Diagnosis and management of ANCA-associated vasculitis.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis consists of two main diseases, granulomatosis with polyangiitis and microscopic polyangiitis, and remains among the most devastating and potentially lethal forms of autoimmune inflammatory disease. Granulomatosis with polyangiitis and microscopic polyangiitis are characterised by a necrotising vasculitis that can involve almost any organ, and have generally been studied together. The diseases commonly affect the kidneys, lungs, upper respiratory tract, skin, eyes, and peripheral nerves. Granulomatous inflammation and multinucleated giant cells are key pathological hallmarks of granulomatosis with polyangiitis, but are absent in microscopic polyangiitis. Many immune system events are essential to disease aetiopathogenesis, such as activation of the alternative complement pathway, neutrophil activation via complement receptors, and the influx of inflammatory cells, including monocytes and macrophages. These cells perpetuate inflammation and lead to organ damage. During the 21st century, the management of ANCA-associated vasculitis has moved away from reliance on cytotoxic medications and towards targeted biological medications for both the induction and maintenance of disease remission. Earlier diagnosis, partly the result of more reliable ANCA testing, has led to improved patient outcomes and better survival. Reductions in acute disease-related mortality have now shifted focus to long-term morbidities related to ANCA-associated vasculitis and their treatments, such as chronic kidney disease and cardiovascular disease. Therapeutic approaches in both clinical trials and clinical practice still remain too reliant on glucocorticoids, and continued efforts to reduce toxicity from glucocorticoids remain a priority in the development of new treatment strategies.

Data quality and patient characteristics in European ANCA-associated vasculitis registries: data retrieval by federated querying.

OBJECTIVES: This study aims to describe the data structure and harmonisation process, explore data quality and define characteristics, treatment, and outcomes of patients across six federated antineutrophil cytoplasmic antibody-associated vasculitis (AAV) registries. METHODS: Through creation of the vasculitis-specific Findable, Accessible, Interoperable, Reusable, VASCulitis ontology, we harmonised the registries and enabled semantic interoperability. We assessed data quality across the domains of uniqueness, consistency, completeness and correctness. Aggregated data were retrieved using the semantic query language SPARQL Protocol and Resource Description Framework Query Language (SPARQL) and outcome rates were assessed through random effects meta-analysis. RESULTS: A total of 5282 cases of AAV were identified. Uniqueness and data-type consistency were 100% across all assessed variables. Completeness and correctness varied from 49%-100% to 60%-100%, respectively. There were 2754 (52.1%) cases classified as granulomatosis with polyangiitis (GPA), 1580 (29.9%) as microscopic polyangiitis and 937 (17.7%) as eosinophilic GPA. The pattern of organ involvement included: lung in 3281 (65.1%), ear-nose-throat in 2860 (56.7%) and kidney in 2534 (50.2%). Intravenous cyclophosphamide was used as remission induction therapy in 982 (50.7%), rituximab in 505 (17.7%) and pulsed intravenous glucocorticoid use was highly variable (11%-91%). Overall mortality and incidence rates of end-stage kidney disease were 28.8 (95% CI 19.7 to 42.2) and 24.8 (95% CI 19.7 to 31.1) per 1000 patient-years, respectively. CONCLUSIONS: In the largest reported AAV cohort-study, we federated patient registries using semantic web technologies and highlighted concerns about data quality. The comparison of patient characteristics, treatment and outcomes was hampered by heterogeneous recruitment settings.

Rituximab induction and reinduction in granulomatosis with polyangiitis and microscopic polyangiitis: A retrospective multicenter study in Taiwan.

