IgG4-related Tubulointerstitial Nephritis Research Articles

Relationship between MRI findings and renal histopathology in IgG4-related tubulointerstitial nephritis.

MRI is expected to be a valuable tool for evaluating disease activity in immunoglobulin G4 (IgG4)-related tubulointerstitial nephritis (IgG4-TIN). However, the correlation between MRI findings and renal histopathological findings remains to be elucidated. This study aimed to clarify the correlation between MRI findings and renal histopathological findings in IgG4-TIN. This retrospective cross-sectional study investigated 26 patients with biopsy-proven IgG4-TIN who underwent simultaneous percutaneous kidney biopsies and abdominal MRI examinations at Toranomon Hospital or Toranomon Hospital Kajigaya between December 2007 and November 2022. We reviewed kidney biopsy specimens and scored the degree of inflammatory cell infiltration and interstitial fibrosis. We assessed abdominal MRI, specifically examining T1WI, T2WI, and DWI, for the presence of abnormal signals in the inferior pole of the kidney on the side where the kidney biopsy was performed. Spearman's correlation coefficient test was conducted to examine the relationship between the images and histological findings. For T1WI, eight cases showed a positive low-intensity signal, and 18 cases were negative. For T2WI, 19 cases were positive for a low-intensity signal, and seven cases were negative. In DWI, 23 cases were positive for a high-intensity signal, and one was negative. T1WI low-intensity signal and T2WI low-intensity signal were significantly correlated with interstitial fibrosis score (correlation coefficient 0.52 and 0.64). DWI revealed IgG4-TIN detected IgG4-TIN lesions with the highest sensitivity; however, the correlation with inflammatory cell infiltration score was not significant. Low-intensity signal on T2WI is useful for predicting the degree of fibrosis in IgG4-TIN.

IgG4-associated disease with systemic lupus erythematosus: A case report and review.

We report a 67-year-old man who presented with poor dietary intake and fatigue. Laboratory tests showed leukopenia, antinuclear antibody (ANA) positivity, anti-dsDNA antibody (A-dsDNA) and anti-Smith antibody (anti-Sm) negativity, decreased C3 and C4, elevated serum immunoglobulin G (IgG), IgG4, and creatinine, and 1.25 g urinary protein at 24 hours. As his condition worsened, re-examination showed thrombocytopenia and A-dsDNA positivity, and renal biopsy pathology showed IgG4-related tubulointerstitial nephritis. The final diagnosis was IgG4-related disease (IgG4-RD) with systemic lupus erythematosus (SLE). His condition improved with glucocorticoid (GC) combined with hydroxychloroquine (HCQ) and mycophenolate mofetil (MMF) treatment. This case highlights that IgG4-RD and SLE may occur successively or co-exist and may convert into each other.

Clinicopathologic Features of IgG4-Related Kidney Disease

IntroductionIgG4-related disease (IgG4-RD) is a systemic immune-mediated disease that can involve nearly any organ. IgG4-RD can affect the kidney in different disease patterns, collectively referred to as IgG4-related kidney disease (IgG4-RKD). MethodsWe conducted a tissue-based cohort study with clinicopathological correlation in 125 patients with IgG4-RKD. ResultsThe mean age at biopsy (n=120) or nephrectomy (n=5) was 63 years; 80% were male. 118 patients (94%) had IgG4-related tubulointerstitial nephritis (IgG4-TIN); 20 patients (16%) had IgG4-related membranous glomerulonephritis (IgG4-MGN; 13 with concurrent IgG4-TIN). The primary clinical indication for biopsy/nephrectomy was acute or chronic renal failure in 78%, proteinuria in 17%, and mass lesion(s) in 15% (with overlap in primary indication). 52% (41/79) had abnormal radiographic findings, including mass(es) in 30% (24/79). All patients with IgG4-MGN had proteinuria. Extra-renal involvement by IgG4-RD was present in 79%. Median serum creatinine at presentation was 2.5 mg/dL (range 0.7-12). Serum IgG and/or IgG4 was increased in 91% (53/58); hypocomplementemia was present in 56% (43/77). Light microscopy showed plasma cell-rich interstitial nephritis in all cases of IgG4-TIN. 92% showed increased IgG4+ plasma cells. 7% showed an acute interstitial nephritis (AIN) pattern, and 5% showed non-necrotizing arteritis. Tubular basement membrane immune deposits were present in 83% of IgG4-TIN. Treatment information was available for 71 patients; 62 were treated with immunosuppression. Of those with elevated creatinine, 72% (41/57) showed a treatment response. ConclusionThis largest tissue-based series more clearly defines the disease phenotype of IgG4-RKD.

