Pathological Diagnosis of Pulmonary Aspergillosis

Pulmonary aspergillosis constitutes an increasingly prevalent and potentially fatal complex of mycotic diseases, caused by different species of Aspergillus. The broad spectrum of pathological manifestations associated with pulmonary aspergillosis necessitates a differentiation of commensalism from saprophytic colonization, hypersensitivity reactions, and true invasive infections, which highlights the importance of histopathology as a gold standard in a diagnostic setting. For the past decades, changes in terminology and contradicting contributions from different diagnostic disciplines have made the classification of pulmonary aspergillosis rather confusing. This review offers a categorization of aspergillosis lesions based on what can be histopathologically identified and distinguished, differentiating between acute invasive infection and forms of subacute, chronic, and allergic diseases and coinfections, and summarizes important manifestations of lesions associated with the different forms of pulmonary aspergillosis.

Imaging of Pulmonary Fibrosis: An Update, From the AJR Special Series on Imaging of Fibrosis

Pulmonary fibrosis is recognized as occurring in association with a wide and increasing array of conditions, and it presents with a spectrum of chest CT appearances. Idiopathic pulmonary fibrosis (IPF), which corresponds histologically with usual interstitial pneumonia and represents the most common idiopathic interstitial pneumonia, is a chronic progressive fibrotic interstitial lung disease (ILD) of unknown cause. Progressive pulmonary fibrosis (PPF) describes the radiologic development of pulmonary fibrosis in patients with ILD of a known or unknown cause other than IPF. The recognition of PPF impacts management of patients with ILD-for example, in guiding initiation of antifibrotic therapy. Interstitial lung abnormalities are an incidental CT finding in patients without suspected ILD and may represent an early intervenable form of pulmonary fibrosis. Traction bronchiectasis and/or bronchiolectasis, when detected in the setting of chronic fibrosis, is generally considered evidence of irreversible disease, and progression predicts worsening mortality risk. Awareness of the association between pulmonary fibrosis and connective tissue diseases, particularly rheumatoid arthritis, is increasing. This review provides an update on the imaging of pulmonary fibrosis, with attention given to recent advances in disease understanding with relevance to radiologic practice. The essential role of a multidisciplinary approach to clinical and radiologic data is highlighted.

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.

Impact of concomitant gastroesophageal reflux disease symptomology on prognosis and pulmonary function of chronic hypersensitivity pneumonitis

Background and Objectives

Comorbid risk factors in chronic hypersensitivity pneumonitis (CHP) are poorly characterised. Gastroesophageal reflux disease (GERD) is linked to interstitial lung diseases like idiopathic pulmonary fibrosis (IPF), but its association and treatment in CHP is less understood. This study aims to understand the role and prevalence of GERD in CHP, plus the effect of GERD treatment on lung function and mortality.

Methods

A tertiary referral centre panel was retrospectively reviewed for 214 patients diagnosed with CHP based on clinical history, bronchoalveolar lavage fluid analysis, imaging and histopathology. GERD diagnostic criteria included symptomology, acid suppressive therapy use and diagnostic testing. CHP patients with GERD (n = 89) and without GERD (n = 125) were compared via descriptive statistical analysis. Pulmonary function, GERD diagnosis plus treatment and other comorbidities were evaluated against CHP outcomes.

Results

Respective differences between diagnosis and study termination dates in the GERD population versus without GERD for functional vital capacity (FVC) were - 1 L vs - 2.5 L, diffusing capacity of the lungs for carbon monoxide (DLCO) were - 2 mL/min/mmHg versus - 1 mL/min/mmHg, per cent alive at the time of study 88% versus 81%, median date of survival 574.5 versus 850 and supplemental oxygen requirement 41% versus 37%. GERD prevalence was higher in CHP patients relative to the general population. No statistical significance was found between survival curves, oxygen requirement, smoking history, FVC, or DLCO.

Conclusions

GERD could be a harmful comorbidity in CHP though may not necessarily affect survival or functional outcomes. This aligns with previous IPF studies, though remains controversial. Further research is needed regarding this association and treatment benefit.

5-methyladenosine regulators play a crucial role in development of chronic hypersensitivity pneumonitis and idiopathic pulmonary fibrosis

5-methyladenosine (m5C) modification regulates gene expression and biological functions in oncologic areas. However, the effect of m5C modification in chronic hypersensitivity pneumonitis (CHP) and idiopathic pulmonary fibrosis (IPF) remains unknown. Expression data for 12 significant m5C regulators were obtained from the interstitial lung disease dataset. Five candidate m5C regulators, namely tet methylcytosine dioxygenase 2, NOP2/Sun RNA methyltransferase 5, Y-box binding protein 1, tRNA aspartic acid methyltransferase 1, and NOP2/Sun RNA methyltransferase 3 were screened using random forest and nomogram models to predict risks of pulmonary fibrosis. Next, we applied the consensus clustering method to stratify the samples with different m5C patterns into two groups (cluster A and B). Finally, we calculated immune cell infiltration scores via single-sample gene set enrichment analysis, then compared immune cell infiltration, related functions as well as the expression of programmed cell death 1 (PD-1, PDCD1) and programmed death protein ligand-1 (PD-L1, CD274) between the two clusters. Principal component analysis of m5C-related scores across the 288 samples revealed that cluster A had higher immune-related expression than B. Notably, T helper cell (Th) 2 type cytokines and Th1 signatures were more abundant in clusters A and B, respectively. Our results suggest that m5C is associated with and plays a crucial role in development of pulmonary fibrosis. These m5C patterns could be potential biomarkers for identification of CHP and IPF, and guide future development of immunotherapy or other new drugs strategies for pulmonary fibrosis.

Centri-lobular pulmonary nodules on HRCT: incidence and approach for etiological diagnosis

Background

Centri-lobular nodules are the most common pattern of diffuse pulmonary nodules encountered on high-resolution computed tomography (HRCT). HRCT with post-processing techniques such as obtaining maximum intensity projection (MIP) is helpful in making centri-lobular nodules more conspicuous. The study aimed to highlight the role of HRCT with its reconstruction capabilities in the detection and characterization of centri-lobular pulmonary nodules, interpret the most frequent associated findings, and correlate with the clinical findings to reach the most appropriate diagnosis.

Results

The study included 58 patients; 41.4% males and 58.6% females. Their age ranged from 2 to 67 years with mean age of 25.69. The centri-lobular nodules numbers, distribution, shape, and associated HRCT chest findings were identified. The top three etiological diagnoses were infection/inflammation in 50.0% of cases followed by acute viral bronchiolitis in 27.6% and inhalation bronchiolitis in 19.0% of cases. Correlation of HRCT findings with the clinical diagnosis was carried out with consequent formulation of an algorithm for the diagnostic approach of various etiologies of centri-lobular pulmonary nodules.

Conclusions

HRCT is a useful tool in the detection and characterization of centri-lobular pulmonary nodules. It can be used to differentiate the different etiologies that share centri-lobular nodularity. Other associated features and multidisciplinary approach are essential for further characterization of the most relevant etiological diagnosis.

