Imaging of pulmonary vasculitis

Pulmonary pathology in vasculitis

Pulmonary involvement is frequent in vasculitis, particularly in ANCA-associated small vessel vasculitis. Laboratory and radiological data alone are often sufficient to confirm the clinical hypothesis, but sometimes the pathologist plays a crucial role in the differential diagnosis and the patient's management. In this review, the pathologic features of pulmonary vasculitis and the pathologist's role in this field are illustrated.

HRCT imaging of pulmonary involvement in granulomatosis with polyangiitis and microscopic polyangiitis at disease onset and during follow-up

BACKGROUND

The pulmonary involvement in patients with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) is well known at disease onset but data during follow-up (after the induction regimen and when the first relapse occurs) are limited. Our goal was to analyze chest high-resolution computed tomography (HRCT) findings of (ANCA)-associated vasculitis patients.

METHOD

All consecutive unselected AAV patients over eighteen with positive ANCA status and with HRCT chest performed at the diagnosis were retrospectively enrolled between 2004 and 2019 at the Toulouse University Hospital (France). Two experienced pulmonologists and one expert respiratory radiologist reviewed independently HRCT chest scans.

RESULTS

A total of 157 AAV patients were included in the study. Two-thirds of AAV patients had pulmonary involvement at diagnosis. Diffuse alveolar hemorrhage (DAH) was observed in 31.2 % of cases, nodules and masses in 18.5 %, bronchial airway involvement in 13.4 %, and interstitial involvement in 12.7 %. Following the induction regimen, chest HRCT scans over a two-year period demonstrated significant improvement in DAH and nodular manifestations, whereas bronchial airway involvement exhibited variability and half of cases of interstitial lung disease (ILD) had progressive course. Outcomes and survival rates are better for nodular and bronchial involvement. DAH was the most frequent cause of deaths. Progressive fibrotic changes in ILD over time could impact prognosis despite AAV remission.

CONCLUSION

Employing a pattern-based approach with HRCT chest scans to assess lung involvement could be valuable in predicting treatment response, relapse, mortality, and could improved the management of AAV patients.

Role of bronchoscopy for respiratory involvement in granulomatosis with polyangiitis and microscopic polyangiitis

Objectives

This study describes data from bronchoscopy performed at the diagnosis of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV).

Methods

We conducted a retrospective study between 2004 and 2019 in patients aged >18 years with a diagnosis of microscopic polyangiitis (MPA) or granulomatosis with polyangiitis (GPA) who underwent bronchoscopy at onset of the disease. We collected bronchoalveolar lavage (BAL) and histological findings obtained during bronchoscopy.

Results

274 patients with AAV were identified. Among 92 bronchoscopies, 62 were performed at diagnosis, and 58 procedures were finally analysed. Cough was more frequent in patients with MPA than GPA (p=0.02). The presence of endobronchial lesions (24.1%) was found to be significantly associated with GPA (p<0.0001) and proteinase 3-ANCA (p=0.01). The most frequent endobronchial lesions were inflammation and hyperaemia of the bronchial mucosa (50%), followed by stenoses (28%), ulcerations (21%) and mass-like granulomatosis (7%). The diagnostic yield of bronchial biopsies was useful for visible lesions (66.6% versus 0%; p=0.006). On BAL, diffuse alveolar haemorrhage (DAH) was detected in 31 (53.4%) patients and was more frequent in MPA patients (70.4% versus 38.7%; p=0.016). In 16.1% of DAH cases, BAL confirmed the diagnosis despite the absence of clinical or biological arguments. The incidence of microbial infections on BAL (38%) was similar between MPA and GPA (p=0.54).

Conclusion

Bronchoscopy is an informative procedure at the onset of AAV disease in patients with respiratory manifestations. Endobronchial lesions are more frequently found in GPA and should be biopsied. BAL can be used to confirm DAH or diagnose superadded infection.

An unexpected diagnosis of a 57-year-old women with migratory pulmonary infiltrates

A 57-year-old female presented with sudden shortness of breath and migratory pulmonary infiltrates on imaging, which corresponds with a diagnosis of cryptogenic organizing pneumonia. Initial treatment with corticosteroids showed only mild improvement during follow-up. BAL was performed and revealed diffuse alveolar hemorrhage. Immune testing showed positive P-ANCA with positive MPO, leading to a diagnosis of microscopic polyangiitis.

Eosinophilic Lung Diseases

The eosinophilic lung diseases may manifest as chronic eosinophilic pneumonia, acute eosinophilic pneumonia, or as the Löffler syndrome (generally of parasitic etiology). The diagnosis of eosinophilic pneumonia is made when both characteristic clinical-imaging features and alveolar eosinophilia are present. Peripheral blood eosinophils are generally markedly elevated; however, eosinophilia may be absent at presentation. Lung biopsy is not indicated except in atypical cases after multidisciplinary discussion. The inquiry to possible causes (medications, toxic drugs, exposures, and infections especially parasitic) must be meticulous. Idiopathic acute eosinophilic pneumonia may be misdiagnosed as infectious pneumonia. Extrathoracic manifestations raise the suspicion of a systemic disease especially eosinophilic granulomatosis with polyangiitis. Airflow obstruction is frequent in allergic bronchopulmonary aspergillosis, idiopathic chronic eosinophilic pneumonia, eosinophilic granulomatosis with polyangiitis, and hypereosinophilic obliterative bronchiolitis. Corticosteroids are the cornerstone of therapy, but relapses are common. Therapies targeting interleukin 5/interleukin-5 are increasingly used in eosinophilic lung diseases.

