FLC) reduction at Day 21 (92 versus 24%, P = 0.006) and median number of casts/10 fields (14 versus 25, P = 0.005). The extent of interstitial fibrosis and tubular atrophy was similar. In multivariate analysis, only FLC reduction at Day 21 was significantly associated with renal response. However, when considering only the subgroup of haematological responders, both median number of casts [odds ratio (OR) = 0.93, 95% confidence interval (95% CI): 0.88-0.98, P = 0.01] and extent of tubular atrophy (OR = 0.03, 95% CI: 0.00-0.52, P = 0.02) were independent predictors of renal response.

CONCLUSIONS

In MCN, the presence of numerous casts and diffuse tubular atrophy is associated with poor renal prognosis. These data suggest that additional strategies to reduce FLC burden should be considered in patients with extensive cast formation.

Antineutrophil Cytoplasmic Antibodies-Negative Pauci-Immune Crescentic Glomerulonephritis Associated with Multiple Myeloma

Pauci-immune crescentic glomerulonephritis (PICGN) is most commonly associated with antineutrophil cytoplasmic antibodies (ANCA). We report a case of chronic, sclerosing ANCA-negative PICGN discovered when a patient presented with multiple myeloma. A 57-year-old woman presented with complaints of nausea, emesis and weakness. She was found to be in renal failure with a serum creatinine of 9.4 mg/dl, mild hyperkalemia and acidosis. She was noted to have normochromic, normocytic anemia with normal platelet and white cell counts, normal plasma proteins and serum protein electrophoresis. Further studies revealed increased concentrations of κ and λ light chains in a ratio of 34.89; a bone marrow biopsy found 12% plasma cells. Serum protein electrophoresis revealed no spike. ANCA, anti-glomerular basement membrane, antineutrophil antibody, hepatitis panel and serum complements were normal. A kidney biopsy result showed chronic sclerosing PICGN plus tubular necrosis, severe tubular atrophy, interstitial fibrosis and severe arteriosclerosis. Congo red stains were negative and electron microscopy showed no intraglomerular deposits. The patient was subsequently treated for myeloma with bortezomib and dexamethasone with good hematologic response but never recovered renal function. She remains on outpatient hemodialysis. Renal manifestations of myeloma often involve glomerular deposition disease, tubulointerstitial disease, with characteristic proteinaceous casts, or both. In contrast, our patient demonstrated neither of these findings but had chronic sclerosing PICGN. Crescentic glomerulonephritis occurring in patients with plasma cell dyscrasias has been previously reported, but the association remains extremely rare.

Myeloma-related kidney disease

Multiple myeloma is a malignant plasma cell disorder characterized by the overproduction of monoclonal proteins. The kidney is 1 of the major target organs of multiple myeloma. Most often, this is the result of the monoclonal proteins, which can injure the kidney via several mechanisms. In some cases, direct invasion by myeloma cells and/or bone marrow cells can also result in kidney injury. A kidney biopsy can help distinguish the various myeloma-related kidney diseases and aid in the treatment plan.

Light chain renal amyloidosis with prominent giant cells

Clinical diagnosis of amyloidosis may be very challenging because signs, symptoms, and laboratory study results can be highly variable and may overlap with other disease entities. Amyloid has characteristic features on kidney biopsy, involving glomeruli, vessels, and/or interstitium as typically amorphous waxy material that is periodic acid-Schiff pale and Congo Red birefringent under polarized light. Electron microscopy demonstrates characteristic randomly oriented fibrils. However, in rare cases, amyloid may present with atypical morphologic features on kidney biopsy, closely mimicking other histopathologic diagnoses. We present a case of light chain (AL) κ amyloidosis with an unusual inflammatory infiltrate including prominent multinucleated giant cells in the interstitium and at the glomerular hilus. Amyloid was apparent within giant cells on Congo Red staining, as well as on ultrastructural evaluation. Together with prior studies of tumoral nonrenal amyloid and renal amyloid A, we suggest that the amyloid fibril constituents κ and serum amyloid A have some predilection for inciting the rare multinucleated giant cell reaction.

Clinicopathologic correlations in multiple myeloma: a case series of 190 patients with kidney biopsies

BACKGROUND

Renal involvement is common in multiple myeloma. In this study, we examined kidney biopsy findings in patients with multiple myeloma and correlated them with their clinical renal and hematologic characteristics.

STUDY DESIGN

Case series.

SETTING & PARTICIPANTS

190 Mayo Clinic patients with multiple myeloma who underwent kidney biopsy between 1997-2011 were identified from our kidney biopsy database. Patients had an established diagnosis of multiple myeloma or multiple myeloma was diagnosed shortly after the results of kidney biopsy, which prompted bone marrow biopsy.

PREDICTORS

Myeloma cast nephropathy (MCN), AL amyloidosis, and monoclonal immunoglobulin deposition disease (MIDD).