Relevance of RNA N6-Methyladenosine Regulators for Pulmonary Fibrosis: Implications for Chronic Hypersensitivity Pneumonitis and Idiopathic Pulmonary Fibrosis

N6-methyladenosine (m6A) modification plays a pivotal role in post-transcriptionally regulating gene expression and biological functions. Nonetheless, the roles of m6A modification in the regulation of chronic hypersensitivity pneumonitis (CHP) and idiopathic pulmonary fibrosis (IPF) remain unclear. Twenty-two significant m6A regulators were selected from differential gene analysis between the control and treatment groups from the GSE150910 dataset. Five candidate m6A regulators (insulin-like growth factor binding protein 2, insulin-like growth factor binding protein 3, YTH domain-containing protein 1, zinc finger CCCH domain-containing protein 13, and methyltransferase-like 3) were screened by the application of a random forest model and nomogram model to predict risks of pulmonary fibrosis. The consensus clustering method was applied to divide the treatment samples into two groups with different m6A patterns (clusters A and B) based on the 22 m6A regulators. Our study performed principal component analysis to obtain the m6A-related score of the 288 samples to quantify the two m6A patterns. The study reveals that cluster A was linked to T helper cell (Th) 2-type cytokines, while the immune infiltration of Th1 cytokines was higher in cluster B. Our results suggest that m6A cluster A is likely related to pulmonary fibrosis, indicating m6A regulators play notable roles in the occurrence of pulmonary fibrosis. The m6A patterns could be considered as biomarkers to identify CHP and IPF, which will be helpful to develop immunotherapy strategies for pulmonary fibrosis in the future.

Diagnosis of Hypersensitivity Pneumonitis: Review and Summary of American College of Chest Physicians Statement

Assessment of lung biopsies for the diagnosis of hypersensitivity pneumonitis (HP) is one of the most difficult diagnostic problems for surgical pathologists. It is a form of interstitial lung disease resulting from an immune reaction provoked by an inhaled antigen in susceptible individuals. Although this definition sounds simple, in practice, the diagnosis of HP can be challenging. To address these issues, the American College of Chest Physicians (CHEST) has recently published a guideline for the diagnosis of HP. In this review, we will explore the multidisciplinary diagnostic evaluation of HP with a focus on the pathologic features as outlined in the CHEST guidelines. The histologic criteria are divided into 4 diagnostic categories: (1) Typical nonfibrotic HP or fibrotic HP; (2) Compatible with nonfibrotic HP or fibrotic HP; (3) Indeterminate for nonfibrotic or fibrotic HP; and (4) Alternative Diagnosis. It is important to emphasize that patterns 1 to 3 do not represent discrete histologic entities or pathologic diagnoses. Rather, these categories are meant to serve as a practical guide for organizing a complex set of overlapping histologic patterns into an integrated diagnostic framework for facilitating multidisciplinary discussion. High-resolution computed tomography features are also summarized, emphasizing how the correlation of lung biopsies with computed tomography findings can help to favor the diagnosis, particularly in cases where biopsies are not typical for HP. This review highlights details of the histologic spectrum of HP as well as the utility of different types of biopsies and bronchoalveolar lavage. We also emphasize the importance of multidisciplinary discussion and the complex differential diagnosis.

Diagnosis, course and management of hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a complex and heterogeneous interstitial lung disease (ILD) that occurs when susceptible individuals develop an exaggerated immune response to an inhaled antigen. In this review, we discuss the latest guidelines for the diagnostic evaluation of patients with suspected HP, the importance of identifying patients with fibrotic and progressive disease, and the evidence supporting the drugs commonly used in the treatment of HP. Differential diagnosis of HP can be challenging and requires a thorough exposure history, multidisciplinary discussion of clinical and radiologic data, and, in some cases, assessment of bronchoalveolar lavage lymphocytosis and histopathologic findings. Patients with HP may be categorised as having non-fibrotic or fibrotic HP. The presence of fibrosis is associated with worse outcomes. A proportion of patients with fibrotic HP develop a progressive phenotype, characterised by worsening fibrosis, decline in lung function and early mortality. There are no established guidelines for the treatment of HP. Antigen avoidance should be implemented wherever possible. Immunosuppressants are commonly used in patients with HP but have not been shown to slow the worsening of fibrotic disease. Nintedanib, a tyrosine kinase inhibitor, has been approved by the US Food and Drug Administration for slowing the progression of chronic fibrosing ILDs with a progressive phenotype, including progressive fibrotic HP. Non-pharmacological interventions, such as oxygen therapy, pulmonary rehabilitation and supportive care, may be important components of the overall care of patients with progressive HP.

Challenges in the Diagnosis and Management of Fibrotic Hypersensitivity Pneumonitis: A Practical Review of Current Approaches

Recent advances in fibrotic hypersensitivity pneumonitis include improved diagnostic guidance, systematic assessments of immunosuppressive therapy, and the recent availability of antifibrotic therapy (nintedanib) for those with progressive disease. A standardized approach to diagnosis may lead to better inclusion criteria for future therapeutic protocols and delineation of disease or treatment response predictors for real-world management. This review will highlight current diagnostic and treatment challenges and remaining knowledge gaps or areas of uncertainty, with a practical overview of supporting evidence and its clinical implications. Exposure history, serologic testing for antigen sensitivity, bronchoalveolar lavage lymphocytosis, histopathology, and radiologic findings will be covered in the diagnosis section, with immunosuppression, antifibrotic therapy, lung transplantation, and disease prognosis in the treatment and management section.

Comparative Analysis of Gene Expression in Fibroblastic Foci in Patients with Idiopathic Pulmonary Fibrosis and Pulmonary Sarcoidosis

Background: Fibroblastic foci (FF) are characteristic features of usual interstitial pneumonia (UIP)/idiopathic pulmonary fibrosis (IPF) and one cardinal feature thought to represent a key mechanism of pathogenesis. Hence, FF have a high impact on UIP/IPF diagnosis in current guidelines. However, although less frequent, these histomorphological hallmarks also occur in other fibrotic pulmonary diseases. Currently, there is therefore a gap in knowledge regarding the underlying molecular similarities and differences of FF in different disease entities. Methods: In this work, we analyzed the compartment-specific gene expression profiles of FF in IPF and sarcoidosis in order to elucidate similarities and differences as well as shared pathomechanisms. For this purpose, we used laser capture microdissection, mRNA and protein expression analysis. Biological pathway analysis was performed using two different gene expression databases. As control samples, we used healthy lung tissue that was donated but not used for lung transplantation. Results: Based on Holm Bonferroni corrected expression data, mRNA expression analysis revealed a significantly altered expression signature for 136 out of 760 genes compared to healthy controls while half of these showed a similar regulation in both groups. Immunostaining of selected markers from each group corroborated these results. However, when comparing all differentially expressed genes with the fdr-based expression data, only 2 of these genes were differentially expressed between sarcoidosis and IPF compared to controls, i.e., calcium transport protein 1 (CAT1) and SMAD specific E3 ubiquitin protein ligase 1 (SMURF1), both in the sarcoidosis group. Direct comparison of sarcoidosis and IPF did not show any differentially regulated genes independent from the statistical methodology. Biological pathway analysis revealed a number of fibrosis-related pathways pronounced in IPF without differences in the regulatory direction. Conclusions: These results demonstrate that FF of end-stage IPF and sarcoidosis lungs, although different in initiation, are similar in gene and protein expression, encouraging further studies on the use of antifibrotic agents in sarcoidosis.