Two in one: Overlapping CT findings of COVID-19 and underlying lung diseases

Coronavirus disease 2019 (COVID-19) is associated with pneumonia and has various pulmonary manifestations on computed tomography (CT). Although COVID-19 pneumonia is usually seen as bilateral predominantly peripheral ground-glass opacities with or without consolidation, it can present with atypical radiological findings and resemble the imaging findings of other lung diseases. Diagnosis of COVID-19 pneumonia is much more challenging for both clinicians and radiologists in the presence of pre-existing lung disease. The imaging features of COVID-19 and underlying lung disease can overlap and obscure the findings of each other. Knowledge of the radiological findings of both diseases and possible complications, correct diagnosis, and multidisciplinary consensus play key roles in the appropriate management of diseases. In this pictorial review, the chest CT findings are presented of patients with underlying lung diseases and overlapping COVID-19 pneumonia and the various reasons for radiological lung abnormalities in these patients are discussed.

Imaging of intestinal vasculitis focusing on MR and CT enterography: a two-way street between radiologic findings and clinical data

Diagnosis of intestinal vasculitis is often challenging due to the non-specific clinical and imaging findings. Vasculitides with gastrointestinal (GI) manifestations are rare, but their diagnosis holds immense significance as late or missed recognition can result in high mortality rates. Given the resemblance of radiologic findings with some other entities, GI vasculitis is often overlooked on small bowel studies done using computed tomography/magnetic resonance enterography (CTE/MRE). Hereon, we reviewed radiologic findings of vasculitis with gastrointestinal involvement on CTE and MRE. The variety of findings on MRE/CTE depend upon the size of the involved vessels. Signs of intestinal ischemia, e.g., mural thickening, submucosal edema, mural hyperenhancement, and restricted diffusion on diffusion-weighted imaging, are common in intestinal vasculitis. Involvement of the abdominal aorta and the major visceral arteries is presented as concentric mural thickening, transmural calcification, luminal stenosis, occlusion, aneurysmal changes, and collateral vessels. Such findings can be observed particularly in large- and medium-vessel vasculitis. The presence of extra-intestinal findings, including within the liver, kidneys, or spleen in the form of focal areas of infarction or heterogeneous enhancement due to microvascular involvement, can be another radiologic clue in diagnosis of vasculitis. The link between the clinical/laboratory findings and MRE/CTE abnormalities needs to be corresponded when it comes to the diagnosis of intestinal vasculitis.

Cannonball Pulmonary Opacities Disclosing a Granulomatosis With Polyangiitis (GPA) With C-Antimyeloperoxidase (C-Anti-MPO) Antineutrophil Cytoplasm Antibodies (ANCAs)

Granulomatosis with polyangiitis (GPA) is a necrotizing granulomatous vasculitis of medium- and small-caliber vessels associated with the presence of antineutrophil cytoplasm antibodies (ANCAs) and antibodies specific for proteinase 3 (anti-PR3). The interest of this case lies on the fact that these antibodies are directed against myeloperoxidase revealed by the presence of scattered multiple pulmonary nodules.

We report a 65-year-old-female patient who presented with a productive cough with mucus sputum associated with a cephalea for six months. The chest x-ray showed multiple pulmonary nodules, first suggesting a neoplastic origin. The initial etiological assessment was non-contributory. A month later, the patient developed pulmonary condensations and ocular signs. The etiological assessment then found ANCA anti-myeloperoxidase (anti-MPO)-GPA. A good knowledge of the clinical and radiological signs of GPA is important to quickly guide the diagnosis that will condition the prognosis of this disease.

Pulmonary Vasculitides: A Radiological Review Emphasizing Parenchymal HRCT Features

Vasculitides represent a heterogeneous group of immune-mediated disorders, characterized by a systemic inflammatory destructive process of the blood vessels resulting either in ischemia or hemorrhage. The organ involved and vessel size influence the pattern of presentation of the pathology. The lung is commonly involved in systemic vasculitides, with heterogeneous clinical, radiological, and histopathological presentations. Primary vasculitides most commonly associated with lung parenchymal involvement include small-vessel antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitides, such as granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA), and microscopic polyangiitis (MPA). Several studies have reported cases of interstitial lung diseases (ILDs) associated with systemic vasculitis, particularly those positive for ANCA associated vasculitis/vasculitidis: AAV. We have selected from our case series different radiological features of pulmonary vasculitis (i.e., solitary or multiple nodules, cavitary lesions, nodules with centrilobular or peribronchial distribution, airspace consolidations, “crazy paving” appearance, interstitial disease), including cases with interstitial lung alterations. Therefore, the aim of this review is to describe the typical clinical manifestations of vasculitides and their main radiologic features (especially AAV).