IgG4-Related Disease with IgG1-Dominant Membranous Nephropathy: A Rare Case Report

ABSTRACT Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disorder affecting various organs and tissues. Kidney involvement in IgG4-RD commonly manifests as IgG4-related tubulointerstitial nephritis or IgG4-related membranous nephropathy, with the latter occurring less frequently. The identification of the phospholipase A2 receptor (PLA2R) antigen has improved our understanding of primary membranous nephropathy. Here, we present the case of a 60-year-old Chinese man initially diagnosed with IgG4-related pancreatitis, who achieved clinical remission with glucocorticoid therapy followed by low-dose glucocorticoid maintenance therapy. Two years later, the patient developed nephrotic syndrome. A kidney biopsy revealed membranous nephropathy characterized by glomerular subepithelial deposition of IgG1 and positive PLA2R staining. Rituximab (RTX) treatment resulted in complete clinical remission of nephrotic syndrome, and no recurrence was observed during the 24-month follow-up period. IgG4-RD complicated by membranous nephropathy is a rare pathological feature characterized by glomerular subepithelial IgG1 deposition and positive PLA2R antigen staining. In the present case, RTX treatment was effective in achieving clinical remission. These findings contribute to the evolving understanding of the relationship between IgG4-RD and membranous nephropathy.

IgG4-related tubulointerstitial nephritis: renal capsule-like rim.

IgG4-related tubulointerstitial nephritis: renal capsule-like rim.

Urticaria with Immunoglobulin G4-Related Disease: An Association or Coincidence?

Immunoglobulin (Ig) G4-related disease is a recently described fibro-inflammatory disease with diverse clinical manifestations but consistent and characteristic histopathological features across multiple organ systems and skin, leading to tissue sclerosis and ultimately organ failure if not treated adequately. Here, we report a case of 56-year-old male patient presenting with urticarial lesions and generalized itching for 4 months. Routine investigations showed elevated 24-h urine protein, absolute eosinophil count, serum IgE, reversed albumin: globulin ratio, and “M” spike on serum electrophoresis. Renal biopsy showed storiform fibrosis, diffuse dense inflammatory cells (plasma cells and eosinophils), and IgG4-positive cells on immunohistochemistry which was histologically highly suggestive of IgG4-related chronic tubulointerstitial nephritis. Quick response was seen with oral corticosteroids.

IgG4-related disease with kidney and lymph nodes involvement: a case-based review.

IgG4-related disease (IgG4-RD), a rare immune-mediated chronic fibro-inflammatory condition, has various initial symptoms, thus posing diagnostic and therapeutic challenges. Here, we report a case of IgG4-RD in a 35-year-old man with initial clinical symptoms of facial edema and recent onset of proteinuria. It took more than 1year from the onset of clinical symptoms to diagnosis. Pathological examination of renal biopsy revealed significant renal interstitial lymphoid tissue hyperplasia simulating growth pattern of lymphoma. Immunohistochemical (IHC) staining results showed that CD4 + T lymphocyte hyperplasia was dominant. There was no significant deletion of CD2/CD3/CD5/CD7. No monoclone was detected in TCR gene rearrangement. IHC staining showed that the number of IgG4-positive cells was greater than 100/HPF. The ratio of IgG4/IgG was greater than 40%. Combined with clinically examinations, IgG4-related tubulointerstitial nephritis was considered. Further cervical lymph node biopsy results suggested IgG4-related lymphadenopathy. He received methylprednisolone 40mg/day intravenously for 10days, leading to normal results of laboratory tests and clinical manifestations. The patient had a good prognosis without recurrence during 14months of follow-up. This case report can be used as a reference for early diagnosis and treatment of such patients in the future.