Hypersensitivity pneumonitis: new concepts and classifications

The clinical and pathologic diagnosis of hypersensitivity pneumonitis has been confounded by conflicting definitions, with two recent guidelines suggesting that hypersensitivity pneumonitis simply be diagnosed as nonfibrotic or fibrotic. Nonfibrotic hypersensitivity pneumonitis is usually characterized by a bronchiolocentric chronic interstitial inflammatory infiltrate, frequently but by no means always with associated granulomas or giant cells. Fibrotic hypersensitivity pneumonitis may take the form of interstitial fibrosis confined to the peribronchiolar regions, or fibrotic nonspecific interstitial pneumonia, or a process similar to and sometimes indistinguishable from usual interstitial pneumonia/idiopathic interstitial fibrosis, but the exact pathologic features that favor a diagnosis of fibrotic hypersensitivity pneumonitis are disputed. Granulomas/giant cells are much less frequent in fibrotic compared to nonfibrotic hypersensitivity pneumonitis. Extensive peribronchiolar metaplasia, particularly peribronchiolar metaplasia affecting more than half the bronchioles, supports a diagnosis of fibrotic hypersensitivity pneumonitis over usual interstitial pneumonia, as does the presence of predominantly peribronchiolar disease with relative subpleural sparing. Clinical and CT features are crucial to the diagnosis of hypersensitivity pneumonitis: sparing of the lung bases, centrilobular nodules, air-trapping, or the triple density sign with fibrosis favor a diagnosis of fibrotic hypersensitivity pneumonitis. At this point there are no molecular tests that reliably separate fibrotic hypersensitivity pneumonitis from other forms of interstitial lung disease. Currently the separation of fibrotic hypersensitivity pneumonitis from usual interstitial pneumonia is crucial to treatment (immunosuppressives for the former, anti-fibrotics for the latter) but this approach is changing and all progressive fibrosing interstitial pneumonias will probably be treated with antifibrotics in the future.

Derivation and validation of a prediction model for histopathologic fibrotic hypersensitivity pneumonitis

BACKGROUND

Clinical differentiation of fibrotic hypersensitivity pneumonitis (f-HP) remains challenging given variable and overlapping presentations with other fibrotic interstitial lung disease (f-ILD).

OBJECTIVE

We derived a multivariable model for predicting histopathologic f-HP to better inform multidisciplinary team discussion (MDD) diagnosis, particularly when biopsy may be unsafe or cannot be achieved.

METHODS

Patients with histopathologically-defined f-HP and other overlapping f-ILD were reviewed for distinguishing clinical and radiological variables. Using elastic net logistic regression, a penalized regression approach to minimize overfitting, a clinical model built on non-invasive assessments was derived for the prediction of histopathologic f-HP. This model was then validated in an independently derived external cohort from three sites.

RESULTS

The derivation and validation cohorts consisted of 248 (84 cHP and 164 other f-ILD) and 157 (82 f-HP and 75 other f-ILD) histopathologically-defined patients, respectively (total study N = 405). Variables retained from the elastic net model included age in years (regression coefficient 0.033), male sex (-1.109), positive exposure history (1.318), percent predicted forced vital capacity (-0.021), radiologic peribronchovascular axial ILD distribution (0.199), mid (-0.22) or lower lobe (-0.839) craniocaudal or patchy (0.287) ILD distribution, upper (1.188) or equivalent upper and lower lobe (0.237) traction bronchiectasis, mosaic attenuation (1.164), and centrilobular nodules (2.045). Bias corrected AUC was 0.84 (standard error = 0.02) for the derivation cohort and 0.80 (CI 0.73-0.87) for the validation cohort.

CONCLUSIONS

This multivariable model demonstrated good predictive performance for delineating histopathologically-defined f-HP from other f-ILD as a means of avoiding or justifying biopsy and supporting MDD diagnostic confidence.

Usual Interstitial Pneumonia in Contemporary Surgical Pathology Practice: Impact of International Consensus Guidelines for Idiopathic Pulmonary Fibrosis on Pathologists

CONTEXT.—

Idiopathic pulmonary fibrosis is a clinical syndrome characterized by the presence of usual interstitial pneumonia (UIP) radiologically and pathologically. Per consensus criteria adopted in 2011, diagnosis of idiopathic pulmonary fibrosis no longer requires a biopsy in an appropriate context if UIP is seen on imaging. As a result, lung biopsies are now typically reserved for patients having indeterminate clinical or imaging findings or suspicion for alternative diagnoses, but the impact of updated guidelines on pathology practice remains unclear.

OBJECTIVE.—

To determine the frequency of histologic UIP before and after 2011.

DESIGN.—

Surgical lung biopsies from adults were studied within two 4-year periods: July 1, 2006 through June 30, 2010 and January 1, 2012 through December 31, 2015. Pathology slides were reviewed in a fashion blinded to clinical information and were classified using current guidelines.

RESULTS.—

Biopsies from 177 and 86 patients (mean [SD] age, 62 [12] and 59 [14] years; 50.3% [89 of 177] and 48.8% [42 of 86] men) before and after 2011, respectively, were reviewed. Probable UIP or UIP was less-frequently encountered after 2011 in all patients with fibrosis (9 of 54 [16.7%] versus 41 of 119 [34.5%] before 2011, P = .02) and also in patients 50 years old and older (8 of 46 [17.4%] versus 39 of 109 [35.8%] before 2011, P = .02), with a concomitant rise in cases indeterminate for UIP or showing alternative diagnoses.

CONCLUSIONS.—

Histology for UIP is less frequently encountered in our contemporary practice compared with the historic era. The pretest probability of a non-UIP diagnosis is now high, even in elderly patients, underscoring the need for pathologists to be familiar with the histologic features of alternative diagnoses.

Management of Fibrotic Hypersensitivity Pneumonitis

Fibrotic hypersensitivity pneumonitis (fHP) is a chronic, often progressive fibrosing form of interstitial lung disease caused by inhaled antigenic exposures. fHP can lead to impaired respiratory function, reduced disease-related quality of life, and early mortality. Management of fHP should start with exposure remediation where possible, with systemic immunosuppression and antifibrotic therapy considered in patients with symptomatic or progressive disease. Nonpharmacologic and supportive management should be offered and, in cases of treatment-resistant, progressive illness, lung transplant should be considered.

Reliability of histopathologic diagnosis of fibrotic interstitial lung disease: an international collaborative standardization project

Background

Current interstitial lung disease (ILD) diagnostic guidelines assess criteria across clinical, radiologic and pathologic domains. Significant interobserver variation in histopathologic evaluation has previously been shown but the specific source of these discrepancies is poorly documented. We sought to document specific areas of difficulty and develop improved criteria that would reduce overall interobserver variation.

Methods

Using an internet-based approach, we reviewed selected images of specific diagnostic features of ILD histopathology and whole slide images of fibrotic ILD. After an initial round of review, we confirmed the presence of interobserver variation among our group. We then developed refined criteria and reviewed a second set of cases.

Results

The initial round reproduced the existing literature on interobserver variation in diagnosis of ILD. Cases which were pre-selected as inconsistent with usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) were confirmed as such by multi-observer review. Cases which were thought to be in the spectrum of chronic fibrotic ILD for which UIP/IPF were in the differential showed marked variation in nearly all aspects of ILD evaluation including extent of inflammation and extent and pattern of fibrosis. A proposed set of more explicit criteria had only modest effects on this outcome. While we were only modestly successful in reducing interobserver variation, we did identify specific reasons that current histopathologic criteria of fibrotic ILD are not well defined in practice.

Conclusions

Any additional classification scheme must address interobserver variation in histopathologic diagnosis of fibrotic ILD order to remain clinically relevant. Improvements to tissue-based diagnostics may require substantial resources such as larger datasets or novel technologies to improve reproducibility. Benchmarks should be established for expected outcomes among clinically defined subgroups as a quality metric.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01522-6.