OUTCOMES & MEASUREMENTS

Renal morphologic changes, clinical renal and hematologic characteristics at kidney biopsy, renal and patient outcomes.

RESULTS

Paraprotein-associated lesions were seen in 73% of patients; non-paraprotein-associated lesions, in 25%; and no pathology, in 2%. The most common paraprotein-associated lesions were MCN (33%), MIDD (22%), and amyloidosis (21%). The most common non-paraprotein-associated lesions were acute tubular necrosis (9%), hypertensive arteriosclerosis (6%), and diabetic nephropathy (5%). Patients with MIDD were younger than those with MCN or amyloidosis. Urine paraprotein size and bone marrow plasma cell percentage were higher in MCN than amyloidosis or MIDD. Nephrotic syndrome was more common in amyloidosis than MIDD. Percentage of albuminuria was highest in amyloidosis and lowest in MCN. Median kidney survival from kidney biopsy was 20, 30, and 51 months for MCN, amyloidosis, and MIDD, respectively (P = 0.2). Median patient survival from multiple myeloma diagnosis was 44, 58, and 62 months for MCN, amyloidosis, and MIDD, respectively (P = 0.4).

LIMITATIONS

Retrospective nature.

CONCLUSIONS

The spectrum of renal lesions in multiple myeloma is more heterogeneous than previously reported. Clinical features favoring amyloidosis over MIDD include older age, absence of kidney failure, presence of nephrotic syndrome, absence of hematuria, and >50% albuminuria.

Renal failure caused by plasma cell infiltration in multiple myeloma

We report on a case of severe renal failure in a 61-year-old female with multiple myeloma (MM). Two months prior to admission, the patient was diagnosed to have anemia and progressive renal failure associated with urinary Bence Jones protein and was referred to our hospital. A bone marrow biopsy revealed 40% plasma cells with κ light chain restriction. Thus, she was considered to have MM. A renal biopsy revealed neoplastic plasma cell infiltration within the kidney, moderate interstitial fibrosis, tubular atrophy, and punctate, electron-dense material along the peripheral capillary walls, tubular basement membrane, and in the interstitium of the kidney. This suggested that a combination of compression of the tubules and the microvasculature by the infiltrative process, and local light chain deposition-mediated tissue damage might be implicated in the development of renal failure in this patient. Despite a remission of bone marrow plasmacytosis with a bortezomib-based regimen, her renal function gradually deteriorated and a periodic hemodialysis program was finally required. Although the clinical impact of the direct kidney infiltration of neoplastic plasma cells on the longitudinal changes in renal function remains to be delineated, it is reasonable to consider that the infiltration of neoplastic plasma cells associated with local light chain depositions may result in irreversible renal injuries. Obviously, further studies and accumulation of additional experience with renal biopsy are required to better determine the precise and prognostic relationship between renal outcome and morphological alterations among MM patients with varying degrees of renal impairment.

Tubular nuclear accumulation of Snail and epithelial phenotypic changes in human myeloma cast nephropathy

The transcription factor Snail is an important repressor of E-cadherin gene expression. It plays a key role in the induction of epithelial-mesenchymal transition, an essential process important not only in embryonic development and tumor progression but also in organ fibrogenesis. We studied the expression of Snail by immunohistochemistry, along with several epithelial phenotypic changes suggestive of epithelial-mesenchymal transition, in 14 patients with multiple myeloma cast nephropathy. This nephropathy is characterized by a rapid progression toward fibrosis. As controls, we used normal kidneys and kidneys from patients displaying an idiopathic nephrotic syndrome, a syndrome unassociated with renal fibrosis. We discovered that, in all patients with multiple myeloma nephropathy, a drastic accumulation of Snail is seen in the nuclei from tubular epithelial cells showing epithelial phenotypic changes. In contrast, normal and idiopathic nephrotic syndrome kidneys did not exhibit either of these markers. Snail, a major player in the process of epithelial-to-mesenchymal transition, is highly expressed by tubular epithelial cells during multiple myeloma nephropathy. It is, therefore, a potential target to prevent multiple myeloma kidneys from fibrosing. Intranuclear accumulation of Snail is a characteristic in phenotypically altered tubular cells from multiple myeloma kidneys. The epithelial-mesenchymal transition pathway could, therefore, be involved in the rapid renal fibrogenesis observed in this setting.

Renal disorder preceding multiple myeloma

Renal disorders preceding multiple myeloma (MM) is a rare type of presentation for plasma cell dyscrasias. We report a case of 40-year-old female who first admitted to the hospital with symptoms and signs of weight loss, nausea and vomiting, and with findings of proteinuria renal dysfunction and anemia. Renal biopsy revealed light chain deposition and findings mimicking membranoproliferative glomerulonephritis (MPGN). Investigation of the patient for plasma cell dyscrasia was resulted in normal findings. After 28 months, she was re-evaluated and MM was diagnosed.