From Head to Toe: Granulomatosis with Polyangiitis

Granulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic antibody-associated vasculitis. It is an uncommon multisystem disease involving predominantly small vessels and is characterized by granulomatous inflammation, pauci-immune necrotizing glomerulonephritis, and vasculitis. GPA can involve virtually any organ. Clinical manifestations are heterogeneous and can be classified as granulomatous (eg, ear, nose, and throat disease; lung nodules or masses; retro-orbital tumors; pachymeningitis) or vasculitic (eg, glomerulonephritis, alveolar hemorrhage, mononeuritis multiplex, scleritis). The diagnosis of GPA relies on a combination of clinical findings, imaging study results, laboratory test results, serologic markers, and histopathologic results. Radiology has a crucial role in the diagnosis and follow-up of patients with GPA. CT and MRI are the primary imaging modalities used to evaluate GPA manifestations, allowing the differentiation of GPA from other diseases that could simulate GPA. The authors review the main clinical, histopathologic, and imaging features of GPA to address the differential diagnosis in the affected organs and provide a panoramic picture of the protean manifestations of this infrequent disease. The heterogeneous manifestations of GPA pose a significant challenge in the diagnosis of this rare condition. By recognizing the common and unusual imaging findings, radiologists play an important role in the diagnosis and follow-up of patients with GPA and aid clinicians in the differentiation of disease activity versus disease-induced damage, which ultimately affects therapeutic decisions. Online supplemental material is available for this article. ^©RSNA, 2021.

Granulomatosis with polyangiitis: A case report and brief review of literature

Granulomatosis with polyangiitis formerly known as Wegener's granulomatosis was first described by German pathologist Friedrich Wegener in 1936. It is a multi-system necrotizing noncaseating granulomatous vasculitis which affects small to medium-sized vessels. It can involve any organ system, most commonly the lungs and kidneys. American College of Rheumatology requires 2 of 4 criteria for diagnosis: Positive biopsy for granulomatous vasculitis, urinary sediment with red blood cells, abnormal chest radiograph and oral/nasal inflammation. Here we present a case of Granulomatosis with polyangiitis with brief review of literature.

Interstitial Lung Disease and Diffuse Alveolar Hemorrhage, the Two Key Pulmonary Manifestations in Microscopic Polyangiitis

Microscopic polyangiitis (MPA) is an antineutrophil cytoplasmic antibody (ANCA)‒associated necrotizing vasculitis, which mainly affects small vessels in various organs, especially the lungs. The two key pulmonary manifestations, interstitial lung disease (ILD) and diffuse alveolar hemorrhage (DAH), increase the morbidity and death rate of patients with MPA. ILD is more common in MPA than in other ANCA-associated vasculitis subsets and is primarily associated with myeloperoxidase-ANCA. Unlike alveolar hemorrhage due to pulmonary capillaritis, ILD can initially manifest as isolated pulmonary fibrosis. Of note, its most frequent radiographic pattern is the usual interstitial pneumonia pattern, similar to the characteristic pattern seen in idiopathic pulmonary fibrosis. In this review we present the pathogenesis, clinical manifestations, and radiographic and histopathologic features of ILD and DAH in MPA. We also briefly summarize the outcome and therapeutic options for the two conditions.

MR imaging findings of musculoskeletal involvement in microscopic polyangiitis: a comparison with inflammatory myopathy

OBJECTIVE

The purpose of this study was to evaluate the importance of MR imaging findings of musculoskeletal involvement of the lower limbs in diagnosing microscopic polyangiitis (MPA) vs polymyositis (PM) or dermatomyositis (DM).

MATERIALS AND METHODS

This study included 13 patients diagnosed with MPA clinically and through histologically, and 38 diagnosed with PM/DM, who underwent MR imaging of the lower limbs prior to treatment. Axial and coronal short tau inversion recovery (STIR) images were reviewed retrospectively.

RESULTS

The sites affected by MPA were the lower legs in six (46%) patients and the thighs in seven (54%). Intramuscular hyperintensity and fascial hyperintensity were observed in all cases of MPA (100%). Fascial hyperintensity was more frequently encountered in MPA than in PM/DM (100% vs. 45%, p < 0.01). As the predominantly involved sites, the fascial regions were more frequently affected by MPA than by PM/DM (77% vs. 18%, p < 0.01). Diffuse subcutaneous fat hyperintensity was more frequently observed in MPA than in PM/DM (100% vs. 16%, p < 0.01). However, no significant differences in intramuscular hyperintensity (100% vs. 97%, p = 0.745) and subcutaneous fat hyperintensity (54% vs. 50%, p = 0.533) were found between MPA and PM/DM.

CONCLUSION

Intramuscular hyperintensity and fascial hyperintensity have always been observed in MPA, and the predominantly affected sites were usually the fascial regions. Compared with PM/DM, fascial hyperintensity and diffuse subcutaneous fat hyperintensity were more frequent in MPA.