Morphologic Features of Fibrotic Hypersensitivity Pneumonitis in Transbronchial Cryobiopsies Versus Video-Assisted Thoracoscopic Biopsies: An In Silico Study

CONTEXT.—

There is interest in using transbronchial cryobiopsies (CBs) for the diagnosis of fibrotic (chronic) hypersensitivity pneumonitis (FHP), but with little information in the literature about what features are diagnostic in CBs.

OBJECTIVE.—

To determine, using in silico investigation, whether features supporting a diagnosis of FHP in video-assisted thoracoscopic (VATS) biopsies can be identified in CBs.

DESIGN.—

In silico circular "cryobiopsies," 5.25 mm in diameter (21.6 mm2), were created on the slides of 15 VATS biopsy cases that had been assigned a 60% or greater confident diagnosis of FHP at a specially devised multidisciplinary discussion. Using stratified random sampling, up to 8 "cryobiopsies" per case were analyzed for the presence of giant cells/granulomas or peribronchiolar metaplasia affecting 50% or more of the bronchioles, features that had statistically supported a diagnosis of FHP on the VATS biopsies in the multidisciplinary discussion exercise.

RESULTS.—

Giant cells/granulomas were detected with very low sensitivities in the "cryobiopsies." Using peribronchiolar metaplasia in 50% or more of bronchioles alone, the sensitivity/specificity for a diagnosis of FHP of 2 "cryobiopsies" compared to the corresponding VATS biopsy was 0.57/0.63; for 4 "cryobiopsies," 0.86/0.75; and for 8 "cryobiopsies," 0.83/0.71. Adding giant cells/granulomas slightly improved these numbers to 0.63/0.71 for 2 "cryobiopsies"; 1.00/0.86 for 4; and 1.00/0.80 for 8.

CONCLUSIONS.—

In the setting of a multidisciplinary discussion where FHP is part of the differential diagnostic choices, 4 actual CBs with an area of roughly 20 mm2 each should have good sensitivity and reasonable specificity for diagnosing FHP using these specific morphologic criteria.

Non-Infectious Granulomatous Lung Disease: Imaging Findings with Pathologic Correlation

Non-infectious granulomatous lung disease represents a diverse group of disorders characterized by pulmonary opacities associated with granulomatous inflammation, a relatively nonspecific finding commonly encountered by pathologists. Some lesions may present a diagnostic challenge because of nonspecific imaging features; however, recognition of the various imaging manifestations of these disorders in conjunction with patients' clinical history, such as age, symptom onset and duration, immune status, and presence of asthma or cutaneous lesions, is imperative for narrowing the differential diagnosis and determining appropriate management of this rare group of disorders. In this pictorial review, we describe the pathologic findings of various non-infectious granulomatous lung diseases as well as the radiologic features and high-resolution computed tomography imaging features.

Pathology of Granulomatous Pulmonary Diseases

CONTEXT.—

Because granulomas are represented in almost every disease category, the number of clinically and pathologically important granulomatous pulmonary diseases is large. Their diagnosis by pathologists is particularly challenging because of their nonspecificity. A specific diagnosis can be achieved only when a granuloma-inciting agent(s) (eg, acid-fast bacilli, fungi, foreign bodies, etc) are identified microscopically or by culture; this does not occur in most cases. Furthermore, a specific diagnosis cannot be reached in a high percentage of cases. Although sarcoidosis and infectious diseases account for approximately half of pulmonary granulomatous diseases worldwide, there is significant geographic variation in their prevalence.

OBJECTIVES.—

To present updated information to serve as a guide to pathologic diagnosis of pulmonary granulomatous diseases, to address some commonly held misconceptions and to stress the importance of multidisciplinary coordination. Presentation of basic aspects of granulomas is followed by discussion of specific disease entities, such as tuberculous and nontuberculous Mycobacterial infections, fungal, bacterial, and parasitic infections, sarcoidosis, necrotizing sarcoid granulomatosis, berylliosis, hypersensitivity pneumonitis, hot tub lung, rheumatoid nodule, bronchocentric granulomatosis, aspirated, inhaled, and embolized foreign bodies, drug-induced granulomas, chronic granulomatous disease, common variable immunodeficiency, and granulomatous lesions associated with various types of cancer.

DATA SOURCES.—

Review of pertinent medical literature using the PubMed search engine and the author's practical experience.

CONCLUSIONS.—

Although the diagnosis of granulomatous lung diseases continues to present significant challenges to pathologists, the information presented in this review can be helpful in overcoming them. The importance of multidisciplinary coordination in cases where morphologic diagnosis is not possible cannot be overstated.

Characteristics and evaluation of acute exacerbations in chronic interstitial lung diseases

Acute exacerbations of fibrosing interstitial lung disease (ILD) occur in both idiopathic pulmonary fibrosis (IPF) as well as non-IPF ILDs. An expert consensus definition has allowed for more frequent reporting of IPF exacerbations. The same is lacking for non-IPF ILD exacerbations. The incidence of non-IPF ILD exacerbations is likely less than in IPF, but the two entities share similar risk factors, such as increased frequency as physiologic derangements advance. The radiologic and histopathologic spectrum of acute ILD exacerbations extends from organizing pneumonia (OP) to the more treatment-refractory diffuse alveolar damage (DAD) pattern. Indeed, responsiveness to various therapies may depend on the relative components of these entities, favoring OP over DAD. There are no proven therapies for acute ILD exacerbations. Corticosteroids are a mainstay in any regimen although clear evidence of benefit does not exist. A variety of immunosuppressant agents have purported success in historical cohort studies - cyclophosphamide, cyclosporine A, and tacrolimus most commonly. Only one randomized controlled trial has been published, studying recombinant thrombomodulin for IPF exacerbation, but the primary outcome of survivor proportion at 90 days was not met. Other novel therapies for ILD exacerbations are still under investigation. The short and long-term prognosis of acute exacerbations of ILD is poor, especially in patients with IPF. Transplant referral should be considered early for both IPF as well as fibrosing non-IPF ILDs, given the unpredictability of the exacerbation event.

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.

Carbohydrate antigen 15-3 as a marker of disease severity in patients with chronic hypersensitivity pneumonitis

Objective:

Biomarkers associated with mucin 1, such as Krebs von den Lungen-6 and carbohydrate antigen (CA) 15-3, are increased in various interstitial lung diseases. Our aim was to determine whether CA 15-3 could be considered a biomarker of disease severity in patients with chronic hypersensitivity pneumonitis (cHP).

Methods:

This was a prospective observational study involving adult patients with cHP. Serum levels of CA 15-3 were measured and were correlated with variables related to disease severity and extension. HRCT scans were quantitatively analyzed using a computational platform and an image analysis tool (Computer Aided Lung Informatics for Pathology Evaluation and Rating). CA 15-3 levels were normalized by logarithmic transformation.

Results:

The sample comprised 41 patients. The mean age of the patients was 60.1 ± 11.6 years. The mean FVC in % of predicted was 70.3% ± 17.3%, and the median of the serum level of CA 15-3 was 48.1 U/mL. CA 15-3 levels inversely correlated with FVC in % of predicted (r = −0,30; p = 0,05), DLCO in % of predicted (r = −0,54; p < 0,01), and SpO₂ at the end of a 4-min step test (r = −0,59; p < 0,01), but they directly correlated with total quantitative HRCT scores (r = 0,47; p = 0,004), especially regarding ground-glass opacities (r = 0.58; p < 0,001).

