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

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.

Interstitial Score and Concentrations of IL-4Rα, PAR-2, and MMP-7 in Bronchoalveolar Lavage Fluid Could Be Useful Markers for Distinguishing Idiopathic Interstitial Pneumonias

Idiopathic interstitial pneumonia (IIP) entails a variable group of lung diseases of unknown etiology. Idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, interstitial lung diseases related to connective tissue disease (CTD-ILD), and hypersensitivity pneumonitis (HP) can manifest with similar clinical, radiological, and histopathological features. In a differential diagnosis, biomarkers can play a significant role. We assume that levels of specific cyto- or chemokines or their receptors can signal pathogenetic processes in the lungs. Eighty patients with different types of idiopathic interstitial pneumonia were enrolled in this study. Cell counts and concentrations of tumor necrosis factor (TNF)-α, interleukin-4 receptor α, proteinase-activated receptor (PAR)-2, matrix metalloproteinase (MMP)-7, and B cell-activating factor were measured in bronchoalveolar lavage fluid using commercial ELISA kits. High resolution computer tomography results were evaluated using alveolar and interstitial (IS) score scales. Levels of TNF-α were significantly higher in HP compared to fibrosing IIP (p < 0.0001) and CTD-ILD (p = 0.0381). Concentrations of IL-4Rα, PAR-2, and MMP-7 were positively correlated with IS (p = 0.0009; p = 0.0256; p = 0.0015, respectively). Since TNF-α plays a major role in inflammation, our results suggest that HP is predominantly an inflammatory disease. From the positive correlation with IS we believe that IL-4Rα, PAR-2, and MMP-7 could serve as fibroproliferative biomarkers in differential diagnosis of IIP.

Progression in the Management of Non-Idiopathic Pulmonary Fibrosis Interstitial Lung Diseases, Where Are We Now and Where We Would Like to Be

A significant proportion of patients with interstitial lung disease (ILD) may develop a progressive fibrosing phenotype characterized by worsening of symptoms and pulmonary function, progressive fibrosis on chest computed tomography and increased mortality. The clinical course in these patients mimics the relentless progressiveness of idiopathic pulmonary fibrosis (IPF). Common pathophysiological mechanisms such as a shared genetic susceptibility and a common downstream pathway—self-sustaining fibroproliferation—support the concept of a progressive fibrosing phenotype, which is applicable to a broad range of non-IPF ILDs. While antifibrotic drugs became the standard of care in IPF, immunosuppressive agents are still the mainstay of treatment in non-IPF fibrosing ILD (F-ILD). However, recently, randomized placebo-controlled trials have demonstrated the efficacy and safety of antifibrotic treatment in systemic sclerosis-associated F-ILD and a broad range of F-ILDs with a progressive phenotype. This review summarizes the current pharmacological management and highlights the unmet needs in patients with non-IPF ILD.

The Diagnosis and Treatment of Pulmonary Fibrosis

BACKGROUND

The different types of pulmonary fibrosis are a subgroup of the interstitial lung diseases (ILDs). They are associated with a chronic and often progressive course.

METHODS

This review is based on pertinent publications retrieved by a selective search in the EMBASE and PubMed databases, with an emphasis on articles published from 2000 to 2020.

RESULTS

The most common type of pulmonary fibrosis is idiopathic pulmonary fibrosis (IPF). Among other relevant types, the most important ones are fibrosing hypersensitivity pneumonitis (fHP) and ILDs associated with systemic diseases, all of which are rare and generally carry a poor prognosis. The essential prerequisite to accurate diagnosis is aninterdisciplinary approach, taking account of the clinical, histological, and radiological aspects. The main complications of pulmonary fibrosis are acute exacerbations and pulmonary hypertension; comorbidities are also of prognostic relevance. Treatment of pulmonary fibrosis depends on the subtype and clinical behavior. For IPF, antifibrotic therapy is indicated; fHP, on the other hand, is mainly treated by antigen avoidance and immune modulation. The predominant mode of treatment for systemic disease-associated pulmonary fibrosis is immune suppression. Antifibrotic agents can also be useful in the treatment of other types of progressivepulmonary fibrosis besides IPF.

