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

Polymorphisms and haplotypes of TOLLIP and MUC5B are associated with susceptibility and survival in patients with fibrotic hypersensitivity pneumonitis

INTRODUCTION AND OBJECTIVES

Hypersensitivity pneumonitis (HP) is an interstitial lung disease with diverse clinical features that can present a fibrotic phenotype similar to idiopathic pulmonary fibrosis (IPF) in genetically predisposed individuals. While several single nucleotide polymorphisms (SNPs) have been associated with IPF, the genetic factors contributing to fibrotic HP (fHP) remain poorly understood. This study investigated the association of MUC5B and TOLLIP variants with susceptibility, clinical presentation and survival in Portuguese patients with fHP.

MATERIAL AND METHODS

A case-control study was undertaken with 97 fHP patients and 112 controls. Six SNPs residing in the MUC5B and TOLLIP genes and their haplotypes were analyzed. Associations with risk, survival, and clinical, radiographic, and pathological features of fHP were probed through comparisons among patients and controls.

RESULTS

MUC5B rs35705950 and three neighboring TOLLIP variants (rs3750920, rs111521887, and rs5743894) were associated with increased susceptibility to fHP. Minor allele frequencies were greater among fHP patients than in controls (40.7% vs 12.1%, P<0.0001; 52.6% vs 40.2%, P = 0.011; 22.7% vs 13.4%, P = 0.013; and 23.2% vs 12.9%, P = 0.006, respectively). Haplotypes formed by these variants were also linked to fHP susceptibility. Moreover, carriers of a specific haplotype (G-T-G-C) had a significant decrease in survival (adjusted hazard ratio 6.92, 95% CI 1.73-27.64, P = 0.006). Additional associations were found between TOLLIP rs111521887 and rs5743894 variants and decreased lung function at baseline, and the MUC5B SNP and radiographic features, further highlighting the influence of genetic factors in fHP.

CONCLUSION

These findings suggest that TOLLIP and MUC5B variants and haplotypes may serve as valuable tools for risk assessment and prognosis in fibrotic hypersensitivity pneumonitis, potentially contributing to its patient stratification, and offer insights into the genetic factors influencing the clinical course of the condition.

Diagnostic yield and safety of transbronchial lung cryobiopsy for diffuse parenchymal lung diseases diagnosis: Comparison between 1.7-mm and 1.9-mm probes

Purpose of the research: transbronchial lung cryobiopsy has been recently accepted as a valid and less invasive alternative to surgical lung biopsy. The purpose of this randomized controlled study was to evaluate, for the first time, the quality and safety of biopsy specimens obtained by using the new disposable 1.7-mm cryoprobe compared with the standard re-usable 1.9 mm cryoprobe in the diagnosis of diffuse parenchymal lung diseases. Methods: 60 consecutive patients were prospectively enrolled and randomly assigned to two different groups: 1.9 mm (group A) and 1.7 mm (group B); primary endpoints were pathological and multidisciplinary diagnostic yield, sample size and complication rate. Principal results: the pathological diagnostic yield of cryobiopsy was 100% in group A and 93.3% in group B (p = 0.718); cryobiopsy median diameter was 6.8 mm in group A and 6.7 mm in group B (p = 0,5241). Pneumothorax occurred in 9 patients in group A and 10 in group B (p = 0.951); mild-to-moderate bleeding in 7 cases and 9 cases in group A and B respectively (p = 0.559). No death or severe adverse events were observed. Conclusions: there was no statistically significant difference between the two groups, regarding diagnostic yield, adverse events and sampling adequacy.

Development and validation of a clinical, CT, genomic classifier and BAL scoring system for diagnosing idiopathic pulmonary fibrosis

BACKGROUND

The utility of incorporating a usual interstitial pneumonia (UIP) genomic classifier (GC) and bronchoalveolar lavage (BAL) cell count analysis alongside traditional clinical-imaging assessment in aiding in the multidisciplinary diagnosis of idiopathic pulmonary fibrosis (IPF) in patients with a non-definite high-resolution computed tomography (HRCT) UIP pattern is uncertain.

METHODS

We reviewed consecutive adult patients presenting with fibrotic interstitial lung disease (fILD) and a non-definite HRCT UIP pattern who underwent BAL and GC. The initial fILD diagnoses were re-evaluated after bronchoscopy and a final multidisciplinary consensus diagnosis was provided. We created a clinical score by analysing fILD clinical characteristics, GC and BAL results from 139 National Jewish Health patients and validated it at the University of Arizona (n=52). A multivariable model was developed and assessed using receiver operating characteristic curves.

RESULTS

43/139 (31%) and 29/52 (56%) patients in the derivation and validation cohort, respectively, were diagnosed with IPF after bronchoscopy, and 85/139 (61%) and 32/52 (61%) had a change in treatment, respectively. Compared to non-IPF, IPF patients had a similar progression-free survival (hazard ratio 1.50, 95% CI 0.76-2.95). The final model assigned a score to eight predictors: age, sex, HRCT probable UIP pattern, exposures, connective tissue disease signs/symptoms, Velcro crackles, GC results and BAL lymphocyte and macrophage counts. The final score demonstrated an area under the curve of 0.90 (95% CI 0.85-0.95) in the derivation cohort and 0.91 (95% CI 0.83-0.99) in the validation cohort.

CONCLUSION

The clinical-HRCT-BAL-GC IPF score may accurately estimate the post-test probability of IPF in patients with a non-definite HRCT UIP pattern.

Clinical impact of pre-determined guideline selection for the diagnosis of fibrotic hypersensitivity pneumonitis

INTRODUCTION AND OBJECTIVES

International guidelines for the diagnosis of Hypersensitivity Pneumonitis (HP) have improved the diagnostic standardization of this heterogeneous interstitial lung disease. Our goal was to determine how the final multidisciplinary discussion confidence level for suspected fibrotic HP (fHP) can be impacted by the application of different guidelines validated in this context.

MATERIALS AND METHODS

Retrospective study including patients submitted to transbronchial lung cryobiopsy (TBLC) with a final multidisciplinary meeting diagnosis of fHP. Both guidelines were applied to all patients in a stepwise fashion and directly compared according to the level of confidence in a fHP diagnosis.

RESULTS

A total of 170 patients were diagnosed with fHP after TBLC and subsequent multidisciplinary discussion. Overall, there was a statistically significant change in proportion towards higher confidence diagnostic levels using the CHEST guideline (p < 0.0001). Changes were significant at three different levels: ATS/JRS/ALAT's "fHP not excluded" subgroup significantly upscaled to CHEST's "provisional low-confidence" subgroup (76.2 % increase; p < 0.001) and the proportion of patients in ATS/JRS/ALAT's "low confidence" subgroup significantly upscaled to both CHEST's "provisional high-confidence" (67.4 % increase; p < 0.001) and "definitive fHP" (50 % increase; p < 0.001) subgroups. The alternative application of the CHEST guideline in multidisciplinary discussion would have resulted in 73 less TBLC (42.9 % decrease versus the ATS/JRS/ALAT-oriented decision).

CONCLUSIONS

This study suggests a significant increase in definite fHP diagnosis when applying the CHEST versus the ATS/JRS/ALAT guideline, resulting in almost a 43 % decrease in referrals to TBLC when compared with the latter due to a combination of less strict radiological criteria and a more prominent role of BAL.

Estimated prevalence and incidence of hypersensitivity pneumonitis in Japan

BACKGROUND

The latest guidelines on hypersensitivity pneumonitis (HP) categorise the disease as either fibrotic or non-fibrotic because of the greater clinical utility of this stratification. However, the prevalence and incidence of fibrotic and non-fibrotic HP are unknown. This study assessed the exact prevalence and incidence of fibrotic and non-fibrotic HP in Japan in 2021.

METHODS

For adults, the study hospitals were selected by stratified random sampling according to numbers of beds. The sampling rate was set at about 20%. The questionnaire survey was submitted to the target hospitals. For pediatric cases, a survey was distributed to all members of the Japanese Society of Pediatric Pulmonology and Japanese Society of Pediatric Allergy and Clinical Immunology.

RESULTS

Regarding adult cases, in total, 575 facilities responded to the survey, resulting in a response rate of 36.4%. The estimated prevalence and incidence of fibrotic HP were 6.3 and 2.5 per 100,000 population, respectively, versus 3.6 and 2.0 per 100,000 population, respectively, for non-fibrotic HP. Both fibrotic and non-fibrotic HP were more prevalent in southern Japan (Kyushu) and less prevalent in northern Japan (Hokkaido). The incidence of non-fibrotic HP was significantly lower in December than in the other months (relative risk ratio = 0.36, p < 0.001). Three cases of fibrotic HP and five cases of non-fibrotic HP were identified in children.

