Hypersensitivity pneumonitis: sensitivity of high-resolution CT in a population-based study

Japanese clinical practice guide 2022 for hypersensitivity pneumonitis

Considering recently published two guidelines for the diagnosis of hypersensitivity pneumonitis (HP), the Japanese Respiratory Society (JRS) has now published its own Japanese clinical practice guide for HP. Major types of HP in Japan include summer-type, home-related, bird-related, farmer's lung, painter's lung, humidifier lung, and mushroom grower's lung. Identifying causative antigens is critical for increasing diagnostic confidence, as well as improving prognosis through appropriate antigen avoidance. This guide proposes a comprehensive antigen questionnaire including the outbreak sources reported in Japan. Drawing on the 2021 CHEST guideline, this guide highlights the antigen identification confidence level and adaptations for environmental surveys. The detection of specific antibodies against causative antigens is an important diagnostic predictor of HP. In Japan, the assessments of bird-specific IgG (pigeons, budgerigars) and the Trichosporon asahii antibody are covered by medical insurance. Although this guide adopts the 2020 ATS/JRS/ALAT guideline diagnostic criteria based on the combination of imaging findings, exposure assessment, bronchoalveolar lavage lymphocytosis, and histopathological findings, it added some annotations to facilitate the interpretation of the content and correlate the medical situation in Japan. It recommends checking biomarkers; seasonal changes in the KL-6 concentration (increase in winter for bird-related HP/humidifier lung and in summer for summer-type HP) and high KL-6 concentrations providing a basis for the suspicion of HP. Antigen avoidance is critical for disease management of HP. This guide also addresses the pharmacological management of HP, highlighting the treatment strategy for fibrotic HP including combination therapies with anti-inflammatory/immunosuppressive and antifibrotic drugs.

Diagnosis and Evaluation of Hypersensitivity Pneumonitis: CHEST Guideline and Expert Panel Report

BACKGROUND

The purpose of this analysis is to provide evidence-based and consensus-derived guidance for clinicians to improve individual diagnostic decision-making for hypersensitivity pneumonitis (HP) and decrease diagnostic practice variability.

STUDY DESIGN AND METHODS

Approved panelists developed key questions regarding the diagnosis of HP using the PICO (Population, Intervention, Comparator, Outcome) format. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion, and vetted evaluation tools were used to assess the quality of included studies, to extract data, and to grade the level of evidence supporting each recommendation or statement. The quality of the evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Graded recommendations and ungraded consensus-based statements were drafted and voted on using a modified Delphi technique to achieve consensus. A diagnostic algorithm is provided, using supporting data from the recommendations where possible, along with expert consensus to help physicians gauge the probability of HP.

RESULTS

The systematic review of the literature based on 14 PICO questions resulted in 14 key action statements: 12 evidence-based, graded recommendations and 2 ungraded consensus-based statements. All evidence was of very low quality.

INTERPRETATION

Diagnosis of HP should employ a patient-centered approach and include a multidisciplinary assessment that incorporates the environmental and occupational exposure history and CT pattern to establish diagnostic confidence prior to considering BAL and/or lung biopsy. Criteria are presented to facilitate diagnosis of HP. Additional research is needed on the performance characteristics and generalizability of exposure assessment tools and traditional and new diagnostic tests in modifying clinical decision-making for HP, particularly among those with a provisional diagnosis.

Executive Summary: Diagnosis and Evaluation of Hypersensitivity Pneumonitis: CHEST Guideline and Expert Panel Report

BACKGROUND

The purpose of this summary is to provide a synopsis of evidence-based and consensus-derived guidance for clinicians to improve individual diagnostic decision-making for hypersensitivity pneumonitis (HP) and decrease diagnostic practice variability.

STUDY DESIGN AND METHODS

Approved panelists developed key questions regarding the diagnosis of HP using the PICO (Population, Intervention, Comparator, and Outcome) format. MEDLINE (via PubMed) and the Cochrane Library were systematically searched for relevant literature, which was supplemented by manual searches. References were screened for inclusion and vetted evaluation tools were used to assess the quality of included studies, to extract data, and to grade the level of evidence supporting each recommendation or statement. The quality of the evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach. Graded recommendations and ungraded consensus-based statements were drafted and voted on using a modified Delphi technique to achieve consensus.

RESULTS

The systematic review of the literature based on 14 PICO questions resulted in 14 key action statements: 12 evidence-based, graded recommendations, and 2 ungraded consensus-based statements. All evidence was of very low quality.

INTERPRETATION

Diagnosis of HP should employ a patient-centered approach and include a multidisciplinary assessment that incorporates the environmental and occupational exposure history and CT pattern to establish diagnostic confidence prior to considering BAL and/or lung biopsy. Additional research is needed on the performance characteristics and generalizability of exposure assessment tools and traditional and new diagnostic tests in modifying clinical decision-making for HP, particularly among those with a provisional diagnosis.

Granulomatous lung disease: clinical aspects

INTRODUCTION

Granulomatous lung diseases (GLD) are heterogeneous group of diseases that can be broadly categorized as infectious or noninfectious. This distinction is extremely important, as the misdiagnosis of a GLD can have serious consequences. In this manuscript, we describe the clinical manifestations, histopathology, and diagnostic approach to GLD. We propose an algorithm to distinguish infectious from noninfectious GLD.

AREAS COVERED

We have searched PubMed and Medline database from 1950 to December 2019, using multiple keywords as described below. Major GLDs covered include those caused by mycobacteria and fungi, sarcoidosis, hypersensitivity pneumonitis, and vasculidities.

EXPERT OPINION

The cause of infectious GLD is usually identified through microbiological culture and molecular techniques. Most noninfectious GLD are diagnosed by clinical and laboratory criteria, often with exclusion of infectious pathogens. Further understanding of the immunopathogenesis of the granulomatous response may allow improved diagnosis and treatment of GLD.