CONCLUSION

The differential diagnosis of pulmonary fibrosis, though complex, is clinically essential, as different types of pulmonary fibrosis are treated differently.

Pilot Study Using Recombinant Antigens r-PROE and r-IGLL1 for the Serodiagnosis of Feather Duvet Lung

BACKGROUND

Feather duvet lung (FDL) is an underestimated form of acute and chronic hypersensitivity pneumonitis. Serological tests for FDL need to be validated. We investigated the ability of recombinant pigeon Proproteinase E (r-PROE) and Immunoglobulin-lambda-like-polypeptide-1 (r-IGLL1) proteins to support the serological diagnosis of FDL, and propose them as a serological tool for clinicians to differentiate cases from FDL and Bird fancier's lung (BFL).

METHODS

Specific IgG antibodies against r-PROE and r-IGLL1, analyzed with ELISA, were measured in patients diagnosed with FDL (n=31), BFL (n=15) controls exposed (n=15) and unexposed to feathers (n=15).

RESULTS

The sensitivity and specificity of the r-PROE ELISA for the serological diagnosis of FDL cases versus exposed and unexposed controls were 74.2% and 86.7% respectively, with an index threshold of 0.5 (AUC: 0.89). In addition, this serological test was effective to support the serological diagnosis of FDL and BFL cases with significantly different thresholds. The r-IGLL1 ELISA was only effective for the serological diagnosis of BFL. Also, these two serological tests were useful for the diagnosis of both chronic and acute forms.

CONCLUSIONS

The new diagnostic test for FDL using r-PROE protein should help to detect overt and hidden cases of FDL. The combination of both test will help the clinician in distinguish between the etiology of birds or feathers duvet.

The Role of Transthoracic Ultrasound in the Study of Interstitial Lung Diseases: High-Resolution Computed Tomography Versus Ultrasound Patterns: Our Preliminary Experience

Transthoracic ultrasound (TUS) is a readily available imaging tool that can provide a quick real-time evaluation. The aim of this preliminary study was to establish a complementary role for this imaging method in the approach of interstitial lung diseases (ILDs). TUS examination was performed in 43 consecutive patients with pulmonary fibrosis and TUS findings were compared with the corresponding high-resolution computed tomography (HRCT) scans. All patients showed a thickened hyperechoic pleural line, despite no difference between dominant HRCT patterns (ground glass, honeycombing, mixed pattern) being recorded (p > 0.05). However, pleural lines' thickening showed a significant difference between different HRCT degree of fibrosis (p < 0.001) and a negative correlation with functional parameters. The presence of >3 B-lines and subpleural nodules was also assessed in a large number of patients, although they did not demonstrate any particular association with a specific HRCT finding or fibrotic degree. Results allow us to suggest a complementary role for TUS in facilitating an early diagnosis of ILD or helping to detect a possible disease progression or eventual complications during routine clinical practice (with pleural line measurements and subpleural nodules), although HRCT remains the gold standard in the definition of ILD pattern, disease extent and follow-up.

An update on hypersensitivity pneumonitis: what a clinician wants to know

PURPOSE OF REVIEW

A recent international collaboration has updated the clinical definition and diagnostic recommendations for hypersensitivity pneumonitis, focusing on fibrotic and non-fibrotic phenotypes. However, how these transfer to clinical practice and their impact upon clinical management and prognosis of hypersensitivity pneumonitis is unclear. This review will focus on recent advances in the understanding of the clinical aspects of hypersensitivity pneumonitis, predominantly its epidemiology, diagnosis, classification and treatment.

RECENT FINDINGS

Hypersensitivity pneumonitis is a rare disease within the general population, with variable geographical incidence because of environmental, cultural and occupational factors. Confidence in diagnosis relies upon the presence of clinical features with a temporal relationship to an associated exposure, radiological and histopathological features, bronchiolo-alveolar lavage lymphocytosis and precipitating antibodies/specific immunoglobulin G to antigens. Although emerging evidence regarding nintedanib use in progressive fibrotic interstitial lung disease is promising, the majority of therapies (corticosteroids and immunosuppressive agents) used traditionally in hypersensitivity pneumonitis lack a robust evidence base.

