A case of eosinophilic granulomatosis with polyangiitis preceded by allergic bullous lesions.

A 62-year-old man with a history of diabetes mellitus was hospitalised with numbness of lower limbs, bullous lesions of the whole body, kidney dysfunction, presence of eosinophils, and elevated antineutrophil cytoplasmic antibodies to myeloperoxidase and anti-bullous pemphigoid 180 antibodies and was diagnosed with mononeuritis multiplex. Kidney and muscle biopsies showed vasculitis with fibrinoid necrosis, whereas skin biopsies showed only blister formation between the epidermis and dermis; a high eosinophilic infiltrate was present in all three tissues. These findings led to a diagnosis of eosinophilic granulomatosis with polyangiitis combined with allergic bullous lesions. Immunohistological examination indicated cytolytic eosinophils and extracellular traps, suggesting the presence of eosinophil extracellular trap cell death (eosinophil ETosis) in diseased tissue.

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

BACKGROUND: 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. PURPOSE: This study aimed to clarify the correlation between MRI findings and renal histopathological findings in IgG4-TIN. METHOD: 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. RESULT: 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. CONCLUSION: Low-intensity signal on T2WI is useful for predicting the degree of fibrosis in IgG4-TIN.

Dapagliflozin treatment in patients with chronic kidney disease associated with autosomal dominant polycystic kidney disease.

Introduction: The DAPA-CKD study showed a protective effect of dapagliflozin on kidney function in chronic kidney disease (CKD) patients with and without diabetes mellitus. Although dapagliflozin is expected to be effective also in CKD patients with autosomal dominant polycystic kidney disease (ADPKD), its efficacy and safety in this population remain unknown because ADPKD was an exclusion criterion in the DAPA-CKD study. Therefore, we evaluated the effects of dapagliflozin in CKD patients with ADPKD. Methods: We performed a retrospective observational study of seven patients with ADPKD treated with dapagliflozin at Toranomon Hospital, Tokyo, Japan. We analyzed changes in estimated glomerular filtration rate (eGFR) slope and annual height-corrected total kidney volume before and after starting dapagliflozin treatment. Results: The median observation period after starting dapagliflozin was 20 months. Four patients received concomitant tolvaptan. The eGFR slope before and after initiation of dapagliflozin could be calculated in six patients and improved in all of them except the one who did not receive a renin-angiotensin system (RAS) inhibitor. Annual height-corrected total kidney volume increased in all patients. Concurrent tolvaptan treatment had no effect. Conclusion: In CKD patients with ADPKD, dapagliflozin may increase kidney volume but may have a protective effect on kidney function when used concomitantly with RAS inhibitors.

A case report of dipeptidyl peptidase 4 inhibitor-related kidney disease combined with renal cancer.

A kidney biopsy was performed in a 64-year-old woman with type 2 diabetes mellitus and less than 1 g of proteinuria who rapidly progressed to end-stage renal failure after approximately 2 years of treatment with two dipeptidyl peptidase 4 (DPP-4) inhibitors for type 2 diabetes mellitus. The biopsy revealed not only a coincidental diagnosis of renal cell carcinoma, which was not evident on pre-biopsy computed tomography, but also severe thrombotic microangiopathy (TMA)-like glomerular endothelial cell damage in the noncancerous areas. These results suggest that DPP4 inhibitors may have been involved in two kidney diseases.

Renal cell carcinoma preceded by a rheumatoid­like paraneoplastic syndrome: A case report.

A man with polycystic kidney disease and a history of renal transplantation at the age of 55 years developed seronegative rheumatoid arthritis (RA) at the age of 68 years. Treatment with a biological derivative led to remission; however, the patient relapsed 2 years later. After being switched to baricitinib, the patient again achieved remission. After 2 years, when the patient was aged 72 years, RA recurred, and the right native kidney became enlarged due to the presence of a large tumor. Surgical nephrectomy was performed, and the tumor was classified as renal cell carcinoma (RCC), not otherwise specified. The cancer tissue comprised sarcomatoid and rhabdoid cells with marked neutrophil infiltration, and the tumor cells were positive for interleukin-6. The patient, aged 73 years, experienced a resolution of joint pain following surgical intervention; however, they died because of systemic metastases ~10 weeks post-operation. Based on the clinical course, the RA-like lesions and subsequent RCC were considered to represent a paraneoplastic syndrome.

Long-term clinicopathological characteristics of TAFRO syndrome and its relapse: a case series study.