CONCLUSIONS

This study determined the prevalence and incidence of fibrotic and non-fibrotic HP in Japan for the first time.

Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report

Bird fancier's lung (BFL) is a subtype of hypersensitivity pneumonitis (HP), an immune-mediated interstitial lung disease (ILD) resulting from the repeated inhalation of avian proteins found in bird droppings, feathers, and serum. Diagnosing BFL is challenging due to nonspecific symptoms that overlap with other ILDs like idiopathic pulmonary fibrosis and sarcoidosis. This complexity is heightened during pandemics such as coronavirus disease 2019 (COVID-19), where respiratory symptoms may be misattributed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, leading to diagnostic anchoring and delays in appropriate management. High-resolution computed tomography (HRCT) is pivotal in detecting subtle pulmonary changes, characteristic of HP, surpassing standard chest radiographs. We present the case of a 43-year-old male pigeon keeper with an eight-week history of progressive dyspnea on exertion and intermittent chest pain. Despite unremarkable chest X-rays, HRCT revealed bilateral diffuse centrilobular nodules, patchy ground-glass opacities, and a mosaic attenuation pattern without fibrosis, consistent with acute HP. A thorough occupational history uncovered significant avian antigen exposure, and a family history suggested genetic susceptibility. The patient was diagnosed with BFL and treated with a tapering regimen of oral corticosteroids, starting at 40 mg/day. He was advised to cease pigeon keeping and avoid future avian exposure. Significant symptomatic improvement occurred within three months. Follow-up imaging over one year confirmed stable lung parenchyma with no disease progression or recurrence. This case underscores the importance of incorporating detailed occupational histories and utilizing advanced imaging modalities like HRCT when standard imaging is inconclusive. Early identification and intervention are crucial to prevent progression to chronic HP and irreversible fibrosis. Management should focus on reducing inflammation with corticosteroids and implementing strict environmental controls to prevent re-exposure. Long-term follow-up is essential to monitor for recurrence and maintain remission. Clinicians should remain vigilant for alternative diagnoses during pandemics to avoid diagnostic anchoring. This case contributes to the evidence supporting HRCT's critical role in early HP detection and emphasizes heightened clinical awareness of occupational lung diseases. A multidisciplinary approach involving pulmonologists, radiologists, and occupational medicine specialists is key to optimizing outcomes in HP and other ILDs.

Hypersensitivity pneumonitis: A high index of clinical suspicion is key for early diagnosis and successful treatment

See related article

Use of mycophenolate mofetil for the treatment of fibrotic hypersensitivity pneumonitis

INTRODUCTION

The optimal treatment of fibrosing hypersensitivity pneumonitis (fHP) is not well understood. The aim of the study was to obtain information about the usefulness of mycophenolate mofetil (MMF) in its treatment.

MATERIAL AND METHODS

Quasi-experimental analysis of patients diagnosed with fHP and treated with MMF for one year, in a single centre. From the start of treatment, data collection was prospective.

RESULTS

73 were included and 58 completed the study. FVC% and DLCO% decreased until starting MMF (year -1 to year 0). After completion of treatment (year 1), FVC% stabilised (p=0.336) and DLCO% improved significantly (p=0.004) compared to year 0. Dyspnoea, number of patients without corticosteroids and mean corticosteroid dose also improved significantly (p<0.001 in all cases). Being male and having a history of tuberculosis were predictors of poor drug response [AUC = 0.89 (95% CI: 0.80-0.98)]. 45 adverse effects were observed in 34 patients (46.6%). In 4 cases (5.5%), the adverse effect was severe and required discontinuation of treatment.

CONCLUSIONS

In patients with fHP, MMF improves lung function and dyspnoea and reduces both the number of patients requiring oral corticosteroids and their mean dose in those who completed 1 year of treatment. The model constructed predicts which patients will respond poorly to treatment, with good discriminative ability and only a small percentage of patients will not tolerate treatment. Further prospective, randomised clinical trials are needed to define the role of this treatment in fHP.

Aspergillus IgG antibody testing in the diagnosis of hypersensitivity pneumonitis: A scoping review

BackgroundDiagnosis of hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis requires a combination of tests with antibody testing playing a supportive role to identify exposures.ObjectivesWe conducted a scoping review on Aspergillus antibody testing in Aspergillus-related HP to identify the utility and diagnostic cutoffs proposed in the literature. We compared these cutoffs with studies of chronic pulmonary aspergillosis (CPA) and manufacturers' cutoffs.Eligibility criteriaOnly studies addressing the diagnostic value of Aspergillus IgG or precipitins for HP were included. Separately papers defining cutoffs for CPA were tabulated.Sources of evidencePublished papers were identified in literature searches in Embase, Web of Science, and Medline.ResultsWe identified 414 papers, of which 12 were included, all published between 1965 and 2005. Occupational HP linked to Aspergillus spp. exposure included Farmer's Lung, Malt-Worker's Lung, Esparto Worker's Lung, and Woodworker's lung (Sawmill-workers). No studies directly addressed serological testing in Tobacco Worker's lung, Compost Lung, or poultry workers. Among Aspergillus species exposure, A. fumigatus was most commonly described; others included A. umbrosus (now A. glaucus), A. clavatus, and A. niger. Antibody tests included ELISA, BALISA, precipitin tests and ImmunoCAP, with a higher sensitivity of ELISA and ImmunoCAP tests compared to precipitin tests. Patients with HP linked to Aspergillus exposures, were positive in 156/290 (53.8%) compared to 96/615 (15.6%) in those with similar occupational exposures without HP. In malt workers with HP 35/53 (66%) had detectable A. clavatus IgG antibody compared to 0/53 A. fumigatus IgG, and 13/74 (18%) exposed but unaffected workers, but are not commercially available.ConclusionsImproved means of establishing or ruling out Aspergillus exposure are required, given the negative consequences for patients of continued Aspergillus inhalation. Modern studies with commercially available Aspergillus IgG antibody assays are required to define appropriate cutoffs for HP, given numerous studies published for chronic pulmonary aspergillosis.

Predictive factors of progression in mild fibrosing interstitial lung disease patients with gender-age-physiology score of 3 or less

BACKGROUND

The prognostic factors in mild fibrosing interstitial lung disease (FILD) have not been established.

METHODS

We retrospectively attempted to identify predictive factors of annual progression in mild FILD with gender-age-physiology (GAP) score of 3 or less using logistic regression analysis. Annual FILD progression was defined as meeting any two or more of the following conditions: 1, more than 10% decrease in forced vital capacity (FVC) or 15% decrease in diffusing capacity of the lungs for carbon monoxide (DLCO); 2, worsening of dyspnea; 3, worsening of fibrotic change on CT at 1 year after admission.

RESULTS

Univariate analysis showed that diagnosis of connective tissue disease-associated ILD, CT-definite usual interstitial pneumonia (UIP) pattern, composite physiologic index, FVC, DLCO, lowest SpO2 and decrease in SpO2, and walk distance in the 6-minutes walk test (6MWT), chronic pulmonary emphysema assessment test (CAT) score, and some variables in Short-Form 36 were significantly associated with incidence of annual progression. Multivariate analysis showed that independent predictive factors were diagnosis of idiopathic pulmonary fibrosis (IPF) and fibrotic hypersensitivity pneumonitis (HP), CT-definite UIP pattern, lowest SpO2 and decrease in SpO2 in the 6MWT, and CAT score. In logistic regression analysis among 63 patients with non-IPF-ILD, diagnosis with fibrotic HP, lowest SpO2 and decrease in SpO2 in the 6MWT, and CAT score were also independent risk factors for annual FILD progression.

CONCLUSIONS

Exercise-induced hypoxia, patient-reported outcome, radiological UIP pattern, and diagnosis with fibrotic HP are independent predictors of annual progression in mild FILD.