Clinicopathological Patterns and Predictors of the Functional Restoration of Immunoglobulin G4-Related Kidney Disease: A Chinese Single-Center Cohort Study.

Background: Immunoglobulin G4-related disease (IgG4-RD) is a systemic immunoreactivity-based fibro-inflammatory disease. Immunoglobulin G4-related kidney disease (IgG4-RKD) is a frequently overlooked diagnosis. This study aimed to describe IgG4-RKD and examine the factors relevant to the renal outcomes of IgG4-RD.Methods: We studied a prospective IgG4-RKD cohort between January 2012 and December 2020 with close follow-up. Clinicopathologic data at kidney biopsy were collected and analyzed. We aimed to explore independent risk factors for long-term renal outcome and disease relapse. Patients with an eGFR<45 ml/min per 1.73m2 at 12 months were defined as having poor outcomes.Results: The included 42 patients with IgG4-RKD had a mean age of 58.5 ± 8.7 years (male-to-female ratio = 5:1). The IgG4-RD responder index (RI) was 12.2 ± 3.3. A total of 66.7% of the patients presented with acute on kidney disease or acute on chronic kidney disease. Eight patients (19.0%) showed nephrotic-range proteinuria, and nine (21.4%) had high-titer IgG4-autoantibodies, including antineutrophil cytoplasmic antibody and anti-phospholipase A2 receptor. A kidney biopsy was conducted in 40 patients. Thirty-seven (90.0%) patients were diagnosed with IgG4-related tubulointerstitial nephritis, and 19 (47.5%) of them had concurrent glomerular diseases (membranous nephropathy [MN], n = 3; crescentic glomerulonephritis [CrGN], n = 11; diabetic kidney disease, n = 3; and both MN and CrGN, n = 2). IgG4-RD RI had a close relationship with serum C3 (R = −0.509, P = 0.001), C4 (R = −0.314, P = 0.049) levels, and peripheral blood eosinophil count (PBEC; R = 0.377, P = 0.024), factors that were not included in RI scores. Correlation analysis disclosed that IgG4-RD RI (R = 0.422, P = 0.007), organs involved (R = 0.452, P = 0.003), and C3 (R = −0.487, R = 0.002) were correlated with the percentage decrease of serum creatinine at 1 month. However, multivariate regression analysis failed to identify any clinicopathological parameters that could predict short-term renal restoration and IgG4-RKD relapse. Ten out of 29 variables, of most importance, were identified by the least absolute shrinkage and selection operator (LASSO) regression analysis. By multivariate logistic regression a higher serum IgG4 (OR = 0.671, P = 0.010), IgG1 (OR = 1.396, P = 0.049), IgG3 (OR = 19.154, P = 0.039), and erythrocyte sedimentation rate (ESR; OR = 1.042, P = 0.032) were found to be independent factors for poor long-term outcome. Conventional immunosuppressive medications and/or rituximab were prescribed, and in 83.3% of the patients, the kidney function improved. Repeat kidney biopsies confirmed the remission of interstitial inflammation in two patients under immunosuppressive therapy. However, the disease relapse rate was as high as 31.0%.Conclusions: We strongly recommend a kidney biopsy in active IgG4-RD, especially when there is proteinuria and renal dysfunction, because concurrent glomerular involvement and active interstitial inflammation should be assessed. A higher serum IgG1, IgG3, and ESR were independent factors for the poor long-term renal outcome; however, elevated IgG4 predicted a good renal prognosis, and appropriate and timely immunosuppressive therapy can help achieve a better prognosis.