The mechanism and risk factors for immune checkpoint inhibitor pneumonitis in non-small cell lung cancer patients

Immune checkpoint inhibitors (ICIs) are new and promising therapeutic agents for non-small cell lung cancer (NSCLC). However, along with demonstrating remarkable efficacy, ICIs can also trigger immune-related adverse events. Checkpoint inhibitor pneumonitis (CIP) has been reported to have a morbidity rate of 3% to 5% and a mortality rate of 10% to 17%. Moreover, the incidence of CIP in NSCLC is higher than that in other tumor types, reaching 7% to 13%. With the increased use of ICIs in NSCLC, CIP has drawn extensive attention from oncologists and cancer researchers. Identifying high risk factors for CIP and the potential mechanism of CIP are key points in preventing and monitoring serious adverse events. In this review, the results of our analysis and summary of previous studies suggested that the risk factors for CIP may include previous lung disease, prior thoracic irradiation, and combinations with other drugs. Our review also explored potential mechanisms closely related to CIP, including increased T cell activity against associated antigens in tumor and normal tissues, preexisting autoantibodies, and inflammatory cytokines.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a complex syndrome caused by the inhalation of a variety of antigens in susceptible and sensitized individuals. These antigens are found in the environment, mostly derived from bird proteins and fungi. The prevalence and incidence of HP vary widely depending on the intensity of exposure, the geographical area and the local climate. Immunopathologically, HP is characterized by an exaggerated humoral and cellular immune response affecting the small airways and lung parenchyma. A complex interplay of genetic, host and environmental factors underlies the development and progression of HP. HP can be classified into acute, chronic non-fibrotic and chronic fibrotic forms. Acute HP results from intermittent, high-level exposure to the inducing antigen, usually within a few hours of exposure, whereas chronic HP mostly originates from long-term, low-level exposure (usually to birds or moulds in the home), is not easy to define in terms of time, and may occur within weeks, months or even years of exposure. Some patients with fibrotic HP may evolve to a progressive phenotype, even with complete exposure avoidance. Diagnosis is based on an accurate exposure history, clinical presentation, characteristic high-resolution CT findings, specific IgG antibodies to the offending antigen, bronchoalveolar lavage and pathological features. Complete antigen avoidance is the mainstay of treatment. The pharmacotherapy of chronic HP consists of immunosuppressive drugs such as corticosteroids, with antifibrotic therapy being a potential therapy for patients with progressive disease.

Acute Hypersensitivity Pneumonitis Associated With a High Ki-67 Proliferative Index

Hypersensitivity pneumonitis (HSP) is an interstitial lung disease caused by exposure to a large range of environmental antigens. Inhaling aerosolized particles leads to a heightened immune response. HSP comes in acute, subacute, or chronic forms, all with their own potential clinical and radiographic findings. Mycobacterium avium complex (MAC) is the most common nontuberculous mycobacteria and is known to cause HSP with certain exposures. However, although certain histologic findings can be seen with HSP, a high ki-67 proliferation index is unusual and more commonly associated with malignancy. In this report, we discuss a case of MAC that had acute HSP associated with a high ki-67 proliferative index.

Multidisciplinary approach in the diagnosis of idiopathic nonspecific interstitial pneumonia

The article provides a modern classification of interstitial lung diseases. The focus is on the poorly studied and difficult to diagnose idiopathic nonspecific interstitial pneumonia, isolated in a separate nosological form and included in the classification only in 2002. The paper presents the features of the clinical, radiological, histological picture of idiopathic nonspecific interstitial pneumonia in comparison with idiopathic pulmonary fibrosis. The presented materials are based on the results of the largest study conducted by the working group of the American Thoracic Society, which shows the importance of the interaction of specialists in the diagnosis of idiopathic nonspecific interstitial pneumonia. A comprehensive assessment of the examination of patients conducted in collaboration with the clinician and radiologist, after their cooperative discussion, in many cases can help to avoid lung biopsy, and the study of morphological material is more often necessary only in difficult diagnostic situations.

Diagnosis and management of pulmonary toxicity associated with cancer immunotherapy

Pulmonary toxicity of cancer immunotherapies has emerged as an important clinical event that requires prompt identification and management. Although often referred to as pneumonitis, pulmonary toxicity associated with immunotherapy covers a broad and overlapping spectrum of pulmonary manifestations, and, once suspected, the range of differential diagnoses of infectious and neoplastic processes might make the diagnostic process challenging for physicians. Optimal care can require multidisciplinary effort by pulmonologists, medical oncologists, and radiologists, and awareness of the possibility of treatment-induced pulmonary toxicity by emergency department and primary care physicians. This Viewpoint gives an overview of the diagnosis and management of pulmonary toxicity arising from cancer immunotherapy, including widely used treatments, such as immune checkpoint inhibitors, and emerging therapies, such as chimeric antigen receptor T cells.

Current and emerging techniques for the diagnosis of hypersensitivity pneumonitis

INTRODUCTION

Hypersensitivity pneumonitis (HP) is the result of an immunologically induced inflammation of the lung parenchyma in response to inhalation exposure to a large variety of antigens in genetically susceptible individuals. HP shares clinical and radiological features with other acute and chronic interstitial lung diseases and is sometimes difficult to diagnose if exposure to an antigenic agent is not detected. Several classifications and diagnostic criteria have been proposed but are not currently recommended by guidelines from any scientific society. However, advances have been made over the past ten years in improving the diagnosis of HP. Areas covered: This article will provide a summary of the different classification and diagnostic criteria proposed in acute and chronic forms of HP. In addition, we review current diagnostic procedures including antigen detection, high resolution computed tomography, histopathology and provide an overview of emerging techniques. Expert commentary: Important changes are occurring in the field of HP and knowledge of the disease will likely progress enormously in the coming 5 to 10 years as many techniques continue to be developed, including genomic signature and diagnostic biomarkers.

