Common Characteristics of Sinonasal Inflammation Associated with IgG4-Related Disease and Other Chronic Inflammatory Diseases: A Retrospective Observational Study.

INTRODUCTION: Immunoglobulin G4-related disease (IgG4-RD) is a systemic inflammatory disease characterized by elevated serum IgG4, tissue infiltration of IgG4-positive cells, and fibrosis. Although a number of IgG4-RD patients show sinonasal involvement, there is little known about sinonasal inflammation associated with IgG4-RD. This study aimed to describe the clinicopathological features of sinonasal inflammation associated with IgG4-RD and to compare with other inflammatory diseases, such as eosinophilic chronic rhinosinusitis (ECRS) and granulomatosis with polyangiitis (GPA). METHODS: A retrospective analysis of clinicopathological features of patients with sinonasal lesions and high serum IgG4 was performed. Patient data were reviewed to determine whether they fulfilled the diagnostic criteria for other inflammatory diseases. RESULTS: Six of 7 patients were diagnosed with IgG4-RD, while 1 patient was diagnosed with GPA. In the 6 patients with IgG4-RD, intranasal findings showed nasal polyps in 3 patients (50%) and nasal crusting in the 3 patients (50%). Computed tomography showed ethmoid sinus involvement in 5 patients (83%). Five of the 6 patients (83%) were diagnosed with IgG4-RD based on nasal biopsy, whereas 1 patient (17%) was diagnosed based on lacrimal gland biopsy. Four patients fulfilled the Japanese epidemiological survey of refractory ECRS (JESREC) criteria. However, none of the patients showed eosinophil infiltration. Although the patient with GPA showed high levels of serum IgG4 and tissue infiltration of IgG4-positive cells in the nasal biopsy, the patient showed common clinical features of GPA. CONCLUSION: Patients with sinonasal inflammation associated with IgG4-RD had similar clinical characteristics with ECRS and GPA. Histopathological findings of the nasal biopsy from clinically diagnosed GPA was consistent with that of IgG4-RD. Sinonasal inflammation associated with IgG4-RD should be diagnosed based not only on tissue infiltration of IgG4-positive cells but in conjunction with clinical findings such as local nasal characteristics, involvement of other organs, and serum antineutrophil cytoplasmic antibody levels. IgG4-RD should be ruled out in patients with eosinophilia without histopathological eosinophil infiltration.

Successful use of eculizumab in immediate ANCA vasculitis recurrence in a pediatric kidney transplant.

BACKGROUND: Kidney transplantation is an acceptable therapy end-stage kidney disease secondary to antineutrophil cytoplasmic antibody-associated vasculitis with risk of disease recurrence ranging from 3% to 17%. Standard posttransplant immunosuppression is the mainstay of therapy after recurrence. Recently, new medications focused on complement regulation and avoidance of steroids have been shown to be effective in treating antineutrophil cytoplasmic antibody (ANCA) vasculitis with no studies in the pediatric population. METHODS: We report a 5-year-old patient with immediate recurrence of positive myeloperoxidase (MPO)-ANCA vasculitis after deceased donor kidney transplant and the novel use of eculizumab to salvage the graft. RESULTS: Eculizumab and transition to ravulizumab has been successful in improving graft function and maintenance of disease remission after immediate MPO-ANCA vasculitis recurrence posttransplant. CONCLUSIONS: Complement inhibitors may be used in addition to standard immunosuppression postkidney transplant in a pediatric patient with MPO-ANCA vasculitis recurrence without higher rates of infections.

Avacopan's potential to decrease MPO-ANCA titres concurrent with ameliorated activity in ANCA-associated vasculitis.

Avacopan, an orally administered C5a receptor antagonist, is effective in microscopic polyangiitis via the inhibition of neutrophil priming induced by C5a. However, the exact effect of avacopan on the production of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) is yet to be clearly established. This report presents a microscopic polyangiitis patient without major organ damage where high levels of MPO-ANCA persisted with high-dose steroid therapy and azathioprine, but the addition of avacopan led to a reduction in MPO-ANCA titres. The present case implies that avacopan-mediated inhibition of C5a may lead to a reduction in MPO-ANCA levels, thereby potentially ameliorating the pathophysiology of ANCA-associated vasculitis. Nevertheless, the impact of avacopan on MPO-ANCA production cannot be asserted solely based on this report; therefore, further examination is necessary through subgroup analysis using data from larger-scale studies.

Antineutrophil cytoplasmic antibody in children with nephrotic syndrome treated with levamisole: a cross-sectional cohort study.