Interstitial lung disease presents with varying characteristics in patients with non-Hodgkin lymphoma undergoing rituximab-containing therapies

Although the incidence and outcomes of rituximab-induced interstitial lung disease (RILD) have been partially reported, there are no systematic studies on the characteristics and types of RILD. This study aimed to investigate the clinical characteristics, bronchoalveolar lavage (BAL) findings, and treatment course of RILD in patients with non-Hodgkin lymphoma. We retrospectively analyzed the data from 321 patients with non-Hodgkin lymphoma who developed RILD between 2020 and 2022. The extent, distribution, and radiologic patterns of interstitial lung disease were determined using high-resolution computed tomography of the chest. BAL was performed in 299 (93.1%) patients to determine cellular distribution patterns and identify pathogenic microorganisms using metagenomic next-generation sequencing. All patients received combination therapy, with cyclophosphamide, doxorubicin, vincristine, and prednisone being the most commonly administered regimens. The median time from treatment to RILD development was 1.7 months. In the 217 patients who underwent metagenomic next-generation sequencing, 179 pathogenic microorganisms were detected, including 77 (43.0%) bacteria, 45 (25.1%) viruses, 28 (15.6%) Pneumocystis jirovecii strains, 17 (9.5%) fungi, 6 (3.5%) Mycobacterium tuberculosis, and 6 (3.5%) atypical pathogens. All RILD diagnoses were based on multidisciplinary team discussions and compliance with international standards. In conclusion, RILD exhibits a range of radiological and BAL patterns, reflecting different interstitial lung disease types. The most common patterns of RILD are infectious lung disease, organizing pneumonia, and nonspecific interstitial pneumonia. These findings enhance the understanding of RILD in patients with non-Hodgkin lymphoma and serve as a reference for best management guidelines in these patients.

3D-CT-derived lung volumes and mortality risk in patients with fibrotic hypersensitivity pneumonitis

BACKGROUND

Hypersensitivity pneumonitis (HP) is a complex and heterogenous interstitial lung disease (ILD) that occurs in susceptible individuals due to certain inhaled antigens. Fibrotic-HP is a major underlying disease of progressive pulmonary fibrosis. Therefore, in addition to the radiological features of HP, quantitatively measuring fibrosis is important to evaluate disease severity and progression. The present study aimed to compare three-dimensional computed tomography (3D-CT)-derived lung volumes (LVs) of patients with HP and determine its association with mortality risk.

METHODS

In this retrospective and multicenter cohort study, 126 patients diagnosed with HP (fibrotic, n = 72 and non-fibrotic, n = 54) with a confidence level higher than moderate were enrolled. Each lobe LV was measured using 3D-CT at the time of diagnosis and standardized using predicted forced vital capacity. The 3D-CT LV was compared with those of 42 controls and 140 patients with idiopathic pulmonary fibrosis (IPF).

RESULTS

Compared to patients with fibrotic-HP, the standardized total LV was significantly higher in controls and patients with non-fibrotic-HP and was similar in patients with IPF. Longitudinal analyses demonstrated that approximately half of the patients with fibrotic-HP had an annual decrease in total LV. Decreased total and lower-lobe LVs were associated with shorter survival, and were independently associated with mortality together with ongoing exposure to inciting antigens. A composite model consisting of ongoing exposure to inciting antigens and total or lower-lobe LV successfully classified mortality risk into three groups.

CONCLUSIONS

Quantitatively measuring standardized LV can help determine disease severity, progression, and mortality risk in patients with fibrotic-HP.

Hypersensitivity pneumonitis radiologic features in interstitial lung diseases

BACKGROUND

The radiologic criteria of hypersensitivity pneumonitis (HP) guidelines focus on four HP compatible features (HPCF) in high-resolution computed tomography (HRCT): ground glass opacities, mosaic attenuation, air-trapping, and centrilobular nodules. However, evidence to support these criteria are limited.

METHODS

Consecutive interstitial lung disease (ILD) patients who underwent HRCT between 2016 and 2021 in three medical centers were included. We assessed the prevalence of HPCF in each ILD and their association with HP diagnosis. We evaluated the impact of HPCF amount for HP diagnosis and the performance of the radiologic criteria by the ATS/JRS/ALAT and CHEST HP guidelines.

RESULTS

436 patients with ILD were included (mean age 66, 48 % females), of them, 56 (13 %) with HP. All four HPCF were more prevalent in HP than in non-HP ILD (p < 0.001 for all). In multivariate analysis, air-trapping was the strongest independent predictor (AOR 4.1, 95 % CI 2-8.4, p < 0.001). Centrilobular nodules were present almost exclusively in HP and smoking-related ILD. The amount of HPCF in HRCT had an excellent predictive ability for HP diagnosis (receiver operating characteristic AUC 0.85, 95 % CI 0.80-0.90). The radiologic criteria of both guidelines had high specificity for "typical HP" and high sensitivity for "compatible with HP", although with low positive predictive values. Our findings remained robust even when including only patients that had a diagnostic biopsy.

CONCLUSION

The presence and amount of HPCF in HRCT predicted HP diagnosis in real-life settings. While current HP radiologic criteria demonstrated good diagnostic performance, our findings highlight areas for future improvement.

Pathological features of connective tissue disease-associated interstitial lung disease in transbronchial cryobiopsies

AIM

Transbronchial cryobiopsies are increasingly used for the diagnosis of interstitial lung disease (ILD), but there is a lack of published information on the features of specific ILD in cryobiopsies. Here we attempt to provide pathological guidelines for separating usual interstitial pneumonia (UIP) of idiopathic pulmonary fibrosis (IPF), fibrotic hypersensitivity pneumonitis (FHP) and connective tissue disease-associated ILD (CTD-ILD) in cryobiopsies.

METHODS

We examined 120 cryobiopsies from patients with multidisciplinary discussion (MDD)-established CTD-ILD and compared them to a prior series of 121 biopsies from patients with MDD-established IPF or FHP.

RESULTS

A non-specific interstitial pneumonia (NSIP) pattern alone was seen in 36 of 120 (30%) CTD-ILD, three of 83 (3.6%) FHP and two of 38 (5.2%) IPF cases, statistically favouring a diagnosis of CTD-ILD. The combination of NSIP + OP was present in 29 of 120 (24%) CTD-ILD, two of 83 (2.4%) FHP and none of 38 (0%) IPF cases, favouring a diagnosis of CTD-ILD. A UIP pattern, defined as fibroblast foci plus any of patchy old fibrosis/fibrosis with architectural distortion/honeycombing, was identified in 28 of 120 (23%) CTD-ILD, 45 of 83 (54%) FHP and 27 of 38 (71%) IPF cases and supported a diagnosis of FHP or IPF. The number of lymphoid aggregates/mm2 and fibroblast foci/mm2 was not different in IPF, CTD-ILD or FHP cases with a UIP pattern. Interstitial giant cells supported a diagnosis of FHP or CTD-ILD over IPF, but were infrequent.

CONCLUSIONS

In the correct clinical/radiological context the pathological findings of NSIP, and particularly NSIP plus OP, favour a diagnosis of CTD-ILD in a cryobiopsy, but CTD-ILD with a UIP pattern, FHP with a UIP pattern and IPF generally cannot be distinguished.

[Diagnosis and Treatment of Hypersensitivity Pneumonitis - S2k Guideline of the German Respiratory Society and the German Society for Allergology and Clinical Immunology]

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD) in sensitized individuals caused by a large variety of inhaled antigens. The clinical form of acute HP is often misdiagnosed, while the chronic form, especially the chronic fibrotic HP, is difficult to differentiate from other fibrotic ILDs. The present guideline for the diagnosis and treatment of HP replaces the former German recommendations for the diagnosis of HP from 2007 and is amended explicitly by the issue of the chronic fibrotic form, as well as by treatment recommendations for the first time. The evidence was discussed by a multidisciplinary committee of experts. Then, recommendations were formulated for twelve questions on important issues of diagnosis and treatment strategies. Recently published national and international guidelines for ILDs and HP were considered. Detailed background information on HP is useful for a deeper insight into HP and the handling of the guideline.

Diagnosis and management of hypersensitivity pneumonitis in adults: A position statement from the Thoracic Society of Australia and New Zealand

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD) relating to specific occupational, environmental or medication exposures. Disease behaviour is influenced by the nature of exposure and the host response, with varying degrees of lung inflammation and fibrosis seen within individuals. The differentiation of HP from other ILDs is important due to distinct causes, pathophysiology, prognosis and management implications. This Thoracic Society of Australia and New Zealand (TSANZ) position statement aims to provide an up-to-date summary of the evidence for clinicians relating to the diagnosis and management of HP in adults, in the Australian and New Zealand context. This document highlights recent relevant findings and gaps in the literature for which further research is required.