Early-stage diffuse panbronchiolitis in a young patient confirmed by video-assisted lung biopsy: A case report

A 29-year-old man presented with sputum and cough, which were pointed out by his neighbors. A high-resolution chest computed tomography scan showed well-defined multiple centrilobular nodules and a tree-in-bud pattern. Chest auscultation revealed coarse crackles. He did not report any nasal sinus symptoms. We subsequently performed a video-assisted lung biopsy; the specimen confirmed diffuse panbronchiolitis. Subsequently, sinusitis was confirmed by an otolaryngologist. His symptoms gradually improved following treatment with erythromycin. We report a case of early-stage diffuse panbronchiolitis in a young patient, with multiple intralobular nodules, no bronchiectasis, and a good clinical course.

Stop Being So Sensitive: An Exceptionally Rare Report of Ustekinumab-Induced Sub-acute Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HSP) is a rare syndrome characterised by granulomatous inflammatory lung disease due to repeated sensitisation from a specific antigen. We present the case of a 61-year old male veteran with a history of nodular eczema who presented with 2 weeks of progressive dyspnoea on exertion and pleuritic chest pain. The patient was started on ustekinumab 5 weeks prior to presentation. Initial workup revealed ground-glass opacities on computed tomography (CT) scan of the chest. Cardiac workup was unrevealing with a normal myocardial perfusion stress test. The patient was started on inhaled corticosteroids and albuterol for reactive airway disease. Due to the persistence of symptoms despite treatment, the patient underwent bronchoscopy with bronchoalveolar lavage (BAL), transbronchial biopsy and endobronchial ultrasound-guided biopsy (EBUS). Bronchoscopy showed normal appearing airways of both right and left lungs. The BAL was remarkable for chronic inflammation and pulmonary macrophages. The BAL cell count differential was 1% granulocytes, 50% lymphocytes, 17% eosinophils and 32 mononuclear cells. The pathology from the mediastinal lymph nodes showed reactive inflammatory cells and no malignancy. The pathology from the transbronchial biopsy of the anterior basilar segment of the right lower lobe showed organising pneumonia with occasional ill-defined granulomas that stained negative for Acid Fast Bacilli (AFB) and Grocott's methenamine (GMS) appeared to be consistent with hypersensitivity pneumonitis. Based on the pathological diagnosis of HSP, the patient was managed with discontinuation of ustekinumab, with subsequent improvement of his symptoms. To our knowledge, this is the first report suggesting ustekinumab, like other biological therapies, has the potential to cause HSP.

Differential diagnosis of granulomatous lung disease: clues and pitfalls

Granulomatous lung diseases are a heterogeneous group of disorders that have a wide spectrum of pathologies with variable clinical manifestations and outcomes. Precise clinical evaluation, laboratory testing, pulmonary function testing, radiological imaging including high-resolution computed tomography and often histopathological assessment contribute to make a confident diagnosis of granulomatous lung diseases. Differential diagnosis is challenging, and includes both infectious (mycobacteria and fungi) and noninfectious lung diseases (sarcoidosis, necrotising sarcoid granulomatosis, hypersensitivity pneumonitis, hot tub lung, berylliosis, granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, rheumatoid nodules, talc granulomatosis, Langerhans cell histiocytosis and bronchocentric granulomatosis). Bronchoalveolar lavage, endobronchial ultrasound-guided transbronchial needle aspiration, transbronchial cryobiopsy, positron emission tomography and genetic evaluation are potential candidates to improve the diagnostic accuracy for granulomatous lung diseases. As granuloma alone is a nonspecific histopathological finding, the multidisciplinary approach is important for a confident diagnosis.

A multidisciplinary approach is crucial for the accurate differential diagnosis of granulomatous lung diseaseshttp://ow.ly/FxsP30cebtf

Interstitial Lung Disease in India. Results of a Prospective Registry

RATIONALE

Interstitial lung disease (ILD) is a heterogeneous group of acute and chronic inflammatory and fibrotic lung diseases. Existing ILD registries have had variable findings. Little is known about the clinical profile of ILDs in India.

OBJECTIVES

To characterize new-onset ILDs in India by creating a prospective ILD using multidisciplinary discussion (MDD) to validate diagnoses.

METHODS

Adult patients of Indian origin living in India with new-onset ILD (27 centers, 19 Indian cities, March 2012-June 2015) without malignancy or infection were included. All had connective tissue disease (CTD) serologies, spirometry, and high-resolution computed tomography chest. ILD pattern was defined by high-resolution computed tomography images. Three groups independently made diagnoses after review of clinical data including that from prompted case report forms: local site investigators, ILD experts at the National Data Coordinating Center (NDCC; Jaipur, India) with MDD, and experienced ILD experts at the Center for ILD (CILD; Seattle, WA) with MDD. Cohen's κ was used to assess reliability of interobserver agreement.

MEASUREMENTS AND MAIN RESULTS

A total of 1,084 patients were recruited. Final diagnosis: hypersensitivity pneumonitis in 47.3% (n = 513; exposure, 48.1% air coolers), CTD-ILD in 13.9%, and idiopathic pulmonary fibrosis in 13.7%. Cohen's κ: 0.351 site investigator/CILD, 0.519 site investigator/NDCC, and 0.618 NDCC/CILD.

CONCLUSIONS

Hypersensitivity pneumonitis was the most common new-onset ILD in India, followed by CTD-ILD and idiopathic pulmonary fibrosis; diagnoses varied between site investigators and CILD experts, emphasizing the value of MDD in ILD diagnosis. Prompted case report forms including environmental exposures in prospective registries will likely provide further insight into the etiology and management of ILD worldwide.

Pathology of Chronic Hypersensitivity Pneumonitis What Is It? What Are the Diagnostic Criteria? Why Do We Care?