IgG4-related kidney disease

IgG4-related disease (IgG4-RD) is an immune-mediated fibro-inflammatory disease characterized by the formation of sclerotic tumor-like masses with dense lymphoplasmacytic infiltrates containing a significant number of IgG4-plasma cells. IgG4-RD is characterized by a wide range of clinical manifestations since the disease can involve almost any organ. Renal da­mage is observed in about 15 % of patients with IgG4-RD. The article presents a review of data about clinical manifestations of IgG4-related kidney disease (IgG4-RKD), specific features of diagnosis, and modern treatment approaches. The review of scientific publications was conducted in the international electronic scientometric database PubMed using keywords “IgG4-related kidney disease”, “IgG4-RKD radiographic findings”, “IgG4-related tubulointerstitial nephritis”, “IgG4-related membranous glomerulonephritis” over the period 2012–2020. The most common renal lesions in IgG4-RD are tubulointerstitial nephritis and membranous glomerulonephritis. They occur predominantly in older males. At the time of diagnosis, patients mostly already have concomitant extrarenal manifestations of IgG4-RD (sialadenitis, pancreatitis, lymphadenopathy). The clinical picture is usually vague, although nephrotic syndrome and chronic renal failure may occur. Typical manifestations of IgG4-RKD on CT are multiple low-dense foci, thickening of the renal pelvis, diffuse kidney enlargement. Renal involvement in IgG4-RD is often accompanied by low levels of complement. Early detection and treatment of IgG4-RKD are extremely important due to the increase in morbidity and mortality due to the development of chronic kidney disease. Glucocorticoids (GC) are first-line drugs for IgG4-RD. Despite a good response to GC, even a slight delay in treatment can lead to the development of renal tissue atrophy. The use of immunosuppressive drugs is advisable in cases when the dose of GC cannot be reduced due to the constantly high activity of the di­sease. Rituximab (a CD20+ B-lymphocyte inhibitor) may be used in patients with a recurrent course of IgG4-RKD.

A case report of IgG4-related kidney disease with cirrhosis as the first manifestation

Abstract Introduction: Immunoglobulin G4-related kidney disease (IgG4-RKD) is a recently identified inflammatory disorder most often classified as IgG4-related tubulointerstitial nephritis or IgG4-related membranous nephropathy based on the predominant renal pathology. However, almost all the cases are complicated by extrarenal organ involvement that includes lymph nodes, pancreas, lacrimal glands, salivary glands, and/or retroperitoneum. IgG4-RKD with cirrhosis as the initial presentation followed by massive proteinuria and renal dysfunction is very rare. Patient concerns: A 35-year-old Chinese male presented to a local hospital with abdominal distension, edema, and black tarry stool 5 years before. Abdominal color ultrasonography at that time suggested cirrhosis, and the diagnosis was upper gastrointestinal hemorrhage with decompensated cirrhosis. About two weeks before, edema was aggravated, and massive proteinuria and renal impairment were detected with significantly elevated serum IgG. Abdominal computed tomography indicated cirrhosis and diffuse renal enlargement with multiple low-density foci, while light microscopy of renal biopsy tissue indicated atypical membranous nephropathy with interstitial nephritis. Immunohistochemistry revealed 20–50 IgG-positive plasma cells per high-power field among interstitial infiltrating cells, accounting for ∼40% of all IgG-positive plasma cells. Diagnoses: According to clinical manifestations and immunohistochemical findings, the diagnosis was IgG4-RD/IgG4-RKD featuring atypical membranous nephropathy, interstitial nephritis, and decompensated cirrhosis. Interventions: Methylprednisolone 40 mg/day was administered for IgG4 related kidney disease. Other symptomatic therapies were also administered. Outcomes: Half a month following the treatment, 24-hour proteinuria decreased from 10.67 g/d to 2.16 g/d and serum creatinine decreased significantly. Conclusion: IgG4-RKD with cirrhosis as the first manifestation followed by renal dysfunction is very rare. Simultaneous occurrence of these two conditions which improved after the treatment indicates that there may be an association between IgG4 related kidney disease and cirrhosis.