Giant cell tubulitis with immune complex deposits in a patient with lupus nephritis

We report a case of acute tubulointerstitial nephritis with giant cell tubulitis and tubular basement membrane immune complex deposits in a patient with membranous lupus nephritis. The patient, who had no prior evidence of lupus nephritis, developed acute kidney failure and mild proteinuria after cardiac valve replacement surgery. Giant cell tubulitis with tubular basement membrane immune complex deposits has been described in 4 patients after cardiac surgery, 3 of whom received cefuroxime, suggesting the possibility of a drug hypersensitivity reaction. The present case suggests there may also be a pathogenetic role for autoimmunity in this condition.

Complications of multiple myeloma

Multiple myeloma, also known as myeloma or plasma cell myeloma, is a progressive hematologic disease. Complications of multiple myeloma include renal insufficiency, hematologic complications (anemia, bone marrow failure, bleeding disorders), infections, bone complications (pathologic fractures, spinal cord compression, hyercalcemia), and neurologic complications (spinal cord and nerve root compression, intracranial plasmacytomas, leptomeningeal involvement, among others). This article reviews these various complications connected to multiple myeloma, examining their various causes and possible treatment.

Giant Cell Tubulitis with Tubular Basement Membrane Immune Deposits: A Report of Two Cases after Cardiac Valve Replacement Surgery

This paper presents two elderly patients who had normal baseline renal function and had stenotic valvular lesions secondary to rheumatic fever and underwent aortic valve replacements with mechanical valves. Both patients developed acute renal failure after cardiac valve replacement procedures. The renal biopsies revealed acute granulomatous tubulointerstitial nephritis. The unique histologic features were tubular basement membrane (TBM) immune complex deposition detected by both immunofluorescence and electron microscopy and prominent multinucleated giant cells surrounding intact TBM. The temporal relationship to the surgical procedure and the subsequent recovery of the patients' renal functions upon therapy suggested that the renal failure may have been due to an allergic drug reaction from the perioperative exposure to unknown agents, such as prophylactic antibiotics and furosemide. The literature on TBM immune complex deposition was reviewed, and the pathophysiologic mechanisms that may account for the similarities between the clinicopathologic features of these two cases were examined. These two cases expand the histopathologic spectrum of previously described cases of putative drug-induced acute tubulointerstitial nephritis.

Lambda Light Chain Deposition Disease in a Renal Allograft

Light chain deposition disease (LCDD) of the kidney is characterized by deposition of monoclonal light chains predominantly in glomeruli and in tubular basement membranes. The disease is frequently associated with a lymphoproliferative disorder, and the majority of cases are caused by deposition of kappa light chains. Although the occurrence of de novo multiple myeloma after renal transplantation is uncommon, there are several reports of LCDD involving renal allografts, either de novo or in patients with a diagnosis of LCDD prior to transplantation. To the best of our knowledge, all previously described cases in allografts have been in patients with kappa chain deposition. The relative importance of intrinsic properties of the kidney in predisposing to either kappa or lambda light chain deposition is not known. We present a case of LCDD caused by deposition of lambda light chains in a patient who received a cadaveric renal transplant.

Renal, hematologic and infectious complications in multiple myeloma

Renal failure is a common complication in patients with multiple myeloma. It is generally due to tubular light-chain damage, and it is reversible in about 50% of patients. The reversibility rate depends on the degree of light-chain nephropathy. The initial therapy should consist of dexamethasone- or cyclophosphamide-based regimens. High-dose therapy/autologous transplant may be of benefit in selected patients. Early plasma exchange may be useful in patients who have severe renal failure but do not yet require dialysis. Renal replacement with dialysis is a worthwhile measure in patients with end-stage renal failure. Anemia is the most common hematologic complication. About 70% of anemic patients respond to recombinant human erythropoietin (rHuEPO), resulting not only in an increase in the hemoglobin level but also in an improvement in the quality of life. The hemoglobin level should ideally be maintained at around 12 g/dL. Infection is the main cause of morbidity and mortality in patients with myeloma. The highest risk of infection is within the first 2 months of initiation of therapy as well as in patients with renal failure and in those with relapsed and refractory disease.

Crystalloid deposits in the kidney. Case Report

Light chain-producing lymphoproliferative disorders such as multiple myeloma are frequently complicated by renal impairment. Typically, the renal biopsy of a patient with renal failure caused by multiple myeloma shows cast nephropathy, but occasionally crystals may be seen. We describe the case of a patient with acute renal failure caused by multiple myeloma in which, on renal and bone marrow biopsy, there were widespread crystalloid deposits. Crystalloid nephropathy is a very rare condition associated with multiple myeloma and other light chain-secreting disorders. An underlying lymphoproliferative disorder should be considered in the differential diagnosis if crystalloid deposits are seen on a renal or other tissue biopsy.