OBJECTIVES: This study aimed to investigate the clinical outcomes of granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) under rituximab induction and reinduction therapy in Taiwan. METHODS: We performed a retrospective study in patients with GPA or MPA receiving rituximab therapy from August 2008 to July 2020 in seven medical centers in Taiwan. The clinical characteristics and outcomes of these patients were analyzed. RESULTS: In total, 53 patients (18 with GPA and 35 with MPA) were included. Kidney involvement (82.9% vs. 22.2%, p < .001) and initial creatinine (3.25 ± 2.37 vs. 1.07 ± 0.82, p < .001) were significantly higher in MPA. Within 24 weeks after the first course of rituximab, there were seven deaths (five due to infection and two due to active disease) in patients with MPA (7/35, 20%) compared to 0 in patients with GPA. Of 33 patients receiving rituximab for kidney involvement, 23 survived and were free from renal replacement therapy at 24 weeks. Their chronic kidney disease (CKD) stages improved in 2 but progressed in 7, while 24 had stable CKD stages. Death or end-stage renal disease (ESRD) was associated with infection and higher initial creatinine. Reinduction therapy for relapse was required in 18 (39.1%) of 46 survivors, which was associated with anti-proteinase 3 (PR3) positive (odds ratio 3.667, p = .049) and younger age with a cutoff of 49.4 (AUC = 0.679, p = .030, sensitivity = 66.67%, specificity = 75%). CONCLUSION: Significant mortality occurred after rituximab induction, especially in patients with MPA. In survivors, age younger than 50 and anti-PR3 positive were associated with the risk of relapse requiring reinduction.

Single-cell multi-omics analysis identifies two distinct phenotypes of newly-onset microscopic polyangiitis.

The immunological basis of the clinical heterogeneity in autoimmune vasculitis remains poorly understood. In this study, we conduct single-cell transcriptome analyses on peripheral blood mononuclear cells (PBMCs) from newly-onset patients with microscopic polyangiitis (MPA). Increased proportions of activated CD14+ monocytes and CD14+ monocytes expressing interferon signature genes (ISGs) are distinctive features of MPA. Patient-specific analysis further classifies MPA into two groups. The MPA-MONO group is characterized by a high proportion of activated CD14+ monocytes, which persist before and after immunosuppressive therapy. These patients are clinically defined by increased monocyte ratio in the total PBMC count and have a high relapse rate. The MPA-IFN group is characterized by a high proportion of ISG+ CD14+ monocytes. These patients are clinically defined by high serum interferon-alpha concentrations and show good response to immunosuppressive therapy. Our findings identify the immunological phenotypes of MPA and provide clinical insights for personalized treatment and accurate prognostic prediction.

[Pharmacological and clinical profiles of avacopan (TAVNEOS® capsule), a selective C5a receptor antagonist].

Avacopan (TAVNEOS® capsules) is an orally available selective C5a receptor (C5aR) antagonist. It has been approved in Japan since 2021 for the treatment of microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA), the two major subtypes of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The current standard therapy combining glucocorticoids (GC) and immunosuppressants has greatly improved the prognosis of AAV, however, issues such as side effects associated with GC use remain to be resolved. Avacopan suppresses priming of neutrophils induced by the complement component C5a, a process deeply involved in the pathogenesis of AAV. In pre-clinical studies, avacopan inhibited chemotaxis and priming of neutrophils induced by C5a-C5aR signaling. It also significantly suppressed nephritis and renal damage in an ANCA-induced glomerulonephritis mouse model. In the global phase 3 study "ADVOCATE", avacopan achieved both primary endpoints being 1) non-inferior to prednisone in inducing remission at week 26 and 2) superior in sustained remission at week 52 for MPA and GPA patients. Additionally, with avacopan, GC toxicity score was significantly lower and fewer adverse events possibly related to GC were observed. Furthermore, avacopan increased estimated glomerular filtration rate (eGFR) more than prednisone indicating improved renal function. Thus, the novel mechanism of avacopan targeting the complement system is a promising new therapeutic option for AAV with fewer GC-related side effects and better improvement of renal function.

Childhood-Onset ANCA- Associated Vasculitis: single center experience from Central California.