Context.—

Chronic hypersensitivity pneumonitis (CHP) has emerged from obscurity during the past 15 years and is now recognized as a very common form of fibrosing interstitial pneumonia but one that is frequently misdiagnosed both clinically and on surgical lung biopsy as usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) or fibrotic nonspecific interstitial pneumonia.

Objective.—

To review the pathologic features of CHP.

Data Sources.—

Clinical, pathology, and radiology literature were used.

Conclusions.—

Upper lobe–predominant fibrosis and/or air-trapping on computed tomography scan are features of CHP but not UIP/IPF; however, radiologic separation is possible in only about 50% of cases. Morphologically, CHP sometimes mimics UIP/IPF, but CHP often shows isolated foci of peribronchiolar (centrilobular) fibrosis, frequently associated with fibroblast foci, and in CHP, fibrosis may bridge from the centrilobular region to another bronchiole, an interlobular septum, or the pleura (“bridging fibrosis”). This set of findings is uncommon in UIP/IPF. In addition, CHP may produce a picture of fibrotic nonspecific interstitial pneumonia. Although giant cells/granulomas are usually present in subacute hypersensitivity pneumonitis, they are much less frequently found in CHP, and their absence does not contradict the diagnosis. This diagnostic separation is clinically important because CHP is treated differently than UIP/IPF is (immunosuppressive agents versus antifibrotic agents); further, there are some data to suggest that removing the patient from antigen exposure improves outcome, and there is evidence that patients with CHP have a much better survival prognosis after lung transplantation than do patients with UIP/IPF. In most cases, accurate diagnosis of CHP requires consultation among clinicians, radiologists, and pathologists.

Clinico- pathologic presentation of hypersensitivity pneumonitis in Egyptian patients: a multidisciplinary study

Background

Hypersensitivity pneumonitis (HP) is a common diffuse parenchymal lung disease in Egypt which can be difficult to recognize due to the dynamic symptoms & associated environmental factors.

Methods

Forty-three Egyptian patients were enrolled in this study, presenting with dyspnea and cough, predominant ground-glass opacity (GGO) in high-resolution computed tomography (HRCT) where lung biopsy was needed to establish the diagnosis.

Results

The age range was 15 to 60 years. Females represented 90.7% (39 patients) while 9.3% (4 patients) of our patients were males. History of contact with birds was detected in 9 (20.9%) patients. Most of our patients (60.5%) didn’t have exposure history, and only 8 patients (18.6%) were living in geographic areas in Egypt that are known for the exposure to environmental etiologic factors (cane sugar exhaust fumes). The most common HRCT pattern was GGO with mosaic parenchyma in 18 patients (41.86%), followed by GGO with centrilobular nodules in 9 patients (20.93%), then isolated diffuse GGO in 5 patients (11.62%), GGO with traction bronchiectasis in 4 patients (9.3%), GGO with consolidation in 3 patients (6.97%), GGO with reticulations in 2 patients (4.65%), and GGO with cysts in 2 patients (4.65%). The most common histologic finding was isolated multinucleated giant cells in 38 patients (88.3%) commonly found in airspaces (24 patients) and less commonly in the interstitium (14 patients), followed by interstitial pneumonia and cellular bronchiolitis in 36 patients (83.7% each), interstitial ill-formed non-necrotizing granulomas in 12 patients (27.9%), fibrosis in 10 patients (23.2%), and organizing pneumonia pattern in 4 patients (9.3%).

Conclusion

The diagnosis of HP presenting with predominant GGO pattern in HRCT requires a close interaction among clinicians, radiologists, and pathologists. Some environmental and household factors may be underestimated as etiologic factors. Further environmental and genetic studies are needed especially in patients with negative exposure history.

Chronic hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HSP) is a common interstitial lung disease resulting from inhalation of a large variety of antigens by susceptible individuals. The disease is best classified as acute and chronic. Chronic HSP can be fibrosing or not. Fibrotic HSP has a large differential diagnosis and has a worse prognosis. The most common etiologies for HSP are reviewed. Diagnostic criteria are proposed for both chronic forms based on exposure, lung auscultation, lung function tests, HRCT findings, bronchoalveolar lavage, and biopsies. Treatment options are limited, but lung transplantation results in greater survival in comparison to idiopathic pulmonary fibrosis. Randomized trials with new antifibrotic agents are necessary.

Occupational hypersensitivity pneumonitis: an EAACI position paper

The aim of this document was to provide a critical review of the current knowledge on hypersensitivity pneumonitis caused by the occupational environment and to propose practical guidance for the diagnosis and management of this condition. Occupational hypersensitivity pneumonitis (OHP) is an immunologic lung disease resulting from lymphocytic and frequently granulomatous inflammation of the peripheral airways, alveoli, and surrounding interstitial tissue which develops as the result of a non-IgE-mediated allergic reaction to a variety of organic materials or low molecular weight agents that are present in the workplace. The offending agents can be classified into six broad categories that include bacteria, fungi, animal proteins, plant proteins, low molecular weight chemicals, and metals. The diagnosis of OHP requires a multidisciplinary approach and relies on a combination of diagnostic tests to ascertain the work relatedness of the disease. Both the clinical and the occupational history are keys to the diagnosis and often will lead to the initial suspicion. Diagnostic criteria adapted to OHP are proposed. The cornerstone of treatment is early removal from exposure to the eliciting antigen, although the disease may show an adverse outcome even after avoidance of exposure to the causal agent.