Introduction: This study aimed to analyze the clinical course of TAFRO syndrome in patients through extended follow-up, focusing on recurrent cases and long-term remission. Methods: This was a retrospective case series study. We assessed the clinical course of patients diagnosed with TAFRO syndrome between January 2012 and September 2022 at Toranomon Hospital or Toranomon Hospital Kajigaya, excluding those patients who died during the initial hospitalization. Results: Twelve patients were included. Baseline characteristics, laboratory findings, treatment modalities, and outcomes were assessed. During the median follow-up period of 1474 days, two patients experienced recurrence following a reduction in tocilizumab (TCZ) dose, whereas two achieved remission for >400 days without TCZ treatment. The remaining eight patients maintained remission under the continued TCZ therapy. Recurrence diagnosis was complicated by the non-simultaneous presentation of the five manifestations of TAFRO syndrome. The patients who experienced recurrence showed milder manifestations and faster recovery than the initial onset. Glomerular endotheliopathy was evident in kidney biopsies during recurrence, which was similar to the initial presentation. In a case where only inflammation preceded other manifestation, a kidney biopsy was pivotal in distinguishing TAFRO syndrome relapse from other inflammatory conditions such as infection. Pretreatment serum IL-6 levels were within the reference range only in patients who experienced long-term remission without TCZ treatment. Conclusions: This is the first study to perform kidney biopsies on recurrent TAFRO cases, highlighting recurrence after TCZ dosage reduction, non-simultaneous manifestation of symptoms, the utility of kidney biopsies in recurrence diagnosis, and potential non-IL-6 pathogenesis factors. Pretreatment serum IL-6 levels may help identify patients suitable for maintenance therapy without TCZ. Further investigation is warranted to identify stratified treatment approaches based on individual etiologic factors.

Renal and cardiac biopsy findings in an adolescent patient with the 3243A>G mitochondrial DNA mutation: Favorable renal prognosis post renal transplantation from the mother.

We investigated the pathogenesis of a perihilar variant of focal segmental glomerulosclerosis detected by kidney biopsy in a 16-year-old male. The disease was refractory to steroid therapy, and at the second kidney biopsy, abnormal mitochondrial proliferation was newly observed in the podocytes. The patient also developed late-onset hearing loss and had a family history of diabetes, and genetic testing confirmed the mitochondrial DNA mutation 3243A>G (48%). Eight months after hemodialysis was started, encephalopathy occurred presumably due to rapid dehydration. After changing dialysis into continuous ambulatory peritoneal dialysis, encephalopathy was resolved, but the patient developed myocardial hypertrophy, probably because of the myocardial overreaction to congestion. A myocardial biopsy showed mitochondrial proliferation in the myocardium. After renal transplantation from his mother with a heteroplasmy of 4%, the cardiomyopathy improved, and the renal function has remained stable for 4 years. We speculated that the abnormal mitochondrial morphology in the kidney and heart may be characteristic of mitochondrial genetic disease, and renal transplantation from the mother with a low heteroplasmy was considered desirable for mitochondrial nephropathy with poor prognosis.

A case of renal limited myeloperoxidase anti-neutrophil cytoplasmic antibody-positive vasculitis treated with maintenance avacopan monotherapy.

A 76-year-old woman was admitted with progressive renal function decline. A kidney biopsy was performed because of myeloperoxidase anti-neutrophil cytoplasmic antibody (ANCA; 333 IU/mL), proteinuria (1.21 g/d), and urinary erythrocyte sediment (10-19/high-power field). Renal-limited ANCA-positive vasculitis with pauci-immune necrotizing crescentic glomerulonephritis (ANCA-associated vasculitis, AAV) was diagnosed. Glucocorticoid therapy was started, and the patient responded well. About 1 year later, avacopan treatment was started and glucocorticoid therapy was discontinued. Avacopan did not normalize ANCA levels and did not make urinary findings negative. However, further progression of renal function decline is prevented. Factors attributed to the development of AAV in this case were investigated; AAV developed after the second dose of the COVID-19 vaccine and ANCA levels re-elevated after the fifth dose. This suggests that the COVID-19 vaccine may have contributed to the development of AAV in this elderly patient. Avacopan monotherapy has been shown to be effective as maintenance therapy to control the progression of renal failure although not sufficient for complete remission of AAV.

Digital whole-slide imaging of changes in amyloid after peripheral blood stem cell transplantation in patients with amyloid light-chain amyloidosis.