BACKGROUND: Levamisole is a commonly used steroid-sparing agent (SSA), but the reported incidence of antineutrophil cytoplasmic antibody (ANCA) positivity has been concerning. METHODS: Observational cross-sectional study wherein children aged 2 to 18 years with frequently relapsing/steroid dependent nephrotic syndrome (FRNS/SDNS) on levamisole for ≥ 12 months were tested for ANCA. RESULTS: A total of 210 children (33% female), median age of 7.3 (IQR: 5.6-9.6) years, and a median duration of levamisole exposure of 21 (IQR: 15-30) months were tested. ANCA was positive in 18% (n = 37): 89% (n = 33) perinuclear ANCA (pANCA), 3% (n = 1) cytoplasmic ANCA (cANCA), and 8% (n = 3) both. Of ANCA-positive children, none had reduced eGFR or abnormal urinalysis. The majority of these children were asymptomatic (81%, n = 30). Rash was more common among ANCA-positive children [6/37 (16%) vs. 3/173 (2%), p = 0.0001]. On multivariate analysis, higher age (OR = 1.02, [95th CI: 1.01 to 1.03], p = 0.007) and longer duration of levamisole exposure (OR = 1.05, [95th CI: 1.02 to 1.08], p = 0.0007) were associated with ANCA positivity. Levamisole was stopped in ANCA-positive children with the resolution of any clinical manifestations if present. Repeat ANCA testing was performed in 54% (20/37), and all were ANCA negative by 18 months. CONCLUSIONS: Children with FRNS/SDNS on longer duration of levamisole were associated with increasing prevalence of ANCA positivity, but most of these children were clinically asymptomatic. Prospective studies are required to determine the chronology of ANCA positivity and its clinical implication.

An Autopsy Case of Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Induced by Propylthiouracil.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a complication caused by antithyroid drugs, particularly propylthiouracil (PTU). Most patients experience organ failure due to the affects of the treatment regimen. We herein report the case of an 89-year-old woman whose severe AAV induced by PTU resulted in various instances of organ failure that eventually led to death after 9 years of PTU therapy. During autopsy, we identified five types of organ failure. As AAV is a potentially fatal disease, the development of various vasculitis symptoms during PTU therapy should therefore be carefully monitored.

Proteinase­3­antineutrophil cytoplasmic antibody­associated vasculitis secondary to subacute infective endocarditis: A case report.

A 58-year-old male patient was admitted to Peking University First Hospital (Beijing, China) due to recurrent hematuria, proteinuria and kidney dysfunction. The patient was positive for proteinase-3 (PR3)-antineutrophil cytoplasmic antibody (ANCA). Pathology of the kidney showed focal proliferative necrotizing glomerulonephritis with crescent formation and immune complex-mediated glomerulonephritis. The patient was diagnosed with PR3-ANCA-associated vasculitis (AAV), received intensive immunosuppressive therapy and experienced two relapses within 1 year. After admission, aortic valve vegetation was observed via echocardiography. The patient subsequently received antibiotic treatment and valve replacement, and achieved complete remission of kidney and cardiac function. The present case emphasized the importance of identifying secondary reasons for ANCA formation, especially infective endocarditis in patients with PR3-AAV.

Neutrophil Extracellular Trap Formation and Deoxyribonuclease I Activity in Patients with Otitis Media with Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

INTRODUCTION: No previous studies have evaluated the levels of neutrophil extracellular trap (NET) remnants or the importance of deoxyribonuclease (DNase) I activity based on the disease activity of otitis media with antineutrophil cytoplasmic antibody-associated vasculitis (OMAAV). The aim of this study was to explore the formation of NETs in the middle ear of patients with OMAAV during the onset and remission phases of the disease, with a particular focus on the relationships between the quantifiable levels of NET remnants and DNase I activity. METHODS: OMAAV patients were eligible for inclusion. Patients with otitis media with effusion (OME) were examined as controls. The levels of cell-free deoxyribonucleic acid (DNA), citrullinated-histone H3 (cit-H3)-DNA complex, and myeloperoxidase (MPO)-DNA complex were quantified using an enzyme-linked immunosorbent assay. DNase I activity was measured using a fluorometric method. RESULTS: The quantifiable levels of cell-free DNA, cit-H3-DNA complex, and MPO-DNA complex in the middle ear lavage of patients with OMAAV at onset were significantly higher than those in patients with OMAAV at remission and in patients with OME. DNase I activity in the patients with OMAAV at onset was significantly lower than those in patients with OMAAV at remission and OME and was negatively correlated with the level of MPO-DNA complex. CONCLUSIONS: This study suggests that NET remnants and DNase I activity may be potentially useful biomarkers for the diagnosis and disease activity of OMAAV.