Hypersensitivity pneumonitis : a broader perspective

Hypersensitivity pneumonitis (HP) represents a group of lung disorders caused by the inhalation of a wide variety of organic particles by susceptible individuals. HP occurs mainly in nonsmokers, but smoking may promote an insidious and chronic disease. The prevalence of HP is difficult to estimate accurately since several antigens can produce the disease, but the range spans infancy to old age. Regardless of the causative antigen or its environmental setting, the clinical manifestations are essentially the same. Three different clinical presentations have been recognized: acute, subacute, and chronic. In the acute form, patients show flu-like symptomatology, followed by dyspnea and dry cough. Symptoms subside a few hours or days later. The subacute and chronic forms result from recurrent low-level antigen exposure and are characterized by progressive dyspnea and dry cough. Other constitutional symptoms such as fatigue, anorexia, and weight loss can be apparent. Fever may occur in the subacute form. Importantly, chronic HP may evolve insidiously or may result from repeated acute/subacute episodes. Recurrent acute, subacute, and chronic HP may progress to irreversible lung fibrosis or provoke emphysematous changes.HP can be difficult to identify, and precise diagnosis requires a history of exposure and a constellation of clinical, imaging, laboratory, bronchoalveolar lavage and pathologic findings. General laboratory tests show an increase of acute phase reactants. Specific precipitating antibodies, when present, are evidence of antigen exposure, and are a hallmark for diagnosis. Chest radiograph usually reveals widespread ground-glass attenuation, and nodular or reticulonodular shadowing. High-resolution CT features include diffuse or patchy ground-glass opacities with small poorly defined nodules and air trapping. Pulmonary function tests are characterized by a predominantly restrictive ventilatory defect with loss of lung volume and hypoxemia at rest that worsens with exercise. Bronchoalveolar lavage reveals a significant increase in lymphocytes, mostly over 40%. In the acute form there is also an increase in neutrophils. Antigen-induced lymphocyte proliferation, and environmental or laboratory-controlled inhalation challenge, may be used for diagnostic purposes and can help to establish a diagnosis of insidious forms of HP. In subacute or chronic cases, lung biopsy may be necessary. Typical findings include bronchiolitis, lymphocytic alveolitis, and loosely formed granulomas, although occasionally other morphologic patterns such as nonspecific interstitial pneumonia may exist. Treatment focuses on avoiding further exposure to the offending antigen(s). Corticosteroids are recommended in subacute and chronic forms. The usual regimen consists of initial high doses of systemic corticosteroid (e.g. prednisone 0.5-1.0 mg/kg/day), followed by gradual tapering.

Hypersensitivity Pneumonitis in a Housewife Exposed to Aspergillus flavus in Poor Living Conditions: A Case Report

Hypersensitivity Pneumonitis (HP) or Extrinsic Allergic Alveolitis (EAA) is a disease resulting from immunologically induced inflammation in response to inhalation of a wide variety of airborne allergens. The condition develops mainly in non atopic individuals sensitized to organic dust due to repeated exposures. It is a relatively rare disease constituting upto 2% of interstitial lung diseases. Knowledge of classical High Resolution Computed Tomography (HRCT) of lung findings aid in early diagnosis. We report a case of subacute hypersensitivity pneumonitis in a housewife who despite being symptomatic remained undiagnosed for two years. She showed a good response to therapy, but soon relapsed. Visit to her home revealed that she lived in a damp house full of moldy walls.

Pitfalls in diagnosis and management of hypersensitivity pneumonitis

PURPOSE OF REVIEW

Hypersensitivity pneumonitis is a complex syndrome characterized by a combination of inflammation and fibrosis located in both the airways and the lung parenchyma. Both diagnosis and treatment are a real challenge for physicians. This review will focus on recent developments in this emerging field; furthermore, we will emphasize major gaps in the current knowledge, to stimulate further research in this field.

RECENT FINDINGS

The main diagnostic issue is not to miss the entity as the clinical presentation is extremely variable even as the nature of the causal antigen. This article provides an overview of current ways to uncover possible causes of hypersensitivity pneumonitis. A problem of another kind is treatment of this disorder. Crucial in treatment is antigen avoidance, often in combination with immunosuppressive agents. The treatment of acute forms is rather straightforward, but the biggest endeavour, however, is treatment of chronic forms of hypersensitivity pneumonitis, which not always respond to immunosuppressive agents. Therefore, new initiatives should be taken in order to help clinicians in making a proper diagnosis and develop more efficacious treatment especially for patients suffering from chronic hypersensitivity pneumonitis.

SUMMARY

Diagnosis and treatment of hypersensitivity pneumonitis remain a real challenge; this article provides an overview of our current understanding and points out new opportunities for further research.

High-Resolution Computed Tomography in the Diagnosis of Diffuse Parenchymal Lung Diseases: Is it Possible to Improve Radiologist's Performance?

OBJECTIVE

The aims of this study were to assess the concordance between high-resolution computed tomography (HRCT) diagnostic hypotheses (DH) and final diagnosis in patients with diffuse lung disease and to evaluate whether clinical data or the radiologist's degree of certainty influence concordance.

METHODS

Concordances between first and any one of radiologists' DH and final diagnosis were assessed before and after access to clinical data, with study of importance of degree of certainty in the DH formulated.

RESULTS

Concordances of HRCT DH and final diagnosis were 48% and 76%, respectively, considering first or any of the DH without access to clinical data. Accessing clinical data improved concordance especially for hypersensitivity pneumonitis. Diagnostic hypotheses formulated with high degree of confidence were correct in 69% of cases.

CONCLUSIONS

First HRCT DH was concordant with final diagnosis in approximately half of cases, increasing to approximately 75% when considering any 1 of the 3 DH. Radiologists' knowledge of clinical data or increased degree of certainty improved concordance of HRCT DH and the final diagnosis.

Hypersensitivity pneumonitis: a review and update of histologic findings

Hypersensitivity pneumonitis (HSP) is a poorly understood entity typically caused by exposure to an inciting antigen such as fungi, thermophilic bacteria or animal protein. Clinically, HSP is often divided into acute, subacute and chronic forms. While the subacute form is best described from a pathologic standpoint, the pathology of chronic HSP has only been critically evaluated in the past decade and the pathology of acute HSP is poorly described. The aim of this review is to summarise the current knowledge of pathogenetic theories of HSP and to review the current knowledge of the pathology of each stage of HSP and the main entities in the differential diagnosis.