SUMMARY

With a clear definition of fibrotic and nonfibrotic hypersensitivity pneumonitis phenotypes now established, clinical research trials (predominantly randomized controlled trials) should clarify and resolve the discussion regarding antigen avoidance, corticosteroid therapy, immunosuppressive therapy and antifibrotic therapy in fibrotic and nonfibrotic subtypes of hypersensitivity pneumonitis.

Prognostic value of lymphocyte counts in bronchoalveolar lavage fluid in patients with acute respiratory failure: a retrospective cohort study

Background

Cellular patterns in bronchoalveolar lavage fluid (BALF) are used to distinguish or rule out particular diseases in patients with acute respiratory failure (ARF). However, whether BALF cellular patterns can predict mortality or not is unknown. We test the hypothesis that BALF cellular patterns have predictive value for mortality in patients with ARF.

Methods

This was a retrospective single-center observational study conducted in a Japanese University Hospital. Consecutive patients (n = 78) with both pulmonary infiltrates and ARF who were examined by bronchoalveolar lavage (BAL) between April 2015 and May 2018 with at least 1 year of follow-up were analyzed. Primary analysis was receiver operating characteristic curve—area under the curve (ROC-AUC) analysis for 1-year mortality.

Results

Among the final sample size of 78 patients, survivors (n = 56) had significantly increased lymphocyte and eosinophil counts and decreased neutrophil counts in BALF compared with non-survivors (n = 22). Among the fractions, lymphocyte count was the most significantly different (30 [12-50] vs. 7.0 [2.9-13]%, P <0.0001). In the ROC curve analysis of the association of BALF lymphocytes with 1-year mortality, the AUC was 0.787 (P <0.0001, cut-off value [Youden index] 19.0%). Furthermore, ≥20% BALF lymphocytes were significantly associated with increased survival with adjustment for baseline imbalances (1-year adjusted hazard ratio, 0.0929; 95% confidence interval, 0.0147–0.323, P <0.0001; 90-day P =0.0012). Increased survival was significantly associated with ≥20% BALF lymphocytes in both interstitial lung disease (ILD) and non-ILD subgroups (P =0.0052 and P =0.0033, respectively). In secondary outcome analysis, patients with ≥20% BALF lymphocytes had significantly increased ventilator-free days, which represents less respiratory dysfunction than those with <20% BALF lymphocytes.

Conclusions

In the patients with ARF, ≥20% lymphocytes in BALF was associated with significantly less ventilatory support, lower mortality at both 90-day and 1-year follow-ups.

Comparison of Clinical Characteristics and Outcomes between Idiopathic and Secondary Pleuroparenchymal Fibroelastosis

Background: Pleuroparenchymal fibroelastosis (PPFE) is a unique clinical, radiologic, and histopathologic entity for which several potential etiologies have been reported recently. However, there has been no comprehensive study of secondary PPFE. Objective: Assessment of the clinical characteristics, outcomes, and prognostic factors of secondary and idiopathic PPFE. Methods: We retrospectively reviewed the medical records of consecutive PPFE patients between January 1999 and December 2018. We identified 132 idiopathic PPFE patients and 32 secondary PPFE patients. Results: The incidence of interstitial lung disease (ILD) pattern different from the usual interstitial pneumonia (UIP) pattern in the lower lobes was higher in secondary PPFE patients (38.5%) than in idiopathic PPFE patients (61.5%, p = 0.02). The idiopathic and secondary PPFE groups did not differ significantly in terms of laboratory data, respiratory complications, and survival (median: 5.0 years vs. 4.1 years, p = 0.95). The presence of UIP pattern was independently associated with increased mortality in multivariate analyses in idiopathic PPFE patients, but not in secondary PPFE patients. Conclusions: The frequency and prognostic impact of UIP-pattern ILD differed between idiopathic and secondary PPFE patients. Lung transplantation should be considered in secondary PPFE patients with low diffusing capacity of the lungs for carbon monoxide (DLCO) regardless of lower-lobe ILD pattern.