Reevaluating diagnosis in interstitial lung disease with a second multidisciplinary discussion

BACKGROUND

The importance of multidisciplinary discussion (MDD) for diagnosing interstitial lung disease (ILD) is emphasized by several international guidelines. While initial diagnoses are often provisional and require periodic re-evaluation, there is a lack of literature regarding the role of follow-up MDD in clinical practice.

METHODS

From September 2020 to January 2022, patients underwent an initial MDD (MDD1) based on clinical, radiological, and pathological evaluations. Each diagnosis was assigned a confidence level. One year later, a second MDD (MDD2) was conducted for re-evaluation, based on subsequent clinical and radiological information. Changes in diagnosis and confidence levels between MDD1 and MDD2 were assessed.

RESULTS

Among 52 patients enrolled in both MDDs, the diagnosis for 13 (25%) was revised at MDD2. Of these, 10 patients were initially diagnosed with unclassifiable ILD, and 3 received a low confidence diagnosis of either idiopathic pulmonary fibrosis or idiopathic nonspecific interstitial pneumonia. The most common diagnostic revision was due to the deterioration after antigen exposure or improvement after antigen avoidance, which resulted in a revised diagnosis of HP at MDD2.

CONCLUSIONS

Our findings underscore the importance of periodic reassessment of MDD to improve the accuracy of ILD diagnosis. This study highlights the significance of longitudinal clinical and radiological evaluation for diagnostic revision, even in situations when rebiopsy is not feasible.

Neutrophils and Lymphocytes: Yin and Yang of Lung Fibrosis and Patient Outcome in Diffuse Interstitial Lung Diseases

Objective: Antifibrotics can improve the outcome of patients with idiopathic pulmonary fibrosis (IPF) and other fibrosing interstitial lung diseases (F-ILDs), but predictive biomarkers at diagnosis are needed to guide the use of immunomodulating and antifibrotic therapies. Methods: Flow cytometry quantification of lymphocytes and neutrophils in bronchoalveolar lavage (BAL) of 145 IPFs, 561 non-IPF-ILDs (125 F-ILDs), and 112 BAL controls were retrospectively correlated with the incidence of fibrosis and third-quartile overall survival (Q3-OS). Results: The incidence of IPF was directly proportional (9.6%, 22.2%, and 42.6%, p < 0.001) to BAL neutrophil counts (<5%, 5-15%, and >15%), but inversely proportional (34.1%, 18.6%, and 8.8%, p < 0.001) to BAL lymphocyte counts (<7%, 7-20%, and >20%). Elevated neutrophils (>5%) with low lymphocytes (<7%) were associated with an increasingly higher incidence of IPF (10.0-56.3%, p < 0.001) in patients aged 40 to 80, compared to the rest of patients (13.0-17.1%). Lymphocytes >20% compared to lymphocytes <7% strongly protected patients with neutrophils >15% (59.7% vs. 20.7%, p < 0.001) from IPF. In contrast, the incidence of F-ILD was not clearly related to BAL lymphocyte/neutrophil counts. Although, IPF and F-ILD showed a shorter Q3-OS (1.8 ± 0.3 and 4.6 ± 0.8 years; p < 0.001) than non-fibrotic-ILDs (11.1 ± 1.3 years), lymphocyte and neutrophil counts were associated with a longer and shorter Q3-OS of non-fibrotic-ILDs (p < 0.03) and F-ILDs (p < 0.04), respectively, but not with a Q3-OS of IPF patients (p < 0.708). Corticosteroids in patients with fibrosis showed a shorter Q3-OS than other immunomodulators (2.4 ± 0.3 vs. 4.0 ± 1.8 years, p = 0.011). Conclusions: Accurate counting of BAL lymphocytes and neutrophils by flow cytometry in ILD patients at diagnosis could help guide immunomodulatory and antifibrotic therapies.

Development and evaluation of a questionnaire to capture environmental and occupational inhalational exposures in adults with fibrotic interstitial lung disease

BACKGROUND

Identification of exposures in patients with interstitial lung diseases (ILDs) is essential for diagnosis and management and can be facilitated through the use of exposure questionnaires. However, for most ILDs, a patient-focused questionnaire is lacking. Cognitive interviewing is a methodology used to evaluate sources of understanding and misunderstanding in a questionnaire and to provide evidence of content validity. We developed and refined a new exposure questionnaire for patients with fibrotic ILDs by using cognitive interviewing to establish its understandability and content validity.

METHODS

An exposure assessment questionnaire was developed by a multidisciplinary team. Cognitive interviews with 24 patients with fibrosing ILDs were conducted by trained interviewers over the phone or Zoom using a semi-structured interview guide. The questionnaire was amended based on the interviewers' interpretation of sources of misunderstanding. The revised questionnaire was tested in a second round of cognitive interviews with a different group of 24 patients.

RESULTS

Among the 48 patients who completed interviews, mean age was 61 years, 58.3% were male and 75.0% were white. Based on the first round of cognitive interviews, the multidisciplinary team modified the questions, organization, and instructions of the questionnaire to facilitate recall, adjust for exposures that were frequently misunderstood or required clarification, and focus on clinically relevant exposures. The revised questionnaire performed well in the second round of interviews.

CONCLUSION

An exposure questionnaire, developed with input from patients, can be used to assess clinically relevant exposures in adults with fibrosing ILDs. This is the first questionnaire for all types of fibrosing ILD to have undergone content validation.

Solitary Pure Ground-glass Opacity Suspected of Being the Initial Presentation of Nonfibrotic Hypersensitivity Pneumonitis

We herein report a rare case of hypersensitivity pneumonitis (HP) that was initially demonstrated as solitary pure ground-glass opacity (GGO) on chest computed tomography (CT). A 51-year-old woman with a history of breast cancer underwent follow-up CT, which revealed solitary pure GGO. The patient developed exertional dyspnea after two years, and CT revealed diffuse centrilobular nodules in addition to GGO, which had increased in size. An antigen avoidance test was performed to diagnose HP, leading to the resolution of CT abnormalities, including the GGO. Our findings suggested that nonfibrotic HP can present as solitary pure GGO.

Validation of a computed tomography diagnostic model for differentiating fibrotic hypersensitivity pneumonitis from idiopathic pulmonary fibrosis

BACKGROUND

The diagnosis of fibrotic hypersensitivity pneumonitis (fHP) from other interstitial lung diseases, particularly idiopathic pulmonary fibrosis (IPF), is often difficult. This study aimed to examine computed tomography (CT) findings that were useful for differentiating between fHP and IPF and to develop and validate a radiological diagnostic model.

METHODS

In this study, 246 patients (fHP, n = 104; IPF, n = 142) from two institutions were included and randomly divided into the test (n = 164) and validation (n = 82) groups (at a 2:1 ratio). Three radiologists evaluated CT findings, such as pulmonary fibrosis, small airway disease, and predominant distribution, and compared them between fHP and IPF using binomial logistic regression and multivariate analysis. A prognostic model was developed from the test group and validated with the validation group.

RESULTS

Ground-glass opacity (GGO) with traction bronchiectasis (TB), honeycombing, hypoattenuation area, three-density pattern, diffuse craniocaudal distribution, peribronchovascular opacities in the upper lung, and random distribution were more common in fHP than in IPF. In multivariate analysis, GGO with TB, peribronchovascular opacities in the upper lung, and random distribution were significant features. The area under the curve of the fHP diagnostic model with the three aforementioned CT features was 0.733 (95% confidence interval [CI], 0.655-0.811, p < 0.001) in the test group and 0.630 (95% CI, 0.504-0.755, p < 0.047) in the validation group.

CONCLUSION

GGO with TB, peribronchovascular opacities in the upper lung, and random distribution were important CT features for differentiating fHP from IPF.

Does a Type of Inciting Antigen Correlate with the Presence of Lung Fibrosis in Patients with Hypersensitivity Pneumonitis?