Granulomatosis with polyangiitis or its mimic? A case report.

Differentiation between granulomatosis with polyangiitis (GPA) limited to the upper airways and cocaine-induced midline destructive lesion (CIMDL) may be particularly difficult because of their common histopathologic features and antineutrophil cytoplasmic antibody (ANCA) profiles. We herein present a case involving a young woman with an initial diagnosis of GPA based on upper and lower airway manifestations and constitutional symptoms, histopathologic evidence of granulomas, a positive cytoplasmic ANCA indirect immunofluorescent test result, and proteinase 3 positivity by enzyme-linked immunosorbent assay (ELISA). CIMDL was confirmed based on the appearance of a hard palate perforation, positivity for methylecgonine on urine toxicology, a positive perinuclear ANCA indirect immunofluorescent test result, and subsequent human neutrophil elastase (HNE) ANCA positivity by ELISA. Finally, based on the coexistence of CIMDL, constitutional symptoms, and lower airway manifestations, the diagnosis was modified to cocaine-induced GPA mimic. Urine toxicology for cocaine and HNE ELISA are indicated in young patients with GPA who develop limited airway disease to check for the presence of CIMDL and cocaine-/levamisole-induced ANCA-associated vasculitis. Continued abstinence from cocaine is the first-choice therapy for both CIMDL and cocaine-induced GPA mimic.

Low platelet count at diagnosis of anti-neutrophil cytoplasmic antibody-associated vasculitis is correlated with the severity of disease and renal prognosis.

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is an autoimmune disease that involves inflammation of blood vessels. There is increasing evidence that platelets play a crucial role not only in hemostasis but also in inflammation and innate immunity. In this study, we explored the relationship between platelet count, clinical characteristics, and the prognosis of patients with AAV. We divided 187 patients into two groups based on their platelet count. Clinicopathological data and prognostic information were retrospectively gathered from medical records. Univariate and multivariate regression analyses were used to identify risk factors for prognosis, including end-stage renal disease (ESRD) and mortality. The cutoff point for platelet count was set at 264.5 × 109/L, as determined by the receiver operating characteristic (ROC) curve for predicting progression to ESRD in patients with AAV. We observed patients with low platelet count (platelets < 264.5 × 109/L) had lower leukocytes, hemoglobin, complement, acute reactants, and worse renal function (P for eGFR < 0.001). They were also more likely to progress to ESRD or death compared to the high platelet count group (platelets > 264.5 × 109/L) (P < 0.0001, P = 0.0338, respectively). Low platelet count was potentially an independent predictor of poor renal prognosis in the multivariate regression analysis [HR 1.670 (95% CI 1.019-2.515), P = 0.014]. Lower platelet count at diagnosis is associated with more severe clinical characteristics and impaired renal function. Therefore, platelet count may be an accessible prognostic indicator for renal outcomes in patients with AAV.

A case of seronegative microscopic polyangiitis following the diagnosis of renal pelvic carcinoma.

The incidence rate of malignancy in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is higher than that in the general population. Malignancy has been indicated to be a risk factor or inducer of AAV. Herein, we report the case of a healthy 84-year-old man with seronegative microscopic polyangiitis (MPA) after the diagnosis of renal pelvic carcinoma. Four weeks before admission, his estimated glomerular filtration rate (eGFR) was 85 ml/min/1.73 m2, and no hematuria or proteinuria was detected. Renal biopsy on admission revealed invasive urothelial carcinoma of the right renal pelvis. On day 15, his eGFR decreased to 30 ml/min/1.73 m2 without any incitement. The renal specimen extracted via right robot-assisted nephroureterectomy indicated the presence of ANCA-associated glomerulonephritis. On day 37, urinary protein/urinary creatinine level of 6.48 g/gCre, serum albumin level of 2.1 mg/dL, and eGFR of 20 ml/min/1.73 m2 indicated the presence of nephrotic syndrome. His blood sputum was analyzed via chest computed tomography, which revealed alveolar hemorrhage. Although his myeloperoxidase-ANCA was negative, he was diagnosed with MPA based on the 2022 American College of Rheumatology/European League Against Rheumatism classification criteria. This is the first case report of  MPA or AAV complicated with renal pelvic carcinoma. The clinical indicators demonstrated that renal pelvic carcinoma preceded the onset of MPA. The spatial proximity of both diseases indicated that renal pelvic carcinoma had some influence on MPA development via the mechanism of inflammatory cytokines or neutrophil extracellular traps. Our report may be useful in elucidating the mechanism of MPA development.