Identification and Remediation of Environmental Exposures in Patients With Interstitial Lung Disease: Evidence Review and Practical Considerations

A relationship between inhalational exposure to materials in the environment and development of interstitial lung disease (ILD) is long recognized. Hypersensitivity pneumonitis is an environmentally -induced diffuse parenchymal lung disease. In addition to hypersensitivity pneumonitis, domestic and occupational exposures have been shown to influence onset and progression of other ILDs, including idiopathic interstitial pneumonias such as idiopathic pulmonary fibrosis. A key component of the clinical evaluation of patients presenting with ILD includes elucidation of a complete exposure history, which may influence diagnostic classification of the ILD as well as its management. Currently, there is no standardized approach to environmental evaluation or remediation of potentially harmful exposures in home or workplace environments for patients with ILD. This review discusses evidence for environmental contributions to ILD pathogenesis and draws on asthma and occupational medicine literature to frame the potential utility of a professional evaluation for environmental factors contributing to the development and progression of ILD. Although several reports suggest benefits of environmental assessment for those with asthma or certain occupational exposures, lack of information about benefits in broader populations may limit application. Determining the feasibility, long-term outcomes, and cost-effectiveness of environmental evaluation and remediation in acute and chronic ILDs should be a focus of future research.

A comprehensive assessment of environmental exposures and the medical history guides multidisciplinary discussion in interstitial lung disease

BACKGROUND

Multidisciplinary discussion (MDD) is widely recommended for patients with interstitial lung disease (ILD), but published primary data from MDD has been scarce, and factors influencing MDD other than chest computed tomography (CT) and lung histopathology interpretations have not been well-described.

METHODS

Single institution MDD of 179 patients with ILD.

RESULTS

MDD consensus clinical diagnoses included autoimmune-related ILD, chronic hypersensitivity pneumonitis, smoking-related ILD, idiopathic pulmonary fibrosis, medication-induced ILD, occupation-related ILD, unclassifiable ILD, and a few less common pulmonary disorders. In 168 of 179 patients, one or more environmental exposures or pertinent features of the medical history were identified, including recreational/avocational, residential, and occupational exposures, systemic autoimmune disease, malignancy, medication use, and family history. The MDD process demonstrated the importance of comprehensively assessing these exposures and features, beyond merely noting their presence, for rendering consensus clinical diagnoses. Precise, well-defined chest CT and lung histopathology interpretations were rendered at MDD, including usual interstitial pneumonia, nonspecific interstitial pneumonia, and organizing pneumonia, but these interpretations were associated with a variety of MDD consensus clinical diagnoses, demonstrating their nonspecific nature in many instances. In 77 patients in which MDD consensus diagnosis differed from referring diagnosis, assessment of environmental exposures and medical history was found retrospectively to be the most impactful factor.

CONCLUSIONS

A comprehensive assessment of environmental exposures and pertinent features of the medical history guided MDD. In addition to rendering consensus clinical diagnoses, MDD presented clinicians with opportunities to initiate environmental remediation, behavior modification, or medication alteration likely to benefit individual patients with ILD.

When things go wrong: exploring possible mechanisms driving the progressive fibrosis phenotype in interstitial lung diseases

Interstitial lung diseases (ILDs) comprise a large and heterogeneous group of disorders of known and unknown aetiology characterised by diffuse damage of the lung parenchyma. In recent years it has become evident that patients with different types of ILD are at risk of developing progressive pulmonary fibrosis, known as progressive fibrosing ILD (PF-ILD). This is a phenotype that behaves similar to idiopathic pulmonary fibrosis, the archetypical example of progressive fibrosis. PF-ILD is not a distinct clinical entity but describes a group of ILDs with similar clinical behaviour. This phenotype may occur in diseases displaying distinct aetiologies and different biopathology during their initiation and development. Importantly, these entities may have the potential for improvement or stabilisation prior to entering the progressive fibrosing phase. The crucial questions are: 1) why does a subset of patients develop a progressive and irreversible fibrotic phenotype even with appropriate treatment? and 2) what are the possible pathogenic mechanisms driving progression? Here, we provide a framework highlighting putative mechanisms underlying progression, including genetic susceptibility, ageing, epigenetics, structural fibrotic distortion, aberrant composition and stiffness of the extracellular matrix, and the emergence of distinct pro-fibrotic cell subsets. Understanding the cellular and molecular mechanisms behind PF-ILD will provide the basis for identifying risk factors and appropriate therapeutic strategies.