Monoclonal gammopathy: significance and possible causality in renal disease

BACKGROUND

Patients with monoclonal gammopathy can develop a variety of related renal lesions or possibly have kidney disease unrelated to their monoclonal gammopathy. We characterized the spectrum of renal diseases associated with monoclonal gammopathy and renal diseases.

METHODS

Patients who underwent renal biopsy and had monoclonal gammopathy on serum and/or urine electrophoresis and/or had a renal biopsy diagnosis related to paraprotein (cryoglobulinemic glomerulonephritis [CG], monoclonal immunoglobulin deposition disease [MIDD], light chain cast nephropathy [CN], or light chain amyloidosis [AL]) were identified.

RESULTS

One hundred twenty-one patients met the inclusion criteria and were classified as having renal disease related or unrelated to monoclonal gammopathy. Among 66 cases of renal disease related to monoclonal gammopathy, diagnoses were CG (30.3%), MIDD (28.8%), CN (19.7%), AL (19.7%), and CN plus MIDD (1.5%). Among patients with monoclonal gammopathy in serum and/or urine (n = 87), 32 patients (36.8%, included in listing above) had related renal disease. Among 55 patients with monoclonal gammopathy and unrelated renal disease (63.2% of all patients with monoclonal gammopathy), various lesions were found, including diabetic nephropathy (18.1%), focal segmental glomerulosclerosis (18.1%), arterionephrosclerosis (12.7%), membranous glomerulonephritis (9.0%), minimal change disease (7.3%), various immune complex diseases, interstitial nephritis, or nonspecific changes.

CONCLUSION

The majority of patients with serum and/or urine monoclonal gammopathy who undergo renal biopsy have disease unrelated to monoclonal gammopathy deposition. This likely reflects the high frequency of monoclonal gammopathy of undetermined significance in older patients and the frequent use of serum and/or urine protein electrophoresis as screening tools in adult patients with renal disease.

Urinary proteins and renal dysfunction in patients with multiple myeloma

Besides bone pain, pathologic fractures, anaemia, and recurrent infectious diseases, renal failure is one of the most serious complications in multiple myeloma patients. Its incidence is generally underestimated because of the low reliability of the parameters routinely used for the evaluation of renal dysfunction. Other laboratory tests in the literature are reported to be more suitable to better define the extension of the renal impairment, namely urinary proteins or creatinine clearance. We here report on the clinical implication of urinary parameters in defining the renal function in myeloma patients.

Binding of nascent collagen by amyloidogenic light chains and amyloid fibrillogenesis in monolayers of human fibrocytes

Light (L) chain dimers expressed by multiple myeloma cells and collected as Bence-Jones proteins from the urine of human subjects were tested for their ability to form deposits in fibroblast monolayer cell cultures. Bence-Jones proteins from subjects with primary amyloidosis associated with L chains were shown to form fibrillar deposits by the in vitro assay introduced in this report. Filaments interspersed with nascent collagen could be detected after only 48 h. Deposition of L chains continued over a period of 72 h culminating in the appearance of dense fibrils with widths of 80-100 A and a variety of lengths. Formation of amyloid-like fibrils was accompanied by interference with the maturation of the collagen produced by the fibroblast cells. Fibrils composed of the Mcg lambda-type L chain were deposited between collagen fibers, thus expanding them laterally and leading to their partial disintegration. Mature collagen was completely missing from fibroblast monolayers exposed to the Sea lambda chain and the Jen kappa chain. Collagen with the characteristic striped pattern matured normally in control samples, such as those not dosed with amyloid precursors or those treated with a non-amyloidogenic Bence-Jones protein (e.g., the Hud lambda chain dimer). By immunochemical techniques using fluorescein- and gold-labeled anti-L chain antibodies, amyloidogenic L chains were shown to decorate the strands of nascent collagen. This observation suggests that amyloidogenic L chains are concentrated in the extracellular matrix by monovalent antigen-antibody type reactions. The capacity of the Mcg L chain dimer to bind collagen-derived sequences was tested by soaking crystals with a collagenase substrate, PZ-Pro-Leu-Gly-Pro-D-Arg. Difference Fourier analysis at 2.7 A resolution indicated that the PZ-peptide is a site-filling ligand. It could not be removed from the active site by perfusion of the crystal with ammonium sulfate crystallizing media. Similar experiments with the collagen-derived peptide (Pro-Pro-Gly)(5) showed substantial hysteresis effects extending from one end of the Mcg dimer to the other. After the ligand was withdrawn, the active site of the Mcg dimer could no longer bind the PZ-peptide. However, if the active site was first blocked by the PZ-peptide and subsequently exposed to the (Pro-Pro-Gly)(5) peptide, the difference Fourier map was indistinguishable from that obtained with the PZ-peptide alone. We concluded that amyloidogenic L chains such as the Mcg dimer could be concentrated in the perivascular space by binding to normal tissue constituents. These components include nascent collagen, which can be deterred from maturing as a result of this binding. Participation in such pathological activity is also self-destructive to the amyloidogenic L chains, which lose their binding capabilities for collagen-derived peptides and also become susceptible to irreversible conversion to amyloid fibrils. All of these events may be prevented by prior treatment of the amyloidogenic L chains with site-filling ligands. (c) 2000 John Wiley & Sons, Ltd.