Peripheral blood stem cell transplantation (PBSCT) has made amyloid light-chain (AL) amyloidosis treatable. After PBSCT, hematological complete remission (HCR) can be achieved, leading to improved renal prognosis. The purpose of this study was to evaluate whether whole slide imaging of biopsy samples shows a post-treatment reduction in amyloid deposits in patients with AL amyloidosis. Patients were divided into three groups: Group A (n = 8), not eligible for PBSCT and treated with other therapies; Group B (n = 11), treated with PBSCT and achieved HCR; and Group C (n = 5), treated with PBSCT but did not achieve HCR. Clinical findings and amyloid deposition in glomeruli, interstitium, and blood vessels were compared before and after treatment using digital whole-slide imaging. Proteinuria and hypoalbuminemia improved more in Group B than in the other groups, and in Group B, amyloid deposition improved more in the glomeruli than in the interstitium and blood vessels. The long-term renal and survival prognosis was better in Group B than in the other groups. PBSCT can be expected to improve long-term clinical and renal histological prognosis in patients with AL amyloidosis who achieve HCR. Amyloid disappearance from renal tissue may take a long time even after clinical HCR.

Efficacy and safety of first-line biological DMARDs in rheumatoid arthritis patients with chronic kidney disease.

OBJECTIVE: To evaluate the efficacy and safety of first-line biological disease-modifying antirheumatic drugs (bDMARDs) in patients with rheumatoid arthritis (RA) with chronic kidney disease (CKD), including those undergoing haemodialysis (HD). METHODS: This retrospective cohort study included 425 patients with RA prescribed their first bDMARDs at two hospitals from 2004 to 2021. Patients were categorised by kidney function and bDMARD modality (TNFα inhibitors (TNFαis), interleukin-6 inhibitors (IL-6is), cytotoxic T-lymphocyte antigen-4 immunoglobulin (CTLA4-Ig)). The primary outcome was the 36-month drug retention rate, with secondary outcomes including changes in Disease Activity Score 28 (DAS28)-C reactive protein (CRP)/erythrocyte sedimentation rate (ESR), prednisolone dosage and reasons for discontinuation. RESULTS: The 36-month drug retention rates by estimated glomerular filtration rate (eGFR) (≥60, 30-60, <30 mL/min/1.73 m2) were as follows: all bDMARDs (45.2%, 32.0%, 41.4%), TNFαis (45.3%, 28.2%, 34.0%), IL-6is (47.4%, 66.7%, 71.4%) and CTLA-4Ig (50.0%, 31.3%, 33.3%). Even in groups with lower kidney function, the drug retention rate of bDMARDs was generally maintained. However, the retention rate of TNFαis was significantly lower in patients with eGFR <30 mL/min/1.73 m2. IL-6is showed the highest retention rate and the lowest discontinuation rate due to ineffectiveness in this group (HR 0.11, 95% CI 0.02 to 0.85, p=0.03). All bDMARDs improved DAS28-CRP/ESR and reduced prednisolone dosage across all groups. CONCLUSION: bDMARDs demonstrated effective and safe profiles in patients with RA with CKD, even among patients on HD. In particular, IL-6is had a significantly higher drug retention rate in patients with an eGFR of <30 mL/min/1.73 m2 and fewer discontinuations due to ineffectiveness. IL-6is were more efficacious as monotherapy compared with the other bDMARDs.

A case of immunoglobulin G4-related kidney disease manifesting after dipeptidyl peptidase-4 inhibitor treatment.

A 68-year-old man with type 2 diabetes mellitus was admitted with decreased renal function. He had high IgG4 (1070 mg/dL) and hypocomplementemia (CH50, 25 U/mL). Kidney biopsy showed tubulointerstitial nephritis with IgG4-positive plasma cell infiltration. Four years later, a second kidney biopsy revealed a new manifestation of membranous nephropathy and tubulointerstitial nephritis with exacerbated fibrosis formation. Six years later, the patient developed bullous pemphigoid, which was thought to be caused by DPP4 inhibitors, so DPP4 inhibitor treatment was discontinued. The use of DPP4 inhibitors correlated with changes in renal function, and the patient was diagnosed with IgG4-related kidney disease related to DPP4 inhibitors.

Early diagnosis of tuberculous peritonitis in peritoneal dialysis patients using the T-SPOT test.

A 49-year-old man was admitted with peritonitis nine months after starting continuous ambulatory peritoneal dialysis (CAPD) for kidney failure. Ceftazidime and cefazolin were started. Peritoneal dialysate culture was negative for bacteria, but antibiotic treatment was continued because peritonitis improved. Twenty days later, the patient was discharged with no signs of peritonitis. However, 40-day culture of the original peritoneal dialysate detected Mycobacterium tuberculosis, and peritonitis recurred, leading to readmission. A T-SPOT test was performed and was positive in 4 days. Anti-tuberculosis therapy was started, which cured the peritonitis. The T-SPOT test may enable early diagnosis of tuberculosis.