The association between fungi exposure and hypersensitivity pneumonitis: a systematic review

A systematic review of published studies focused on the association between hypersensitivity pneumonitis (HP) and fungi exposure was conducted on PubMed, following PRISMA guidelines for systematic reviews. A total of 14 studies met the inclusion criteria but only 6 of these studies were eligible, as the remaining 8 represented case reports that were separately included for further discussion. HP is an interstitial lung disease (ILD) characterized by a hypersensitization response to inhalable antigens and represents 1.5% to 12% of all ILD in the European population. Several fungi species that populate the indoor environment have been associated with the incidence of HP upon cumulative exposure, with Penicillium spp and Aspergillus spp being the fungi species most frequently associated with the onset of disease. Although some studies have shown that avoiding exposure to causative HP fungi tends to improve patients’ symptoms, other studies were unable to identify the source of sensitization. More microbial exposure studies are needed to properly estimate the risk of HP development in the built environment.

Sooty bark disease of maples: the risk for hypersensitivity pneumonitis by fungal spores not only for woodman

In the middle of the twentieth century, the from North America sooty bark disease (SBD) of maples was first discovered in England and has spread in the last decades in Central Europe, in particular. The trigger of SBD is the mould fungus Cryptostroma (C.) corticale. The most common infested maple is the sycamore, Acer pseudoplatanus, a common tree in woods and parks. The disease is characterised by peeling of the outer layer of the bark and brownish-black spores under the peeled off bark. These spores can cause maple bark disease (MBD) in humans, a hypersensitivity pneumonitis (HP) with similar symptoms like COPD, allergic asthma, influenza or flu-like infections and interstitial pneumonia. Persons who have intensive respectively occupational contact with infested trees or wood, e.g., woodman, foresters, sawyers or paper mill workers, are at risk in particular. Since C. corticale favours hot summers and host trees weakened by drought, SBD will increasingly spread in the future due to ongoing climate change. Consequently, the risk of developing MBD will increase, too. As with all HPs, e.g., farmer's lung and pigeon breeder's disease, the diagnosis of MBD is intricate because it has no clear distinguishing characteristics compared to other interstitial lung diseases. Therefore, the establishment of consistent diagnosis guidelines is required. For correct diagnosis and successful therapy, multidisciplinary expertise including pulmonologists, radiologists, pathologists and occupational physicians is recommended. If MBD is diagnosed in time, the removal of the triggering fungus or the infested maple wood leads to complete recovery in most cases. Chronic HP can lead to lung fibrosis and a total loss of lung function culminating in death. HP and, thus, MBD, is a disease with a very high occupational amount. To avoid contact with spores of C. corticale, persons working on infested wood or trees have to wear personal protective equipment. To protect the public, areas with infested maples have to be cordoned off, and the trees should be removed. This is also for impeding further spreading of the spores.

Establishing content-validity of a disease-specific health-related quality of life instrument for patients with chronic hypersensitivity pneumonitis

Background

Chronic Hypersensitivity Pneumonitis (CHP) is caused by an immune mediated response in the lung tissue after exposure to an inhaled environmental antigenic stimulant. We previously documented the ways in which CHP impacts patients’ lives and have now developed a disease-specific instrument, the CHP-HRQOL instrument, to measure health-related quality of life (HRQOL). The objective of this study was to assess content validity for the CHP-HRQOL.

Methods

Cognitive interviews were conducted among adults with CHP. The instrument was revised and refined between each round of interviews. Feedback was obtained on the instructions, items, response options, and recall period. Items where participants had difficulty with comprehension, wording, or misinterpretation were marked by the interviewer and participant feedback was reviewed to make revisions, add or delete items when appropriate. Readability statistics were calculated using Flesch-Kincaid grade level and reading ease scores.

Results

Ten participants were interviewed over three rounds, with revisions made to the questionnaire in an iterative process. In the initial 39 item instrument, we identified 7 items where two or more participants reported difficulty. Participants preferred a four-week recall period (compared to a two-week recall period) and response options with a 5-point response scale. The final version of the CHP-HRQOL includes 40 items with a median reading level between 6th and 7th grade.