Renal manifestations of plasma cell dyscrasias: an appraisal from the patients' bedside to the research laboratory

One of the most prominent features of plasma cell dyscrasias is the frequent occurrence of renal dysfunction. Renal insufficiency is a common finding with elevated serum creatinine in more than 50% of patients with multiple myeloma at the time of diagnosis. Renal failure is the second most common cause of death in myeloma surpassed only by infections. The reasons for renal failure are multifactorial and early accurate diagnosis of the renal alterations may significantly impact morbidity and survival. Renal failure may result from selective glomerular, tubular interstitial, or vascular pathology or from a combination of pathologic events. The disorders associated with plasma cell dyscrasias include those characterized by monoclonal light chain deposition, encompassing AL-amyloidosis, in addition to the less well-characterized entities, such as heavy chain deposition disease and heavy chain amyloidosis. Therefore, it is more accurate to refer to them as monoclonal immunoglobulin deposition diseases. Staining of renal biopsy specimens for kappa and lambda light chains using immunofluorescence techniques and more sophisticated advanced diagnostic techniques such as immunoelectron microscopy permit detailed characterization of the various renal pathologic manifestations. Renal biopsies can identify monoclonal immunoglobulin deposition, and nephrologists have an opportunity to detect an underlying plasma cell dyscrasia early in its clinical course before overt hematologic alterations become manifest and irreversible renal damage has occurred. The overall spectrum of clinical and pathologic manifestations of monoclonal immunoglobulin deposition renal diseases has expanded considerably in recent years. Recent developments in the research arena promise new therapeutic interventions aimed at avoiding or ameliorating renal damage and even promoting reversal of some of the pathologic alterations. Currently, the 5-year survival rate in myeloma is 29% in white patients and 30% in African-American patients, a rather modest improvement from 24% in the 1970s. Bone marrow ablation followed by transplantation is available as an alternative mode of therapy that may be extraordinarily helpful in a subset of patients with early myeloma.

Free light chains in multiple sclerosis urine

We measured free kappa (kappa) and lambda (lambda) light chains in urine from patients with definite multiple sclerosis (MS), other neurologic diseases (OND), and normal controls by using an enzyme linked immunosorbent assay. Both kappa and lambda light chains were higher in MS than OND or controls. In seven of eight relapsing-remitting (R-R) MS patients serial studies showed that urinary kappa chains were elevated during periods of worsening, and decreased during clinical recovery. In contrast, the levels of kappa chains did not correlate with clinical activity in 10 progressive (P) MS patients. Further correlation of urinary light chains with neurologic evaluations in R-R and P MS patients over a longer period are needed to determine their clinical and biological relevance.

Electrophoretic study of the physico-chemical characteristics of Bence-Jones proteinuria and its association with kidney damage

AIM

To identify a physico-chemical criterion, or set of criteria, explaining and possibly predicting the nephrotoxic behaviour of Bence-Jones proteins (BJP).

METHODS

The electrophoretic mobility and isoelectric point (pI) of 92 BJP isolates were determined using various electrophoresis procedures on polyacrylamide gel. The proportions of monomers and dimers were determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS PAGE) in 58 cases. PAGE data for 10 BJP isolates were used to construct Ferguson plots and titration curves.

RESULTS

The distribution of electrophoretic mobility and pI values was bimodal and showed a positive correlation when the pI was above 6. The values of these two parameters in 22 patients with renal impairment were not significantly different from those in the patients without renal impairment, and the statistical analysis showed no predictive value for the onset of renal impairment. However, patients excreting the lambda light chain isotype had a 2.8-fold higher risk of developing renal impairment compared with the other patients. Studies of the charge variation of the protein with pH indicated three types of behaviour, suggesting that the charge of BJP is highly variable at physiological pH.

CONCLUSION

It is important to study not only the positivity or negativity of the BJP charge at a given pH, but also its intensity. The study of the BJP titration curves in patients with renal impairment suggests that a low charge at physiological urinary pH could predict renal impairment.