Co-occurrence of IgA nephropathy and IgG4-Tubulointersitial nephritis effectively treated with tacrolimus: a case report

BackgroundCases of concurrent immunoglobulin A nephropathy (IgAN) and IgG4-related tubulointerstitial nephritis (IgG4-TIN) are rare and previous case reports have lacked important data. KDIGO suggests a treatment with systemic glucocorticoids in IgAN patients. Glucocorticoids are recommended as the first-line therapy for IgG4-TIN. The use of tacrolimus as a long-term maintenance treatment has not been described. We report the case of a man who developed IgAN and IgG4-TIN without abnormalities in extra-renal tissue, without renal function abnormalities or impairment as well, and was treated by tacrolimus as a long-term maintenance during 45 months follow-up.Case presentationA 56-year-old Chinese man first presented to our hospital with the chief complaint of foamy urine for 1 year and hematuria for 3 months, with a medical history of hypertension. Testing revealed a notable increase in serum IgG4 level without abnormalities in renal function or imaging, or in dysfunction other organs. Renal biopsy showed mesangial extracellular matrix proliferation, increased mesangial cell numbers and infiltration of plasma cells. Immunofluorescence showed mesangial positivity for IgA and C3. Immunohistochemistry staining showed widespread IgG4 and increased CD38 and CD138 expression. Electron microscopy showed immune complexes located on the tubular basement membrane. He was diagnosed with IgAN and IgG4-TIN. He received glucocorticoids, leflunomide and tacrolimus to induce remission. He was given tacrolimus as long-term maintenance treatment. When tacrolimus was temporarily withdrawn, proteinuria recurred. After resuming tacrolimus therapy, he again entered complete remission. After 45 months of therapy, he remains in complete remission and the serum IgG4 level is normal.ConclusionsThe finding of concurrent IgAN and IgG4-TIN without abnormalities in renal function, imaging or extra-renal tissue is rare and their coexistence may be coincidental. Long-term treatment with tacrolimus proved effective and he has remained in remission during 45 months follow-up.

Renal Involvement in IgG4-Related Disease: From Sunlight to Twilight.

IgG4-Related Disease (IgG4-RD) is a fibroinflammatory condition characterized by a typical histopathological pattern (dense lymphoplasmacytic infiltrate with prevalent IgG4+ plasma cells and storiform fibrosis), which may involve the kidney both directly (IgG4-related kidney disease, IgG4-RKD) or indirectly, as a consequence of post-renal ureteral obstruction due to retroperitoneal fibrosis (IgG4-RD RF). The most frequent presentation of IgG4-RKD is IgG4-related tubulointerstitial nephritis (TIN), but a glomerular disease can be present, in most of the cases a membranous nephropathy. Albeit steroid-responsive, in some cases renal manifestations may lead to progressive and permanent organ damage. In this review we describe four clinical cases representative of typical and less typical renal manifestations of IgG4-RD, emphasizing a potential, subclinical, early involvement of the kidney in the disease.

Monoclonal and polyclonal immunoglobulin G deposits on tubular basement membranes of native and pretransplant kidneys: A retrospective study

Monoclonal tubular basement membrane immune deposits (TBMID) are associated with progression of interstitial injury in renal allograft. However, the significance of monoclonal and polyclonal TBMID in the native kidney remains unclear. We retrospectively analyzed 1894 native kidney biopsies and 1724 zero-hour biopsies performed between 2008 and 2018 in our institution. The rate of immunoglobulin G (IgG) TBMID was found to be 8.4% among native kidney biopsies and 0.4% among zero-hour biopsies. Polyclonal TBMID is common in IgG4-related tubulointerstitial nephritis (37.5%), diabetic nephropathy (31.3%) and lupus nephritis (25.5%). Monoclonal IgG TBMID was identified in seven cases, including three zero-hour biopsies. The combination of IgG1κ was observed in two cases, IgG1λ in three, and IgG2κ in two. Electron microscopy revealed powdery electron-dense deposits in all cases. Monoclonal gammopathy of undetermined significance was diagnosed in one case. Although one patient with focal segmental glomerulosclerosis developed renal failure, all others exhibited stable renal function. Monoclonal IgG TBMID in the native kidney is not associated with renal prognosis. However, this may be an interesting immunopathological finding that would help clarify the pathogenesis of TBM immune deposits. Further study for both monoclonal and polyclonal TBMID is required in the future.