BACKGROUND: Childhood-onset ANCA-associated vasculitides (AAV) are characterized by necrotizing inflammation and include granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). Pediatric data is scare and there have been no prior studies examining the characteristics of pediatric AAV in Central California. METHODS: This retrospective study comprised AAV patients ≤18 years of age, diagnosed between 2010 and 2021, in Central California. We analyzed initial presentation including demographics, clinical, laboratory characteristics, treatment, and initial outcomes. RESULTS: Of 21 patients with AAV, 12 were categorized as MPA and 9 with GPA. Median age at diagnosis was 13.7 years in MPA cohort and 14 years in GPA. MPA cohort were majority females (92% versus 44%). 57% of the cohort were racial/ethnic minority including Hispanics (n = 9), Asians (n = 2), multiracial (n = 1) and 43% were white (n = 9). MPA patients were more frequently Hispanic (67%), meanwhile GPA patients were frequently white (78%). Median duration of symptoms prior to diagnosis was 14 days in MPA cohort and 21 days in GPA cohort. Renal involvement was frequent (100% in MPA and 78% in GPA). GPA cohort had frequent ear, nose and throat (ENT) involvement (89%). All patients were ANCA positive. All Hispanic patients were MPO positive, meanwhile 89% of white patients were PR3 positive. MPA cohort tended towards more severe disease with 67% requiring ICU admission and 50% requiring dialysis. Two deaths were reported in MPA cohort, related to Aspergillus pneumonia and pulmonary hemorrhage. In MPA cohort, 42% received cyclophosphamide in combination with steroids and 42% received rituximab in combination with steroids. GPA patients received cyclophosphamide, either with steroids alone (78%) or in combination with steroids and rituximab (22%). CONCLUSIONS: Microscopic polyangiitis was the most frequent AAV subtype with female preponderance, shorter duration of symptoms at onset and higher proportion of racial/ ethnic minority patients. Hispanic children demonstrated frequent MPO positivity. Trends towards higher rates of ICU requirement and need for dialysis upon initial presentation was noted in MPA. Patients with MPA received rituximab more frequently. Future prospective studies are needed to understand differences in presentation and outcomes in childhood onset AAV between diverse racial-ethnic groups.

Treatment Approaches to Granulomatosis with Polyangiitis and Microscopic Polyangiitis.

We have made significant headway in our ability to induce and maintain remission in patients with granulomatosis with polyangiitis and microscopic polyangiitis. With increased understanding of the pathogenesis of antineutrophilic cytoplasmic antibody-associated vasculitides (AAV), therapeutic targets have been identified and studied in clinical trials. From initial induction strategies including glucocorticoids and cyclophosphamide, we have discovered effective induction regimens with rituximab and complement inhibition that can significantly decrease the glucocorticoid cumulative doses in patients with AAV. There are many trials underway evaluating management strategies for refractory patients and exploring new and old therapies that may help to continuously improve outcomes for patients with AAV.

Development of microscopic polyangiitis following idiopathic pleuroparenchymal l fibroelastosis: A case report.

Idiopathic pleuroparenchymal fibroelastosis (PPFE) is a rare type of idiopathic interstitial pneumonia, which is characterised by pleural fibrosis and subjacent parenchymal fibroelastosis of the upper lobes. Herein, we present a case of microscopic polyangiitis (MPA) following PPFE. The patient had abnormal shadows on chest radiographs 15 years before the onset of MPA, and the patient was diagnosed with PPFE. Four years after the PPFE diagnosis, the patient was diagnosed with MPA based on persistent fever, purpura, mononeuritis multiplex, myeloperoxidase-antineutrophil cytoplasmic antibody positivity, and pathological findings of peritubular capillaritis on kidney biopsy. The patient was treated with glucocorticoids, including methylprednisolone pulse therapy and rituximab, followed by maintenance therapy with rituximab. One year after treatment, the PPFE had not worsened. PPFE occasionally occurs secondary to connective tissue disease, including MPA; however, to the best of our knowledge, this is the first report of PPFE preceding MPA. Our case suggests that PPFE, as other interstitial lung diseases, may be associated with MPA and precede the onset of MPA. The accumulation of more cases is needed to clarify the characteristics of MPA-associated PPFE.

Clinical significance of microscopic polyangiitis with interstitial lung disease and bronchiectasis: probability of preexisting comorbidities.