Long-term follow-up and response to chemotherapy in patients with light-chain deposition disease

Nineteen patients with light-chain deposition disease (LCDD) were studied retrospectively. This report presents data on long-term patient and renal survival and the response to intermittent administration of melphalan and prednisone. Immunoelectrophoresis or immunofixation demonstrated a monoclonal protein in the serum of 78% and in the urine of 84% of the patients; 16% had no demonstrable monoclonal protein in serum or urine. The median age at presentation was 51 years (range, 37 to 77 years). Twelve (63%) of the patients had a monoclonal protein of undetermined significance without evidence of myeloma. The typical glomerular lesion was a diffuse mesangial nodular lesion that was positive for periodic acid-Schiff (PAS) stain with acute and chronic tubulointerstitial changes. Fifteen patients had kappa light-chain deposition and four had lambda light-chain deposition. Five-year actuarial patient survival and survival free of end-stage renal disease were 70% and 37%, respectively. Seventeen patients received melphalan and prednisone, and one patient received chlorambucil and prednisone. All of the patients had some impairment of renal function at presentation, and 58% had a serum creatinine concentration greater than 354 mumol/L (4.0 mg/dL). There was either stabilization or improvement in renal function after chemotherapy in five of eight patients who had a serum creatinine concentration less than 354 mumol/L (4.0 mg/dL) at the initiation of therapy. Of the 11 patients with a high serum creatinine concentration (greater than 354 mumol/dL [4.0 mg/dL]), 82% progressed to end-stage renal disease despite therapy. Follow-up urine protein studies demonstrated at least a 50% decrease in urine protein excretion in five of 15 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Nephrotoxic potential of Bence Jones proteins

BACKGROUND

The renal manifestations of diseases associated with the production of monoclonal light chains--myeloma (cast) nephropathy, light-chain deposition disease, and amyloidosis AL--result from the deposition of certain Bence Jones proteins as tubular casts, basement-membrane precipitates, or fibrils, respectively. For unknown reasons, the severity of the renal manifestations of these diseases varies greatly from patient to patient. We employed an experimental in vivo model to determine the pathologic importance of various Bence Jones proteins.

METHODS

Mice were injected intraperitoneally with 300 mg of Bence Jones protein from 40 patients with multiple myeloma or amyloidosis AL and killed 48 hours later. The mouse kidneys were examined by light and electron microscopy, and light-chain deposits were identified immunohistochemically with highly specific antihuman light-chain antiserum.

RESULTS

Of the 40 different human Bence Jones proteins studied, 26 were deposited in the mouse kidneys predominantly as tubular casts, basement-membrane precipitates, or crystals; no light-chain deposits were detected in the kidneys of the mice that received the other 14 Bence Jones proteins. Of the 18 patients for whom renal tissue was available for study, the findings in 14 were comparable to those in the mice. Furthermore, the proteins obtained from 22 of the 27 patients whose serum creatinine concentrations equaled or exceeded 168 mumol per liter (1.9 mg per deciliter) were deposited in the mouse kidneys, whereas protein deposition occurred after the injection of proteins from only 4 of the 13 patients with serum creatinine concentrations below 168 mumol per liter. The repeated injection of Bence Jones proteins from two patients who had amyloidosis AL resulted in deposition of the protein in the mouse kidneys as amyloid.

CONCLUSIONS

Particular Bence Jones proteins are primarily responsible for producing the distinctive types of protein deposition in renal tissue and the clinical manifestations that occur in patients with light-chain-associated diseases. This experimental model has potential value for the identification of nephrotoxic or amyloidogenic light chains.

Utility of immunofluorescence of urine sediment for identifying patients with renal disease due to monoclonal gammopathies

Immunofluorescence (IF) of urine sediment with antisera to light-chain immunoglobulins (LC) was used for patients with renal disease due to various monoclonal gammopathies. Urinary casts and/or masses from 20 of 27 patients (74%) of this group stained predominantly for one or another of the two LC, but from none of the 25 controls, who all had renal diseases other than monoclonal gammopathies. In all but one patient with monoclonal gammopathy the more intensely staining LC in the urine sediment was the same as that found in the paraprotein. For 68.7% of patients, the prevailing LC in urinary casts was the same as that prevailing in the casts of the renal biopsies. The sensitivity of IF of urine sediment for identifying patients with plasma cell dyscrasias was 74%, the specificity 100%, and the accuracy 86.5%. The positive predictive value was 100% and the negative predictive value was 78%. Globally, urine sediment IF was more sensitive than serum or urine electrophoresis (74% v 63% and 66.6%), but less than serum or urine immunoelectrophoresis (74% v 85%). In light-chain deposition disease, a disorder in which there are often no definite symptoms, urine sediment IF was more sensitive than both traditional methods. We conclude that IF of urine sediment is a useful test to identify patients with renal disease associated with monoclonal gammopathies.