Tertiary lymphoid tissue in early\u2010stage IgG4-related tubulointerstitial nephritis incidentally detected with a tumor lesion of the ureteropelvic junction: a case report

BackgroundIgG4-related kidney disease causes renal impairment of unknown pathogenesis that may progress to kidney failure. Although ectopic germinal centers contribute to the pathogenesis of the head and neck lesions of IgG4-related disease, the presence of tertiary lymphoid tissue (TLT) containing germinal centers in IgG4-RKD has rarely been reported. Case presentationWe report a 72-year-old Japanese man who had IgG4-related tubulointerstitial nephritis (TIN) with TLT formation incidentally detected in a resected kidney with mass lesion of IgG4-related ureteritis in the ureteropelvic junction. During follow-up for past surgical resection of a bladder tumor, renal dysfunction developed and a ureter mass was found in the right ureteropelvic junction, which was treated by nephroureterectomy after chemotherapy. Pathology revealed no malignancy but abundant IgG4-positive cell infiltration, obliterative phlebitis and storiform fibrosis, confirming the diagnosis of IgG4-related ureteritis. In the resected right kidney, lymphoplasmacytes infiltrated the interstitium with focal distribution in the renal subcapsule and around medium vessels without storiform fibrosis, suggesting the very early stage of IgG4-TIN. Lymphocyte aggregates were also detected at these sites and consisted of B, T, and follicular dendritic cells, indicating TLT formation. IgG4-positive cells infiltrated around TLTs.ConclusionsOur case suggests that TLT formation is related with the development of IgG4-TIN and our analysis of distribution of TLT have possibility to elucidate IgG4-TIN pathophysiology.

Case Review of lgG4-Related Disease Patient with Combined Tubulointerstitial Nephritis and Membranous Nephropathy Coexisting with Cholangiocarcinoma: Case Report

Immunoglobulin G4-related disease (IgG4-RD) has recently been recognized as an autoimmune disorder involving multiple organs. The kidney is a represented organ with a wide range of renal manifestations. The authors report a case of an 83-year-old Thai male with combined IgG4 tubulointerstitial nephritis and membranous nephropathy coexisting with cholangiocarcinoma. The patient presented with proteinuria, acute renal failure, eosinophilia, hypocomplementemia, and high serum IgG4 concentration. The diagnosis was IgG 4-related tubulointerstitial nephritis and membranous nephropathy on renal biopsy, with negative immunohistochemistry for anti-phospholipase A2 receptor antibodies. Magnetic resonance imaging (MRI) abdomen showed two wedge shaped arterial enhancing lesions of liver. Liver biopsy revealed adenocarcinoma, compatible with cholangiocarcinoma. Proteinuria and renal failure were resolved with initial steroid treatment. Meanwhile, IgG4-related membranous nephropathy should be considered in the differential diagnosis for patients with proteinuria. Potentially, IgG4-RD may be rarely associated with carcinoma development. However, further studies are recommended to ratify and confirm the association between IgG4-RD and incidence of malignancies. Keywords: IgG4-related disease, Membranous nephropathy, Secondary membranous nephropathy, Tubulointerstitial nephritis, Cholangiocarcinoma

Long-term changes in renal function after treatment initiation and the importance of early diagnosis in maintaining renal function among IgG4-related tubulointerstitial nephritis patients in Japan