Alcoholic Liver Disease/Nonalcoholic Fatty Liver Disease Index at Diagnosis Is Associated with All-Cause Mortality during Follow-Up in Patients with Antineutrophil Cytoplasmic Antibody-Associated Vasculitis.

Background and Objectives: The purpose of this study was to investigate whether a new index related to chronic liver disease, the alcoholic liver disease/nonalcoholic fatty liver disease index (ANI) at diagnosis, is associated with all-cause mortality during follow-up in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Materials and Methods: In this study, we included 270 patients with AAV. ANI was calculated using the following equation: ANI = -58.5 + 0.637 (adjusted mean corpuscular volume) + 3.91 (adjusted aspartate transaminase/alanine transaminase) - 0.406 (body mass index) + 6.35 (if male sex). All-cause mortality was defined as death from any cause during follow-up. Results: The median age of the 270 patients with AAV was 61.0 years (34.4% male and 66.6% female). The median ANI was significantly higher in deceased patients than in surviving patients. In the receiver operating characteristic curve analysis, ANI at diagnosis exhibited a statistically significant area under the curve for all-cause mortality during follow-up, and its cut-off was determined to be -0.59. Patients with ANI at diagnosis ≥ -0.59 exhibited a significantly higher risk for all-cause mortality and a significantly lower cumulative patient survival rate than those without. In the multivariable Cox analysis, ANI at diagnosis ≥ -0.59, together with age at diagnosis, was independently associated with all-cause mortality. Conclusions: This study is the first to demonstrate the predictive potential of ANI at diagnosis for all-cause mortality during follow-up in AAV patients without significant chronic liver diseases.

Transcription factor Nrf2 activation regulates NETosis, endothelial injury, and kidney disease in myeloperoxidase-positive antineutrophil cytoplasmic antibody-associated vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a systemic autoimmune disease pathologically characterized by vascular necrosis with inflammation. During AAV development, activated neutrophils produce reactive oxygen species (ROS), leading to the aberrant formation of neutrophil extracellular traps (NETs) via NETosis and subsequent fibrinoid vascular necrosis. Nuclear factor-erythroid 2-related factor 2 (Nrf2) functions as an intracellular defense system to counteract oxidative stress by providing antioxidant properties. Herein, we explored the role of Nrf2 in the pathogenesis of AAV. The role and mechanism of Nrf2 in ANCA-stimulated neutrophils and subsequent endothelial injury were evaluated in vitro using Nrf2 genetic deletion and Nrf2 activator treatment. In corresponding in vivo studies, the role of Nrf2 in ANCA-transfer AAV and spontaneous AAV murine models was examined. Pharmacological activation of Nrf2 in vitro suppressed ANCA-induced NET formation via the inhibition of ROS. In contrast, NET formation was enhanced in Nrf2-deficient neutrophils. Furthermore, Nrf2 activation protected endothelial cells from ANC-induced NETs-mediated injury. In vivo, Nrf2 activation ameliorated glomerulonephritis in two AAV models by upregulating antioxidants and inhibiting ROS-mediated NETs. Furthermore, Nrf2 activation restrained the expansion of splenic immune cells, including T lymphocytes and limited the infiltration of Th17 cells into the kidney. In contrast, Nrf2 genetic deficiency exacerbated vasculitis in a spontaneous AAV model. Thus, the pathophysiological process in AAV may be downregulated by Nrf2 activation, potentially leading to a new therapeutic strategy by regulating NETosis.

Patulous Eustachian Tube and Otitis Media With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis (OMAAV).

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a systemic necrotizing vasculitis that affects small to medium-sized vessels. We describe two cases of patulous Eustachian tube (PET) in patients with otitis media with ANCA-associated vasculitis (OMAAV). The two cases presented in this paper had previously been diagnosed with Eustachian tube (ET) stenosis, and both presented with bilateral aural fullness, with one also experiencing postnasal drip and hearing loss. Both patients experienced positive myeloperoxidase (MPO)-ANCA and negative proteinase 3 (PR3)-ANCA, and treatment for ANCA-associated vasculitis (AAV) resulted in a diagnosis of PET. The patients were treated with transnasal self-installation of physiological saline into the pharyngeal orifice of the ET. This paper highlights the importance of considering PET in the differential diagnosis of OMAAV patients presenting with aural fullness.