Urinary excretion of kappa light chains in patients with diabetes mellitus

The urinary excretion of kappa light chains, beta 2-microglobulin and albumin was examined in patients with newly diagnosed and long-standing insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus, and compared to age-matched control subjects. Patients with IDDM diagnosed within two months, presented with normal albumin excretion, whereas the concentrations of beta 2-microglobulin and kappa light chain in urine were higher than in control subjects. The initiation of insulin therapy reduced, but did not completely normalize, the elevated rate of kappa light chain excretion. Patients with IDDM of long duration showed increased urine excretion of kappa light chains and albumin. In keeping with the findings in IDDM, patients with newly diagnosed NIDDM (within one year) showed increased urinary excretion of kappa light chains compared with control subjects. There was, however, no further increase in light chain excretion with longer duration of NIDDM. To study the effect of short-term hyperglycemia on urinary protein excretion, 12 normal subjects participated in a three-step hyperglycemic clamp study, during which their plasma glucose concentration was raised by +50, +125 and +300 mg/dl. The urine excretion of albumin and beta 2-microglobulin rose progressively with each hyperglycemic clamp step, whereas that of kappa light chain excretion was unaffected by hyperglycemia. We conclude that increased urinary excretion of kappa light chain is a consistent finding in all types of diabetes mellitus, and can be observed even when the albumin excretion is normal. Since the serum concentration of kappa light chain is normal in diabetes, the increased urinary excretion of kappa light chains must be of renal origin.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms of intranephronal proteinaceous cast formation by low molecular weight proteins

Proteinaceous cast formation in the distal nephron of the kidney from low molecular weight proteinuria is a significant, but poorly characterized, cause of renal failure. To study this phenomenon, we: (a) microperfused the loop segment (LS) of rats in vivo with artificial tubule fluid (ATF) containing four different low molecular weight proteins, 0.01-50 mg/ml, to detect alterations in LS function, and (b) examined the interaction between several proteins and Tamm-Horsfall glycoprotein (THP) in vitro with turbidity and dynamic light-scattering measurements. Perfusion of the LS for less than 2 min with cast-forming proteins (Bence Jones protein [BJP3] and myoglobin) decreased chloride absorption and elevated early distal tubule fluid (ED) [Cl-], compared with results obtained with control perfusions that used ATF alone. BJP3 decreased chloride absorption in a concentration-dependent fashion. Perfusion with non-cast-forming proteins (albumin and BJP1) enhanced chloride absorption and decreased ED [Cl-]. In vitro, proteins that had isoelectric points (pI) greater than 5.1 aggregated with THP. Aggregation was enhanced with increasing [NaCl] or [CaCl2]. Albumin (pI 4.8) and beta-lactoglobulin (pI 5.1) did not coprecipitate. The molecular size of THP alone increased when [NaCl] greater than 80 mM. Thus, cast-forming proteins aggregated with THP in vitro and caused in vivo LS dysfunction, which elevated ED [Cl-], facilitating aggregation. In contrast, non-cast-forming proteins either did not interact with THP or lowered ED [Cl-], which did not provide an environment for aggregation. Altered LS function and interaction of some proteins with THP were related to different physicochemical properties of the proteins and independently contributed to the formation of proteinaceous casts in the kidney.

Crystalline glomerular inclusions in multiple myeloma

Prominent crystalline inclusions were noted in the glomeruli of a 57-year-old man with a 6-month history of swelling and pain in the hands, slight proteinuria, and elevated serum creatinine and BUN. The crystalline inclusions were most prominent in the visceral epithelium but were also noted in endothelial and mesangial cells, in the parietal epithelium, and in the epithelial cells of the proximal tubules. On electron microscopy the crystalline structures were of various geometric shapes but had no definite substructure. Immunofluorescence was negative. The patient was considered to have a hitherto undescribed metabolic disease. Several months later the patient underwent an operation for carpal tunnel syndrome and amyloid deposits, crystalline inclusions similar to those noted in the kidney were observed in the synovial tissue. Shortly after this the patient was found to have multiple myeloma of IgG, kappa type with Bence Jones proteinuria. Lymphoplasmacytic cells in the bone marrow contained the same crystalline inclusions noted in the kidney and synovium. This case therefore seems to represent a new and very rare form of glomerular involvement in multiple myeloma.

Renal impairment in myeloma: negative association with isoelectric point of excreted Bence-Jones protein

The isoelectric point (pI) of the major form of Bence-Jones protein excreted by 62 patients with myeloma and six with macroglobulinaemia was measured by combining isoelectric focusing with immunoblotting techniques. The distribution of the pI values for both kappa and lambda type proteins was bimodal, most falling in the ranges 5.0-6.0 and 7.0-7.5. Plasma creatinine and creatinine clearance and the urine excretion of alpha-1-microglobulin and beta-2-microglobulin were measured in 24 of the patients. These patients, who were free of additional factors known to have an association with the development of renal impairment, were followed up for a mean period of 16 months (range three to 28 months). It was found that renal impairment was not related to the pI of the Bence-Jones protein excreted.