Introduction: Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens. In some patients, fibrotic HP is diagnosed. Factors predisposing to the development of fibrotic lung disease in HP patients are not well documented in the literature. The genetic susceptibility of the patient, type of inciting antigen, and type of exposure, as well as various demographic and clinical variables, may influence the fibrotic process. Aim: The aim of the present study was to investigate whether the type of inciting antigen increases the risk of fibrotic lung disease in HP patients. Methods: Clinical data of consecutive patients with HP diagnosed between 2019 and 2023 were retrospectively reviewed. The exposition to the inciting antigens was investigated by the standardized questionnaire. Recent HP classification into fibrotic (fHP) and non-fibrotic (non-fHP) types was applied. Results: Sixty-six patients diagnosed with HP were analyzed. All patients filled out the exposure questionnaire, and 62 (94%) reported at least one possible exposure. The most prevalent exposures reported were avian, water systems, feather duvets, and hay/straw. Exposure to avian antigens as well as to coal/biomass heating were significantly more prevalent among patients with fHP compared to those with non-fHP (70% vs. 40%, p = 0.03 and 27% vs. 5%, p = 0.04, respectively). Nevertheless, in the multivariate analysis, older age at diagnosis was the only factor influencing the development of fHP (OR 1.064, 95% CI 1.004 to 1.138, p = 0.04). Reported avian antigen exposure correlated well with positive precipitins to avian antigens, whereas no correlation was found between hay/straw exposure and positive antibodies to termophilic actinomycetes. Conclusions: Exposure to birds and coal heating was the most frequently present factor in subjects with fHP, but only older age at diagnosis remained a significant fHP predictor in the multifactor analysis.

Effect of antigen removal in hypersensitivity pneumonitis

BACKGROUND

Antigen removal is a cornerstone of treatment of hypersensitivity pneumonitis (HP), but its association with transplant-free survival remains unclear. Further, HP guidelines conflict as to whether antigen removal is a recommended diagnostic test in patients with suspected HP.

OBJECTIVE

The purpose of this study is to (1) evaluate the impact of antigen removal on transplant-free survival and (2) to describe the impact of antigen removal on pulmonary function testing and imaging in a retrospective cohort of patients with HP.

METHODS

We retrospectively identified HP patients evaluated between 2011 and 2020. Demographic, physiologic, radiographic, and pathologic data were recorded.

RESULTS

212 patients were included in the cohort. Patients who identified and removed antigen had a better transplant-free survival than patients who did not identify antigen and patients who identified but did not remove antigen. Antigen removal was associated with improvement in FVC by 10% predicted in 16.9% of patients with fibrotic HP and 56.7% of patients with nonfibrotic HP.

DISCUSSION

Our results suggest that over 50% of nonfibrotic HP patients and 16.9% of fibrotic HP patients improve with exposure removal. In addition, antigen removal, rather than antigen identification, is associated with transplant-free survival in HP.

Computed Tomography of Contemporary Occupational Lung Disease: A Pictorial Review

Occupational lung disease remains one of the most common work-related illnesses and accounts for most deaths from occupational illness. Occupational lung diseases often have delayed manifestation over decades and nonspecific clinical presentations, making it challenging for clinicians to promptly identify the disease and implement preventive measures. Radiologists play a crucial role in identifying and diagnosing occupational lung diseases, allowing for removal of the exposure and early medical intervention. In this review, we share our clinical and radiologic approach to diagnosing occupational lung disease and its subtypes. A collection of sample cases of occupational lung diseases commonly encountered in the modern era at a large Canadian university hospital is included to facilitate understanding. This review will provide radiologists with valuable insights into recognizing and diagnosing occupational lung diseases.

Hypersensitivity Pneumonitis on Thin-Section Chest CT Scans: Diagnostic Performance of the ATS/JRS/ALAT versus ACCP Imaging Guidelines

Purpose To compare the diagnostic performance of the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax (ATS/JRS/ALAT) versus the American College of Chest Physicians (ACCP) imaging classifications for hypersensitivity pneumonitis (HP). Materials and Methods Patients in the institutional review board-approved Interstitial Lung Disease (ILD) registry referred for multidisciplinary discussion (MDD) at the authors' institution (January 1, 2006-April 1, 2021) were included in this retrospective study when ILD was diagnosed at MDD. MDD diagnoses included HP, connective tissue disease-ILD, and idiopathic pulmonary fibrosis. Retrospective review of thin-section CT images was performed in consensus by two cardiothoracic radiologists blinded to the diagnosis. Diagnostic patterns were determined for thin-section CT images using both classifications. Discordance rates were determined. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were assessed using MDD diagnosis as the reference standard. Results A total of 297 patients were included in the study: 200 (67%) with HP, 49 (16%) with connective tissue disease-ILD, and 48 (16%) with idiopathic pulmonary fibrosis at MDD. The discordance rate between the two classifications was 21%. Assuming low HP prevalence (10%), ATS/JRS/ALAT classification outperformed ACCP classification, with greater accuracy (92.3% vs 87.6%) and greater positive predictive value (60.7% vs 42.9%). Assuming high prevalence (50%), accuracy and negative predictive value were superior using ACCP classification (81.7% vs 79.7% and 77.7% vs 72.6%, respectively), and positive predictive value was superior using ATS/JRS/ALAT classification (93.3% vs 87.1%). Conclusion Accuracy of the ATS/JRS/ALAT and ACCP HP classifications was greater in settings with low and high HP prevalence, respectively. Diagnostic performance of both classifications was discordant in a minority of cases. Keywords: CT, Thorax, Hypersensitivity Pneumonitis, Interstitial Lung Disease Supplemental material is available for this article. © RSNA, 2024.

Growing from common ground: nontuberculous mycobacteria and bronchiectasis

Bronchiectasis and nontuberculous mycobacteria (NTM) are intricately intertwined, with NTM capable of being both a cause and consequence of bronchiectatic disease. This narrative review focuses on the common ground of bronchiectasis and NTM pulmonary disease (NTM-PD) in terms of diagnostic approach, underlying risk factors and treatment strategies. NTM-PD diagnosis relies on a combination of clinical, radiological and microbiological criteria. Although their epidemiology is complicated by detection and reporting biases, the prevalence and pathogenicity of NTM species vary geographically, with Mycobacterium avium complex and Mycobacterium abscessus subspecies most frequently isolated in bronchiectasis-associated NTM-PD. Diagnosis of nodular bronchiectatic NTM-PD should prompt investigation of host factors, including disorders of mucociliary clearance, connective tissue diseases and immunodeficiencies, either genetic or acquired. Treatment of NTM-PD in bronchiectasis involves a multidisciplinary approach and considers the (sub)species involved, disease severity and comorbidities. Current guideline-based antimicrobial treatment of NTM-PD is considered long, cumbersome and unsatisfying in terms of outcomes. Novel treatment regimens and strategies are being explored, including rifampicin-free regimens and inclusion of clofazimine and inhaled antibiotics. Host-directed therapies, such as immunomodulators and cytokine-based therapies, might enhance antimycobacterial immune responses. Optimising supportive care, as well as pathogen- and host-directed strategies, is crucial, highlighting the need for personalised approaches tailored to individual patient needs. Further research is warranted to elucidate the complex interplay between host and mycobacterial factors, informing more effective management strategies.

Usefulness of Transbronchial Lung Cryobiopsy When Starting Antifibrotic Treatment and Predicting Progressive Fibrosing Interstitial Lung Disease: Descriptive Research

BACKGROUND

Although transbronchial lung cryobiopsy (TBLC) is widely used in diagnostic algorithms for various interstitial lung diseases (ILDs), its real-world utility in the therapeutic decision-making strategy for ILD patients remains unclear, in particular, when judging the time to start antifibrotic agents.

METHODS

We analyzed medical records of 40 consecutive patients with idiopathic or fibrotic hypersensitivity pneumonitis who underwent TBLC. A TBLC-based usual interstitial pneumonia (UIP) score was used to assess three morphologic descriptors: patchy fibrosis, fibroblastic foci, and honeycombing.

RESULTS

In our 40 patients with ILD, the most frequent radiological feature was indeterminate for UIP (45.0%). Final diagnosis included idiopathic pulmonary fibrosis (22.5%), fibrotic nonspecific interstitial pneumonia (5.0%), fibrotic hypersensitivity pneumonitis (35.0%), and unclassifiable ILD (37.5%). Linear mixed-effects analysis showed that declines in the slopes of %FVC and %DLCO in patients with TBLC-based UIP "Score ≥ 2" were significantly steeper than those of patients with "Score ≤ 1." During follow-up of patients with Score ≥ 2 (n = 24), more than half of them (n = 17) received an antifibrotic agent, with most patients (n = 13) receiving early administration of the antifibrotic agent within 6 months after the TBLC procedure.

CONCLUSIONS

TBLC-based UIP Score ≥ 2 indicated the increased possibility of a progressive fibrosis course that may prove helpful in predicting progressive pulmonary fibrosis/progressive fibrosing ILD even if disease is temporarily stabilized due to anti-inflammatory agents. Patients may benefit from early introduction of antifibrotic agents by treating clinicians.