Pulmonary Interstitium

The first step in the radiographic evaluation of interstitial lung disease begins with a fundamental knowledge of the anatomy of the pulmonary interstitium and the different patterns of disruption. The anatomy of the pulmonary interstitium as demonstrated on CT of the chest with high resolution cuts is largely essential to establish the various radiological patterns that define interstitial lung disease such as the tree-in-bud, ground-glass opacity, crazy -paving, etc.

Hypersensitivity pneumonitis

Clinical manifestations of hypersensitivity pneumonitis may closely mimic other interstitial lung diseases, and the disease onset is usually insidious. High-resolution computed tomography and bronchoalveolar lavage are the sensitive and characteristic diagnostic tests for hypersensitivity pneumonitis. The relevant antigen to hypersensitivity pneumonitis cannot be identified in up to 20% to 30% of patients. Clinicians should be aware that hypersensitivity pneumonitis must be considered in all cases of interstitial lung disease, and a detailed environmental exposure history is mandatory.

Hypersensitivity pneumonitis: insights in diagnosis and pathobiology

Hypersensitivity pneumonitis (HP) is a complex syndrome resulting from repeated exposure to a variety of organic particles. HP may present as acute, subacute, or chronic clinical forms but with frequent overlap of these various forms. An intriguing question is why only few of the exposed individuals develop the disease. According to a two-hit model, antigen exposure associated with genetic or environmental promoting factors provokes an immunopathological response. This response is mediated by immune complexes in the acute form and by Th1 and likely Th17 T cells in subacute/chronic cases. Pathologically, HP is characterized by a bronchiolocentric granulomatous lymphocytic alveolitis, which evolves to fibrosis in chronic advanced cases. On high-resolution computed tomography scan, ground-glass and poorly defined nodules, with patchy areas of air trapping, are seen in acute/subacute cases, whereas reticular opacities, volume loss, and traction bronchiectasis superimposed on subacute changes are observed in chronic cases. Importantly, subacute and chronic HP may mimic several interstitial lung diseases, including nonspecific interstitial pneumonia and usual interstitial pneumonia, making diagnosis extremely difficult. Thus, the diagnosis of HP requires a high index of suspicion and should be considered in any patient presenting with clinical evidence of interstitial lung disease. The definitive diagnosis requires exposure to known antigen, and the assemblage of clinical, radiologic, laboratory, and pathologic findings. Early diagnosis and avoidance of further exposure are keys in management of the disease. Corticosteroids are generally used, although their long-term efficacy has not been proved in prospective clinical trials. Lung transplantation should be recommended in cases of progressive end-stage illness.

Mycobacterium avium complex--the role of potable water in disease transmission

Mycobacterium avium complex (MAC) is a group of opportunistic pathogens of major public health concern. It is responsible for a wide spectrum of disease dependent on subspecies, route of infection and patients pre-existing conditions. Presently, there is limited research on the incidence of MAC infection that considers both pulmonary and other clinical manifestations. MAC has been isolated from various terrestrial and aquatic environments including natural waters, engineered water systems and soils. Identifying the specific environmental sources responsible for human infection is essential in minimizing disease prevalence. This paper reviews current literature and case studies regarding the wide spectrum of disease caused by MAC and the role of potable water in disease transmission. Potable water was recognized as a putative pathway for MAC infection. Contaminated potable water sources associated with human infection included warm water distribution systems, showers, faucets, household drinking water, swimming pools and hot tub spas. MAC can maintain long-term contamination of potable water sources through its high resistance to disinfectants, association with biofilms and intracellular parasitism of free-living protozoa. Further research is required to investigate the efficiency of water treatment processes against MAC and into construction and maintenance of warm water distribution systems and the role they play in MAC proliferation.

Hazards of the 'hard cash': hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a nonimmunoglobulin E-related immune-mediated parenchymal lung disease. A 45-year-old woman who was a lifelong nonsmoker with a six-month history of frequent episodes of cough and dyspnea was admitted to hospital. She had been working as a money counter for 20 years at a central bank. Bibasilar crackles on lung auscultation, ground-glass opacities and a mosaic pattern on high-resolution computed tomography, restrictive abnormality on pulmonary function tests and mild hypoxemia were the prominent findings. Bronchoalveolar lavage fluid analysis revealed a predominance of CD4-positive T cells, and she tested positive on her natural challenge test. She was diagnosed with subacute HP based on established criteria. She was advised to discontinue counting fresh banknotes. Prednisolone was commenced, then tapered to discontinue in the ensuing six months. Clinical and radiological improvement was achieved within two months. To the authors' knowledge, the present report is the first to describe 'hard cash HP', possibly caused by chipping dust or printing dye.

Nontuberculous mycobacterial hypersensitivity pneumonitis related to a home shower: treatment and secondary prevention

A 57-year-old physician with increasing dyspnoea and hypoxaemia had a high-resolution CT scan of the chest, which disclosed diffuse pulmonary ground glass opacities, more pronounced in the upper lobes with minimal mediastinal lymphadenopathy. Transbronchial biopsy of the right middle and lower lobes was performed, demonstrating varying degrees of well circumscribed organising granulomatous pneumonitis thought to be most consistent with hypersensitivity to nontuberculous mycobacteria. Cultures of water obtained from the patient's home shower were positive for Mycobacterium avium complex. The patient began substituting baths for showers, experiencing some gradual improvement of his symptoms. Subsequently, he installed point-of-use 0.2 micron membrane filters on his shower, and resumed regular showering after installation with continued symptomatic improvement. CT scans at 3 and 18 months revealed improvement and resolution, respectively. Four years later, he continues to shower in filtered home shower water and remains clinically well.