Mesangiolysis in diabetic glomeruli: its role in the formation of nodular lesions

In order to elucidate a participation of the mesangiolysis in the formation of diabetic nodular lesions, 355 kidney specimens obtained from 327 patients with primary diabetes mellitus were studied. Mesangiolyses begun by focal and segmental disintegration of the pivotal structure of the mesangium ("torn off phase"), resulting in cystic or aneurysmal dilatation of the involved tuft, were found in 56 specimens (16%). The dilated tufts were filled with lysed mesangial matrix, which showed a reticular or fibrillar arrangement ("structureless phase"), being followed by a concentrical re-arrangement ("reconstructive phase") and by the ultimate formation of diabetic nodules. The mesangiolysis of various phases was frequently found concomitant with severe diabetic arteriolosclerosis and, in the reconstructive phase, the lysed mesangial matrix near the recanalized capillary along the inner aspect of glomerular basement membrane was observed to be rearranged in a layered structure. These results suggest the hypothesis that: 1) the mesangiolysis is the initial lesion occurring in glomeruli in the process of diabetic nodule formation, and disturbed blood flow into glomeruli, caused by diabetic arteriolosclerosis, may be implicated in the development of the mesangiolysis; and 2) concentric compression of the lysed mesangial matrix by recanalized capillaries forms layered structures and ultimate completed diabetic nodules.

Morphologic alterations of the proximal tubules in light chain-related renal disease

Previous studies from our laboratory have shown that human immunoglobulin light chains (LC) can be toxic to the epithelium of the rat proximal tubule. To examine the toxicity of monoclonal LC's in man, 11 kidney specimens (EXP group) obtained from patients with monotypical LC-related renal disease (7 lambda, 4 kappa), documented by the presence of monoclonal LC's in the serum or urine and in the tissue, were examined by light, immunofluorescence, electron, and immunoelectron microscopy. This EXP group had monotypical LC deposition in the tubules and/or the glomeruli and did not have evidence of intraluminal LC precipitation and cast formation, which alters tubule morphology. A control group (CON; N = 12) of kidney specimens was obtained from patients who had proteinuria greater than 2.5 g/24 hr and mean age (49 +/- 4 vs. 59 +/- 3 years; P = NS), serum creatinine concentration (2.4 +/- 0.5 vs. 3.2 +/- 1.5 mg/dl; P = NS) and creatinine clearance (65 +/- 13 vs. 63 +/- 12 ml/min; P = NS) similar to the EXP group. All of the EXP specimens demonstrated varying degrees of proximal tubule damage, manifested by cell vacuolation, desquamation, loss of the luminal brush border, and, often, coagulation necrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma cell dyscrasias: current status

This is a review of the current status of the monoclonal gammopathies (plasma cell dyscrasias). We begin with the recognition of a monoclonal protein in serum and urine. We briefly discuss the differential diagnosis of the monoclonal gammopathies. Clinical and laboratory findings as well as the management of multiple myeloma are addressed. Future approaches for the treatment of myeloma are provided. The variant forms of multiple myeloma, including smoldering myeloma, plasma cell leukemia, nonsecretory myeloma, IgD myeloma, osteosclerotic myeloma, solitary plasmacytoma of bone, and extramedullary plasmacytoma, are briefly reviewed. Diagnosis and treatment of Waldenström's macroglobulinemia are presented. The recognition and differential diagnosis of the heavy-chain diseases (gamma, alpha, and mu) are included. Monoclonal gammopathy of undetermined significance ("benign" monoclonal gammopathy) is presented in detail. Amyloidosis is not included in this review.

Renal lesions in plasma cell dyscrasias: ultrastructural observations

The renal biopsies from 47 patients with plasma cell dyscrasias were studied by light and electronmicroscopy, and by immunohistochemical methods. This report is primarily concerned with the ultrastructural features of 24 cases of Bence Jones cast nephropathy and of ten cases of light chain deposit disease. In Bence Jones cast nephropathy, crystals derived from light chain proteins were detected in the majority of cases within the casts or in tubular cells and appeared to be related to the "hard" and "fractured" appearance of the casts as well as to the presence of foreign body type giant cells, the latter probably being of monocyte-macrophage origin. In light chain deposit disease, linear deposits of light chain proteins (eight kappa and two lambda) were present in a subendothelial position along the glomerular basement membrane and along the outer aspect of the tubular basement membranes in all cases, quite often in the mesangial matrix, but much less commonly in the interstitium and in the wall of small arteries. The light and electronmicroscopic features of both Bence Jones cast nephropathy and light chain deposit disease can be considered diagnostic for plasma cell dyscrasia. The possible pathogenetic mechanisms of these two different forms of renal involvement are discussed briefly.