Conclusion

The CHP-HRQOL instrument demonstrated high content validity and is ready for psychometric testing in further validation studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41687-020-00282-x.

Sarcoidosis: Pitfalls and Challenging Mimickers

Sarcoidosis, a systemic granulomatous disease of unknown etiology, may mimic other conditions at presentation often resulting in delayed diagnosis. These conditions include infections, neoplasms, autoimmune, cardiovascular, and drug-induced diseases. This review highlights the most common sarcoidosis mimics that often lead to pitfalls in diagnosis and delay in appropriate treatment. Prior to invasive testing and initiating immunosuppressants (commonly corticosteroids), it is important to exclude sarcoid mimickers.

SNP and Haplotype Interaction Models Reveal Association of Surfactant Protein Gene Polymorphisms With Hypersensitivity Pneumonitis of Mexican Population

Background: Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by inhalation of common environmental organic particles. Surfactant proteins (SPs) play a role in innate immunity and surfactant function. We hypothesized that single nucleotide polymorphisms (SNPs) or haplotypes of the SP genes associate with HP. Methods: Seventy-five HP patients caused by avian antigen and 258 controls, asymptomatic antigen exposed and non-exposed were enrolled. SNP association was performed using logistic regression analysis and SNP-SNP interaction models. Results: Based on odds ratio, regression analyses showed association of (a) rs7316_G, 1A3 (protective) compared to antigen exposed; (b) male sex, smoking, rs721917_T and rs1130866_T (protective) compared to non-exposed controls with HP; (c) compared to antigen exposed, 25 interactions associated with HP in a three-SNP model; (d) compared to non-exposed, (i) rs1136451 associated with increased, whereas rs1136450 and rs1130866 associated with lower HP risk, (ii) 97 interactions associated with HP in a three-SNP model. The majority of SNP-SNP interactions associated with increased HP risk involved SNPs of the hydrophilic SPs, whereas, the majority of interactions associated with lower HP risk involved SNPs of both hydrophilic and hydrophobic SPs; (e) haplotypes of SP genes associated with HP risk. Conclusions: The complexity of SNPs interactions of the SFTP genes observed indicate that the lung inflammatory response to avian antigens is modulated by a complex gene interplay rather than by single SNPs.

Clinical Features of Hypersensitivity Pneumonitis in Children: A Single Center Study

BACKGROUND

Hypersensitivity pneumonia (HP) is an interstitial lung disease (ILD) mainly involving small airways and lung parenchyma that is caused by the inhalation of antigens in susceptible people to stimulate the body's immune response.

METHODS

A total of 6 Chinese children with HP treated in our center from July 2017 to July 2021 were included in our study.

RESULTS

Among the children, there were 4 males and 2 females, ranging in age from 4 to 14 years. Three cases had chest tightness and shortness of breath, 2 cases had cough, 1 case had chest pain, and 1 case had fever. Two cases of children had a history of close contact with pet dogs, 1 case had a history of contact with pigeons, 2 cases lived in a moldy house recently, and 1 case recently played a saxophone that had been idle for more than 2 years. The parents of two cases also had similar symptoms recently. The specific signs of chest HRCT of 6 cases all were in line with the characteristics of HP. After avoiding the sensitization environment, 2 children quickly recovered, 4 patients received low-dose glucocorticoid oral treatment, and after symptom control the dose was gradually reduced. The course of treatment was about 3-6 months.

CONCLUSIONS

Exposure to a potential antigen has been found in all 6 HP children. The clinical manifestations are heterogeneous and easy to confuse with other diseases. A clear history of exposure to the antigens, respiratory symptoms associated with HP, signs of HP on HRCT, and improvement after removal from the antigenic environment constitute the cornerstone of the diagnosis of HP children in our unit. Avoiding exposure to antigenic environment is the first step in treatment, and glucocorticoid use is necessary in children with persistent symptoms.

Monitoring and management of fibrosing interstitial lung diseases: a narrative review for practicing clinicians

Close monitoring of patients with fibrosing interstitial lung diseases (ILDs) is important to enable prompt identification and management of progressive disease. Monitoring should involve regular assessment of physiology (including pulmonary function tests), symptoms, and, when appropriate, high-resolution computed tomography. The management of patients with fibrosing ILDs requires a multidisciplinary approach and should be individualized based on factors such as disease severity, evidence of progression, risk factors for progression, comorbidities, and the preferences of the patient. In this narrative review, we discuss how patients with fibrosing ILDs can be effectively monitored and managed in clinical practice.