BACKGROUND: The association between pulmonary involvement and microscopic polyangiitis (MPA) has been increasingly recognized in recent years. Whether interstitial lung disease (ILD) and bronchiectasis (BE) are disease manifestations of MPA, preexisting comorbidities or important complications remains unclear. The purpose of this study was to determine the clinical characteristics and prognosis of MPA with pulmonary involvement to further guide clinical management. METHODS: The data for 97 patients with a definitive diagnosis of MPA were retrospectively reviewed. The MPA diagnosis was based on the 2012 revised Chapel Hill Consensus Conference (CHCC) criteria. The baseline clinical information and laboratory parameters were collected and analysed at each patient's initial diagnosis. RESULTS: Forty-seven out of the 97 (48.5%) patients who were diagnosed with MPA presented with pulmonary involvement, including 37 patients with ILD, 12 patients with BE and two patients with diffuse alveolar haemorrhage (DAH). ILD and BE antedated MPA in 56.76% and 75.00% of the patients, respectively. Compared with that in the MPA-BE group, the serum LDH level (222.86 ± 68.19 vs. 171.58 ± 31.43, p = .016) in the MPA-ILD group was significantly higher. In the multivariate Cox analysis, elevated serum creatinine (HR 4.08, confidence interval (CI) 1.38-12.05, p = .011) was an independent risk factor for shorter survival in MPA patients with pulmonary involvement, and treatment with glucocorticoid pulse cyclophosphamide therapy (HR 0.095, 95% CI 0.019-0.47, p = .004) was independently associated with prolonged survival. Among the patients in the MPA-ILD group, acute exacerbations of ILD (HR 4.55 CI 1.16-17.86, p = .029) and elevated serum creatinine (HR 4.95, CI 1.39-17.54, p = .014) were independently associated with a poor prognosis, and treatment with glucocorticoids (HR 0.057, 95% CI 0.012-0.28, p < .001) was independently associated with significant prolongation of survival. CONCLUSIONS: Patients with MPA have a high prevalence of pulmonary involvement, and ILD is the most common subtype of MPA. ILD and BE can be considered preexisting comorbidities of MPA. Elevated serum creatinine was associated with shorter survival. However, remission induction regimens with glucocorticoids and/or immunosuppressants may improve this outcome.

An update on diagnosis and treatment of ANCA associated renal vasculitis.

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides are a group of diseases characterised by necrotizing inflammation of small vessels such as arterioles, venules, and capillaries. ANCA-associated vasculitides (AAV) are referred to as small vessel vasculitides. Three AAV subgroups, namely granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) and eosinophilic GPA (EGPA), are defined according to clinical features. The most common disease with renal involvement in AAV is MPA Approximately 90% of patients with MPA have renal involvement. While this rate is 70-80% in GPA, less than half of EGPA patients have renal involvement. Untreated survival in AAVs is less than one year. With appropriate immunosuppressive therapy, the 5-year renal survival rate is 70-75%. Without therapy, the prognosis is poor but treatments, typically immunosuppressants, have improved survival, albeit with considerable morbidity from glucocorticoids and other immunosuppressive medications. Current challenges include improving the measures of disease activity and risk of relapse, uncertainty about optimal therapy duration and a need for targeted therapies with fewer adverse effects. In this review, we described the treatment of renal involvement in AAV in line with current studies.

Association between hypogammaglobulinaemia and severe infections during induction therapy in ANCA-associated vasculitis: from J-CANVAS study.

OBJECTIVES: To investigate the association between decreased serum IgG levels caused by remission-induction immunosuppressive therapy of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and the development of severe infections. METHODS: We conducted a retrospective cohort study of patients with new-onset or severe relapsing AAV enrolled in the J-CANVAS registry, which was established at 24 referral sites in Japan. The minimum serum IgG levels up to 24 weeks and the incidence of severe infection up to 48 weeks after treatment initiation were evaluated. After multiple imputations for all explanatory variables, we performed the multivariate analysis using a Fine-Gray model to assess the association between low IgG (the minimum IgG levels <500 mg/dl) and severe infections. In addition, the association was expressed as a restricted cubic spline (RCS) and analysed by treatment subgroups. RESULTS: Of 657 included patients (microscopic polyangiitis, 392; granulomatosis with polyangiitis, 139; eosinophilic granulomatosis with polyangiitis, 126), 111 (16.9%) developed severe infections. The minimum serum IgG levels were measured in 510 patients, of whom 77 (15.1%) had low IgG. After multiple imputations, the confounder-adjusted hazard ratio of low IgG for the incidence of severe infections was 1.75 (95% confidence interval: 1.03-3.00). The RCS revealed a U-shaped association between serum IgG levels and the incidence of severe infection with serum IgG 946 mg/dl as the lowest point. Subgroup analysis showed no obvious heterogeneity between treatment regimens. CONCLUSION: Regardless of treatment regimens, low IgG after remission-induction treatment was associated with the development of severe infections up to 48 weeks after treatment initiation.