Validation of the Diagnostic Criteria for IgG4-Related Periaortitis/Periarteritis and Retroperitoneal Fibrosis (IgG4PA/RPF) 2018, and Proposal of a Revised 2023 Version for IgG4-Related Cardiovascular/Retroperitoneal Disease.

BACKGROUND: In 2018, diagnostic criteria were introduced for IgG4-related periaortitis/periarteritis and retroperitoneal fibrosis (PA/RPF). This study assessed the existing criteria and formulated an improved version. METHODS AND RESULTS: Between August 2022 and January 2023, we retrospectively analyzed 110 Japanese patients diagnosed with IgG4-related disease (IgG4-RD) involving cardiovascular and/or retroperitoneal manifestations, along with 73 non-IgG4-RD patients ("mimickers") identified by experts. Patients were stratified into derivation (n=88) and validation (n=95) groups. Classification as IgG4-RD or non-IgG4-RD was based on the 2018 diagnostic criteria and various revised versions. Sensitivity and specificity were calculated using experts' diagnosis as the gold standard for the diagnosis of true IgG4-RD and mimickers. In the derivation group, the 2018 criteria showed 58.5% sensitivity and 100% specificity. The revised version, incorporating "radiologic findings of pericarditis", "eosinophilic infiltration or lymphoid follicles", and "probable diagnosis of extra-PA/-RPF lesions", improved sensitivity to 69.8% while maintaining 100% specificity. In the validation group, the original and revised criteria had sensitivities of 68.4% and 77.2%, respectively, and specificities of 97.4% and 94.7%, respectively. CONCLUSIONS: Proposed 2023 revised IgG4-related cardiovascular/retroperitoneal disease criteria show significantly enhanced sensitivity while preserving high specificity, achieved through the inclusion of new items in radiologic, pathological, and extra-cardiovascular/retroperitoneal organ categories.

A case of hypertensive emergency with alveolar hemorrhage and thrombotic microangiopathy.

A 28-year-old woman with a 5-year history of untreated hypertension was admitted for respiratory distress, hemoptysis, and retinopathy. Computed tomography showed diffuse plaques in both lung fields. Acute kidney injury, hemolytic anemia, and thrombocytopenia were noted. Kidney biopsy showed thrombosis with fibrinoid necrosis and edematous intimal thickening and luminal narrowing of the small renal artery, indicating thrombotic microangiopathy; the majority of glomeruli were collapsed. After 8 weeks of treatment with antihypertensive drugs, serum creatinine decreased to 1.0 mg/dL, and the patient recovered. In the absence of any other underlying disease, malignant nephrosclerosis associated with a hypertensive emergency was diagnosed.

De novo posttransplant membranous nephropathy after COVID-19 vaccination 9 years after renal transplantation in a patient with polycystic kidney disease.

A 63-year-old man with polycystic kidney disease underwent kidney transplantation from his wife. Nine years later, after the first and second doses of the COVID-19 vaccination, he developed proteinuria, hematuria, and elevated C-reactive protein. Kidney biopsy 7 months after the initial appearance of proteinuria showed immunoglobulin (Ig)-G granular stain, predominantly IgG1, and spike formation in the glomerular basement membrane. Electron microscopy revealed mainly subepithelial deposits, which corresponds to membranous nephropathy (MN) stage 3 of the Ehrenreich-Churg classification indicating chronic disease, but it also showed electron-dense deposits and endothelial damage. Because a kidney biopsy was performed 1 h after renal transplantation and a biopsy of the patient's native kidney showed intact glomeruli, atypical de novo posttransplant membranous nephropathy (MN) was diagnosed, and a close relationship with COVID-19 vaccination was assumed. Clinicians should consider the involvement of COVID-19 vaccination in de novo posttransplant MN with unclear pathogenesis.

Gastric Burkitt's monomorphic post-transplant lymphoproliferative disorder after kidney transplantation: A case report.

We report on a 53-year-old Japanese man diagnosed with gastric Burkitt's monomorphic post-transplant lymphoproliferative disorder (B-PTLD) after endoscopy for gastric discomfort 28 months after the patient underwent renal transplantation in Ethiopia. Serum Epstein-Barr virus (EBV) tests were negative before transplantation, but the tumor cells collected from a gastric biopsy showed positive EBV-encoded small RNAs (EBER) at B-PTLD onset. Intensive treatment started with R(rituximab)-CHOP therapy and continued with DA-EPOCH-R therapy has been effective, and relapse has not yet occurred. Burkitt lymphoma has a poor prognosis, but B-PTLD may be effectively treated with high-dose chemotherapy. This is a rare case of gastric B-PTLD in a Japanese patient.