BackgroundThe present study aimed to investigate associations between long-term renal function, whether IgG4-related tubulointerstitial nephritis (TIN) was diagnosed by renal biopsy at initial examination, chronic kidney disease (CKD) stage, and histological stage in patients with IgG4-related TIN.MethodsThis study used a retrospective cohort design including almost all patients who underwent renal biopsy at Fujita Health University Hospital and Nagoya University or its affiliated hospitals in Aichi between April 2003 and March 2015 (n = 6977 renal biopsies). The primary outcome was longitudinal changes in eGFR. Main exposures were whether IgG4-related TIN was diagnosed by renal biopsy at the initial examination, CKD stage, and its histological stage. Linear mixed models were performed to examine associations.ResultsOf the 6977 samples, there were 24 patients (with 201 records due to repeated measures) with IgG4-related TIN (20 men, mean age, 68.7 ± 9.7 years). They were followed up 6.6 ± 2.8 years after the renal biopsy and underwent glucocorticoid treatment. We found significant increase in eGFR from the baseline to 2 and 6 months after treatment initiation, which was maintained until 60 months. Patients initially diagnosed with IgG4-related TIN had higher eGFR from the baseline (at the start of treatment) to 60 months than those who were not. Compared with patients with CKD stage 3, patients with CKD stages 4 and 5 had lower eGFR at the baseline and other time points. Patients with histological stage B had comparatively lower eGFR at each point than stage A patients. Those mean differences of eGFR were stable from the baseline to 60 months.ConclusionsAfter the treatment initiation, renal function rapidly improved and maintained for a long period, even with advanced CKD stage. We showed importance of early diagnosis of IgG4-related TIN in maintaining eGFR.

Idiopathic membranous nephropathy in a patient diagnosed with IgG4-related disease

Rationale:Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a newly recognized, systemic disease. Membranous nephropathy is the most common glomerular lesion in IgG4- related kidney disease. However, the lack of relationship with IgG4-related kidney disease and monoclonal gammopathy of undetermined significance (MGUS) warrants investigation of the potential mechanisms.Patient concerns:A 62-year-old patient was diagnosed with IgG4-RD, tubulointerstitial nephritis, retroperitoneal fibrosis. After 2 years, she was presented with proteinuria, hypoproteinemia, facial, and bilateral lower limb edema. Furthermore, this patient exhibited deposits of IgG k of monoclonal hyperplasia, and bone marrow plasma cell count was 2.5%.Diagnosis:The patient was diagnosed with nephrotic syndrome, acute kidney injury, and MGUS. The pathological diagnosis was IgG4-related tubulointerstitial nephritis, IgG4-related membranous nephropathy.Interventions:The patient was treated with intravenous methylprednisolone (40 mg daily), which was changed to oral prednisone 50 mg/d after 2 months.Outcomes:After 1 month, the patient exhibited a rapid response only with corticosteroid, and experienced partial remission of serum albumin and proteinuria.Lessons:This case may suggest a possible relationship between IgG4-RD and MGUS, provide some guidance for investigating the mechanism between them.