Impact of Antigen Exposure on Outcomes and Treatment Response in Fibrotic Hypersensitivity Pneumonitis

BACKGROUND

Patients with fibrotic hypersensitivity pneumonitis (fHP) are frequently treated with immunosuppression to slow lung function decline; however, the impact of this treatment has not been studied across different types of antigen exposure.

RESEARCH QUESTION

In patients with fHP, do disease outcomes and response to treatment vary by antigen type?

STUDY DESIGN AND METHODS

A multicenter interstitial lung disease database (Canadian Registry for Pulmonary Fibrosis) was used to identify patients with fHP. The causative antigen was categorized as avian, mold, unknown, or other. Treatment was defined as mycophenolate ≥ 1,000 mg/d or azathioprine ≥ 75 mg/d for ≥ 30 days. Statistical analysis included t tests, χ2 tests, and one-way analysis of variance. Unadjusted and adjusted competing risks and Cox proportional hazards models were used to assess survival.

RESULTS

A total of 344 patients were identified with the following causative antigens: avian (n = 93; 27%), mold (n = 88; 26%), other (n = 15; 4%), and unknown (n = 148; 43%). Patient characteristics and lung function were similar among antigen groups with a mean FVC % predicted of 75 ± 20. The percent of patients treated with immunosuppression was similar between antigens with 58% of patients treated. There was no change in lung function or symptom scores with the initiation of immunosuppression in the full cohort. Immunosuppression was not associated with a change in survival for patients with avian or mold antigen (avian: hazard ratio, 0.41; 95% CI, 0.11-1.59; P = .20; mold: hazard ratio, 1.13; 95% CI, 0.26-4.97; P = .88). For patients with unknown causative antigen, survival was worse when treated with immunosuppression (hazard ratio, 2.65; 95% CI, 1.01-6.92; P = .047).

INTERPRETATION

Response to immunosuppression varies by antigen type in patients with fHP. Additional studies are needed to test the role of immunosuppression in fHP, and particularly in those with an unknown antigen.

Imaging of Small Airways Disease

Bronchiolitis refers to a small airways disease and may be classified by etiology and histologic features. In cellular bronchiolitis inflammatory cells involve the small airway wall and peribronchiolar alveoli and manifest on CT as centrilobular nodules of solid or ground glass attenuation. Constrictive bronchiolitis refers to luminal narrowing by concentric fibrosis. Direct CT signs of small airway disease include centrilobular nodules and branching tree-in-bud opacities. An indirect sign is mosaic attenuation that may be exaggerated on expiratory CT and represent air trapping. Imaging findings can be combined with clinical and pathologic data to facilitate a more accurate diagnosis.

First Report of the Prevalence at Baseline and after 1-Year Follow-Up of Treatable Traits in Interstitial Lung Diseases

Different factors, not limited to the lung, influence the progression of ILDs. A "treatable trait" strategy was recently proposed for ILD patients as a precision model of care to improve outcomes. However, no data have been published so far on the prevalence of TTs in ILD. A prospective, observational, cohort study was conducted within the ILD Program at the IRCCS Humanitas Research Hospital (Milan, Italy) between November 2021 and November 2023. TTs were selected according to recent literature and assigned during multidisciplinary discussion (MDD) to one of the following categories: pulmonary, etiological, comorbidities, and lifestyle. Patients were further divided into four groups according to their post-MDD diagnosis: idiopathic ILD, sarcoidosis, connective tissue disease-ILD, and other ILD. The primary study outcome was the prevalence of each TT in the study population. A total of 116 patients with ILD [63.9% male; median (IQR) age: 69 (54-78) years] were included in the study. All the TTs identified in the literature were found in our cohort, except for intractable chronic cough. We also recognized differences in TTs across the ILD groups, with less TTs in patients with sarcoidosis. This analysis provides the first ancillary characterization of TTs in ILD patients in a real setting to date.

Canadian Association of Radiologists Thoracic Imaging Referral Guideline

The Canadian Association of Radiologists (CAR) Thoracic Expert Panel consists of radiologists, respirologists, emergency and family physicians, a patient advisor, and an epidemiologist/guideline methodologist. After developing a list of 24 clinical/diagnostic scenarios, a rapid scoping review was undertaken to identify systematically produced referral guidelines that provide recommendations for one or more of these clinical/diagnostic scenarios. Recommendations from 30 guidelines and contextualization criteria in the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) for guidelines framework were used to develop 48 recommendation statements across the 24 scenarios. This guideline presents the methods of development and the referral recommendations for screening/asymptomatic individuals, non-specific chest pain, hospital admission for non-thoracic conditions, long-term care admission, routine pre-operative imaging, post-interventional chest procedure, upper respiratory tract infection, acute exacerbation of asthma, acute exacerbation of chronic obstructive pulmonary disease, suspect pneumonia, pneumonia follow-up, immunosuppressed patient with respiratory symptoms/febrile neutropenia, chronic cough, suspected pneumothorax (non-traumatic), clinically suspected pleural effusion, hemoptysis, chronic dyspnea of non-cardiovascular origin, suspected interstitial lung disease, incidental lung nodule, suspected mediastinal lesion, suspected mediastinal lymphadenopathy, and elevated diaphragm on chest radiograph.

Relative incidence of interstitial lung diseases in Brazil

OBJECTIVE

To assess the relative frequency of incident cases of interstitial lung diseases (ILDs) in Brazil.

METHODS

This was a retrospective survey of new cases of ILD in six referral centers between January of 2013 and January of 2020. The diagnosis of ILD followed the criteria suggested by international bodies or was made through multidisciplinary discussion (MDD). The condition was characterized as unclassifiable ILD when there was no specific final diagnosis following MDD or when there was disagreement between clinical, radiological, or histological data.

RESULTS

The sample comprised 1,406 patients (mean age = 61 ± 14 years), and 764 (54%) were female. Of the 747 cases exposed to hypersensitivity pneumonitis (HP)-related antigens, 327 (44%) had a final diagnosis of HP. A family history of ILD was reported in 8% of cases. HRCT findings were indicative of fibrosis in 74% of cases, including honeycombing, in 21%. Relevant autoantibodies were detected in 33% of cases. Transbronchial biopsy was performed in 23% of patients, and surgical lung biopsy, in 17%. The final diagnoses were: connective tissue disease-associated ILD (in 27%), HP (in 23%), idiopathic pulmonary fibrosis (in 14%), unclassifiable ILD (in 10%), and sarcoidosis (in 6%). Diagnoses varied significantly among centers (c2 = 312.4; p < 0.001).

CONCLUSIONS

Our findings show that connective tissue disease-associated ILD is the most common ILD in Brazil, followed by HP. These results highlight the need for close collaboration between pulmonologists and rheumatologists, the importance of detailed questioning of patients in regard with potential exposure to antigens, and the need for public health campaigns to stress the importance of avoiding such exposure.

Hypersensitivity pneumonitis: application of a new diagnostic algorithm to a time series of the disease

BACKGROUND

The diagnostic criteria for Hypersensitivity pneumonitis (HP) have changed over time. Our aim is to apply a recent diagnostic algorithm to a historical series of patients diagnosed with HP to assess its distribution according to current diagnostic criteria and the diagnostic confidence achieved.

RESEARCH DESIGN AND METHODS

Application to each patient the algorithm criteria. The diagnosis was HP (≥90%), provisional high (70-89%) or low confidence (51-69%) or non-HP (unlikely) (≤50%); or HP, provisional or non-HP, if they had lung biopsy.

RESULTS

129 patients [mean age 64 ± 12 years; 79 (61.2%) women] were included of which 16 (12.4%) were diagnosed on the basis of high clinical suspicion. After applying the algorithm, 106 patients (82.2%) could be evaluated and 83 (78.3%) had a diagnosis of HP or high confidence. Lung biopsy was able to establish a diagnosis of certainty in another 21 patients and a provisional diagnosis in 9 more [total, 113 (87.6%)]. The 16 patients without strict diagnostic criteria for HP had a low confidence diagnosis. A total of 56 lung biopsies (64.4%) could have been avoided according to the new guidelines.

CONCLUSIONS

The application of this algorithm achieves a high diagnostic yield in HP, significantly reducing the number of lung biopsies required.