[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.

Predictive value of platelet-to-lymphocyte ratio and neutrophil-to-lymphocyte ratio in patients with hypersensitivity pneumonia

Aim:

To evaluate Platelet-to-Lymphocyte Ratio (PLR) and Neutrophil-to-Lymphocyte Ratio (NLR) in patients with HP.

Method:

A sample of 140 total patients, 50 having chronic HP and 20 having acute HP, and a control group of 70 more patients were included in this retrospective study conducted with hospital Ethical Committee approval.

Results:

PLR and NLR values were significantly higher in all HP patients than in the control group ( p <0.001). In addition, these biomarkers were significantly higher in patients with acute HP than in the chronic HP group (p = 0.017 and p = 0.044, respectively). The cutoff values for PLR and NLR were: (1) 177 (p = 0.020) and 2.76 (p <0.0001) between the HP patients and the control group, and, (2) 110 (p = 0.0054) and 2.15 (p = 0.03), between the acute and chronic HP groups.

Conclusion:

PLR and NLR values are inexpensive and easy parameters that can guide in diagnosing hypersensitivity pneumonia in combination with clinical, radiological and pathology findings.and the acute-chronic differentiation of the disease. (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (4): e2020012)

Pulmonary Aspergillosis: Spectrum of Disease

Aspergillus species are ubiquitous in the environment. Aspergillosis is acquired by inhalation of Aspergillus spores. In normal hosts, spore inhalation rarely causes lung disease. Pulmonary Aspergillosis covers a wide spectrum of clinical syndromes depending on the interaction between Aspergillus and the host (immune-status, prior bronchopulmonary disease). It runs the gamut from invasive Aspergillosis to Aspergillus bronchitis. Invasive Aspergillosis usually occurs in severely immunocompromised patients, typically in neutropenic but also in non-neutropenic patients. Chronic pulmonary Aspergillosis affects patients with chronic structural lung disease such as COPD or previous mycobacterial lung disease, but without other significant immunocompromise. Aspergillus bronchitis affects patients with bronchial disease such as bronchiectasis. Allergic bronchopulmonary Aspergillosis affects patients with bronchial asthma or cystic fibrosis, and is due to an allergic response to Aspergillus.

Exposure Assessment Tools for Hypersensitivity Pneumonitis. An Official American Thoracic Society Workshop Report

This report is based on proceedings from the Exposure Assessment Tools for Hypersensitivity Pneumonitis (HP) Workshop, sponsored by the American Thoracic Society, that took place on May 18, 2019, in Dallas, Texas. The workshop was initiated by members from the Environmental, Occupational, and Population Health and Clinical Problems Assemblies of the American Thoracic Society. Participants included international experts from pulmonary medicine, occupational medicine, radiology, pathology, and exposure science. The meeting objectives were to 1) define currently available tools for exposure assessment in evaluation of HP, 2) describe the evidence base supporting the role for these exposure assessment tools in HP evaluation, 3) identify limitations and barriers to each tool's implementation in clinical practice, 4) determine which exposure assessment tools demonstrate the best performance characteristics and applicability, and 5) identify research needs for improving exposure assessment tools for HP. Specific discussion topics included history-taking and exposure questionnaires, antigen avoidance, environmental assessment, specific inhalational challenge, serum-specific IgG testing, skin testing, lymphocyte proliferation testing, and a multidisciplinary team approach. Priorities for research in this area were identified.