Clinical case of membranous nephropathy in a patient with IgG4-related disease

IgG4-related disease (IgG4-RD) currently is considered as a chronic fibroinflammatory immune-mediated multisystemic condition of unidentified etiology, which can imitate a wide range of malignant, infectious, rheumatologic, and other diseases. It can affect almost any organ system in the body synchronously or sequentially, but the most often affected are the pancreas, hepatobiliary tract, periorbital structures, salivary glands, kidneys, and lymph nodes. The most frequent renal manifestations of IgG4-RD is IgG4-related tubulointerstitial nephritis. Membranous nephropathy is the most common glomerular disease accompanied by IgG4-RD. Regardless of the organ localization, patients with IgG4-RD are characterized by elevated serum IgG4, but this laboratory abnormality is not specific and can be changed in other diseases. In all suspected cases of IgG4-RD the diagnosis should be confirmed by histological examination. Characteristic pathologic features include diffuse or focal lymphoplasmacytic infiltration with prominent IgG4+ plasma cells, storiform fibrosis, and obliterative phlebitis. Patients with IgG4- RD usually have an excellent clinical response to glucocorticoids, but relapse rates after steroid withdrawal are high, which may require additional use of immunosuppressants or rituximab. Due to the low prevalence and multitude of clinical manifestations the disease often remains underdiagnosed on time. This case report describes middle-aged patients with a history of chronic recurrent pancreatitis complicated by the nephrotic syndrome. Kidney biopsy showed membranous nephropathy and diagnosis IgG4-RD with multiorgan involvement was made. Partial remission was achieved on corticosteroid therapy. The presented case clearly demonstrates the difficulties of diagnosis and treatment of IgG4-RD. IgG4-related membranous nephropathy should be included in the differential diagnosis for patients with nephrotic syndrome accompanied by multiorgan dysfunction.

The coexistence of membranous glomerulonephritis and its cause in the same biopsy: the two faces of IgG4-related kidney disease

IgG4-related disease (IgG4-RD) is a systemic immune-mediated disease characterized by fibroinflammatory tumor-like masses that show the peculiar morphological features of storiform fibrosis, lymphoplasmacytic infiltrates rich in IgG4 positive plasma cells and obliterans phlebitis. The disease affects virtually any organ or apparatus and is often associated with increased serum IgG4 levels. Many previously described conditions (e.g. autoimmune pancreatitis, Mikulicz’s syndrome, Küttner’s tumor, and Riedel’s thyroiditis) are now classified to be part of IgG4-RD with the characteristic clinic, serologic and pathologic features. The kidney represents an important target-organ of the disease, mainly as tubulointerstitial nephritis (TIN). Nevertheless, some cases of glomerular disease, especially membranous glomerulonephritis (MNG), have been described in IgG4-related TIN. We report a case of IgG4-related kidney disease in which the two pathological patterns, TIN and MNG, were observed simultaneously in the same biopsy.

Simultaneous occurrence of IgG4-related Tubulointerstitial nephritis and colon adenocarcinoma with hepatic metastasis: a case report and literature review

BackgroundUnderstanding the uncommon association of IgG4-related disease with other disorders is essential for the accurate diagnosis and effective treatment of patients. To the best of our knowledge, there have been only few reports of patients with IgG4-related kidney disease coexisting with metastasis of malignancy. Here, we report a rare case of simultaneous occurring IgG4-related tubulointerstitial nephritis and colon adenocarcinoma with hepatic metastasis.Case presentationA 71-year-old Chinese man presented with dysuria and was initially diagnosed as benign prostatic hyperplasia for one year. He was admitted to the hospital for surgery. After admission, the renal function tests revealed a rapid increase of serum creatinine from 291.0 μmol/L to 415 μmol/L. The hemoglobin level was 89 g/L. Fecal occult blood testing was positive. Urinalysis revealed mild proteinuria. The serum IgG4 level was 13.9 g/L. The abdominal imaging examination revealed multiple solid nodules in the liver. The gastrointestinal endoscopy combined with the biopsy revealed colon adenocarcinoma. Kidney biopsy showed massive IgG4-positive plasma cells and storiform fibrosis infiltration in the tubulointerstitial area, thus establishing the diagnosis of IgG4-related tubulointerstitial nephritis. Corticosteroid therapy was initiated, and subsequently, the renal function dramatically improved without the diminution of the liver nodules. The liver biopsy was performed and a diagnosis of metastatic colon adenocarcinoma was confirmed.ConclusionsWe here reported a rare case of simultaneous occurring of IgG4-related tubulointerstitial nephritis, colon adenocarcinoma with hepatic metastasis. The case highlights the importance of screening for malignancy in patients with IgG4-related disease, and the nature of the mass in other organs of patients with coexisting IgG4-related disease and malignancy should be carefully checked.