Case 323: Minute Pulmonary Meningothelial-like Nodules

HISTORY

A 70-year-old woman with a 6-year history of asthma, a 12-year history of diabetes mellitus, and who did not smoke presented to the pulmonology clinic with dyspnea and cough. Chest CT performed 5 years earlier for similar symptoms revealed multiple pulmonary nodules. However, she was lost to follow-up before the work-up was concluded. Otherwise, her medical history was unremarkable. Family history included maternal endometrial cancer. Physical examination revealed partial oxygen saturation of 98%, respiratory rate of 18 breaths per minute, and heart rate of 77 beats per minute. Her breath sounds and other systemic findings were normal. Pulmonary function test results were as follows: forced expiratory volume in 1 second, 108% predicted (normal range, 80%-120%); total lung capacity, 72% predicted (normal range, 80%-120%); forced vital capacity, 101% predicted (normal range, 80%-120%); diffusing capacity for carbon monoxide, 69% predicted (normal range, 60%-120%); and forced midexpiratory flow, 85% predicted (normal range, 40%-160%). Complete blood count, erythrocyte sedimentation rate, C-reactive protein level, rheumatoid factor, and antinuclear antibody levels were within normal limits. The patient underwent volumetric thin-section CT of the chest using a multidetector CT scanner (Ingenuity Core 128; Philips Medical Systems) to evaluate lung nodules and pulmonary interstitium.

Assessment of clinical relevance of antigen improves diagnostic accuracy of hypersensitivity pneumonitis

BACKGROUND

Exposure assessment is integral to the diagnosis of hypersensitivity pneumonitis (HP). Although the clinical relevance of exposed antigens is essential for the assessment, many of the previous guidelines or reports have only evaluated simple exposure histories or immunological tests. To overcome this problem, the Exposure Assessment Form (EAF) was developed as an assessment tool for classifying the exposure grade from G0 to G4. The EAF was modified from the description in the Japanese clinical practice guide 2022 for HP published by the Japanese Respiratory Society.

METHODS

One hundred and seventy-two consecutive patients with interstitial lung disease who underwent multidisciplinary discussion (MDD) at our hospital were retrospectively examined. We assessed whether the use of the EAF improved the diagnostic performance of the international guideline of HP. We also evaluated whether the exposure grade affected the prognosis of HP.

RESULTS

Even when a HP diagnosis was made with a confidence of 70% or higher according to the international guideline, less than half of these cases resulted in a final diagnosis of HP when the exposure grades were lower than G3. When the result of the EAF was integrated into the exposure definition of the international guideline, the specificity of the diagnostic performance improved, while sensitivity was maintained. Furthermore, HP patients with an exposure grade of G3 or higher showed a tendency to take a longer time to initiate medication.

CONCLUSIONS

This is the first study to evaluate the clinical relevance of possible antigens using the EAF. Assessing the exposure grade prevents overdiagnosis and improves the diagnostic performance of the international guideline.

Hypersensitivity Pneumonitis Due to Living Environmental Pollution Caused by Masked Musangs

Hypersensitivity pneumonitis is an allergic disease caused by various factors such as animal proteins and chemicals. The masked musang, a small animal of the Viverridae family native to East Asia, tends to infiltrate spaces like the attics of residences, causing damage through the deposition of excrement and other means. The older Japanese patient had been experiencing cough, shortness of breath, and fever for two months before presenting to our hospital. The symptoms improved upon admission to a local medical facility but deteriorated upon discharge. This cycle was repeated twice before the patient was admitted to our hospital. Based on the recurrent pattern of improvement during hospitalization and exacerbation upon returning home, along with the results of CT imaging and bronchoscopy, we suspected hypersensitivity pneumonitis. An environmental investigation at the patient's residence revealed a masked musang nest in the attic above the patient's room. After cleaning the attic, the symptoms did not recur. Consequently, we diagnosed hypersensitivity pneumonitis due to living environmental pollution caused by masked musangs. To the best of our knowledge, there have been no previous case reports of hypersensitivity pneumonitis caused by masked musangs. When wild animals invade human living environments, there is a possibility that not only infectious diseases but also immunological disorders, including allergic diseases, may appear.

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.

The Unveiled Triad: Clinical, Radiological and Pathological Insights into Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is a diffuse parenchymal lung disease (DLPD) characterized by complex interstitial lung damage with polymorphic and protean inflammatory aspects affecting lung tissue targets including small airways, the interstitium, alveolar compartments and vascular structures. HP shares clinical and often radiological features with other lung diseases in acute or chronic forms. In its natural temporal evolution, if specific therapy is not initiated promptly, HP leads to progressive fibrotic damage with reduced lung volumes and impaired gas exchange. The prevalence of HP varies considerably worldwide, influenced by factors like imprecise disease classification, diagnostic method limitations for obtaining a confident diagnosis, diagnostic limitations in the correct processing of high-resolution computed tomography (HRCT) radiological parameters, unreliable medical history, diverse geographical conditions, heterogeneous agricultural and industrial practices and occasionally ineffective individual protections regarding occupational exposures and host risk factors. The aim of this review is to present an accurate and detailed 360-degree analysis of HP considering HRCT patterns and the role of the broncho-alveolar lavage (BAL), without neglecting biopsy and anatomopathological aspects and future technological developments that could make the diagnosis of this disease less challenging.

[Morphology of hypersensitivity pneumonitis]

Hypersensitivity pneumonitis (HP) is one of the most common interstitial lung diseases, the manifestations of which are diverse, and the diagnosis is complex and requires a multidisciplinary approach. HP is an immunologically determined disease in response to inhaled antigens. The main feature of the disease is terminal bronchiole's involvement accompanied by interstitial inflammation and/or fibrosis together with the presence of non-necrotizing granulomas in the interalveolar septa and bronchioles. The article presents the histological features of non-fibrous and fibrotic variants of the disease. Well-defined diagnostic criteria were formulated on the basis of published international recommendations and the authors' own experience.

Prognostic factors of progressive fibrotic hypersensitivity pneumonitis: a large, retrospective, multicentre, observational cohort study

Background

Fibrotic hypersensitivity pneumonitis (fHP) is an immune-mediated interstitial lung disease caused by sensitisation to chronic allergen inhalation. This study aimed to determine prognostic indicators of progression and mortality in fHP.

Methods

This was a retrospective, multicentre, observational, cross-sectional cohort study of consecutive patients diagnosed with fHP from 1 January 2012 to 31 December 2021. Multivariate Cox regression analyses were used to calculate hazard ratios (HRs) with 95% confidence intervals for predictors of progression and survival.

Results

A total of 403 patients were diagnosed with fHP: median (interquartile range) age 66.5 (14.0) years, 51.9% females and 55.1% never-smokers. The cause of fHP was mainly fungal (39.7%) or avian (41.4%). Lung biopsy was performed in 269 cases (66.7%). In the whole cohort the variables that were related to mortality or lung transplant were older age (HR 1.08; p<0.001), percentage predicted forced vital capacity (HR 0.96; p=0.001), lymphocytosis in bronchoalveolar lavage (BAL) (HR 0.93; p=0.001), presence of acute exacerbation during follow-up (HR 3.04; p=0.001) and GAP (gender, age and lung physiology) index (HR 1.96; p<0.01). In the group of biopsied patients, the presence of fibroblastic foci at biopsy (HR 8.39; p<0.001) stands out in multivariate Cox regression analyses as a highly significant predictor for increased mortality or lung transplant. GAP index (HR 1.26; p=0.009), lymphocytosis in BAL (HR 0.97; p=0.018) and age (HR 1.03; p=0.018) are also predictors of progression.

Conclusions

The study identified several prognostic factors for progression and/or survival in fHP. The presence of fibroblastic foci at biopsy was a consistent predictor for increased mortality and the presence of lymphocytosis in BAL was inversely related to mortality.

Rationale and design of the prognostic transcriptomic signature in fibrotic hypersensitivity pneumonitis (PREDICT) study

Hypersensitivity pneumonitis is an immunologically mediated form of lung disease, resulting from inhalational exposure to a large variety of antigens. A subgroup of patients with fibrotic hypersensitivity pneumonitis (FHP) develop symptomatic, functional and radiographic disease progression. Mortality occurs primarily from respiratory failure as a result of progressive and self-sustaining lung injury that often occurs despite immunosuppression and removal of the inciting antigen. The development and validation of a prognostic transcriptomic signature for FHP (PREDICT-HP) is an observational multicentre cohort study designed to explore a transcriptomic signature from peripheral blood mononuclear cells in patients with FHP that is predictive of disease progression. This article describes the design and rationale of the PREDICT-HP study. This study will enrol ∼135 patients with FHP at approximately seven academic medical sites. Participants with a confirmed diagnosis of FHP are followed over 24 months and undergo physical examinations, self-administered questionnaires, chest computed tomography, pulmonary function tests, a 6-min walk test and blood testing for transcriptomic analyses. At each 6-month follow-up visit the study will assess the participants' clinical course and clinical events including hospitalisations and respiratory exacerbations. The PREDICT study has the potential to enhance our ability to predict disease progression and fundamentally advance our understanding of the pathobiology of FHP disease progression.