Gradual increase of avacopan dose with concomitant ursodeoxycholic acid use may help avoid the risk of C5a receptor inhibitor-induced liver injury in antineutrophil cytoplasmic antibody-associated vasculitis.

Microscopic polyangiitis is a necrotising vasculitis characterised by anti-neutrophil cytoplasmic antibodies against myeloperoxidase. The complement component 5a receptor inhibitor avacopan effectively sustains remission in microscopic polyangiitis with a reduction in prednisolone dosage. Liver damage is a safety concern for this drug. However, when it occurs and how to treat it remain unknown. A 75-year-old man developed microscopic polyangiitis and presented with hearing impairment and proteinuria. Methylprednisolone pulse therapy followed by 30 mg/day prednisolone and two doses of weekly rituximab were administered. Avacopan was initiated to taper prednisolone for sustained remission. After 9 weeks, liver dysfunction and sparse skin eruptions developed. The cessation of avacopan and the initiation of ursodeoxycholic acid improved liver function without discontinuation of prednisolone and other concomitant drugs. After 3 weeks, avacopan was rechallenged with a small dose that was gradually increased; ursodeoxycholic acid was continued. Full-dose avacopan did not induce recurrence of liver injury. Therefore, gradually increasing the dose of avacopan with concomitant ursodeoxycholic acid use may help avoid possible avacopan-induced liver injury.

Thrombocytopenia during avacopan administration: A case report.

Avacopan is a novel C5a receptor antagonist recently approved for the treatment of microscopic polyangiitis and granulomatosis with polyangiitis. To our knowledge, thrombocytopenia induced by avacopan has not been reported. We report a case of a 78-year-old man with microscopic polyangiitis who developed rapidly progressive glomerulonephritis (RPGN) and vasculitis neuropathy. After developing RPGN, he was treated with prednisolone, which was ineffective. As the dosage of corticosteroids was decreased, he developed impaired dorsiflexion of the left ankle, tingling and numbness in his feet, consistent with vasculitis neuropathy. After a 3-day administration of methylprednisolone, we started avacopan and prednisolone 20 mg/d to reduce the corticosteroid dosage. One week after starting avacopan, platelet counts began to decrease, eventually leading to the cessation of the drug. The possibility of thrombotic microangiopathy and heparin-induced thrombocytopenia was considered unlikely given the clinical course and laboratory studies. After 3 weeks of avacopan cessation, platelet counts began to increase, suggesting avacopan as the most probable cause of thrombocytopenia. Our case highlights the importance of postmarketing surveillance of avacopan to identify its adverse events that were not reported in clinical trials to ensure its safe use. Clinicians should carefully monitor platelet counts when using avacopan.

ANCA-negative microscopic polyangiitis with neuromuscular involvement: When pathology could make the difference.

Microscopic polyangiitis (MPA) is a necrotizing small vessel vasculitis with little or absent immune deposits (pauci-immune vasculitis), usually associated with the presence of antineutrophil cytoplasmic autoantibodies (ANCA) and a wide spectrum of organ manifestations. In our report we describe the case of a 74-year-old Asian man, who rapidly developed lower limb weakness and impaired renal and pulmonary functions. ANCA detection remained borderline throughout the disease course. Electrophysiological and instrumental studies revealed a picture of neuromuscular involvement; renal and muscle biopsies disclosed a small vessel vasculitis. He was started on a targeted immunosuppressive combination therapy and his clinical status progressively improved. In the framework of a multi-organ disease, microscopic polyangiitis should be considered as a differential diagnosis in case of acute/subacute onset of muscle weakness, even in the absence of ANCA detection.

Efficacy and safety of avacopan in Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis: A subanalysis of a randomized Phase 3 study.

OBJECTIVES: This subgroup analysis of the randomized, double-blind, Phase 3 ADVOCATE study evaluated the efficacy and safety of avacopan compared with tapered prednisone in Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis. METHODS: Patients with microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA) received either avacopan 30 mg twice daily for 52 weeks plus prednisone-matching placebo or tapered prednisone over 20 weeks plus avacopan-matching placebo for 52 weeks. The two primary efficacy endpoints were clinical remission at Week 26 and sustained remission at Week 52. RESULTS: Compared with the overall population (N = 330), Japanese patients (N = 21) were older and had worse renal function, and a higher proportion were female and had MPA. The proportion of Japanese patients with clinical remission at Week 26 was 9/11 (81.8%) with avacopan vs. 7/10 (70.0%) with prednisone (overall population: 72.3% vs. 70.1%) and with sustained remission at Week 52 was 8/11 (72.7%) vs. 4/10 (40.0%), respectively (overall population: 65.7% vs. 54.9%). The safety profile of avacopan was similar in Japanese patients and the overall study population. CONCLUSIONS: The efficacy and safety of avacopan in Japanese patients with MPA or GPA were comparable to that observed in the overall ADVOCATE study population.

Severe Enteritis after Cyclophosphamide Administration in a Patient with Microscopic Polyangiitis: A Case Report and Literature Review.

Severe enteritis is a rare side effect of cyclophosphamide (CPA) therapy, and only two cases have been reported to date. We herein report a 60-year-old man who developed severe enteritis after intravenous CPA administration for microscopic polyangiitis. He was successfully treated by discontinuation of CPA administration and long-term intensive supportive care. A diagnosis of CPA-associated enteritis was made based on the clinical course and imaging and pathological findings. This review of three cases of CPA-related enteritis, including our case, suggests that prompt CPA discontinuation and intensive systemic management are necessary when patients have gastrointestinal symptoms after CPA administration.

Remission and Low Disease Activity in Granulomatosis With Polyangiitis and Microscopic Polyangiitis: Prevalence and Impact on Damage Accrual.

OBJECTIVE: To assess the prevalence and impact on damage accrual of different levels of disease activity in patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). METHODS: Patients with GPA and MPA followed for ≥5 years in 2 different centers were included. Disease activity and damage were assessed using the Birmingham Vasculitis Activity Score (BVAS) and Vasculitis Damage Index (VDI), respectively. Three levels of remission were defined: complete remission (BVAS = 0, negative for antineutrophil cytoplasmic antibody [ANCA], off treatment), clinical remission off therapy (CROffT; BVAS = 0, positive for ANCA), and clinical remission on therapy (CROnT; BVAS = 0, negative or positive for ANCA, glucocorticoids ≤5 mg/day and/or immunosuppressant). A low disease activity state (LDAS) was defined as 0 < BVAS ≤3, low-dose glucocorticoids (≤7.5 mg/day), and/or immunosuppressant. Remission or LDAS were defined as prolonged when lasting ≥2 consecutive years. RESULTS: A total of 167 patients were included: 128 (76.6%) with GPA, 39 (23.4%) with MPA, mean ± SD age 51.0 ± 16.7 years. During a 5-year follow-up, 10 patients (6.0%) achieved prolonged complete remission, 6 (3.6%) prolonged CROffT, 89 (53.3%) prolonged CROnT, 42 (25.1%) prolonged LDAS, and 20 (12.0%) never achieved LDAS. The VDI score at 5 years progressively worsened according to increasing levels of disease activity targets (complete remission, CROffT, CROnT, and LDAS). The mean ± SD 5-year VDI score was higher in patients not achieving prolonged remission compared to those who did (3.7 ± 2.0 versus 2.2 ± 1.9; P < 0.0001). By multivariate analysis, baseline ear, nose, and throat (P = 0.006), and lung involvement (P = 0.047) were negative predictors of prolonged remission. CONCLUSION: More than 60% of patients with GPA/MPA achieved prolonged remission, which was associated with better long-term outcomes. In contrast, prolonged LDAS correlated with increased damage accrual and was not a sufficient treatment target.

Muscle Biopsy-proven Drug-induced Microscopic Polyangiitis in a Patient with Tuberculosis.

We herein report a case of muscle biopsy-proven microscopic polyangiitis (MPA) in a patient with tuberculosis. The patient had developed a persistent fever after the initiation of treatment for tuberculosis and was positive for myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA). However, because conventional symptoms were lacking, determination of the biopsy site was difficult. Based on the findings of a biopsy of the biceps femoris, which confirmed small vessel vasculitis, the patient was diagnosed with MPA. The fever was alleviated by glucocorticoids. Tuberculosis and antituberculosis drugs can cause ANCA-associated vasculitis (AAV). A muscle biopsy is useful for the diagnosis of AAV.