Hypersensitivity Pneumonitis: Essential Radiologic and Pathologic Findings

Hypersensitivity pneumonitis is a diffuse, granulomatous interstitial lung disease caused by repeated exposure to a wide spectrum of environmental antigens. Clinical, radiologic, and histologic findings are quite variable and mimic many other diseases; therefore, diagnosis depends on a constellation of findings rather than a single defining feature. High-resolution computed tomography (HRCT) plays a critical role in this setting. The presence of centrilobular nodules, multifocal ground glass opacities, and evidence of air trapping in the expiratory phase of respiration is highly suggestive of hypersensitivity pneumonitis and can direct clinicians to the correct diagnosis. For the pathologist, typical HRCT findings not only corroborate the diagnosis of hypersensitivity pneumonitis when the characteristic triad of airway-centered chronic interstitial inflammation, interstitial poorly formed non-necrotizing granulomas, and organizing pneumonia is present on biopsy, but also improve diagnostic confidence in biopsies lacking components of the diagnostic histologic triad. Importantly, the presence of focal or unilateral imaging findings should prompt a careful search by the pathologist for an infectious etiology, thus avoiding errors in determining the significance of granulomas on biopsy. This article reviews the essential radiologic and pathologic findings in hypersensitivity pneumonitis, discusses the primary considerations in the differential diagnosis, and offers an approach to biopsy evaluation.

The radiological patterns of interstitial change at an early phase: over a 4-year follow-up

OBJECTIVES

The identification of early phase interstitial changes may influence the understanding of idiopathic interstitial pneumonitis. This study aimed to clarify its radiological patterns and the association with smoking.

METHODS

The subjects underwent low-dose computed tomography to screen lung cancer. The selected subjects with interstitial changes were monitored for the precise morphology of interstitial changes using a high-resolution computed tomography (HRCT) scan. The subjects were classified into normal and abnormal HRCT subjects. The radiological findings on the HRCT scan, serum Klebs von der Lungen-6 (KL-6), surfactant protein (SP)-A, SP-D, pulmonary function, and computed tomography (CT) scores were analyzed. Abnormal HRCT subjects were classified based on the radiological patterns, and were followed-up over a 4-year period.

RESULTS

HRCT abnormalities suggesting interstitial changes were identified in 80 of 3079 subjects. Seven subjects with honeycombing and 14 with combined pulmonary fibrosis and emphysema (CPFE) were identified. The frequencies of sex (male) and smoking in the subjects with honeycombing was higher than that of other patterns. The smoking history and the levels of serum KL-6, SP-A, and SP-D in abnormal HRCT subjects were significantly higher than those in normal HRCT subjects. Thirty-two of 73 abnormal HRCT subjects showed a progression of the CT scores in a chest HRCT over a 4-year period. Eighteen abnormal HRCT current smokers were included in the progression of CT scores.

CONCLUSIONS

HRCT patterns, excluding interlobular septal thickening, show the progression of CT scores. Smokers with CT abnormalities may have a tendency to demonstrate worsening interstitial changes.

Pneumonia de hipersensibilidade subaguda: ocorrência em familiares

OBJETIVO: Descrever um caso de pneumonia de hipersensibilidade subaguda em criança com ocorrência concomitante da mesma doença em um familiar. DESCRIÇÃO DO CASO: Paciente de 12 anos encaminhado para investigação de dispnéia progressiva, tosse seca e emagrecimento. Realizou vários tratamentos por hipótese de pneumonias bacterianas de repetição. Após diagnóstico radiológico e histopatológico de pneumonia de hipersensibilidade, apresentou melhora clínica com remoção da exposição. A mãe do paciente foi internada no mesmo período com quadro clínico-radiológico e diagnóstico semelhantes. COMENTÁRIOS: A pneumonia de hipersensibilidade representa um grupo de doenças caracterizadas por processo inflamatório, que compromete o parênquima pulmonar e as vias aéreas em resposta a uma exposição a grande variedade de antígenos inalados. Pode se apresentar sob as formas aguda, subaguda ou crônica. Sua incidência varia de acordo com aspectos ambientais e geográficos. Somente 25% dos pacientes têm histórico familiar. A existência de predisposição genética para a doença ainda é desconhecida.

Pathology of hypersensitivity pneumonitis

PURPOSE OF REVIEW

Hypersensitity pneumonitis, caused by inhalation of various antigens, is characterized by interstitial mononuclear cell infiltration, nonnecrotizing granulomas, cellular bronchiolitis, and fibrosis. The pathological picture of chronic hypersensitivity pneumonitis is, however, complicated; it is sometimes difficult to differentiate chronic hypersensitivity pneumonitis from idiopathic pulmonary fibrosis/usual interstitial pneumonia, nonspecific interstitial pneumonia, and connective-tissue-related lung disease. The clinical, radiological, and pathological features of chronic hypersensitivity pneumonitis have recently been described. This study reviews the previously reported information and provides new insights into the pathological features of chronic hypersensitivity pneumonitis.

RECENT FINDINGS

The pathological features of chronic hypersensitivity pneumonitis comprise overlapping usual interstitial pneumonia-like pattern with subpleural patchy fibrosis, alternating normal alveoli and fibroblastic foci, a nonspecific interstitial pneumonia-like pattern, and centrilobular fibrosis. In contrast to pathological features of acute and subacute hypersensitivity pneumonitis, epithelioid cell granulomas are sparse or absent, but giant cells are seen in the interstitium. Bridging fibrosis between peribronchiolar area and perilobular areas is an outstanding feature of chronic hypersensitivity pneumonitis. Autopsy cases of chronic hypersensitivity pneumonitis have demonstrated not only upper lobe contraction but also lower lobe contraction, mimicking usual interstitial pneumonia pattern and diffuse alveolar damage.

SUMMARY

The present review focuses on the pathological features of chronic hypersensitivity pneumonitis and presents that centrilobular fibrosis and bridging fibrosis are the important hallmarks of chronic hypersensitivity pneumonitis, even with a usual interstitial pneumonia-like pattern.