Pneumoconiosis with a Sarcoid-Like Reaction Other than Beryllium Exposure: A Case Report and Literature Review

Background: Chronic beryllium disease (CBD) is a granulomatous disease that resembles sarcoidosis but is caused by beryllium. Clinical manifestations similar to those observed in CBD have occasionally been reported in exposure to dusts of other metals. However, reports describing the clinical, radiographic, and pathological findings in conditions other than beryllium-induced granulomatous lung diseases, and detailed information on mineralogical analyses of metal dusts, are limited. Case presentation: A 51-year-old Japanese man with rapidly progressing nodular shadows on chest radiography, and a 10-year occupation history of underground construction without beryllium exposure, was referred to our hospital. High-resolution computed tomography showed well-defined multiple centrilobular and perilobular nodules, and thickening of the intralobular septa in the middle and lower zones of both lungs. No extrathoracic manifestations were observed. Pathologically, the lung specimens showed 5–12 mm nodules with dust deposition and several non-necrotizing granulomas along the lymphatic routes. X-ray analytical electron microscopy of the same specimens revealed aluminum, iron, titanium, and silica deposition in the lung tissues. The patient stopped smoking and changed his occupation to avoid further dust exposure; the chest radiography shadows decreased 5 years later. Conclusion: The radiological appearances of CBD and sarcoidosis are similar, although mediastinal or hilar lymphadenopathy is less common in CBD and is usually seen in the presence of parenchymal opacities. Extrathoracic manifestations are also rare. Despite limited evidence, these findings are similar to those observed in pneumoconiosis with a sarcoid-like reaction due to exposure to dust other than of beryllium. Aluminum is frequently detected in patients with pneumoconiosis with a sarcoid-like reaction and is listed as an inorganic agent in the etiology of sarcoidosis. It was also detected in our patient and may have contributed to the etiology. Additionally, our case suggests that cessation of dust exposure may contribute to improvement under the aforementioned conditions.

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.

Assessment and Management of Occupational Hypersensitivity Pneumonitis

The diagnosis and treatment of occupational hypersensitivity pneumonitis (OHP) remain complex and challenging in the absence of diagnostic gold standards or clinical guidelines. This review provides an update of the recent literature regarding the different presentations of OHP and the diagnostic yield and value of the diagnostic tests currently available, which include occupational and medical history, laboratory tests (serum-specific immunoglobulins, environmental sampling), imaging, bronchoalveolar lavage, transbronchial biopsy, transbronchial cryobiopsy, surgical lung biopsy, and specific inhalation challenges. These tools provide a precise differential diagnosis within the framework of interstitial lung diseases. However, among the chronic fibrotic forms, distinguishing OHP from sarcoidosis, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis remains a diagnostic challenge. Avoidance of exposure is pivotal for OHP management, whereas corticosteroids are fundamental in the pharmacological approach to this disease. In addition, studies describing the long-term benefits of immunosuppressive and antifibrotic agents have increased the use of these treatments in OHP.

Inhalation challenge test using pigeon eggs for chronic hypersensitivity pneumonitis

BACKGROUND

Chronic hypersensitivity pneumonitis (CHP) remains a diagnostic challenge. The process of collecting and extracting serum and droppings from causative animals for the inhalation challenge test is complicated and the risk of inducing disease progression exists.

OBJECTIVE

To investigate the utility and safety of an inhalation challenge test using pigeon eggs.

METHODS

Pigeon eggs were pasteurized and mixed with a saline solution to produce an inhalation fluid. An inhalation challenge test was conducted on 19 patients with bird-related CHP and 17 patients with interstitial lung disease other than bird-related CHP. To identify antigens in pigeon eggs, the antigen-antibody responses of the pigeon eggs and serum from patients were evaluated using Western blotting.

RESULTS

The mean changes in C-reactive protein, alveolar-arterial oxygen difference, erythrocyte sedimentation rate, and lactate dehydrogenase significantly increased by 0.32 mg/dL (P = .014), 7.8 Torr (P = .002), 1.4 mm/h (P = .012), and 5.4 U/mL (P = .0019), respectively, in bird-related CHP group compared to the control 24 hours after the inhalation challenge test. Furthermore, within 24 hours of the inhalation test, the mean forced vital capacity decreased by 2.3% in the bird-related CHP group compared with a decline of 0.05% in the control group (P = .035). Serum collected from seven bird-related CHP patients who underwent the inhalation challenge test and reacted to antigens with molecular weights of 37-75 KDa, and these molecular weights were consistent with egg albumin and globulin.

CONCLUSION

Since a mild response was observed after the inhalation challenge test using pigeon eggs, this test was an obvious candidate for diagnosing bird-related CHP.

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.