A case of granulomatosis with polyangiitis-associated scleritis presenting as conjunctivitis.

A 42-year-old male presented initially with conjunctivitis and was treated with topical medical medications without any improvement. He developed ocular pain subsequently and further examination revealed lid edema, conjunctival hyperemia with chemosis, matting of lashes with yellowish discharge, and deeper episcleral congestion which did not blanch with topical vasoconstrictor. Subsequent laboratory investigation revealed positive cytoplasmic-antineutrophil cytoplasmic antibody (Anti-PR 3 antibody). He continued to develop recurrences and finally responded to oral azathioprine. Granulomatosis with polyangitis may rarely present as conjunctivitis and subsequently manifest as scleritis.

Latent class analysis of chest CT abnormalities to define subphenotypes in patients with MPO-ANCA-positive microscopic polyangiitis.

BACKGROUND: Patients with microscopic polyangiitis (MPA) and positive myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) may present with various abnormalities in chest computed tomography (CT). This study aimed to identify subphenotypes using latent class analysis (LCA) and to explore the relationship between the subphenotypes and clinical patterns, as well as compare the clinical characteristics of these subphenotypes in patients with MPO-ANCA-positive MPA (MPO-MPA). METHODS: The study identified subphenotypes using LCA based on chest CT findings in 178 patients with MPO-MPA and pulmonary involvement from June 2014 to August 2022. RESULTS: LCA identified 27 participants (15.2%) in class 1, 43 (24.1%) in class 2, 35 (19.7%) in class 3, and 73 (41.0%) in class 4. Class 1 was characterized by prominent inflammatory exudation, class 2 by fibrosis and architectural distortion, class 3 by predominantly bronchiectasis, and class 4 by lesions mixed with inflammation and fibrosis. Class 1 had the highest level of extrapulmonary disease activity, with 77.8% of patients experiencing diffuse alveolar hemorrhage. Class 2 had the lowest level of extrapulmonary disease activity, with 41.9% of patients showing usual interstitial pneumonia. Class 3 patients were more likely to have complications involving the ear, nose, and throat, as well as pulmonary infections before treatment, and they exhibited the best outcomes. The characteristics and outcomes of class 4 were intermediate among the four classes. CONCLUSIONS: These findings suggest that bronchiectasis may represent a unique pattern of pulmonary involvement in MPO-MPA, highlighting the importance of screening for bronchiectasis in MPO-MPA and identifying optimal management strategies.

Propylthiouracil-Induced Antineutrophil Cytoplasmic Antibody-Associated Vasculitis with Overlap IgA Nephropathy: A Case Report.

Background: The anti-thyroid medication propylthiouracil (PTU) is a recognised cause of drug-induced antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Pauci-immune crescentic glomerulonephritis is the characteristic feature of this condition on renal biopsy. We present a case of PTU-induced AAV with the unusual histological finding of overlap IgA nephropathy (IgAN) in a young female with treatment-resistant Graves' disease. Case Report: A 26-year-old female presented with an acute kidney injury, macroscopic haematuria, and proteinuria 14 months after starting PTU for Graves' disease. She had a history of established thyroid eye disease and a previous severe adverse reaction to carbimazole. Her autoantibodies were strongly positive for myeloperoxidase-ANCA (199 U/mL). Renal biopsy demonstrated both necrotising crescentic glomerulonephritis and prominent (3+) mesangial deposition of IgA. She was treated with glucocorticoids and rituximab with sustained improvement in her renal function but persisting mild proteinuria and microscopic haematuria. PTU was ceased following a dose of radioactive iodine (RAI). Twelve months post-RAI, her Graves' orbitopathy remained stable, and her thyroid function was gradually normalising. Conclusion: This was a case of drug-induced AAV with histological features of overlap IgAN. We suggest that this patient had pre-existing subclinical IgAN and then developed AAV secondary to PTU. The management of her thyroid disease was complex given the PTU-induced vasculitis, previous reaction to carbimazole, the risks of a thyroidectomy on immunosuppression, and the possible worsening of her eye disease with RAI. The glucocorticoids and Rituximab prescribed for vasculitis may have prevented the progression of her Graves' orbitopathy after RAI.