Conclusions:

CA 15-3 is likely to be a biomarker of disease severity of patients with cHP, particularly regarding gas exchange abnormalities.

Insights on chronic hypersensitivity pneumonitis' treatment: Factors associated with a favourable response to azathioprine

BACKGROUND

The use of immunosuppressive and antifibrotic agents for the treatment of chronic hypersensitivity pneumonitis (CHP) appears promising, but there is still no evidence supporting the clinical decision regarding the implementation of each specific pharmacological strategy.

METHODS

Patients diagnosed with CHP and treated with azathioprine (AZA) were retrospectively selected from a single centre for Interstitial Lung Diseases. Baseline clinical data, as well as functional, imaging, bronchoalveolar lavage (BAL) and histology features were assessed. Longitudinal data on functional parameters were collected and comparatively analysed with patients' characteristics.

RESULTS

In this cohort of 80 patients, of those who reached 12 months of treatment, 78.3% presented a preserved forced vital capacity, with 59 being eligible to be classified as AZA responders (n = 36) or non-responders (n = 23). BAL lymphocytosis was associated with a favourable response to AZA treatment (OR 1.051; 95% CI 1.015-1.089), although it didn't identify all responders.

CONCLUSIONS

AZA revealed to be effective in disease stabilisation in most patients, while ineffective for a subset. BAL lymphocytosis appears as a potentially valuable strategy to identify AZA responders, although with limited accuracy. Further studies are needed to clarify other response markers to immunosuppressive agents, in order to optimize the therapeutic options for this condition.

Centrilobular Fibrosis in Fibrotic (Chronic) Hypersensitivity Pneumonitis, Usual Interstitial Pneumonia, and Connective Tissue Disease-Associated Interstitial Lung Disease

CONTEXT.—

Various pulmonary diseases can produce centrilobular (peribronchiolar) fibrosis, which may be isolated or associated with other patterns of more diffuse fibrosis. The major forms of interstitial lung disease in which centrilobular fibrosis is found are fibrotic (chronic) hypersensitivity pneumonitis, connective tissue disease-associated interstitial lung disease, and (a disputed issue) usual interstitial pneumonia/idiopathic interstitial fibrosis.

OBJECTIVE.—

To review recent literature that addresses separation of these entities.

DATA SOURCES.—

Data comprised recent publications.

CONCLUSIONS.—

In a specially constructed multidisciplinary discussion exercise, it was found that peribronchiolar metaplasia affecting more than half the bronchioles or more than 2 foci of peribronchiolar metaplasia per square centimeter of biopsy area was strongly associated with a confident diagnosis of fibrotic hypersensitivity pneumonitis. Giant cells or granulomas were only found in cases with a greater than 50% diagnostic confidence in hypersensitivity pneumonitis. Conversely, greater numbers of fibroblast foci per square centimeter and increasing measured amounts of subpleural fibrosis favored a diagnosis of usual interstitial pneumonia. Recent data also suggest that centrilobular fibrosis can be found in usual interstitial pneumonia, although the presence of centrilobular fibrosis statistically favors an alternate diagnosis. Connective tissue disease is a major confounder because many patterns are very similar to fibrotic hypersensitivity pneumonitis or usual interstitial pneumonia. Genetic abnormalities, such as the MUC5B minor allele overlap, in these conditions and at this point cannot be used for discrimination. Thus, the separation of fibrotic hypersensitivity pneumonitis and usual interstitial pneumonia remains a difficult problem. Accurate biopsy diagnosis of all of these diseases requires correlation with imaging and clinical findings, and is crucial for treatment.

[Fibrotic hypersensitivity pneumonia: focus on pathology-relevant aspects of the new ATS/JRS/ALAT clinical guideline for the diagnosis of hypersensitivity pneumonia in adults]

Hypersensitivity pneumonia (HP), also called exogenous allergic alveolitis, is a chronic interstitial pneumonia induced by a hypersensitivity reaction to an identified or unidentified antigen in exposed and susceptible individuals that may progress to terminal lung fibrosis. The diagnosis of HP presents a diagnostic challenge. Though therapeutically important, it may be particularly difficult to differentiate fibrotic HP, historically termed chronic HP, from idiopathic pulmonary fibrosis (IPF) or interstitial lung disease associated with connective tissue diseases (CTD-ILD). Multidisciplinary discussion and thus a synoptic evaluation of all findings is firmly established as the gold standard diagnostic approach in interstitial lung diseases including HP. Nonetheless, the high interobserver variability between experts from the individual disciplines (pulmonology, radiology, and pathology) and between experienced multidisciplinary teams in assessing the diagnostic probability of HP has highlighted the need for widely accepted guidelines.The present review summarizes pathology-relevant aspects of the new ATS/JRS/ALAT clinical practice guideline for the diagnosis of HP in adults.

Clinical diagnosis of patients subjected to surgical lung biopsy with a probable usual interstitial pneumonia pattern on high-resolution computed tomography

Background

Usual interstitial pneumonia can present with a probable pattern on high-resolution computed tomography (HRCT), but the probability of identifying usual interstitial pneumonia by surgical lung biopsy in such cases remains controversial. We aimed to determine the final clinical diagnosis in patients with a probable usual interstitial pneumonia pattern on HRCT who were subjected to surgical lung biopsy.

Methods

HRCT images were assessed and categorized by three radiologists, and tissue slides were evaluated by two pathologists, all of whom were blinded to the clinical findings. The final clinical diagnosis was accomplished via a multidisciplinary discussion. Patients with a single layer of honeycombing located outside of the lower lobes on HRCT were not excluded.

Results

A total of 50 patients were evaluated. The most common final clinical diagnosis was fibrotic hypersensitivity pneumonitis (38.0%) followed by idiopathic pulmonary fibrosis (24.0%), interstitial lung disease ascribed to gastroesophageal reflux disease (12.0%) and familial interstitial lung disease (10.0%). In the group without environmental exposure (n = 22), 10 patients had a final clinical diagnosis of idiopathic pulmonary fibrosis (45.5%). Irrespective of the final clinical diagnosis, by multivariate Cox analysis, patients with honeycombing, dyspnoea and fibroblastic foci on surgical lung biopsy had a high risk of death.

Conclusions

The most common disease associated with a probable usual interstitial pneumonia pattern on HRCT is fibrotic hypersensitivity pneumonitis followed by idiopathic pulmonary fibrosis and interstitial lung disease ascribed to gastroesophageal reflux disease. In patients without environmental exposure, the frequencies of usual interstitial pneumonia and a final clinical diagnosis of idiopathic pulmonary fibrosis are not sufficiently high to obviate the indications for surgical lung biopsy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-020-01339-9.

Hypersensitivity pneumonitis, allergic bronchopulmonary aspergillosis and other eosinophilic lung diseases

Hypersensitivity pneumonitis (HP) is traditionally classified into acute, subacute and chronic forms. A high index of suspicion and a detailed investigation into the patient's environment is the key to diagnosis and treatment of HP. Eosinophilic lung diseases can be broadly categorized as idiopathic (acute eosinophilic pneumonia, chronic eosinophilic pneumonia, eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndromes), those with known cause (allergic bronchopulmonary aspergillosis, drugs, parasitic and non-parasitic infections), and those associated with other known lung diseases (asthma, interstitial lung diseases and lung cancers). A detailed review of drug intake, toxin exposures, and travel history is essential in the differential diagnosis of eosinophilic lung diseases.