Variation in information needs of patients with interstitial lung disease and their family caregivers according to long-term oxygen therapy: a descriptive study

BACKGROUND

The information needs of patients and their families regarding interstitial lung disease (ILD) have yet to be studied in detail, and few reports have examined the differences in information needs according to patient status. This study aimed to determine whether there are differences in information needs between outpatients with ILD and their family caregivers and whether these differences depend on long-term oxygen therapy use.

METHODS

Patients with fibrotic ILDs and their families who visited Kyoto University Hospital between February 2020 and March 2022 were recruited for this descriptive study. Fibrotic ILDs included idiopathic pulmonary fibrosis (IPF), other idiopathic interstitial pneumonias (IIPs) than IPF, connective tissue disease-associated ILD (CTD-ILD), and fibrotic hypersensitivity pneumonia. Data were obtained from electronic patient records and questionnaires. Descriptive data analyses were performed.

RESULTS

Sixty-five patients and their family caregivers were analyzed. Twenty-seven (41.5%) patients had IIPs (IPF 9 and other IIPs 18), 34 (52.3%) had CTD-ILD, and 4 (6.2%) had fibrotic hypersensitivity pneumonia. The most common relationship between the patient and their family was a spouse (67.7%), with 80% living together. The primary information needs among patients and their family caregivers were common up to the third rank but differed from the rest. Patients were interested in "when and where to contact health care providers" and "end-of-life care and advanced directives," while family caregivers were interested in "diet and nutrition" and "care and support at home." Patients with long-term oxygen therapy had higher needs for "end-of-life care and advanced directives" and "how to manage breathlessness, cough, and fatigue," while the needs for "drugs for ILD" and "acute exacerbation of ILD" were relatively low. Family caregivers were interested in "diet and nutrition" in the long-term oxygen therapy group and "acute exacerbation of ILD" in the no long-term oxygen therapy group.

CONCLUSIONS

This study found that the information needs of patients and their family caregivers were not the same and that the aspect of information needs differed by long-term oxygen therapy status. Healthcare providers should consider the position of the recipient of information, the appropriate time based on the patient's condition, and the necessary information.

Integration and Application of Radiologic Patterns From Clinical Practice Guidelines on Idiopathic Pulmonary Fibrosis and Fibrotic Hypersensitivity Pneumonitis

BACKGROUND

Clinical practice guidelines separately describe radiologic patterns of usual interstitial pneumonia (UIP) and fibrotic hypersensitivity pneumonitis (fHP), without direction on whether or how to apply these approaches concurrently within a single patient.

RESEARCH QUESTION

How can we integrate guideline-defined radiologic patterns to diagnose interstitial lung disease (ILD) and what are the pitfalls associated with described patterns that require reassessment in future guidelines?

STUDY DESIGN AND METHODS

Patients from the Canadian Registry for Pulmonary Fibrosis underwent detailed reevaluation in standardized multidisciplinary discussion. CT scan features were quantified by chest radiologists masked to clinical data, and guideline-defined patterns were assigned. Clinical data then were provided to the radiologist and an ILD clinician, who jointly determined the leading diagnosis.

RESULTS

Clinical-radiologic diagnosis in 1,593 patients was idiopathic pulmonary fibrosis (IPF) in 26%, fHP in 12%, connective tissue disease-associated ILD (CTD-ILD) in 34%, idiopathic pneumonia with autoimmune features in 12%, and unclassifiable ILD in 10%. Typical and probable UIP patterns corresponded to a diagnosis of IPF in 66% and 57% of patients, respectively. Typical fHP pattern corresponded to an fHP clinical diagnosis in 65% of patients, whereas compatible fHP was nonspecific and associated with CTD-ILD or IPAF in 48% of patients. No pattern ruled out CTD-ILD. Gas trapping affecting > 5% of lung parenchyma on expiratory imaging was an important feature broadly separating compatible and typical fHP from other patterns (sensitivity, 0.77; specificity, 0.91).

INTERPRETATION

An integrated approach to guideline-defined UIP and fHP patterns is feasible and supports > 5% gas trapping as an important branch point. Typical or probable UIP and typical fHP patterns have moderate predictive values for a corresponding diagnosis of IPF and fHP, although occasionally confounded by CTD-ILD; compatible fHP is nonspecific.

The Role of Small Airway Disease in Pulmonary Fibrotic Diseases

Small airway disease (SAD) is a pathological condition that affects the bronchioles and non-cartilaginous airways 2 mm or less in diameter. These airways play a crucial role in respiratory function and are often implicated in various pulmonary disorders. Pulmonary fibrotic diseases are characterized by the thickening and scarring of lung tissue, leading to progressive respiratory failure. We aimed to present the link between SAD and fibrotic lung conditions. The evidence suggests that SAD may act as a precursor or exacerbating factor in the progression of fibrotic diseases. Patients with fibrotic conditions often exhibit signs of small airway dysfunction, which can contribute to worsening respiratory symptoms and decreased lung function. Moreover, individuals with advanced SAD are at a heightened risk of developing fibrotic changes in the lung. The interplay between inflammation, environmental factors, and genetic predisposition further complicates this association. The early detection and management of SAD can potentially mitigate the progression of fibrotic diseases, highlighting the need for comprehensive clinical evaluation and research. This review emphasizes the need to understand the evolving connection between SAD and pulmonary fibrosis, urging further detailed research to clarify the causes and potential treatment between the two entities.

Pirfenidone in fibrotic hypersensitivity pneumonitis: a double-blind, randomised clinical trial of efficacy and safety

BACKGROUND

Fibrotic hypersensitivity pneumonitis (FHP) is an irreversible lung disease with high morbidity and mortality. We sought to evaluate the safety and effect of pirfenidone on disease progression in such patients.

METHODS

We conducted a single-centre, randomised, double-blinded, placebo-controlled trial in adults with FHP and disease progression. Patients were assigned in a 2:1 ratio to receive either oral pirfenidone (2403 mg/day) or placebo for 52 weeks. The primary end point was the mean absolute change in the per cent predicted forced vital capacity (FVC%). Secondary end points included progression-free survival (PFS, time to a relative decline ≥10% in FVC and/or diffusing capacity of the lung for carbon monoxide (DLCO), acute respiratory exacerbation, a decrease of ≥50 m in the 6 min walk distance, increase or introduction of immunosuppressive drugs or death), change in FVC slope and mean DLCO%, hospitalisations, radiological progression of lung fibrosis and safety.

RESULTS

After randomising 40 patients, enrolment was interrupted by the COVID-19 pandemic. There was no significant between-group difference in FVC% at week 52 (mean difference -0.76%, 95% CI -6.34 to 4.82). Pirfenidone resulted in a lower rate of decline in the adjusted FVC% at week 26 and improved PFS (HR 0.26, 95% CI 0.12 to 0.60). Results for other secondary end points showed no significant difference between groups. No deaths occurred in the pirfenidone group and one death (respiratory) occurred in the placebo group. There were no treatment-emergent serious adverse events.

CONCLUSIONS

The trial was underpowered to detect a difference in the primary end point. Pirfenidone was found to be safe and improved PFS in patients with FHP.

TRIAL REGISTRATION MUMBER

NCT02958917.

The Importance of Imaging in the Assessment of Interstitial Lung Diseases

High-resolution computed tomography (HRCT) is an essential component of the diagnosis and assessment of patients with interstitial lung diseases (ILDs). In some cases, a diagnosis of ILD can be made solely based on a multidisciplinary discussion of HRCT findings and clinical evaluation. HRCT findings also inform prognosis and may influence treatment decisions. It is essential that high-quality HRCT images are obtained using parameters for optimum spatial resolution. Key terms used to describe HRCT findings should be used consistently among clinicians. Radiologic information should be included as part of the multidisciplinary discussion of patients with ILDs during follow-up.