ANCA-associated vasculitis presenting with isolated neurological manifestations in a patient with cocaine abuse: a case report and literature review.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of rare conditions predominantly affecting small vessels of skin, musculoskeletal, pulmonary, renal, and rarely central and peripheral nervous systems. Isolated neurological manifestations of AAV are uncommon and challenging to diagnose. Cocaine has been reported as a potential trigger for the development of AAV. There are only a few case reports of isolated neurological involvement in cocaine-induced AAV with poorly characterized histopathological features. We present a unique case of AAV with isolated neurological manifestations presenting with multiple cranial neuropathies, leptomeningeal enhancement on imaging and histopathologic evidence of small-vessel vasculitis in the leptomeninges and brain and extensive dural fibrosis in a patient with cocaine abuse. The patient's progressive neurological deficits were controlled after starting immunosuppression with rituximab and prednisone. We also reviewed the literature to provide the diagnostic overview of AAV and evaluate intervention options. To our knowledge, this is the first case of AAV with isolated neurological manifestations and histopathologic evidence of small-vessel vasculitis in a patient with cocaine abuse. Patients with multiple cranial neuropathies and meningeal involvement should be screened for AAV, especially if they have a history of cocaine abuse.

Antineutrophil Cytoplasmic Antibody-Associated Vasculitis with Active Kidney Involvement in the United States: 2016-2020.

Introduction: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and its subtypes, granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic GPA (EGPA), frequently present with acute kidney injury and can often lead to kidney failure, even with successful induction therapy. Few contemporary, nationally representative studies have described hospital complications of AAV. Methods: Using data from the 2016-2020 National Inpatient Sample, a nationally representative database, we identified hospitalizations from adults with a new diagnosis of AAV (subtype or unspecified) and an inpatient kidney biopsy during the index hospitalization. We described baseline characteristics, associated inpatient procedures and complications, and compared lengths of stay and costs by geographic region, hospital characteristics, and AAV subtype. Results: We identified an average of 1,329 cases of hospitalized AAV with a concurrent kidney biopsy per year over the 5-year period. More than 50% were not designated as having a specific subtype, likely owing to delays in documentation of histopathology. Kidney involvement was severe as the majority of patients developed acute kidney injury, and the proportion of patients who required inpatient dialysis was approximately 24%. Approximately 20% of patients developed hypoxia. Inpatient plasmapheresis was delivered to 20.4% and 20.6% of patients with GPA and MPA, respectively. There were no clinically meaningful or statistically significant differences in adjusted length of stay or inpatient costs among AAV subtypes. Admission in the Midwest region was associated with shorter hospital stays and lower costs than that in the Northeast, South, or West regions of the USA (adjusted p = 0.007 and <0.001, respectively). Conclusion: AAV with acute kidney involvement remains a challenging, high-risk condition. Maintaining a high index of suspicion and a low threshold for kidney biopsy should help ameliorate short- and long-term complications.

A Rare Case of Autoimmune Disorder as a Trigger for Atypical Hemolytic Uremic Syndrome.

Autoimmune diseases may act as a trigger for atypical hemolytic uremic syndrome (aHUS). Triggers for aHUS may include autoimmune diseases, infections, metabolic conditions, pregnancy, and transplants. aHUS-mediated injury to various organs, especially kidneys, can be life-threatening. Here, we present the case of a young female who had perinuclear antineutrophil cytoplasmic antibody (p-ANCA)-associated vasculitis and was diagnosed with aHUS. We consider underlying autoimmune p-ANCA-associated vasculitis as a trigger for aHUS in this case.

Successful Treatment of Eosinophilic Granulomatosis With Polyangiitis: A Case of Refractory Peripheral Neuropathy and Comorbid Chronic Progressive Pulmonary Aspergillosis Treated With Mepolizumab.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic necrotizing vasculitis accompanied by granulomas and eosinophilic inflammation, exhibiting marked peripheral blood eosinophiliaandasthma. Neuropathy is a difficult-to-treat common manifestation that frequently remains after achieving clinical remission with current therapy in a subpopulation of patients with EGPA with or without life-threatening organ involvement. Refractory neuropathy regularly reduces the quality of life and requires glucocorticoids (GCs) and/or immunosuppressants for a long time. Long-term immunosuppressive therapy is a factor associated with a high risk of adverse effects. Mepolizumab, at three times the dose for severe asthma, provides benefits to induce the remission of relapsing or refractory EGPA and to reduce the doses of GC. Here, we present a case of EGPA successfully treated with mepolizumab at the reference dose for severe asthma. In this case, mepolizumab resolved peripheral neuropathy resistant to corticosteroids, immunosuppressants, and intravenous immunoglobulin and contributed to the improvement of comorbid chronic pulmonary aspergillosis during GC dose reduction.