Is Podocytopathy Associated with Gross Hematuria after COVID-19 Vaccination in Patients with Immunoglobulin A Nephropathy?

We experienced three cases of a fever and subsequent severe, prolonged gross hematuria after COVID-19 vaccination. A kidney biopsy revealed immunoglobulin A (IgA) nephropathy, and electron microscopy showed two types of podocytopathy (podocyte damage): loss of foot processes from the glomerular basement membrane and foot process effacement. Mesangial interposition was also present in cases 1 and 3 but not in case 2. Podocytopathy is known to be a cause of proteinuria; however, the reactions to COVID-19 vaccination described here suggest that it may also be related to hematuria in IgA nephropathy.

Trajectory of GFR Decline and Fluctuation in Albuminuria Leading to End-Stage Kidney Disease in Patients With Biopsy-Confirmed Diabetic Kidney Disease.

Introduction: Data on longitudinal trajectory of kidney function decline and fluctuation in albuminuria leading to end-stage kidney disease (ESKD) is sparse in patients with type 2 diabetes. Methods: Using data from an observational study of patients with type 2 diabetes and biopsy-confirmed diabetic kidney disease (DKD), generalized additive mixed models (GAMMs) were performed to quantify patterns of longitudinal trajectory of estimated glomerular filtration rate (eGFR) decline to ESKD associated with repeated measures of urine albumin-to-creatinine ratio (ACR). Results: Over a median follow-up period of 3.3 years, 155 of 319 patients progressed to ESKD. Among these patients, 91.6% exhibited a curvilinear pattern in their eGFR trajectory. The median coefficient of variation for ACR, representing the variability in ACR measurements, was 48.9 (interquartile range: 36.9, 68.2). The median compound annual growth rate (CAGR) for ACR, reflecting the variation in ACR progression over time, was 43.6% (interquartile range: 0.0, 102.5); and 84.5% of patients developed nephrotic-range albuminuria, with a majority remaining nephrotic and subsequently progressing to ESKD. There was a positive association between the instantaneous speed of eGFR decline and ACR. Conclusion: The observed curvilinear pattern in eGFR trajectory, high variability in ACR progression over time, and positive correlation between the speed of eGFR decline and ACR highlight the complex dynamics of disease progression and emphasize close monitoring of ACR fluctuation over time in patients with DKD.

Improved Renal Function in Initial Treatment Improves Patient Survival, Renal Outcomes, and Glucocorticoid-Related Complications in IgG4-Related Kidney Disease in Japan.

Introduction: We aimed to clarify long-term renal prognosis, complications of malignancy, glucocorticoid (GC) toxicity, and mortality in immunoglobulin G4 (IgG4)-related kidney disease (IgG4-RKD). Methods: Reviewing the medical records of 95 patients with IgG4-RKD, we investigated clinical and pathologic features at baseline, the course of renal function, complications of malignancy, GC toxicity, and mortality during follow-up (median 71 months). The standardized incidence ratio (SIR) of malignancy and standardized mortality ratio were calculated using national statistics. Factors related to outcomes were assessed by Cox regression analyses. Results: At diagnosis, the median estimated glomerular infiltration rate (eGFR) was 46 ml/min per 1.73 m2. GC achieved initial improvement. Additional renal function recovery within 3-months of initial treatment occurred in patients with highly elevated serum IgG and IgG4 levels and hypocomplementemia. During follow-up, 68%, 17%, and 3% of the patients had chronic kidney disease (CKD), >30% eGFR decline, and end-stage renal disease (ESRD), respectively. Age-adjusted and sex-adjusted Cox regression analyses indicated that eGFR (hazard ratio [HR], 0.71) and extensive fibrosis (HR, 2.58) at treatment initiation had a significant impact on the time to CKD. Ten patients died, and the standardized mortality ratio was 0.94. The SIR of malignancy was 1.52. The incidence rate (IR) of severe infection was 1.80/100 person-years. Cox regression analyses showed that the best eGFR within 3 months after treatment initiation were associated with lower mortality (HR 0.67) and fewer severe infections (HR 0.63). Conclusion: This study suggests that more renal function recovery through early treatment initiation may improve patient survival, renal outcomes, and some GC-related complications in IgG4-RKD.