Ground-glass opacity (GGO): a review of the differential diagnosis in the era of COVID-19

Thoracic imaging is fundamental in the diagnostic route of Coronavirus disease 2019 (COVID-19) especially in patients admitted to hospitals. In particular, chest computed tomography (CT) has a key role in identifying the typical features of the infection. Ground-glass opacities (GGO) are one of the main CT findings, but their presence is not specific for this viral pneumonia. In fact, GGO is a radiological sign of different pathologies with both acute and subacute/chronic clinical manifestations. In the evaluation of a subject with focal or diffuse GGO, the radiologist has to know the patient’s medical history to obtain a valid diagnostic hypothesis. The authors describe the various CT appearance of GGO, related to the onset of symptoms, focusing also on the ancillary signs that can help radiologist to obtain a correct and prompt diagnosis.

A Review of Clinical and Imaging Features of Diffuse Pulmonary Hemorrhage

OBJECTIVE. The purpose of this article is to review the clinical and imaging features of diffuse pulmonary hemorrhage. CONCLUSION. Diffuse pulmonary hemorrhage is a life-threatening syndrome associated with a wide variety of underlying pathologic categories. Nonspecific clinical and imaging features pose challenges to promptly diagnosing this condition. Chest radiography commonly shows alveolar opacification, and CT reveals the extent of disease. Integration of clinical, radiologic, laboratory, and pathologic findings facilitates timely diagnosis and etiologic identification.

Radiologic Approach for Pulmonary Vasculitis

혈관염은 혈관벽의 염증을 특징으로 하는 드문 전신 질환으로 간혹 미만성 폐출혈이나 급성 사구체신염으로 생명을 위협하기도 한다. 원인을 알 수 없는 일차성 혈관염도 있지만 자가면역 질환이나 약물, 감염, 종양 등 수많은 원인들에 의해 발생하는 이차성 혈관염도 있으며 분류가 복잡하고 명확한 진단검사가 없어 진단에 어려움이 있다. 또한 다양하고 비특이적인 증상과 징후 및 검사 소견을 보여 혈관염의 진단에는 임상양상, 영상 검사, 자가항체 검사, 병리 소견 등 여러 가지 결과를 종합하는 것이 필수적이다. 이 종설에서는 혈관염의 분류와 진단에 중요한 증상 및 징후, 특징적으로 폐를 침범하는 대표적인 폐혈관염의 영상 소견과 감별 진단, 그리고 새로운 혈관염 분류를 위한 국제적 연구인 Diagnostic and Classification Criteria in Vasculitis에 대해 소개하고자 한다.

COVID-19 pneumonia: the great radiological mimicker

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread worldwide since December 2019. Although the reference diagnostic test is a real-time reverse transcription-polymerase chain reaction (RT-PCR), chest-computed tomography (CT) has been frequently used in diagnosis because of the low sensitivity rates of RT-PCR. CT findings of COVID-19 are well described in the literature and include predominantly peripheral, bilateral ground-glass opacities (GGOs), combination of GGOs with consolidations, and/or septal thickening creating a "crazy-paving" pattern. Longitudinal changes of typical CT findings and less reported findings (air bronchograms, CT halo sign, and reverse halo sign) may mimic a wide range of lung pathologies radiologically. Moreover, accompanying and underlying lung abnormalities may interfere with the CT findings of COVID-19 pneumonia. The diseases that COVID-19 pneumonia may mimic can be broadly classified as infectious or non-infectious diseases (pulmonary edema, hemorrhage, neoplasms, organizing pneumonia, pulmonary alveolar proteinosis, sarcoidosis, pulmonary infarction, interstitial lung diseases, and aspiration pneumonia). We summarize the imaging findings of COVID-19 and the aforementioned lung pathologies that COVID-19 pneumonia may mimic. We also discuss the features that may aid in the differential diagnosis, as the disease continues to spread and will be one of our main differential diagnoses some time more.

Pathological entities that may affect the lungs and the myocardium. Evaluation with chest CT and cardiac MR

Certain entities may simultaneously involve the lungs and the myocardium. Knowing their cardiac and thoracic manifestations enhances the understanding of those conditions and increases awareness and suspicion for possible concurrent cardiothoracic involvement. Entities that can present with pulmonary and myocardial involvement include infiltrative diseases like sarcoidosis and amyloidosis, eosinophil-associated conditions including eosinophilic granulomatosis with polyangiitis (EGPA) and hypereosinophilic syndrome (HES), connective tissue diseases such as systemic sclerosis (SSc) and lupus erythematosus and genetic disorders like Fabry disease (FD). Lung involvement in sarcoidosis is almost universal. While cardiac involvement is less common, concurrent cardiothoracic involvement can often be seen. Pulmonary amyloidosis is more often a localized process and generally occurs separately from cardiac involvement, except for diffuse alveolar-septal amyloidosis. EGPA and HES can present with consolidative or ground glass opacities, cardiac inflammation and endomyocardial fibrosis. Manifestations of SSc include interstitial lung disease, pulmonary hypertension and cardiomyopathy. Lupus can present with serositis, pneumonitis and cardiac inflammation. FD causes left ventricular thickening and fibrosis, and small airways disease. This article aims to review the clinicopathological features of chest and cardiac involvement of these entities and describe their main findings on chest CT and cardiac MR.

Diagnosis, Prevention, and Treatment of Thromboembolic Complications in COVID-19: Report of the National Institute for Public Health of the Netherlands

A potential link between mortality, d-dimer values, and a prothrombotic syndrome has been reported in patients with coronavirus disease 2019 (COVID-19) infection. The National Institute for Public Health of the Netherlands asked a group of radiology and vascular medicine experts to provide guidance for the imaging work-up and treatment of these important complications. This report summarizes evidence for thromboembolic disease, potential diagnostic and preventive actions, and recommendations for prophylaxis and treatment of patients with COVID-19 infection.

Noninfectious Granulomatous Diseases of the Chest

Granulomas are pathologically defined as focal aggregations of activated macrophages, Langerhans cells, and lymphocytes. Granulomas form in the lungs when the immune system barricades the substances it perceives as foreign but is unable to remove. Granulomas manifest with numerous imaging appearances in thoracic radiology, and their presence is a nonspecific finding. Granulomatous lung diseases comprise multiple entities with variable clinical manifestations and outcomes. Their imaging findings are rarely specific and can mimic malignancies, often triggering an extensive diagnostic workup. Radiologists must be familiar with the clinical manifestations and imaging findings of these entities to generate appropriate differential diagnoses. This review describes the imaging manifestations of various noninfectious, necrotizing, and nonnecrotizing granulomatous diseases that primarily affect the thorax. ©RSNA, 2020.

Pulmonary lymphangitic carcinomatosis from gallbladder cancer mimicking diffuse alveolar haemorrhage

Diagnosis in cases with pulmonary lymphangitic carcinomatosis as a primary manifestation is difficult due to unawareness of the cancer. An 81-year-old man was admitted due to a one-week history of dyspnoea and haemoptysis. Chest computed tomography showed diffuse bilateral ground-grass opacity and partial consolidation. We suspected diffuse alveolar haemorrhage. High-dose methylprednisolone and cyclophosphamide did not improve his condition and he died from respiratory failure. Autopsy revealed pulmonary lymphangitic carcinomatosis of whole lungs and primary gallbladder cancer. We should consider pulmonary lymphangitic carcinomatosis in the differential diagnosis of patients with haemoptysis and diffuse lung opacity of unknown origin.

Imaging of Cardiopulmonary Involvement in Systemic Immune-mediated Diseases: A Comprehensive Review

Systemic immune-mediated diseases (SID) are a large group of disorders characterized by complex inflammatory and autoimmune damage to various organs and tissues. Among the possible manifestations, SIDs may potentially involve each structure of the cardiopulmonary system. Each disease is characterized by a specific clinical presentation. Coronary artery disease, myocarditis, pericarditis, valvular disease, pulmonary arterial hypertension, and interstitial lung disease represent characteristic findings of cardiopulmonary involvement in these disorders and their prompt recognition is crucial for the diagnosis of SIDs and the patient's prognosis. In this setting, chest high-resolution computed tomography and cardiac magnetic resonance are the most important noninvasive techniques for the assessment of these diseases and their complications. The knowledge of various cardiac and pulmonary radiologic patterns increases the likelihood of diagnosing these disorders and can lead to improved understanding of the underlying pathophysiology to personalize the treatment for each patient.

Unclassified Vasculitis with Episcleritis, Thrombophlebitis, Deep Vein Thrombosis, Pulmonary Vasculitis, and Intracranial Vasculitis: An Autopsy Case Report

BACKGROUND Systemic vasculitides constitute heterogenous conditions affecting many organs and systems through blood vessel inflammation. Although there are some classifications for vasculitis, several vasculitides are "unclassified" because they cannot be clearly assigned to one of the known entities. CASE REPORT We report an autopsy case of a 67-year-old Japanese man who presented with fever, ocular pain, erythema, chest pain, and headache. The disease caused episcleritis, thrombophlebitis, extensive deep vein thrombosis, multiple pulmonary nodules and masses, hypertrophic pachymeningitis, and hyper-intensity areas in brain parenchyma on magnetic resonance images. Histopathology of the pulmonary nodule confirmed vasculitis affecting medium-to-small veins and arteries without necrotizing vasculitis or granulomatous inflammation. We diagnosed the patient with unclassified vasculitis based on the clinicopathological characteristics. Steroids in combination with immunosuppressants were used, but the disease was refractory and relapsing. The disease activity was eventually controlled with rituximab, but the patient died of bronchopneumonia. On autopsy, lung and brain findings indicated healed vascular inflammation. CONCLUSIONS This is the first case report of unclassified vasculitis, which is characterized as medium-to-small-sized arteritis and phlebitis, causing episcleritis, thrombophlebitis, deep vein thrombosis, pulmonary vasculitis, and intracranial vasculitis. The clinical conditions share some similarities with granulomatosis with polyangiitis and Behçet's disease; however, they meet no classification criteria of any specific vasculitis. More cases need to be analyzed to confirm our findings.

Approach to Peribronchovascular Disease on CT

Diseases that are predominantly peribronchovascular in distribution on computed tomography by definition involve the bronchi, adjacent vasculature, and associated lymphatics involving the central or axial lung interstitium. An understanding of diseases that can present with focal peribronchovascular findings is useful for establishing diagnoses and guiding patient management. This review will cover clinical and imaging features that may assist in differentiating amongst the various causes of primarily peribronchovascular disease.

Pulmonary vasculitis

Systemic vasculitides frequently affect the pulmonary vasculature. As the signs and symptoms of pulmonary vasculitis are variable and nonspecific, diagnosis and treatment represent a real challenge. Vasculitides should be given consideration, as these diseases present severe manifestations of rapidly progressing pulmonary disease. Examining other organs usually affected by vasculitides (e.g., the skin and kidneys) and determining autoantibody levels are essential to a better management of the disease. A radiological study would also contribute to establishing a diagnosis. The lungs are commonly involved in small-vessel vasculitis, anti-glomerular basement membrane disease, and vasculitides associated with antineutrophil cytoplasmic antibodies. Associated life-threatening diffuse alveolar haemorrhages and irreversible damage to other organs-usually the kidneys-are severe complications that require early diagnosis. Vasculitides are rare diseases that affect multiple organs. An increasing number of treatments-including biological agent-based therapies-requiring cooperation between specialists and centers have become available in the recent years. In the same way, clinicians should be familiar with the complications associated with immunosuppressive therapies.

Pulmonary disorders that are potentially associated with anti- neutrophilic cytoplasmic antibodies: A brief review

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis frequently manifests with involvement of the lungs and kidneys, and it also may affect other anatomic sites. This article presents the patterns of pulmonary injury in which ANCA-associated vasculitis is included in the differential diagnosis, with a discussion of antineutrophil cytoplasmic antibody testing methods. The histologic features of non-vasculitic, potentially-ANCA-associated pulmonary lesions are reviewed briefly as well.

Pulmonary vasculitis: diagnosis and endovascular therapy

Pulmonary vasculitides are caused by a heterogeneous group of diseases with different clinical features and etiologies. Radiologic manifestations depend on the predominant type of vessel involved, which are grouped into large, medium, or small-sized vessels. Diagnosing pulmonary vasculitides is a challenging task, and radiologists play an important role in their management by providing supportive evidence for diagnosis and opportunities for minimally invasive therapy. This paper aims to present a practical approach for understanding the vasculitides that can affect the pulmonary vessels and lungs. We will describe and illustrate the main radiologic findings, discussing opportunities for minimally invasive treatment.

Management of Incidental Lung Nodules

The incidental pulmonary nodule is commonly encountered when interpreting chest CTs. The management of pulmonary nodules requires a multidisciplinary approach entailing integration of nodule size and features, clinical risk factors, and patient preference and comorbidities. Guidelines have been issued for the management of both solid and subsolid nodules, with the Fleischner Society issuing revised guidelines in 2017. This article focuses on the CT imaging characteristics and clinical behavior of pulmonary nodules, with review of the current management guidelines that reflect this knowledge.

CT Features of Vasculitides Based on the 2012 International Chapel Hill Consensus Conference Revised Classification

Vasculitis, characterized by inflammation of vessel walls, is comprised of heterogeneous clinicopathological entities, and thus poses a diagnostic challenge. The most widely used approach for classifying vasculitides is based on the International Chapel Hill Consensus Conference (CHCC) nomenclature system. Based on the recently revised CHCC 2012, we propose computed tomography (CT) features of vasculitides and a differential diagnosis based on location and morphological characteristics. Finally, vasculitis mimics should be differentiated, because erroneous application of immunosuppressive drugs on vasculitis mimics may be ineffective, even deteriorating. This article presents the utility of CT in the diagnosis and differential diagnosis of vasculitides.

Pulmonary Vasculitis: Spectrum of Imaging Appearances

Pulmonary vasculitis is a relatively uncommon disorder, usually manifesting as part of systemic vasculitis. Imaging, specifically computed tomography, is often performed in the initial diagnostic workup. Although the findings in vasculitis can be nonspecific, they can provide important clues in the diagnosis, and guide the clinical team toward the right diagnosis. Radiologists must have knowledge of common and uncommon imaging findings in various vasculitides. Also, radiologists should be able to integrate the clinical presentation and laboratory test findings together with imaging features, so as to provide a meaningful differential diagnosis.

Eosinophilic Lung Diseases

Eosinophilic lung diseases especially comprise eosinophilic pneumonia or as the more transient Löffler syndrome, which is most often due to parasitic infections. The diagnosis of eosinophilic pneumonia is based on characteristic clinical-imaging features and the demonstration of alveolar eosinophilia, defined as at least 25% eosinophils at BAL. Peripheral blood eosinophilia is common but may be absent at presentation in idiopathic acute eosinophilic pneumonia, which may be misdiagnosed as severe infectious pneumonia. All possible causes of eosinophilia, including drug, toxin, fungus related etiologies, must be thoroughly investigated. Extrathoracic manifestations should raise the suspicion of eosinophilic granulomatosis with polyangiitis.

Non-infectious Parenchymal Lung Disease

Acute dyspnea is a common presenting complaint in the emergency room, emergency medicine and intensive care. It may have a cardiovascular or a non-cardiovascular origin, the latter including pulmonary parenchymal diseases. Depending on the cause, it may be associated with fever, cough, hemoptysis, and/or chest pain, with a duration of symptoms that can range from hours to days.

Prompt identification of the underlying cause of acute dyspnea is essential in guiding appropriate therapy and management, as patients may rapidly progress to acute respiratory failure. Evaluation with chest radiography is vital for initial assessment and may reveal diffuse parenchymal abnormalities, which may require further assessment with computed tomography (HRCT).

Acute non-infectious parenchymal lung diseases are often overlooked and may be under-diagnosed. Their diagnosis requires the evaluation, along with the HRCT pattern, of the clinical and laboratory features and of the bronchoalveolar lavage. Biopsy may be necessary in more complex cases.

Although the most frequent cause of diffuse non-infectious parenchymal lung involvement is acute hydrostatic pulmonary edema, there is a wide variety of diseases that may be encountered, including acute drug toxicity, hypersensitivity pneumonitis (HP), acute respiratory distress syndrome (ARDS) and diffuse alveolar hemorrhage (DAH). In trauma patients, fat embolism syndrome (FES) must be taken into account. Acute respiratory failure is an eventuality that can occur during the course of chronic lung diseases (UIP for example), which may have been unknown until then.

Mosaic Attenuation: Etiology, Methods of Differentiation, and Pitfalls

Mosaic attenuation is a commonly encountered pattern on computed tomography that is defined as heterogeneous areas of differing lung attenuation. This heterogeneous pattern of attenuation is the result of diverse causes that include diseases of the small airways, pulmonary vasculature, alveoli, and interstitium, alone or in combination. Small airways disease can be a primary disorder, such as respiratory bronchiolitis or constrictive bronchiolitis, or be part of parenchymal lung disease, such as hypersensitivity pneumonitis, or large airways disease, such as bronchiectasis and asthma. Vascular causes resulting in mosaic attenuation are typically chronic thromboembolic pulmonary hypertension, which is characterized by organizing thrombi in the elastic pulmonary arteries, or pulmonary arterial hypertension, a heterogeneous group of diseases affecting the distal pulmonary arterioles. Diffuse ground-glass opacity can result in a mosaic pattern related to a number of processes in acute (eg, infection, pulmonary edema), subacute (eg, organizing pneumonia), or chronic (eg, fibrotic diseases) settings. Imaging clues that can assist the radiologist in pinpointing a diagnosis include evidence of large airway involvement, cardiovascular abnormalities, septal thickening, signs of fibrosis, and demonstration of airtrapping at expiratory imaging.

Radiological Evaluation and Endovascular Treatment of Hemoptysis

Hemoptysis can be a life-threatening condition that warrants urgent investigation and intervention. Common causes include bronchiectasis, chronic obstructive pulmonary disease, tuberculosis, and malignancy. Computed tomography angiography is an accurate imaging modality for assessment of hemoptysis. The bronchial arteries are the source of bleeding in most cases of hemoptysis, and bronchial artery embolization is the treatment of choice. The aim of this article is to summarize the pathophysiology, causes, initial management, and diagnostic approach of hemoptysis. Endovascular treatment of hemoptysis, technique, embolic materials, outcomes, complications, and follow-up of patients are discussed.

Churg-Strauss syndrome: a case report

Churg-Strauss syndrome is a rare systemic disease primarily characterized by hypereosinophilia, asthma and vasculitis. The lung is the organ most frequently involved. In the present report, the authors describe a relatively rare finding in this disease - the presence of a pulmonary nodule -, while recalling the main radiological findings and the most relevant differential diagnoses.

Pulmonary vasculitis

Pulmonary vasculitis encompasses inflammation in the pulmonary vasculature with involved vessels varying in caliber from large elastic arteries to capillaries. Small pulmonary capillaries are the vessels most commonly involved in vasculitis affecting the lung. The antineutrophil cytoplasmic antibody-associated vasculitides, which include granulomatosis with polyangiitis (formerly Wegener granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (formerly Churg-Strauss syndrome), are the small vessel vasculitides in which pulmonary vasculitis is most frequently observed and are the major focus of this review. Vasculitic involvement of the large pulmonary vessels as may occur in Behçet syndrome and Takayasu arteritis is also discussed.

Antineutrophil cytoplasmic antibody-positive conversion and microscopic polyangiitis development in patients with idiopathic pulmonary fibrosis

Background

Increasing evidence indicates that antineutrophil cytoplasmic antibody (ANCA)-positive conversion occurs in patients initially diagnosed with idiopathic pulmonary fibrosis (IPF) and as a result, some of these patients develop microscopic polyangiitis (MPA). However, the incidence density of these patients is not well known.

Objectives

To explore the incidence of ANCA-positive conversion and development of MPA during the disease course in patients with IPF and to evaluate whether corticosteroid therapy reduces MPA development in patients with IPF with myeloperoxidase (MPO)-ANCA positivity at diagnosis or who later acquire MPO-ANCA positivity.

Methods

We retrospectively analysed the medical records of 504 Asian patients with IPF treated at our institution in Saitama, Japan.

Results

Of the 504 patients with IPF, 20 (4.0%) had MPO-ANCA and 16 (3.2%) had PR-3-ANCA when first evaluated. In 264 of 504 patients with IPF, ANCA was measured repeatedly and seroconversion to MPO-ANCA and PR3-ANCA occurred in 15 (5.7%) and 14 (5.3%) patients, respectively, and 9 of 35 patients who were either MPO-ANCA positive at IPF diagnosis or who subsequently seroconverted developed MPA. None of the nine patients who developed MPA had been previously treated with steroids. The incidence of MPA tended to be lower in patients treated than not treated with corticosteroids although this was not statistically significant.

Conclusions

Some patients with IPF with MPO-ANCA positivity at IPF diagnosis or with MPO-ANCA-positive conversion during follow-up developed MPA. Clinical trials to determine whether corticosteroid therapy can reduce MPA development and prolong survival in MPO-ANCA-positive patients with IPF should be considered.

Eosinophilic Pneumonia

Eosinophilic pneumonia may manifest as chronic or transient infiltrates with mild symptoms, chronic idiopathic eosinophilic pneumonia, or the frequently severe acute eosinophilic pneumonia that may be secondary to a variety of causes (drug intake, new onset of tobacco smoking, infection) and that may necessitate mechanical ventilation. When present, blood eosinophilia greater than 1 × 10⁹ eosinophils/L (and preferably greater than 1.5 × 10⁹/L) is of considerable help for suggesting the diagnosis, however it may be absent, as in the early phase of idiopathic acute eosinophilic pneumonia or when patients are already taking corticosteroids. On bronchoalveolar lavage, high eosinophilia (>25 %, and preferably >40 % of differential cell count) is considered diagnostic of eosinophilic pneumonia in a compatible setting, obviating the need of video-assisted thoracic surgical lung biopsy, which is now performed only on very rare occasions with inconsistency between clinical, biological, and imaging features. Inquiry as to drug intake must be meticulous (www.pneumotox.com) and any suspected drug should be withdrawn. Laboratory investigations for parasitic causes must take into account the travel history or residence and the epidemiology of parasites. In patients with associated extrathoracic manifestations, the diagnosis of eosinophilic granulomatosis with polyangiitis or of the hypereosinophilic syndromes should be raised. Presence of airflow obstruction can be found in hypereosinophilic asthma, allergic bronchopulmonary aspergillosis, idiopathic chronic eosinophilic pneumonia, eosinophilic granulomatosis with polyangiitis, or in the recently identified syndrome of hyperosinophilic obliterative bronchiolitis. Corticosteroids remain the cornerstone of symptomatic treatment for eosinophilic pneumonias, with a generally dramatic response. Relapses are common when tapering the doses or after stopping treatment especially in idiopathic chronic eosinophilic pneumonia. Cyclophosphamide is necessary only in patients with eosinophilic granulomatosis with polyangiitis and poor-prognostic factors. Imatinib is very effective in the treatment of the myeloproliferative variant of hypereosinophilic syndromes. Anti-interleukin-5 monoclonal antibodies are promising in the spectrum of eosinophilic disorders.

Eponyms in cardiothoracic radiology: part III--interstitium

Eponyms serve the purpose of honoring individuals who have made important observations and discoveries. As with other fields of medicine, eponyms are frequently encountered in radiology, particularly in chest radiology. However, inappropriate use of an eponym may lead to potentially dangerous miscommunication. Moreover, an eponym may honor the incorrect person or a person who falls into disrepute. Despite their limitations, eponyms are still widespread in the medical literature. Furthermore, in some circumstances, more than one individual may have contributed to the description or discovery of a particular anatomical structure or disease, whereas in others, an eponym may have been incorrectly applied initially and propagated for years in the medical literature. Nevertheless, radiologic eponyms are a means of honoring those who have made lasting contributions to the field of radiology, and familiarity with these eponyms is critical for proper reporting and accurate communication. In addition, the acquisition of some historical knowledge about those whose names are associated with various structures or pathologic conditions conveys a sense of humanity in the science of medicine. In this third installment of this series, the authors discuss a number of chest radiology eponyms as they relate to the pulmonary interstitium, including relevant clinical and imaging features, as well biographical information of the respective eponym's namesake.

Consolidation

Consolidation refers to an area of homogeneous increase in lung parenchymal attenuation that obscures the margins of vessels and airway walls [1]. Air bronchograms may be present with consolidative area. Pathologically, consolidation represents an exudate or other product of disease that replaces alveolar air, rendering the lung solid [2, 3].

Multiple lung parenchymal abnormalities: Don't panic, let's be pragmatic! The 6 question rule - a checklist strategy

Analysis of multiple lung parenchymal abnormalities on HRCT is a real diagnostic challenge. These abnormalities may be due to a disease of the pulmonary interstitial tissue, the bronchial tree, the cardiovascular system or to abnormal alveolar filling with fluid, blood, cells or tumor, several of these etiologies possibly being concomitant. Systematic pathophysiological reasoning, in the form of a logical checklist, guides reflection and covers many of the most frequent diagnoses and potentially treatable emergencies that can be identified by the non-specialist radiologist. This approach also provides a basis for deepening knowledge of each area. The use of the mnemonic FIBROVAKIM (fibrosis-bronchi-vascular-cancer-infection-medication) is easy to apply and summarizes this strategy.