Idiopathic nonspecific interstitial pneumonia: report of an American Thoracic Society project

RATIONALE

The 2002 American Thoracic Society/European Respiratory Society classification of idiopathic interstitial pneumonias identified nonspecific interstitial pneumonia (NSIP) as a provisional diagnosis. Concern was expressed that NSIP was a "wastebasket" category, difficult to distinguish from other idiopathic interstitial pneumonias.

OBJECTIVES

The following questions were addressed: (1) Is idiopathic NSIP a distinct entity? 2) If so, what are its clinical, radiologic and pathologic characteristics? (3) What is the role of radiology and pathology in establishing the diagnosis? (4) To make a diagnosis of idiopathic NSIP, what other disorders need to be excluded and how should this be done?

METHODS

Investigators who had previously reported cases of idiopathic NSIP were invited to submit cases for review (n = 305). After initial review, cases with complete clinical, radiologic, and pathologic information (n = 193) were reviewed in a series of workshops.

MEASUREMENTS AND MAIN RESULTS

Sixty-seven cases were identified as NSIP. Mean age was 52 years, 67% were women, 69% were never-smokers, and 46% were from Asian countries. The most common symptoms were dyspnea (96%) and cough (87%); 69% had restriction. By high-resolution computed tomography, the lower lung zones were predominantly involved in 92% of cases; 46% had a peripheral distribution; 47% were diffuse. Most showed a reticular pattern (87%) with traction bronchiectasis (82%) and volume loss (77%). Lung biopsies showed uniform thickening of alveolar walls with a spectrum of cellular to fibrosing patterns. Five-year survival was 82.3%.

CONCLUSIONS

Idiopathic NSIP is a distinct clinical entity that occurs mostly in middle-aged women who are never-smokers. The prognosis of NSIP is very good.

Chronic hypersensitivity pneumonitis: differentiation from idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia by using thin-section CT

PURPOSE

To retrospectively assess the accuracy of thin-section computed tomography (CT) in distinguishing chronic hypersensitivity pneumonitis (HP) from idiopathic pulmonary fibrosis (IPF) and nonspecific interstitial pneumonia (NSIP), with histologic results as the reference standard.

MATERIALS AND METHODS

This retrospective study was approved by the institutional research boards of the participating centers, and informed consent was waived. There was HIPAA compliance for all U.S. patients. The study included 66 patients (36 men, 30 women; mean age, 58.8 years +/- 10.9 [standard deviation]) with proved chronic HP (n = 18), IPF (n = 23), or NSIP (n = 25) who underwent CT. Two independent readers assessed the CT images, made a first-choice diagnosis, and noted the degree of confidence in the diagnosis. A general linear model was used to identify CT features that independently differentiated chronic HP from IPF and NSIP. Weighted kappa statistic was used to assess interobserver agreement.

RESULTS

The CT features that best differentiated chronic HP were lobular areas with decreased attenuation and vascularity, centrilobular nodules, and absence of lower zone predominance of abnormalities (P < or = .008). The features that best differentiated NSIP were relative subpleural sparing, absence of lobular areas with decreased attenuation, and lack of honeycombing (P < or = .002). The features that best differentiated IPF were basal predominance of honeycombing, absence of relative subpleural sparing, and absence centrilobular nodules (P < or = .004). A confident diagnosis was made in 70 (53%) of 132 readings. This diagnosis was correct in 66 (94%) of 70 readings. The accuracy for the entire cohort was 80%. Interobserver agreement for confident diagnosis was good to excellent (kappa = 0.77-0.96).

CONCLUSION

Characteristic CT features of chronic HP, IPF, and NSIP allow confident distinction between these entities in approximately 50% of patients.

Twenty-three years of hypersensitivity pneumonitis mortality surveillance in the United States

BACKGROUND

There are few population-based studies addressing hypersensitivity pneumonitis (HP) in the United States. The National Institute for Occupational Safety and Health (NIOSH) has nationally comprehensive longitudinal mortality data that can contribute to a better understanding of the epidemiology of HP.

METHODS

The National Center for Health Statistics multiple cause-of-death data were analyzed for the period 1980-2002. Annual death rate was age-adjusted to the 2000 U.S. standard population. Death rate time-trends were calculated using a linear regression model and geographic distribution of death rates were mapped by state and county. Proportionate mortality ratios (PMRs) by usual industry and occupation adjusted for age, sex, and race, were based on data from 26 states reporting industry and occupation during 1985-1999.

RESULTS

Overall age-adjusted death rates increased significantly (P < 0.0001) between 1980 and 2002, from 0.09 to 0.29 per million. Wisconsin had the highest rate at 1.04 per million. Among industries, PMR for HP was significantly high for agricultural production, livestock (PMR, 19.3; 95% CI, 14.0-25.9) and agricultural production, crops (PMR, 4.3; 95% CI, 3.0-6.0). Among occupations, PMR for HP was significantly elevated for farmers, except horticulture (PMR, 8.1; 95% CI, 6.4-10.2).

CONCLUSIONS

These findings indicate that agricultural industries are closely associated with HP mortality and preventive strategies are needed to protect workers in these industries.

Thin-section CT of the secondary pulmonary lobule: anatomy and the image--the 2004 Fleischner lecture

The secondary pulmonary lobule is a fundamental unit of lung structure, and it reproduces the lung in miniature. Airways, pulmonary arteries, veins, lymphatics, and the lung interstitium are all represented at the level of the secondary lobule. Several of these components of the secondary lobule are normally visible on thin-section computed tomographic (CT) scans of the lung. The recognition of lung abnormalities relative to the structures of the secondary lobule is fundamental to the interpretation of thin-section CT scans. Pathologic alterations in secondary lobular anatomy visible on thin-section CT scans include interlobular septal thickening and diseases with peripheral lobular distribution, centrilobular abnormalities, and panlobular abnormalities. The differential diagnosis of lobular abnormalities is based on comparisons between lobular anatomy and lung pathology.