Diagnosis of Hypersensitivity Pneumonitis in Adults. An Official ATS/JRS/ALAT Clinical Practice Guideline

Background: This guideline addresses the diagnosis of hypersensitivity pneumonitis (HP). It represents a collaborative effort among the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax.Methods: Systematic reviews were performed for six questions. The evidence was discussed, and then recommendations were formulated by a multidisciplinary committee of experts in the field of interstitial lung disease and HP using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.Results: The guideline committee defined HP, and clinical, radiographic, and pathological features were described. HP was classified into nonfibrotic and fibrotic phenotypes. There was limited evidence that was directly applicable to all questions. The need for a thorough history and a validated questionnaire to identify potential exposures was agreed on. Serum IgG testing against potential antigens associated with HP was suggested to identify potential exposures. For patients with nonfibrotic HP, a recommendation was made in favor of obtaining bronchoalveolar lavage (BAL) fluid for lymphocyte cellular analysis, and suggestions for transbronchial lung biopsy and surgical lung biopsy were also made. For patients with fibrotic HP, suggestions were made in favor of obtaining BAL for lymphocyte cellular analysis, transbronchial lung cryobiopsy, and surgical lung biopsy. Diagnostic criteria were established, and a diagnostic algorithm was created by expert consensus. Knowledge gaps were identified as future research directions.Conclusions: The guideline committee developed a systematic approach to the diagnosis of HP. The approach should be reevaluated as new evidence accumulates.

Fibrotic Hypersensitivity Pneumonitis: Diagnosis and Management

Fibrotic hypersensitivity pneumonitis is a complex interstitial lung disease that is not entirely understood. In its chronic and fibrotic form, hypersensitivity pneumonitis is one of the main mimickers of idiopathic pulmonary fibrosis (IPF). Distinguishing between these two conditions is challenging but is of particular clinical relevance. Two approved therapies are available for IPF, and a considerable number of clinical trials are now exploring newer pharmacological options. This impressive research effort is a consequence of new pathogenetic understanding, updated diagnostic criteria and a long history of pharmacological trials. Conversely, current knowledge gaps on pathogenesis of chronic hypersensitivity pneumonitis, coupled with lack of validated diagnostic criteria, make the management of this disease an unsolved clinical challenge. This also reflects the paucity of therapeutic clinical trials in this field. In this review, we describe the current evidence and the possible future options to approach this complex disease.

Pathologic separation of idiopathic pulmonary fibrosis from fibrotic hypersensitivity pneumonitis

Accurate separation of idiopathic pulmonary fibrosis from fibrotic (chronic) hypersensitivity pneumonitis is crucial to patient management, but is frequently a difficult problem. Our objective was to identify pathologic variables that help make this separation. Clinical, radiological, and pathologic data were re-reviewed for 23 patients with a fibrotic interstitial lung disease and biopsy suggesting idiopathic pulmonary fibrosis or fibrotic hypersensitivity pneumonitis. Clinical features, high-resolution computed tomography, and surgical lung biopsies were each examined independently using a prespecified approach. This was followed by a multidisciplinary discussion in which the likelihood of an idiopathic pulmonary fibrosis diagnosis was assigned by the clinician alone based only on clinical data, by the clinician and radiologist based on integrated clinical and radiologic data, and by the clinician, radiologist, and pathologist based on all three domains. A higher multidisciplinary discussion-based confidence of idiopathic pulmonary fibrosis was associated with older age at diagnosis, male sex, higher forced vital capacity, and absence of ground glass changes. Pathologic variables associated with a higher multidisciplinary discussion-based confidence of idiopathic pulmonary fibrosis included increased number of fibroblast foci/cm² and increased subpleural fibrosis. Pathologic variables associated with a higher multidisciplinary discussion-based confidence of hypersensitivity pneumonitis included an increased fraction of bronchioles with peribronchiolar metaplasia, increased foci of peribronchiolar metaplasia/cm², and presence of giant cells/granulomas. These results provide guidance in separating idiopathic pulmonary fibrosis from hypersensitivity pneumonitis; however, a third of cases could not be confidently classified even when using these pathologic features combined with clinical and radiologic information in a multidisciplinary discussion.

Diagnosis of occupational hypersensitivity pneumonitis

PURPOSE OF REVIEW

To discuss the diagnostic methods currently used in the study of patients with hypersensitivity pneumonitis, with special emphasis on the most recent contributions published in the medical literature regarding the diagnosis of occupational hypersensitivity pneumonitis (OHP). This review presents an update of the use of these diagnostic tests, a controversial issue among experts.

RECENT FINDINGS

In spite of the multiple attempts at systematization and the publication of expert consensus statements, standardizing and diagnostic methods and criteria remain particularly difficult. As a result, centers tend to rely on their own experience and establish diagnosis by consensus among their multidisciplinary teams. Though recommendable in many ways, this method presents significant limitations.

SUMMARY

Diagnosis of OHP should be made with a thorough clinical history of the symptoms and clinical signs as well as a meticulous review, if possible by an expert, of possible exposures in the working environment; a meticulous physical examination; high-resolution computed tomography of the thorax; serum determination of specific immunoglobuline Gs; bronchoalveolar lavage and possibly cryobiopsy; fungal culture; and, when appropriate, a specific inhalation challenge test with the suspected antigen.

The value of serum precipitins against specific antigens in patients diagnosed with hypersensitivity pneumonitis - retrospective study

INTRODUCTION

Hypersensitivity pneumonitis (HP) is the third most common interstitial lung disease, and is often under-recognized, especially in patients who are not aware of their occupational or environmental contact with organic antigens. The aim of the present study was to assess the results of serum specific IgG antibodies (ssIgG) in HP patients and their correlation with clinical data.

MATERIAL AND METHODS

128 HP patients, median age 53 years, participated in the study. The control group consisted of 102 patients with interstitial lung diseases (ILDs) other than HP. Assessment of pretreatment ssIgG to thermophilic actinomycetes and protein antigens from bird droppings (pigeons, hens, ducks, parrots, turkeys) was performed by double diffusion in agar gel according to Ouchterlony method.

RESULTS

Positive precipitins were obtained in 57% of all HP patients and in 61% of those exposed to above mentioned antigens. Positive results in the control group were obtained in 7% of patients. Sensitivity of ssIgG in HP group was 0.57 and specificity 0.93. Precipitins to at least one bird antigen was confirmed in 64% of HP patients exposed to birds. Precipitins to thermophilic bacteria were found in 29% of HP patients exposed to hay or hay products.

CONCLUSIONS

The results of the study indicate that ssIgG against birds' allergens were the valuable diagnostic tool in HP patients. Low-rate of confirmation of ssIgG to thermophilic bacteria in patients exposed to hay or hay products indicate that other microorganisms, most likely molds, could be responsible for the disease development.

Comorbidities and survival in patients with chronic hypersensitivity pneumonitis

Introduction

Chronic Hypersensitivity Pneumonitis (cHP) is a fibrotic interstitial lung disease (ILD) resulting from repeated exposure to an offending antigen. Prognostication in cHP remains challenging, and the relationship between comorbidities and survival has yet to be characterized. The aim of this study was to describe the relationship between comorbid conditions and survival in patients with cHP.

Methods

The prospective database from a tertiary referral centre for ILD was reviewed for patient-reported comorbidities, their frequency, and relationship with survival in cHP patients. Comorbidities were assessed by direct questioning of the patient at the baseline visit and by a standardized questionnaire for the diagnosis of interstitial lung diseases. During the follow-up examinations, patients were asked about newly diagnosed comorbidities.

