Chronic hypersensitivity pneumonitis: CT features comparison with pathologic evidence of fibrosis and survival

A Case of Immunomodulator-Responsive Hypersensitivity Pneumonitis Secondary to Chronic Passive Smoke Inhalation

Hypersensitivity pneumonitis (HP) is a pulmonary disease characterized by inflammation and fibrosis of the lung parenchyma following chronic exposure to immunogenic antigens. The pathophysiology of HP involves type 3 and type 4 hypersensitivity reactions leading to acute and chronic manifestations, respectively. Clinically, it manifests as exertional dyspnea and wheezing. Pulmonary function tests display a pattern of restrictive lung disease, and high-resolution CT scans display a pattern of ground glass opacities, centrilobular nodules, and mosaic attenuation. Antigen avoidance remains the only method for primary prevention. Alternative therapy may be needed due to either the inability to avoid antigens or the lack of antigen identification. Prednisone 0.5 mg/kg per day is the first-line treatment for acute non-fibrotic forms of HP. In chronic or fibrotic HP, the immunomodulator mycophenolate mofetil (MMF) was shown to be an effective treatment in improving the diffusing capacity of the lungs for carbon monoxide and forced vital capacity, but not overall survival. The following study aims to bring to attention the need for additional prospective multicenter clinical trials to clarify the role of MMF as an immunomodulator in fibrosing HP.

Predictors of Progression and Mortality in Patients with Chronic Hypersensitivity Pneumonitis: Retrospective Analysis of Registry of Fibrosing Interstitial Lung Diseases

Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) resulting from an immune-mediated response in susceptible and sensitized individuals to a large variety of inhaled antigens. Chronic HP with a fibrotic phenotype is characterized by disease progression and a dismal prognosis. The aim of this study was to identify predictors of progression and mortality in patients with chronic HP in real clinical practice.

MATERIALS AND METHODS

This retrospective, multicenter, observational study used data from a registry of 1355 patients with fibrosing ILDs. The study included 292 patients diagnosed with chronic HP based on the conclusion of a multidisciplinary discussion (MDD).

RESULTS

The patients were divided into groups with progressive (92 (30.3%) patients) and nonprogressive pulmonary fibrosis (200 (69.7%) patients). The most significant predictors of adverse outcomes were a DLco < 50% predicted, an SpO2 at the end of a six-minute walk test (6-MWT) < 85%, and a GAP score ≥ 4 points.

CONCLUSION

Pulmonary fibrosis and a progressive fibrotic phenotype are common in patients with chronic HP. Early detection of the predictors of an adverse prognosis of chronic HP is necessary for the timely initiation of antifibrotic therapy.

Characteristics of a diagnostic bronchoscopy in hypersensitivity pneumonitis

BACKGROUND

Bronchoalveolar lavage and transbronchial biopsy can increase diagnostic confidence in the diagnosis of hypersensitivity pneumonitis (HP). Improving the yield of bronchoscopy may help to improve diagnostic confidence while decreasing the risk of potential adverse outcomes associated with more invasive procedures such as surgical lung biopsy. The purpose of this study is to identify factors that were associated with a diagnostic BAL or TBBx in HP.

METHODS

We conducted a retrospective cohort study of HP patients at a single center who underwent bronchoscopy during the diagnostic evaluation. Imaging characteristics, clinical characteristics including use of immunosuppressive medications and presence of active antigen exposure at the time of bronchoscopy, and procedural characteristics were collected. Univariable and multivariable analysis was performed.

RESULTS

88 patients were included in the study. 75 patients underwent BAL and 79 patients underwent TBBx. Patients who had an active fibrogenic exposure at the time of bronchoscopy had a higher BAL yield than those who were out of exposure at the time of bronchoscopy. TBBx yield was higher when more than 1 lobe was biopsied, with a trend toward higher yield of TBBx when nonfibrotic lung was biopsied compared to fibrotic lung.

DISCUSSION

Our study suggests characteristics that may improve yield of BAL and TBBx in patients with HP. We suggest that bronchoscopy be performed when patients are in the antigen exposure and that TBBx samples are taken from more than 1 lobe in order to improve diagnostic yield of the procedure.

Fibrosis score predicts mortality in patients with fibrotic hypersensitivity pneumonitis

Background

Variable clinical courses make it challenging to predict mortality resulting from fibrotic hypersensitivity pneumonitis (HP). This study evaluated the usefulness of radiologic parameters for predicting mortality in patients with fibrotic HP.

Methods

Clinical data and high-resolution computed tomography (HRCT) images, which were scored for reticulation, honeycombing, ground glass opacity (GGO), consolidation, and mosaic attenuation (MA) by visual assessment, were retrospectively analyzed in a total of 101 patients with fibrotic HP (all biopsy-proven cases). Fibrosis score was defined as the sum of reticulation and honeycombing scores.

Results

The mean age of the 101 patients was 58.9 years, and 60.4% were females. During the follow-up (median: 55.5 months; interquartile range: 37.7-89.0 months), the 1-, 3-and 5-year mortality rates were 3.9, 16.8, and 32.7%, respectively. The non-survivors were older and had significantly lower lung function and minimum oxygen saturation during the 6-min walk test than the survivors. The non-survivors had higher scores of reticulation, honeycombing, GGO, fibrosis, and MA on HRCT than survivors. In the multivariable Cox analysis, reticulation, GGO, and fibrosis scores were independent prognostic factors for mortality in patients with fibrotic HP, as well as age. Fibrosis score showed great performance for predicting the 5-year mortality (AUC = 0.752, p < 0.001) and higher mortality was recorded for patients with high fibrosis score (≥12.0%) (the mean survival time: 58.3 vs. 146.7 months, p < 0.01) than those without.

Conclusion

Our results suggest that radiologic fibrosis score may be a useful predictor of mortality in patients with fibrotic HP.

Imaging of Occupational and Environmental Lung Disease

The respiratory tract is continuously exposed to and filters toxins from the home and work environments. Certain occupations and environmental exposures can cause unique injuries to the upper and lower respiratory system. Despite increasing federal regulations in the workplace, occupation-associated lung disease is still a major cause of lung disease and disability and continues to evolve with changes in industry, regulation, and new emerging exposures and toxins. Establishing a diagnosis can be difficult, often due to long latency between exposure and clinical disease, insufficient patient history, and nonspecific or varying imaging appearance. Identifying key imaging features of occupational lung disease along with a multidisciplinary approach can aid in accurate and timely diagnosis. In this review, we will discuss the importance of a comprehensive patient history, multidisciplinary approach to diagnosis, and key imaging features of occupation-related lung injuries. Radiographic and computed tomographic findings will be described and illustrated.

High-Resolution Computed Tomography of Fibrotic Interstitial Lung Disease

While radiography is the first-line imaging technique for evaluation of pulmonary disease, high-resolution computed tomography (HRCT) provides detailed assessment of the lung parenchyma and interstitium, allowing normal anatomy to be differentiated from superimposed abnormal findings. The fibrotic interstitial lung diseases have HRCT features that include reticulation, traction bronchiectasis and bronchiolectasis, honeycombing, architectural distortion, and volume loss. The characterization and distribution of these features result in distinctive CT patterns. The CT pattern and its progression over time can be combined with clinical, serologic, and pathologic data during multidisciplinary discussion to establish a clinical diagnosis. Serial examinations identify progression, treatment response, complications, and can assist in determining prognosis. This article will describe the technique used to perform HRCT, the normal and abnormal appearance of the lung on HRCT, and the CT patterns identified in common fibrotic lung diseases.

Clinical radiological and pathological staging of children with hypersensitivity pneumonitis

OBJECTIVE

Hypersensitivity pneumonitis (HP) is rare in the pediatric population. To date, there are no studies defining a correlation between clinical, radiological, and pathological findings in children with HP. The objective of this study is to define the clinical, and radiological characteristics and prognosis of childhood HP and to examine the clinical, radiological, and pathological correlation between HP stages.

METHODS

Patients with suspected HP and followed at two tertiary care hospitals between 2000 and 2020 were retrospectively evaluated. Computed tomography (CT) of the chest of patients was evaluated by a single radiologist. The interagreement between clinical and radiological severity of the patients was calculated with the κ test.

RESULTS

Fourteen children with suspected HP were identified. The results of 10 patients with the definitive diagnosis were as follows: one patient (10%) had acute, five patients (50%) had subacute, and four patients (40%) had chronic HP. The most prominent findings in chest CT were hilar, or hilar and subcarinal lymphadenopathy (80%), centrilobular nodules (60%), patchy or diffuse ground-glass opacities (50%), and cysts (50%). The interagreement between clinical and radiological severity of the patients was 100% (approximate significance: 0.003). The diagnosis of four patients with suspected HP who were unresponsive to standardized medical treatments or developed multisystem involvement was diagnosed with other diseases. One patient (10%) with definitive chronic HP died due to respiratory failure during follow up.

CONCLUSION

Similar to adult HP, the prognosis is worse in children with existing fibrotic equivalents in chest CT. Patients who are not responding to standard medical treatments or develop multisystem involvement should be evaluated for other lung diseases.

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

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

Risk factors associated with mortality in hypersensitivity pneumonitis: a meta-analysis

BACKGROUND

Hypersensitivity pneumonitis (HP) related deaths have increased substantially in recent years. It is important to identify the risk factors of HP significantly associated with mortality to ensure close patient monitoring and assess disease progression.

RESEARCH DESIGN AND METHODS

Extensive literature search was conducted in accordance with the PRISMA checklist. Literature search of PUBMED, EMBASE and Cochrane Library database between January 2009 and April 2021 using the terms "hypersensitivity pneumonitis", "hazard ratio", and "mortality" identified 325 articles. A total of 22 independent original studies focusing on mortality of HP patients were assessed.

RESULTS

This systematic review and meta-analysis suggests that increased age, male sex, honeycombing and traction bronchiectasis patterns on high-resolution computed tomography (HRCT) images are the major mortality-related risk factors of patients with HP. In case of chronic HP, antigen exposure appeared to be an additional risk factor.

CONCLUSIONS

The clinico-radiological risk factors of mortality identified for HP will enable effective and close monitoring of patients, prognostication and guide towards appropriate management decisions. However, association between the type of antigen and mortality remains to be explored.

Antigen avoidance and outcome of nonfibrotic and fibrotic hypersensitivity pneumonitis

Background

Hypersensitivity pneumonitis (HP) is classified into nonfibrotic and fibrotic phenotypes. Patients with nonfibrotic HP often experience recurrence and develop fibrosis, whereas those with fibrotic HP have a poor prognosis. Although antigen avoidance has long been the first line of treatment for HP, its impact on prognosis has been poorly reported.

Methods

Medical records of 121 patients with HP diagnosed by new diagnostic criteria of American Thoracic Society/Japanese Respiratory Society/Asociación Latinoamericana del Tórax (ATS/JRS/ALAT) guidelines and treated at our institution in Saitama, Japan, were retrospectively analysed. HP was classified into nonfibrotic and fibrotic phenotypes and six HP subtypes: summer-type, bird-related, home-related and occupational HP, humidifier lung, and hot tub lung. Achievement of reduced exposure to inciting agents was divided into complete antigen avoidance (CAA) and incomplete antigen avoidance (IAA) by HP subtype.

Results

Of the 74 patients with nonfibrotic HP, 30 achieved CAA and experienced no recurrence or development of fibrosis. In the remaining 44 patients with IAA, 24 (54.5%) experienced recurrence and/or development of fibrosis. The all-cause 5-year mortality rate in the 47 patients with fibrotic HP was 47.8%. Negative prognostic factors of HP-related mortality in these patients were <50% lymphocytes in bronchoalveolar lavage (BAL) and honeycombing. Multivariate analysis showed a tendency for IAA to be related to poorer survival (hazard ratio 3.452, 95% CI 0.964–12.359, p=0.057).

Conclusions

In the patients with nonfibrotic HP, CAA resulted in no recurrence or development of fibrosis and longer survival. In the patients with fibrotic HP, <50% lymphocytes in BAL and honeycombing were negative prognostic factors for mortality.

Complete antigen avoidance reduces the recurrence and development of fibrosis in patients with nonfibrotic HP and may be related to longer survival in patients with fibrotic HPhttps://bit.ly/3E5EVLR

Hypersensitivity pneumonitis: Airway-centered pulmonary fibrosis on chest CT

BACKGROUND

To evaluate the chest CT appearance of patients with a clinicopathologic diagnosis of hypersensitivity pneumonia.

METHODS

IRB approval was obtained for a retrospective review of patients with a preoperative CT scan, a surgical pathology report from a transbronchial biopsy or wedge resection consistent with hypersensitivity pneumonitis, and a pulmonary consultation, which also supported the diagnosis. The pathology report was evaluated for granulomas, airway-centered fibrosis, microscopic honeycombing, and fibroblast foci. The medical records were reviewed for any known antigen exposure. Patients were separated into two groups; those with and without a known antigen exposure. The CT scans were assessed for distribution of fibrosis: upper lobe or lower lobe predominance, airway-centered versus peripheral distribution, three-density pattern, and honeycombing.

RESULTS

264 pathology reports included the term chronic hypersensitivity pneumonitis (CHP). Thirty-eight of the patients had a pulmonologist who gave the patient a working diagnosis of CHP. The average age of these patients was 64 years, and 21/38 were women. Seventeen of the 38 patients had at least one antigen exposure described in the medical records. All the patients had fibrosis along the airways on chest CT. Both known antigen exposure and no known antigen patients had upper and lower lung-predominant fibrosis. There were more patients with hiatal hernias in the unknown antigen group. Honeycombing was an uncommon finding.

CONCLUSION

Airway-centered fibrosis was present on chest CT in all 38 patients with CHP (100%), with or without known antigen exposure.

Transbronchial Biopsy and Cryobiopsy in the Diagnosis of Hypersensitivity Pneumonitis among Patients with Interstitial Lung Disease

Rationale: Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) with a diagnosis based on clinical, radiological, and pathological findings. The evidence supporting transbronchial forceps lung biopsy (TBBx) and transbronchial lung cryobiopsy (TBLC) as sampling techniques to diagnose HP in patients with newly detected ILD has not been reviewed systematically.Objectives: A systematic review was performed to assess the diagnostic yield and complication rates of TBBx or TBLC in patients with newly detected ILD whose differential diagnosis includes HP and to inform the development of the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax clinical practice guidelines on the diagnosis of HP.Methods: Medline, Excerpta Medica Database, and the Cochrane Library were searched through October 2019. Studies that enrolled patients with ILD and reported the diagnostic yield of TBBx or TBLC were selected for inclusion. Data related to diagnostic yield and safety outcomes were extracted and then pooled across studies via meta-analysis. The quality of the evidence was appraised using the grading of recommendations, assessment, development, and evaluation (GRADE) approach.Results: The histopathologic diagnostic yields (number of procedures that yielded a histopathologic diagnosis divided by the total number of procedures performed) of TBBx and TBLC were 37% (95% confidence interval [CI], 32-42%) and 82% (95% CI, 78-86%), respectively, among patients with ILD. Among those diagnosed by TBBx, the proportion with HP could not be determined. However, among those diagnosed by TBLC, 13.4% had HP. TBBx was complicated by moderate to severe bleeding, severe bleeding, and pneumothorax in 4% (95% CI, 0-8%), 0% (95% CI, 0-1%), and 7% (95% CI, 2-13%) of patients, respectively. TBLC was complicated by any bleeding, severe bleeding, and pneumothorax in 11% (95% CI, 7-15%), 0% (95% CI, 0-1%), and 11% (95% CI, 9-14%) of patients, respectively. The quality of the evidence was very low because of the uncontrolled study designs, lack of consecutive enrollment, and inconsistent results.Conclusions: Very low-quality evidence indicated that TBLC had a higher diagnostic yield than TBBx among patients with ILD, although complications were similar.

Occupational lung disease: A narrative review of lung conditions from the workplace

Occupational lung diseases are lung conditions caused or made worse by materials when a person is exposed to a workplace. The diagnosis of an occupational disease is important for workers' decision to continue work and for their eligibility under compensation programmes. We revisit the existing lung diseases that are closely associated with the occupation at the workplace namely occupational asthma, silicosis, black lung disease, farmers' lung disease, asbestos-linked disease, and hypersensitivity pneumonitis. Occupational lung diseases contribute toward global health and economic impacts. Prevention and control of occupational lung diseases require a collaborative effort among employers, workers, occupational physicians, pulmonary physicians, industrial hygienists, and members from other disciplines.

Utility of Bronchoalveolar Lavage and Transbronchial Biopsy in Patients with Interstitial Lung Disease

PURPOSE

Bronchoalveolar lavage and transbronchial biopsy can be a useful tool in the evaluation of interstitial lung disease (ILD), but patient selection for this procedure remains poorly defined. Determining clinical characteristics that help with patient selection for bronchoscopy may improve confidence of ILD classification while limiting potential adverse outcomes associated with surgical lung biopsy. The purpose of this study is to identify factors that were associated with change in multidisciplinary ILD diagnosis (MDD) before and after incorporation of BAL and TBBx data.

METHODS

We conducted a retrospective cohort study of ILD patients at a single center who underwent bronchoscopy in the diagnostic workup of ILD. We performed sequential MDD both pre- and post-bronchoscopy to calculate the frequency of change in diagnosis after incorporating information from BAL and TBBx and identify features associated with change in diagnosis.

RESULTS

245 patients were included in the study. Bronchoscopy led to a change in diagnosis in 58 patients (23.7%). The addition of TBBx to BAL increased diagnostic yield from 21.8 to 34.1% (p = 0.027). Identification of antigen, HRCT scan inconsistent with UIP, and absence of a pre-bronchoscopy diagnosis of CTD-ILD or IPAF were associated with a change in diagnosis after bronchoscopy.

CONCLUSION

Our study suggests clinical features that may assist with patient selection for bronchoscopy. We suggest bronchoscopy in patients with identified antigen or an HRCT that is consistent with a non-IPF diagnosis. Appropriate patient selection for bronchoscopy may improve ILD diagnostic confidence and avoid potential complications from more invasive and higher risk procedures.

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.

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

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

Prognostic factors in chronic hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is an immunologically mediated lung disease resulting from exposure to inhaled environmental antigens. Prognosis is variable, with a subset of patients developing progressive fibrosis leading to respiratory failure and death. Therefore, there is an urgent need to identify factors which predict prognosis and survival in patients with HP. We undertook a narrative review of existing evidence to identify prognostic factors in patients with chronic HP. Patient demographics, smoking history, extent of antigen exposure and comorbidities all have reported associations with disease outcome, and physiological, radiological and laboratory markers have been shown to predict overall survival. While no single marker has been demonstrated to accurately and reliably predict prognosis, older age, more severe impairment of pulmonary function at baseline and established fibrosis on either biopsy or high-resolution computed tomography are consistently associated with worse survival. The vast majority of existing studies are retrospective, and this review identifies a need for prospective longitudinal studies with serial assessment of respiratory health to ascertain factors associated with nonfatal deterioration. Future developments, including the development of HP-specific composite scores may help further improve our ability to predict outcomes for individual patients.

Diagnostic approach of fibrosing interstitial lung diseases of unknown origin

Interstitial lung diseases encompass a broad range of numerous individual conditions, some of them characterized histologically by fibrosis, especially idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, chronic hypersensitivity pneumonia, interstitial lung disease associated with connective tissue diseases, and unclassifiable interstitial lung disease. The diagnostic approach relies mainly on the clinical evaluation, especially assessment of the patient's demographics, history, smoking habits, occupational or domestic exposures, use of drugs, and on interpretation of high-quality HRCT of the chest. Imaging is key to the initial diagnostic approach, and often can confirm a definite diagnosis, particularly a diagnosis of idiopathic pulmonary fibrosis when showing a pattern of usual interstitial pneumonia in the appropriate context. In other cases, chest HRCT may orientate toward an alternative diagnosis and appropriate investigations to confirm the suspected diagnosis. Autoimmune serology helps diagnosing connective disease. Indications for bronchoalveolar lavage and for lung biopsy progressively become more restrictive, with better considerations for their discriminate value, of the potential risk associated with the procedure, and of the anticipated impact on management. Innovative techniques and genetics are beginning to contribute to diagnosing interstitial lung disease and to be implemented routinely in the clinic. Multidisciplinary discussion, enabling interaction between pulmonologists, chest radiologists, pathologists and often other healthcare providers, allows integration of all information available. It increases the accuracy of diagnosis and prognosis prediction, proposes a first-choice diagnosis, may suggest additional investigations, and often informs the management. The concept of working diagnosis, which can be revised upon additional information being made available especially longitudinal disease behaviour, helps dealing with diagnostic uncertainty inherent to interstitial lung diseases and facilitates management decisions. Above all, the clinical approach and how thoroughly the patient's history and possible exposures are assessed determine the possibility of an accurate diagnosis.

Immunomodulatory effect of pigeon serum in an acute and chronic murine model of bird fanciers lung

INTRODUCTION

Since the immunopathological mechanisms of bird fancier's lung (BFL) are not well known, we created two models of the disease (acute and chronic BFL) to study and compare the pathways involved in its immunopathogenesis.

MATERIALS AND METHODS

C57BL/6 mice were used. Two intraperitoneal injections of 100 μL of commercial pigeon serum (PS) or saline (SAL) were administered with an interval of 48 h in between. Subsequently, intranasal instillations of 40 μL of PS or SAL were performed three days a week, for three weeks in the acute model (AC/PS) and for twelve weeks in the chronic model (CR/PS). Total lung capacity (TLC) was assessed. Pulmonary inflammation was evaluated in bronchoalveolar lavage (BAL), and total serum immunoglobulin (Ig) G was measured in serum samples 24 h, 7 days and 14 days after the last exposure. Histological studies of lungs were assessed.

RESULTS

A drop in TLC was observed in treated mice. This decrease was more marked in the CR/PS group (p < 0.001). Neutrophil and lymphocyte counts increased in both AC/PS and CR/PS groups (p < 0.01). The extent of airway inflammation was also examined in the histological analysis of the lungs, which showed predominant perivascular and peribronchiolar inflammation, with centrilobular oedema and subpleural inflammation in the AC/PS group. In the CR/PS group, the changes were greater, with increased levels of IL-5, IL-17F, IL-13 and IL-10 and decreased levels of IL-2.

CONCLUSIONS

Bronchial inflammation is present in acute and chronic models of HP following exposure to PS. Our results support the role of neutrophils and IL-17 in the development of the disease and an evolution towards a Th-2 immune response in chronic HP. These models may serve as a tool for future studies of the pathogenesis of HP.

Chronic hypersensitivity pneumonitis in the southeastern United States: an assessment of how clinicians reached the diagnosis

Background

Chronic hypersensitivity pneumonitis (cHP) is a disease caused by exposure to inhaled environmental antigens. Diagnosis of cHP is influenced by the awareness of the disease prevalence, which varies significantly in different regions, and how clinicians utilize relevant clinical information. We conducted a retrospective study to evaluate how clinicians in the Southeast United States, where the climate is humid favoring mold growth, diagnosed cHP using items identified in the international modified Delphi survey of experts, i.e., environmental exposure, CT imaging and lung pathology,

Methods

We searched Duke University Medical Center database for patients over the age of 18 with a diagnosis of cHP (ICD-9 code: 495) between Jan. 1, 2008 to Dec. 31, 2013 using a query tool, Duke Enterprise Data Unified Content Explorer (DEDUCE).

Results

Five hundred patients were identified and 261 patients had cHP confirmed in clinic notes by a pulmonologist or an allergist. About half of the patients lived in the Research Triangle area where our medical center is located, giving an estimated prevalence rate of 6.5 per 100,000 persons. An exposure source was mentioned in 69.3% of the patient. The most common exposure sources were environmental molds (43.1%) and birds (26.0%). We used Venn diagram to evaluate how the patients met the three most common cHP diagnostic criteria: evidence of environmental exposures (history or precipitin) (E), chest CT imaging (C) and pathology from lung biopsies (P). Eighteen patients (6.9%) met none of three criteria. Of the remaining 243 patients, 135 patients (55.6%) had one (E 35.0%, C 3.3%, P 17.3%), 81 patients (33.3%) had two (E + C 12.3%, E + P 17.3%, C + P 4.9%), and 27 patients (11.1%) had all three criteria (E + C + P). Overall, 49.4% of patients had pathology from lung biopsy compared to 31.6% with CT scan.

Conclusions

Environmental mold was the most common exposure for cHP in the Southeast United States. Lung pathology was available in more than half of cHP cases in our tertiary care center, perhaps reflecting the complexity of referrals. Differences in exposure sources and referral patterns should be considered in devising future diagnostic pathways or guidelines for cHP.

Feather duvet lung

A 43-year-old non-smoker was referred with a 3-month history of malaise, fatigue and breathlessness. Blood avian precipitins were strongly positive. Lung function testing confirmed a restrictive pattern with impaired gas transfer. A 'ground glass' mosaic pattern was seen on CT imaging, suggestive of hypersensitivity pneumonitis. Although he had no pet birds, on closer questioning he had recently acquired a duvet and pillows containing feathers. His symptoms, chest radiograph and lung function tests improved after removal of all feather bedding, and he was also started on oral corticosteroid therapy. Our case reinforces the importance of taking a meticulous exposure history and asking about domestic bedding in patients with unexplained breathlessness. Prompt recognition and cessation of antigen exposure may prevent the development of irreversible lung fibrosis.

Epidemiology of Hypersensitivity Pneumonitis among an Insured Population in the United States: A Claims-based Cohort Analysis

RATIONALE

Hypersensitivity pneumonitis is a complex lung disease resulting from repeated inhalation of a variety of antigens. Limited data exist regarding its epidemiology.

OBJECTIVES

To describe the trends in the annual incidence and prevalence of hypersensitivity pneumonitis in the United States.

METHODS

We developed novel claims-based coding algorithms to identify hypersensitivity pneumonitis, chronic hypersensitivity pneumonitis, and fibrotic hypersensitivity pneumonitis cases using the 2004 to 2013 MarketScan Commercial and Medicare Supplemental healthcare claims databases. Algorithm validity and reliability were assessed with clinical data from National Jewish Health. We calculated yearly cumulative incidence and prevalence overall and by age. For the subgroup with vital status, Kaplan-Meier methods were used to analyze survival stratified by evidence of fibrosis.

RESULTS

We identified 7,498 cases that met our hypersensitivity pneumonitis definition over the 10-year study period, including 3,902 with chronic hypersensitivity pneumonitis and 1,852 with fibrotic hypersensitivity pneumonitis. On the basis of the clinical-radiological adjudication of the validation sample, 38 cases (95%) were confirmed as hypersensitivity pneumonitis. The mean age was 52 years, and 58% were women. The 1-year prevalence rates for hypersensitivity pneumonitis ranged from 1.67 to 2.71 per 100,000 persons, and 1-year cumulative incidence rates ranged from 1.28 to 1.94 per 100,000 persons. The prevalence increased with age, ranging from 0.95 per 100,000 among 0- to 9-year-olds to 11.2 per 100,000 among those aged 65 years and older. Between 56 and 68% of hypersensitivity pneumonitis cases in each year were classified as chronic hypersensitivity pneumonitis (prevalence, 0.91-1.70 per 100,000 persons; cumulative incidence, 0.63-1.08 per 100,000 persons). Fewer had fibrotic hypersensitivity pneumonitis (prevalence, 0.41-0.80 per 100,000 persons; cumulative incidence: 0.29-0.43 per 100,000 persons). Most cases (74%) were classified as unspecified hypersensitivity pneumonitis. Older age, male sex, and fibrosis were associated with higher mortality rates in unadjusted analyses.

CONCLUSIONS

Using U.S. administrative claims-based data, we developed an algorithm with a high sensitivity and specificity for hypersensitivity pneumonitis. Between 2004 and 2013, hypersensitivity pneumonitis was more common among women and those older than 65 years. Most cases were classified as chronic hypersensitivity pneumonitis. Approximately one-fourth met our criteria for fibrotic hypersensitivity pneumonitis, which was associated with a higher mortality rate.

Idiopathic pulmonary fibrosis: the radiologist's role in making the diagnosis

Radiologists have a critical role in the evaluation and diagnosis of suspected idiopathic pulmonary fibrosis (IPF). Accurate pattern identification on imaging is key in the multidisciplinary diagnostic process and frequently obviates the need for a surgical lung biopsy. In this review, we describe the clinical and imaging features of IPF in the context of recently revised international guidelines; contrast findings in other diseases that may inform differential diagnosis of fibrotic lung disease; and highlight common complications associated with pulmonary fibrosis.

Pulmonary Tumor Thrombotic Microangiopathy Mimicking Inhalation Lung Injury

Pulmonary tumor thrombotic microangiopathy (PTTM) is a complication characterized by dyspnea, pulmonary hypertension, and occasionally sudden death. We encountered a man who developed PTTM and had an inhalation history of chemical herbicides and abnormal findings on chest computed tomography, mimicking chemical inhalation lung injury. He was diagnosed with PTTM with adenocarcinoma by a transbronchial lung biopsy and received chemotherapy and anticoagulant therapy. He survived for one month. An autopsy revealed primary gastric cancer with PTTM that can have a presentation similar to diffuse pulmonary diseases, including chemical inhalation lung injury. The examination of a biopsy specimen is crucial in such patients.

Long-term outcomes in chronic hypersensitivity pneumonitis

INTRODUCTION

The objective of this study was to analyze mortality, possible predictors of long-term survival, and health-related quality of life of a large chronic hypersensitivity pneumonitis (CHP) patient sample.

METHODS

Longitudinal study in patients diagnosed with CHP during 2004-2013, followed for at least 1 year. Patients remaining alive and consenting to participate had a follow-up visit during 2015, including a complete pulmonary function study and the EuroQol-5D and Beck Depression and Anxiety Inventories.

RESULTS

Out of the 160 patients finally included, 87 remained alive. Seventy-three had died or underwent lung transplantation at the time of the study with a median survival of 7.0 (4.4-14.5) years. A Cox proportional risk model showed that factors associated with lower survival were as follows: increased age, a low percentage of lymphocytes in bronchoalveolar lavage (BAL), a decreased transfer factor of the lung for carbonmonoxide (DLCO), presence of honeycomb in the high-resolution chest scan (HRCT), and the usual interstitial pneumonia (UIP) histologic pattern. At follow-up, all patients presented an EuroQol-5D score <0.8 and 21(50%) and 9(28.6%) subjects presented a probable anxiety and depressive syndrome, respectively.

CONCLUSION

CHP is a severe disease with a bad mid-term prognosis. Lymphocyte values in BAL and DLCO values at baseline, presence of honeycomb in HRCT, and UIP histologic pattern were found to be predictors of survival. Early accurate diagnosis of the disease is fundamental for prompt initiation of antigen avoidance.

Fibrosing interstitial lung diseases: knowns and unknowns

Patients with certain types of fibrosing interstitial lung disease (ILD) are at risk of developing a progressive phenotype characterised by self-sustaining fibrosis, decline in lung function, worsening quality of life, and early mortality. It has been proposed that such progressive fibrosing ILDs, which show commonalities in clinical behaviour and in the pathogenetic mechanisms that drive progressive fibrosis, may be "lumped" together for the purposes of clinical research and, potentially, for treatment. At present, no drugs are approved for the treatment of ILDs other than nintedanib and pirfenidone for the treatment of idiopathic pulmonary fibrosis. For other progressive fibrosing ILDs, the mainstay of drug therapy is immunosuppression. However, it is postulated that, once the response to lung injury in fibrosing ILDs has reached the stage at which fibrosis has become progressive and self-sustaining, targeted antifibrotic therapy would be required to slow disease progression. Nintedanib, an intracellular inhibitor of tyrosine kinases, has shown antifibrotic, anti-inflammatory and vascular remodelling effects in several non-clinical models of fibrosis, irrespective of the trigger for the injury. Ongoing clinical trials will provide insight into the role of antifibrotic treatment with nintedanib or pirfenidone in the management of fibrosing ILDs with a progressive phenotype.

Presentation, diagnosis and clinical course of the spectrum of progressive-fibrosing interstitial lung diseases

Although these conditions are rare, a proportion of patients with interstitial lung diseases (ILDs) may develop a progressive-fibrosing phenotype. Progressive fibrosis is associated with worsening respiratory symptoms, lung function decline, limited response to immunomodulatory therapies, decreased quality of life and, potentially, early death. Idiopathic pulmonary fibrosis may be regarded as a model for other progressive-fibrosing ILDs. Here we focus on other ILDs that may present a progressive-fibrosing phenotype, namely idiopathic nonspecific interstitial pneumonia, unclassifiable idiopathic interstitial pneumonia, connective tissue disease-associated ILDs (e.g. rheumatoid arthritis-related ILD), fibrotic chronic hypersensitivity pneumonitis, fibrotic chronic sarcoidosis and ILDs related to other occupational exposures. Differential diagnosis of these ILDs can be challenging, and requires detailed consideration of clinical, radiological and histopathological features. Accurate and early diagnosis is crucial to ensure that patients are treated optimally.

Effects of Corticosteroid Treatment and Antigen Avoidance in a Large Hypersensitivity Pneumonitis Cohort: A Single-Centre Cohort Study

Background: Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines. We assessed the effect of the commonly used therapeutic interventions (i.e. exposure avoidance and corticosteroid treatment) in an HP cohort. Methods: We collected clinical data of all HP patients followed at our centre between January 1, 2005, and December 31, 2016. HP patients were stratified according to the presence of fibrosis on chest CT. Survival was analysed using the multivariate Cox proportional hazards model. Forced vital capacity (percent predicted, FVC%) and diffusing capacity of the lung for carbon monoxide (percent predicted, DLCO%) evolution were analysed using linear mixed-effect models. Results: Two hundred and two HP patients were identified: 93 non-fibrotic HP (nfHP) and 109 fibrotic HP (fHP), experiencing a monthly FVC% decline before treatment of 0.93% and 0.56%, respectively. While nfHP had an excellent survival, fHP patients experienced a median survival of 9.2 years. Corticosteroid treatment and exposure avoidance did not result in survival differences. Although nfHP patients showed FVC% and DLCO% increase after corticosteroid initiation, no therapeutic effect was seen in fHP patients. FVC% and DLCO% increased in nfHP patients after exposure avoidance, while a positive numerical trend was seen for FVC% after exposure avoidance in fHP patients (p = 0.15). Conclusions: nfHP patients experienced an excellent survival with good therapeutic effect on pulmonary function tests with both corticosteroid initiation as well as antigen avoidance. In contrast, fHP patients experienced a dismal prognosis (median survival of 9.2 years) without any therapeutic effect of corticosteroid treatment. Whether antigen avoidance is useful in fHP patients is still unclear.

Combined pulmonary fibrosis and emphysema as a clinicoradiologic entity: Characterization of presenting lung fibrosis and implications for survival

BACKGROUND

The prevalence of classifiable and unclassifiable causes of lung fibrosis and its implications for survival are mostly unknown in combined pulmonary fibrosis and emphysema (CPFE).

MATERIALS AND METHODS

Patients with >10% involvement of both emphysema and lung fibrosis seen over 11 years at our institution were reviewed independently by expert radiologists for fibrotic and emphysematous findings and overall fibrotic CT pattern. Underlying interstitial lung disease (ILD) diagnoses and baseline demographic and clinical characteristics were collated and assessed for predictors of comparative survival.

RESULTS

In this retrospective cohort, 179 CPFE patients were identified and categorized as 58 usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF) (32%), 42 secondary ILD (23%), and 79 unclassifiable ILD (44%). The most prevalent (47%) radiologic pattern was 'unclassifiable', followed by 'consistent' and 'possible' UIP pattern in 38%. Adjusted predictors of mortality for the cohort as a whole included age (HR 1.03[1.01-1.06], P = 0.002), percent predicted diffusing capacity for carbon monoxide (unit HR 0.97 [0.96-0.99], P = 0.001), honeycombing (HR 1.58 [1.02-2.43], P = 0.04), and right ventricular dysfunction (HR 2.28 [1.39-3.97], P = 0.002). Survival was similar between CPFE with secondary ILD and CPFE with UIP/IPF, while CPFE with unclassifiable ILD had better comparative survival (Log rank = 0.026).

CONCLUSIONS

Our findings suggest only about a third of CPFE patients represent suspected UIP/IPF; the majority were clinically and radiologically unclassifiable ILD whose survival was comparatively better. Identifiable or secondary causes of lung fibrosis in CPFE occurred in about a fifth of presenting patients.

Air trapping in usual interstitial pneumonia pattern at CT: prevalence and prognosis

This study was conducted to evaluate the presence of air trapping in patients with idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases (ILDs) (non-IPF), showing the radiological pattern of usual interstitial pneumonia (UIP). Retrospectively, we included 69 consecutive patients showing the typical UIP pattern on computed tomography (CT), and 15 final diagnosis of IPF with CT pattern “inconsistent with UIP” due to extensive air trapping. Air trapping at CT was assessed qualitatively by visual analysis and quantitatively by automated-software. In the quantitative analysis, significant air trapping was defined as >6% of voxels with attenuation between −950 to −856 HU on expiratory CT (expiratory air trapping index [ATIexp]) or an expiratory to inspiratory (E/I) ratio of mean lung density >0.87. The sample comprised 51 (60.7%) cases of IPF and 33 (39.3%) cases of non-IPF ILD. Most patients did not have air trapping (E/I ratio ≤0.87, n = 53, [63.1%]; ATIexp ≤6%, n = 45, [53.6%]). Air trapping in the upper lobes was the only variable distinguishing IPF from non-IPF ILD (prevalence, 3.9% vs 33.3%, p < 0.001). In conclusion, air trapping is common in patients with ILDs showing a UIP pattern on CT, as determined by qualitative and quantitative evaluation, and should not be considered to be inconsistent with UIP. On subjective visual assessment, air trapping in the upper lobes was associated with a non-IPF diagnoses.

Hypersensitivity Pneumonitis: Radiologic Phenotypes Are Associated With Distinct Survival Time and Pulmonary Function Trajectory

BACKGROUND

Hypersensitivity pneumonitis (HP) is an interstitial lung disease with a better prognosis, on average, than idiopathic pulmonary fibrosis (IPF). We compare survival time and pulmonary function trajectory in patients with HP and IPF by radiologic phenotype.

METHODS

HP (n = 117) was diagnosed if surgical/transbronchial lung biopsy, BAL, and exposure history results suggested this diagnosis. IPF (n = 152) was clinically and histopathologically diagnosed. All participants had a baseline high-resolution CT (HRCT) scan and FVC % predicted. Three thoracic radiologists documented radiologic features. Survival time is from HRCT scan to death or lung transplant. Cox proportional hazards models identify variables associated with survival time. Linear mixed models compare post-HRCT scan FVC % predicted trajectories.

RESULTS

Subjects were grouped by clinical diagnosis and three mutually exclusive radiologic phenotypes: honeycomb present, non-honeycomb fibrosis (traction bronchiectasis and reticulation) present, and nonfibrotic. Nonfibrotic HP had the longest event-free median survival (> 14.73 years) and improving FVC % predicted (1.92%; 95% CI, 0.49-3.35; P = .009). HP with non-honeycomb fibrosis had longer survival than IPF (> 7.95 vs 5.20 years), and both groups experienced a significant decline in FVC % predicted. Subjects with HP and IPF with honeycombing had poor survival (2.76 and 2.81 years, respectively) and significant decline in FVC % predicted.

CONCLUSIONS

Three prognostically distinct, radiologically defined phenotypes are identified among patients with HP. The importance of pursuing a specific diagnosis (eg, HP vs IPF) among patients with non-honeycomb fibrosis is highlighted. When radiologic honeycombing is present, invasive diagnostic testing directed at determining the diagnosis may be of limited value given a uniformly poor prognosis.

Utility of Bronchoalveolar Lavage and Transbronchial Biopsy in Patients with Hypersensitivity Pneumonitis

INTRODUCTION

Making the diagnosis of HP is challenging due to a lack of consensus criteria and variability of both pathologic and radiographic findings. The purpose of this retrospective study was to determine the diagnostic utility of the combination of BAL lymphocyte count and TBBX in patients with HP.

METHODS

We conducted a retrospective cohort study of all patients with a MDD diagnosis of HP at a single center.

RESULTS

155 patients were included in the study. 49% of patients who underwent BAL had a lymphocyte count > 20, 42% had a lymphocyte count > 30, and 34% had lymphocyte count > 40%. The median BAL lymphocyte count was higher in inflammatory HP compared to fibrotic HP. The addition of TBBX to BAL significantly increased the diagnostic yield regardless of the BAL lymphocyte cutoff used. The yield of bronchoscopy with TBBX and BAL when a lymphocyte count > 40% was used as a cutoff was 52%.

CONCLUSIONS

Our study suggests that the combination of TBBX with BAL significantly increases the likelihood that the procedure will provide adequate additional information to allow a confident MDD diagnosis of HP and may reduce the need for SLB in the diagnostic workup of HP.

Presence of Air Trapping and Mosaic Attenuation on Chest Computed Tomography Predicts Survival in Chronic Hypersensitivity Pneumonitis

RATIONALE

Significant heterogeneity of computed tomography (CT) presentation exists within chronic hypersensitivity pneumonitis (HP). There are limited data aimed at delineating the prognostic value of specific CT features, distribution, and patterns in chronic HP.

OBJECTIVES

To examine whether the presence of CT mosaic attenuation (MA) and air trapping (AT), and the distribution or patterns of fibrosis impact survival in subjects with chronic HP.

METHODS

We retrospectively identified 110 consecutively enrolled, well-characterized, biopsy-proven adult subjects with chronic HP between 1982 and 2015 from the National Jewish Health interstitial lung disease research database. The first available CT scan of diagnostic quality from each subject was formally evaluated for specific CT findings associated with chronic HP and for overall CT pattern. A Cox proportional hazards model was used to identify independent predictors in time-to-death analysis, and bootstrap analysis was performed for internal model validation.

RESULTS

Fibrotic HP (65%; 72/110) was most often peripheral in the axial plane and lower lung preponderant. The distribution of lung disease in those without fibrosis was most often axially and zonally diffuse. There was no association between survival and CT distribution or CT pattern in the whole cohort or within the fibrotic subset of subjects. After multivariate adjustment, AT/MA was independently associated with survival in the whole cohort (HR = 0.26; 95% confidence interval = 0.07-0.97). Results were similar after restricting the analyses to fibrotic HP cases.

CONCLUSIONS

Among subjects with chronic HP, the presence of CT AT/MA may identify subjects with better prognosis.

Linear and Nonlinear Analysis of Base Lung Sound in Extrinsic Allergic Alveolitis Patients in Comparison to Healthy Subjects

Objective: Pulmonary disorders are frequently characterized by the presence of adventitious sounds added to the breathing or base lung sound (BLS). The aim of this work was to assess the features of BLS in extrinsic allergic alveolitis (EAA) patients in comparison to healthy subjects, applying linear and nonlinear analysis techniques.

Methods: We investigated the multichannel lung sounds on the posterior chest of 16 females, 8 healthy and 8 EAA patients, when breathing at 1.5 L/s. BLS linear features were obtained from the power spectral density (PSD) while nonlinear features were extracted by the concepts of irregularity and complexity, i.e., spectral, sample and multi-scale entropy.

Results: The results demonstrated that spectral percentiles of BLS were lower in EAA patients than in healthy subjects but statistical significance (p<0.05) was obtained only for expiration at the left apical and both basal regions. Also, the maximum amplitude of the PSD in patients reached statistical significance ( p < 0.05) for the expiratory phase at basal regions. In the case of nonlinear techniques, significant lower values ( p < 0.05) were obtained for EAA patients during both respiratory phases at left apical and both basal regions.

Conclusion: In conclusion, we found that BLS in chronic EAA patients is characterized by lower spectral percentiles, lower irregularity and lower complexity than in healthy subjects suggesting the feasibility of its clinical usefulness by screening its temporal alteration.

Computed tomography in hypersensitivity pneumonitis: main findings, differential diagnosis and pitfalls

INTRODUCTION

Hypersensitivity pneumonitis (HP) is a disease with variable clinical presentation in which inflammation in the lung parenchyma is caused by the inhalation of specific organic antigens or low molecular weight substances in genetically susceptible individuals. Alterations of the acute, subacute and chronic forms may eventually overlap, and the diagnosis based on temporality and presence of fibrosis (acute/inflammatory HP vs. chronic HP) seems to be more feasible and useful in clinical practice. Differential diagnosis of chronic HP with other interstitial fibrotic diseases is challenging due to the overlap of the clinical history, and the functional and imaging findings of these pathologies in the terminal stages. Areas covered: This article reviews the essential features of HP with emphasis on imaging features. Moreover, the main methodological limitations of high-resolution computed tomography (HRCT) interpretation are discussed, as well as new perspectives with volumetric quantitative CT analysis as a useful tool for retrieving detailed and accurate information from the lung parenchyma. