Low seroprevalence and poor specificity of antineutrophil cytoplasmic antibodies in tuberculosis

Mimics of vasculitis

While prompt diagnosis of vasculitis is important, recognition of vasculitis mimics is equally essential. As in the case of vasculitis, an approach to mimics based on the anatomic size of vessels can be useful. Infections can mimic vasculitis of any vessel size, including the formation of aneurysms and induction of ANCAs. Genetic disorders and vasculopathies are important considerations in large and medium vessel vasculitis. Cholesterol emboli, thrombotic conditions and calciphylaxis typically affect the medium and small vessels and, like vasculitis, can cause cutaneous, renal and CNS manifestations. Reversible cerebral vasoconstriction syndrome is important to distinguish from primary angiitis of the CNS. As an incorrect diagnosis of vasculitis can result in harmful consequences, it is imperative that the evaluation of suspected vasculitis includes consideration of mimics. We discuss the above mimics and outline a systematic and practical approach for differentiating vasculitis from its mimics.

Pulmonary granulomas in a patient with positive ANCA and history of tuberculosis: case report

BACKGROUND

Granulomatous polyangiitis (GPA) is a rare multisystem autoimmune disease of unknown aetiology that is pathologically characterised by necrotising vasculitis, tissue necrosis and granulomatous inflammation, typically in the presence of anti-neutrophil cytoplasmic antibodies (ANCA). However infectious diseases may induce high titre ANCA and mimic vasculitis. Tuberculosis may share many clinical features with GPA including fever, arthralgia, granulomatous inflammation and pulmonary lesions and patients.

CASE PRESENTATION

A 39 year old patient was admitted with ocular irritation and redness, arthralgia and multiple new pulmonary lesions. The past medical history was significant for two episodes of tuberculosis previously requiring prolonged treatment. ANCA antibodies were positive and CT showed multiple pulmonary lesions including cavitatory lesions. After extensive investigation, the patient was treated for GPA with high dose immune suppression with good clinical response.

CONCLUSIONS

Here we review the diagnostic considerations between differentiating GPA and tuberculosis in patients from endemic regions. It is recommended that biopsies of lung lesions, sputum microscopy and multidisciplinary team input are sought as part of the workup when these two differentials are being considered.

2020 international consensus on ANCA testing beyond systemic vasculitis

This document follows up on a 2017 revised international consensus on anti-neutrophil cytoplasm antibodies (ANCA) testing in granulomatosis with polyangiitis and microscopic polyangiitis and focuses on the clinical and diagnostic value of ANCA detection in patients with connective tissue diseases, idiopathic interstitial pneumonia, autoimmune liver diseases, inflammatory bowel diseases, anti-glomerular basement membrane (GBM) disease, infections, malignancy, and during drug treatment. Current evidence suggests that in certain settings beyond systemic vasculitis, ANCA may have clinical, pathogenic and/or diagnostic relevance. Antigen-specific ANCA targeting proteinase-3 and myeloperoxidase should be tested by solid phase immunoassays in any patient with clinical features suggesting ANCA-associated vasculitis and in all patients with anti-GBM disease, idiopathic interstitial pneumonia, and infective endocarditis associated with nephritis, whereas in patients with other aforementioned disorders routine ANCA testing is not recommended. Among patients with autoimmune liver diseases or inflammatory bowel diseases, ANCA testing may be justified in patients with suspected autoimmune hepatitis type 1 who do not have conventional autoantibodies or in case of diagnostic uncertainty to discriminate ulcerative colitis from Crohn's disease. In these cases, ANCA should be tested by indirect immunofluorescence as the target antigens are not yet well characterized. Many questions concerning the optimal use of ANCA testing in patients without ANCA-associated vasculitis remain to be answered.

Antineutrophil cytoplasmic antibodies in Chinese patients with tuberculosis

INTRODUCTION

Based on reports, infection with Mycobacterium tuberculosis is believed to induce the development of antibodies that are considered to be biological indicators for the diagnosis of some other diseases. However, conflicting results have been published regarding the presence of antineutrophil cytoplasmic antibodies (ANCAs) in patients with tuberculosis. We aim to study the seroprevalence of ANCA in a population of Chinese patients with tuberculosis, which may lead to the misdiagnosis of vasculitic disorders.

METHODS

The study was conducted from January 2016 to May 2017 to evaluate the presence of ANCA in 103 Chinese patients using indirect immunofluorescent assay. An enzyme-linked immunosorbent assay was performed for anti-myeloperoxidase (MPO) and anti-proteinase 3 (PR3) detection.

RESULTS

Perinuclear ANCA (p-ANCA) was detected in 4.8% (5/103) of patients, whereas cytoplasmic ANCA (c-ANCA) was not detected; 1.9% (2/103) of patients with tuberculosis was positive for anti-MPO antibodies, and none had anti-PR3 antibodies. Both anti-MPO-positive patients were diagnosed with ANCA-associated vasculitides.

CONCLUSIONS

ANCA positivity may be more related to vasculitis and immunological disorders than to a M. tuberculosis infection. Therefore, to improve diagnostic accuracy, patients with M. tuberculosis who are ANCA positive should be investigated for concurrent diseases, including the effects of drugs. Therefore, even in tuberculosis epidemic area, ANCA seropositivity, detected by ELISA, is still more suggestive of ANCA-associated vasculitides.

Granulomatosis with polyangiitis in Northeastern Brazil: study of 25 cases and review of the literature

BACKGROUND

Little has been published about the epidemiology of Granulomatosis with polyangiitis (GPA) in South America, especially in the intertropical zone, and no epidemiological data from Brazil are available. The purpose of the present study was to draw a clinical and demographic profile of GPA patients living in Northeastern Brazil based on laboratory, histological and imaging findings, and evaluate the frequency of organic involvement.

METHODS

Clinical, epidemiological and treatment data of GPA patients were collected retrospectively and compared with the literature.

RESULTS

The cohort included 25 GPA patients (84% female) aged 45.8 ± 16.1 years. Renal and ear-nose-throat (ENT) manifestations were the most common (both 64%). One third (32%) of the patients had 24-h proteinuria > 1 g, 50% had creatinine clearance < 50 mL/min at the time of diagnosis, and 33% had recurrent kidney damage during disease progress. The affected organs included lungs (60%), joints (44%), skin (32%), peripheral nervous system (28%), eyes (28%) and heart (16%). ENT involvement (n = 16/64%) was less frequent in our region than in São Paulo (n = 115/85.8%). Renal (n = 16/64%) and pulmonary (n = 15/60%) involvement was less frequent in our region than in the U.K. (renal n = 30/90%; pulmonary n = 28/84.8%).

CONCLUSION

Most of our patients were female, presented the generalized form and were diagnosed late. The frequency of the main clinical manifestations (ENT, renal and pulmonary) was lower than that observed at higher latitudes, suggesting the existence of a Northeast Brazilian clinical and epidemiological profile and adding to our knowledge of this rare condition.

Tuberculosis, granulomatosis with polyangiitis, or both? A case report

INTRODUCTION

Tuberculosis (TB) is a chronic granulomatose infection, and granulomatosis with polyangiitis (GP) is a small vessel vasculitis, both of which affect the lungs. The combination of these diseases is rare. Both have similar clinical features, making the differential diagnosis difficult.

CASE REPORT

It concerns a 37 year-old female undergoing treatment for pulmonary TB, who presented with left ocular proptosis, eyelid and conjunctival edema and erythema. Orbital biopsy revealed GP. C-Anti-neutrophil cytoplasmic antibodies were elevated. The patient responded well to immunosuppressive treatment.

CONCLUSION

TB and GP can associate. Diagnosis should include not only C-anti-neutrophil cytoplasmic antibodies, but also a biopsy, in order to select the appropriate treatment.

Pulmonary tuberculosis presenting as diffuse alveolar hemorrhage: Believe it or not

Diffuse alveolar hemorrhage (DAH) has been rarely reported with pulmonary infections and even rarer with pulmonary tuberculosis (PTB). We hereby report the case of a 31-year-old male, a known case of ankylosing spondylitis, who presented with clinical and radiological features consistent with DAH. Initial partial improvement with steroids was followed by a microbiological diagnosis of tuberculosis (TB). Starting of antituberculous treatment was followed by complete clinical improvement. This leads to a thought-provoking possible association between the two pathologies, DAH and PTB, if any.

ANCA-associated vasculitis - clinical utility of using ANCA specificity to classify patients

The anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a heterogeneous group of rare syndromes characterized by necrotizing inflammation of small and medium-sized blood vessels and the presence of ANCAs. Several clinicopathological classification systems exist that aim to define homogeneous groups among patients with AAV, the main syndromes being microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA) and eosinophilic GPA (EGPA). Two main types of ANCA can be detected in patients with AAV. These ANCAs are defined according to their autoantigen target, namely leukocyte proteinase 3 (PR3) and myeloperoxidase (MPO). Patients with GPA are predominantly PR3-ANCA-positive, whereas those with MPA are predominantly MPO-ANCA-positive, although ANCA specificity overlaps only partially with these clinical syndromes. Accumulating evidence suggests that ANCA specificity could be better than clinical diagnosis for defining homogeneous groups of patients, as PR3-ANCA and MPO-ANCA are associated with different genetic backgrounds and epidemiology. ANCA specificity affects the phenotype of clinical disease, as well as the patient's initial response to remission-inducing therapy, relapse risk and long-term prognosis. Thus, the classification of AAV by ANCA specificity rather than by clinical diagnosis could convey clinically useful information at the time of diagnosis.

Mycobacteria and autoimmunity

Mycobacterial infections can cause a variety of different manifestations. The increasing incidence of these infections worldwide brought another medical dilemma: immunological manifestations characterized by the presence of many autoantibodies and concomitant presence of autoimmune diseases. The burden of tuberculosis reactivation that emerged with immunosuppressive therapy worsened with the growing use of biological disease-modifying antirheumatic drugs (DMARDs). This review will address the relationship between the immune system and mycobacteria.

Perinuclear antineutrophil cytoplasmic autoantibodies in dogs infected with various vector-borne pathogens and in dogs with immune-mediated hemolytic anemia

OBJECTIVE

To determine the prevalence of perinuclear antineutrophil cytoplasmic autoantibodies (pANCA) in dogs with confirmed or suspected immune-mediated hemolytic anemia (IMHA) or dogs infected with various vector-borne pathogens, including Rickettsia rickettsii, Bartonella henselae, Bartonella vinsonii subsp berkhoffii, Ehrlichia canis, Borrelia burgdorferi, and Leishmania infantum.

ANIMALS

55 dogs with confirmed or suspected IMHA, 140 dogs seroreactive for vector-borne pathogens, and 62 healthy dogs and dogs seronegative for vector-borne pathogens.

PROCEDURES

Samples were allocated to subgroups on the basis of the health status of the dogs and the degree of seroreactivity against various vector-borne pathogens. Serum samples were tested retrospectively via indirect immunofluorescence assay to determine pANCA status.

RESULTS

26 of 55 (47%) dogs with confirmed or suspected IMHA and 67 of 140 (48%) dogs seroreactive for vector-borne pathogens had positive results when tested for pANCA. Serum samples with the highest antibody concentrations against L infantum antigen had the highest proportion (28/43 [65%]) that were positive for pANCA. One of 20 (5%) dogs seronegative for tick-borne pathogens and 8 of 22 (36%) dogs seronegative for L infantum had positive results for pANCA. One of 20 (5%) healthy dogs had serum antibodies against pANCA.

CONCLUSIONS AND CLINICAL RELEVANCE

pANCA were detected in a high percentage of dogs with IMHA and vector-borne infectious diseases. Therefore, pANCA may be a relatively nonspecific marker for dogs with inflammatory bowel disease, although they could represent a biomarker for immune-mediated diseases and infections.

Myeloperoxidase-antineutrophil Cytoplasmic Antibodies with Cytoplasmic Fluorescence Pattern

We report here two rare cases of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA)-positive Wegener's granulomatosis (limited variant) which deceptively produced a cytoplasmic (C-ANCA) pattern on indirect immunofluorescence.

Vasculitides in the context of HIV infection

Vasculitides are a rare but major manifestation of HIV infection, with an incidence of less than 1%, excluding adverse drug reactions. A wide spectrum of vasculitides have been found in association with HIV infection, reflecting almost every pattern and type of vasculitis of small, medium and large vessels. Vasculitis in HIV-infected patients can arise as a result of infection with a known pathogen or in response to a triggering factor, but may also arise in the absence of any identifiable cause. Although the vasculitides seen in HIV infection are varied, one feature--namely inflammation of the vessel wall--is common to all. Various pathogenic mechanisms have been implicated in the induction of vasculitis, including cell-mediated inflammation, immune complex-mediated inflammation and autoantibody-mediated inflammation. This review will focus on some of those vasculitides that have been described in HIV-infected patients, and will discuss the association of atherosclerosis with vasculitides.

Diagnostic pitfall: Mycobacterium avium complex pulmonary infection and positive ANCA

We report the case of a 58-year-old female who presented with productive cough, weight loss, pulmonary nodular infiltrates and cavitations. She had a positive anti-neutrophil cytoplasmic antibodies (ANCA) test. A diagnosis of vasculitis was considered and a video-assisted thoracoscopic biopsy of the lung nodules was organised. However, prior to the biopsy, the sputum results revealed the presence of acid-fast bacilli, which were identified as Mycobacterium avium complex. A repeat ANCA assay was positive for atypical ANCA with negative proteinase-3 and myeloperoxidase titres. The patient was treated with rifampicin, ethambutol and clarithromycin with clinical and radiological improvement. The objective of this report is to highlight a rare association between positive ANCA titres and a non-tuberculous mycobacterial infection as a misdiagnosis and treatment of this patient with immunosuppressive therapy might have led to serious consequences.

Central nervous system involvement in Wegener granulomatosis

Wegener granulomatosis (WG) is an antineutrophil cytoplasmic antibody (ANCA)-associated granulomatous vasculitis of small and medium-sized vessels. This vasculitis involves mainly the upper and lower respiratory tracts and kidneys, although WG may affect any organ. Central nervous system (CNS) involvement is an uncommon manifestation of WG, reported in 7%-11% of patients. Three major mechanisms have been incriminated as causing CNS disease in WG: contiguous invasion of granuloma from extracranial sites, remote intracranial granuloma, and CNS vasculitis. Herein we describe 6 patients with WG-related CNS involvement, 2 of whom had chronic hypertrophic pachymeningitis, 3 with pituitary involvement, and 1 with cerebral vasculitis. CNS involvement was present at disease onset in 2 patients and occurred 5-18 years after WG diagnosis in the remaining 4. Based on these observations and a review of the literature, we discuss the pathogenic mechanisms, clinical features, imaging findings, treatment, and outcome of meningeal, pituitary, and vascular involvement, with an emphasis on differential diagnoses, prognosis, and therapeutic management of WG-related CNS involvement.

Autoimmunity and interstitial lung disease

PURPOSE OF REVIEW

The pathogenesis of idiopathic pulmonary fibrosis as well as that of several other interstitial lung diseases is poorly understood. The role of autoimmunity in interstitial lung diseases associated with connective tissue disorders such as systemic sclerosis, systemic lupus erythematosus, and rheumatoid arthritis as well as the vasculitides is well established. There is at least some evidence in the literature that supports the role of autoimmunity as one of the mechanisms of alveolar injury responsible for idiopathic pulmonary fibrosis. This review is an attempt to summarize the studies on this subject.

RECENT FINDINGS

Repeated extraneous insults and exposures are considered to be responsible for recurrent alveolar injury, inflammation, dysregulated tissue repair, and fibroproliferation resulting in pulmonary fibrosis. The presence of autoantibodies in the sera of patients with idiopathic pulmonary fibrosis has been demonstrated in a few studies. Several autoantibodies, including anti-Sm antibodies, antibodies to U1 ribonucleoproteins, and antibodies to U3 ribonucleoproteins, have been demonstrated in connective tissue disorders, many of which are associated with interstitial lung involvement. Autoimmunity has been also suggested as a possible mechanism of rejection caused by bronchiolitis obliterans after lung transplantation.

SUMMARY

It might seem that the role of autoimmunity in interstitial lung disease has been underestimated or even underinvestigated. The subject requires further investigation, especially with regard to the problems of lung allograft rejection due to bronchiolitis obliterans of nonalloimmunity origin and the failure of patients with idiopathic pulmonary fibrosis to respond to most forms of currently available therapy.

Pulmonary involvement in microscopic polyangiitis

PURPOSE OF REVIEW

Microscopic polyangiitis is a systemic necrotizing vasculitis that affects small vessels, resulting in a wide spectrum of organ involvement including the kidneys and the lungs. This paper reviews recent insights and observations into the pathogenesis, clinical manifestations, and treatment of pulmonary involvement in microscopic polyangiitis.

RECENT FINDINGS

The spectrum of clinical presentations ranges from antecedent interstitial fibrosis to frank hemoptysis secondary to capillaritis. Computerized tomography imaging reveals a variety of pulmonary findings, including ground-glass attenuation, consolidation, thickening of bronchovascular bundles, and honeycombing. Antineutrophil cytoplasmic antibodies are important in diagnosis as well as in the pathogenesis and prognosis of microscopic polyangiitis. There is more evidence to support the various therapeutic modalities currently used in pulmonary manifestations of microscopic polyangiitis, including induction therapy with cyclophosphamide, the use of other novel pharmacologic agents such as the tumor necrosis factor-alpha blockers and rituximab, and nonpharmacologic modalities such as plasmapheresis and ventilatory management.

SUMMARY

The pulmonary manifestations of microscopic polyangiitis are diverse and often difficult to manage; however, as our understanding and experience grows so does our ability to successfully diagnose and treat these patients.