Results

Two hundred eleven patients with cHP were identified (mean age 63 years, 53% male, mean FVC 73%), with mean follow-up of 32 months. The mean number of comorbidities was 3 (10% had 0, 59% 1–3 and 31% ≥4 comorbidities). Most frequent comorbidities groups were cardiovascular (65%) and respiratory (26%), most common comorbidities were hypertension (56%), gastro-esophageal reflux disease (GERD) (24%), diabetes (20%) and coronary heart disease (18%). In general, deceased patients had more comorbidities than survivors (p = 0.005), yet there was no association between the absolute number of comorbidities and survival. Pulmonary hypertension (30.8% versus 5.7%, p = 0.001;), diastolic dysfunction (26.9% versus 6.4%, p = 0.004) and cerebrovascular disease were more frequent in non-survivors (23.1% versus 7.6%, p = 0.026). Lung cancer was not observed, and neither GERD nor antacid drugs were associated with outcome (p = 0.357 and p = 0.961, respectively).

Conclusions

Comorbidities are common in cHP are associated with survival. Further work should determine whether interventions for these specific comorbidities can positively affect survival.

An Open-label Study With Pirfenidone on Chronic Hypersensitivity Pneumonitis

BACKGROUND

Chronic hypersensitivity pneumonitis (cHP) represents a severe lung disease often evolving to fibrosis with the subsequent destruction of the lung parenchyma. There are no approved therapies with confirmed efficacy to deal with this disease.

METHODS

We performed an open-label, proof of concept study, to evaluate the efficacy and safety of pirfenidone added to immunosuppressive drugs on the treatment of cHP. We included 22 patients assigned to two groups: Group 1, nine patients that received prednisone plus azathioprine and Group 2, thirteen patients, received prednisone plus azathioprine and pirfenidone (ClinicalTrials.gov identifier NCT02496182). There were no significant imbalances in clinically relevant baseline characteristics between two study groups.

RESULTS

After 1 year of treatment, inclusion of pirfenidone was not associated with improved forced vital capacity (primary end-point). A not significant tendency to show higher improvement of diffusion capacity of the lung for carbon monoxide (D_LCO) was observed in the group receiving pirfenidone (p=0.06). Likewise, a significant improvement in the total score on the SGRQ was found in the group 2 (p=0.02) without differences in other two questionnaires related to quality of life (ATAQ-IPF and EQ-5D-3L). HRCT showed a decrease of the ground glass attenuation without changes in the fibrotic lesions and without differences between both groups.

CONCLUSIONS

These findings suggest that the addition of pirfenidone to the anti-inflammatory treatment in patients with chronic HP may improve the outcome with acceptable safety profile. However, prospective randomized double-blind, placebo-controlled trials in largest cohorts are needed to validate its efficacy.

Usefulness of new diagnostic criteria for chronic hypersensitivity pneumonitis established on the basis of a Delphi survey: A Japanese cohort study

BACKGROUND

Chronic hypersensitivity pneumonitis (CHP) is a fibrotic interstitial lung disease (ILD) caused by repeated exposure to a variety of organic particles. In November 2017, new criteria for CHP diagnosis were proposed by Morisset et al. based on a modified Delphi survey of ILD experts. However, it remains unclear whether these criteria are useful to accurately diagnose CHP. We aimed to evaluate the newly proposed CHP diagnostic criteria.

METHODS

We retrospectively applied Morisset's CHP diagnostic criteria to consecutive Japanese patients who underwent surgical lung biopsy for diagnosis of ILD from 2008 to 2015. All patients underwent bronchoalveolar lavage and pulmonary function testing. Patients who had connective tissue disease complications or showed an acute or subacute disease onset were excluded.

RESULTS

A total of 251 patients were included. The diagnoses based on multidisciplinary discussion (MDD) were CHP (n = 27), idiopathic pulmonary fibrosis (n = 117), unclassifiable interstitial pneumonia (IP) (n = 65), and other diagnoses (n = 42). Of the 27 MDD-CHP patients, 14 were classified as a CHP group with diagnostic confidence >50% and 13 were not categorized (sensitivity, 51.9%; specificity, 77.7%). Morisset's CHP diagnostic criteria could help avoid SLB for the diagnosis of CHP in seven patients. Of the 13 MDD-CHP patients who were not categorized in the CHP group with diagnostic confidence >50%, the reason for the exclusion was an inconsistent with UIP pattern without CHP features.

CONCLUSIONS

Half of the MDD-CHP patients were diagnosed with CHP using Morisset's CHP diagnostic criteria. Further investigation will be important for developing improved diagnostic criteria for CHP.

Critical reappraisal of underlying histological patterns in patients with suspected idiopathic pulmonary fibrosis

PURPOSE OF REVIEW

Usual interstitial pneumonia (UIP) pattern is the histologic marker of idiopathic pulmonary fibrosis (IPF), but usefulness of ancillary histologic findings may discriminate idiopathic from secondary UIP.

RECENT FINDINGS

Alternative less invasive procedures may identify UIP pattern preventing conventional surgical lung biopsy, whereas genomic analysis may recognize UIP pattern from otherwise poorly diagnostic samples.

SUMMARY

High-resolution computed tomography identifies a 'definite' UIP pattern in about half of cases, failing to recognize UIP in the absence of honeycombing or in limited disease. Although radiologic criteria for UIP need redefinition to improve their diagnostic yield, histologic features of UIP did not significantly change from the 1960s but continue to represent a major diagnostic tool, particularly in challenging interstitial lung diseases. A careful recognition of some histologic ancillary findings in UIP (e.g., cellular/follicular bronchiolitis with germinal centers, chronic pleuritis, interstitial granulomas/giant cells, bridging fibrosis) may be helpful in supporting secondary forms (e.g., connective tissue disease, chronic hypersensitivity pneumonia) from IPF. Cryobiopsy and awake-biopsy are promising approaches to obtain representative lung tissue preventing conventional surgical lung biopsy. Genomic techniques have recently demonstrated good-to-high sensitivity and specificity to disclose UIP pattern starting from RNA obtained in transbronchial biopsy, possibly replacing and/or flanking soon traditional histology.

The Role of Airway Myofibroblasts in Asthma

Airway remodeling is a characteristic feature of asthma and is thought to play an important role in the pathogenesis of airway hyperresponsiveness. Myofibroblasts are key structural cells involved in injury and repair, and there is evidence that dysregulation of their normal function contributes to airway remodeling. Despite the importance of myofibroblasts, a lack of specific cellular markers and inconsistent nomenclature have limited recognition of their key role in airway remodeling. Myofibroblasts are increased several-fold in the airways in asthma, in proportion to the severity of the disease. Myofibroblasts are postulated to be derived from both tissue-resident and bone marrow-derived cells, depending on the stage of injury and the tissue. A small number of studies have demonstrated attenuation of myofibroblast numbers and also reversal of established myofibroblast populations in asthma and other inflammatory processes. In this article, we review what is currently known about the biology of myofibroblasts in the airways in asthma and identify potential targets to reduce or reverse the remodeling process. However, further translational research is required to better understand the mechanistic role of the myofibroblast in asthma.

C-C Motif Chemokine Ligand 15 May Be a Useful Biomarker for Predicting the Prognosis of Patients with Chronic Hypersensitivity Pneumonitis

BACKGROUND

Chronic hypersensitivity pneumonitis (CHP) is characterized by lymphocytic inflammation and progressive fibrosis of the lung caused by a variety of inhaled antigens. Due to the difficulty of accurately diagnosing CHP, and the poor prognosis associated with the condition, a novel clinical biomarker is urgently needed.

OBJECTIVE

To investigate the usefulness of C-C motif chemokine ligand 15 (CCL15), which had been demonstrated to highly express in the lungs of CHP patients, as a clinical biomarker for CHP.

METHOD

Immunohistochemical investigations were performed on lung tissue from CHP patients, and CCL15 levels in serum and bronchoalveolar lavage fluid (BALF) were measured via the enzyme-linked immunosorbent assay.

RESULTS

Immunohistochemistry investigations revealed high CCL15 expression in the lungs of CHP patients. Serum CCL15 levels in CHP patients (29.1 ± 2.1 μg/mL) were significantly higher than those of idiopathic pulmonary fibrosis patients (19.7 ± 1.3 μg/mL, p = 0.01) and healthy subjects (19.5 ± 1.7 μg/mL, p = 0.003). When BALF CCL15 level was divided by BALF albumin (Alb) level (BALF CCL15/Alb), it was significantly inversely correlated with forced vital capacity (β = -0.47, p = 0.0006), percentage of predicted carbon monoxide diffusion capacity of the lung (β = -0.41, p = 0.0048), and BALF lymphocyte count (β = -0.34, p = 0.01) in CHP patients. Multivariate Cox proportional hazards analysis revealed that high BALF CCL15/Alb and poor prognosis were statistically significantly independently correlated in CHP patients (HR 1.1, 95% CI 1.03-1.18, p = 0.004).

CONCLUSION

The results of the current study suggest that CCL15 may be a useful prognostic biomarker for CHP. CCL15 was highly expressed in the lung tissue of CHP patients, and BALF CCL15/Alb was significantly associated with CHP prognosis.

The Analysis of Surgical Lung Biopsy and Explanted Lung Specimens Sheds Light on the Pathological Progression of Chronic Bird-related Hypersensitivity Pneumonitis

Chronic hypersensitivity pneumonitis is an interstitial pneumonia caused by an immunological reaction to the chronic inhalation of an antigen. Little is known, however, about the pathological change of the pulmonary lesions. A 33-year-old man was diagnosed with chronic bird-related hypersensitivity pneumonitis based on the findings of a surgical lung biopsy and an inhalation provocation test. He underwent lung transplantation at 8 years after the diagnosis because of disease progression. We conclude that the analysis of the explant suggests that the presence of extensive fibrosis in the centrilobular and perilobular area with bridging fibrosis is a form of pathological progression of chronic hypersensitivity pneumonitis.

A Nonsmoker Man in His 40s With a Diagnosis of Genetic-Related Idiopathic Pulmonary Fibrosis (Surfactant-Protein C Gene Mutation)

A nonsmoker man in his 40s underwent bilateral lung transplantation with a referral diagnosis of genetic-related idiopathic pulmonary fibrosis (IPF). The patient had no medical history in childhood and early adulthood, nor was there a family history of IPF. His nonsmoker father presented with lung cancer at 59 years of age. The patient was a professional brass instrument player; he had started playing at 9 years of age, and he was recently playing 3 to 4 h per day. He had a 7-year clinical history of chronic cough and shortness of breath. Bilateral fine crackles were present at clinical examination. There was no digital clubbing. Data had been collected since 2015: no clinical or immunologic signs of connective tissue disease were evident, including autoantibodies for myositis or anti-synthetase syndrome. Chest radiograph showed diffuse interstitial lung disease. Results of pulmonary function tests yielded a restrictive pattern with decreased FVC and decreased total lung capacity (69% and 47% of predicted, respectively). The FEV₁/FVC ratio was 86%, and carbon monoxide transfer coefficient was 36% of predicted. BAL cellular analysis consisted of macrophages (66%), lymphocytes (19%; CD4⁺/CD8⁺ ratio, 0.16), neutrophils (10%), and eosinophils (5%).

Interstitial lung diseases in dogs and cats part II: Known cause and other discrete forms

In addition to idiopathic interstitial pneumonias, interstitial lung diseases (ILDs) can occur secondary to known causes or be classified as discrete syndromes. Also known as diffuse parenchymal lung diseases, the ILDs represent a heterogenous group of non-infectious, non-neoplastic disorders characterized by varied patterns of inflammation and fibrosis. Characteristically associated with the true interstitium (i.e. the anatomic space lined by alveolar epithelial cells and capillary endothelial cells and the loose-binding connective tissue), it is important to understand ILDs are associated with pathology of the distal lung parenchyma and thus lesions can be bronchiolocentric or resemble alveolar filling disorders. Injury to the distal lung can occur via inhalation or hematogenous routes. This review will build on a proposed classification scheme adapted from human medicine to describe known cause and discrete forms of ILDs in dogs and cats.

Hypersensitivity pneumonitis: A fibrosing alveolitis produced by inhalation of diverse antigens

Hypersensitivity pneumonitis (HP) is a T_H1 lymphocyte-biased fibrosing alveolitis caused by antigens ranging from avian excreta, fungi, thermophilic bacteria, and protozoa to reactive chemicals found in the workplace. Mimicking a viral syndrome, acute exposures to inciting antigens cause abrupt onset of nonproductive cough, dyspnea, and chills with arthralgias or malaise usually from 4 to 8 hours later so that the temporal relationship between antigen exposure and symptoms might be unsuspected. The histology of HP reveals prominent lymphocyte infiltrates that thicken the alveolar septa with poorly formed granulomas or giant cells. Bronchoalveolar lavage fluid demonstrates greater than 20% lymphocytes in nearly all patients. Abnormalities on high-resolution computed tomographic examinations range from nodular centrilobular opacities in acute/subacute disease to increased reticular markings and honeycombing fibrosis, which typically are predominant in the upper lobes, in patients with advanced disease. Descriptors include "mosaic" attenuation and ground-glass opacities. Repeated episodes can result in nodular pulmonary infiltrates and suspected nonspecific interstitial pneumonia or idiopathic pulmonary fibrosis. Clinicians require a high level of suspicion to make an early diagnosis of HP before extensive pulmonary fibrosis or restrictive lung disease has occurred.

Hypersensitivity pneumonitis: Antigen diversity and disease implications

Hypersensitivity pneumonitis (HP) is an immune-mediated syndrome triggered by inhalation of a wide variety of allergens, to which an individual has previously been sensitized. More than 200 agents responsible for the disease have already been identified; however, HP occurs only in a small number of individuals exposed to causal antigens. The present report provides an overview of the role of antigen role in HP, highlighting its diversity, research methods, and prevention strategies, as well as the impact on disease prognosis following elimination of antigen. HP is an underdiagnosed disease and, therefore, it is difficult to accurately estimate its incidence. Triggering antigens can be divided into six broad categories: bacteria, fungi, mycobacteria, animal and plant proteins, chemicals, and metals, represented by disease prototypes. The identification of causal antigen is a major challenge; it is impossible to obtain in about 30-60% of cases. The acute form of HP, with early detection and immediate eviction of causal antigen, tends to have an excellent prognosis. In the chronic form, partial recovery of disease is still possible; however, some cases tend to progress to fibrosis, even after removal from exposure. In conclusion, HP diagnosis should be based on a proactive search for potential antigen sources, although their identification is hampered by the lack of standardized methods of demonstrating the specific antigen sensitization. Antigen avoidance is a critical determinant in disease prognosis.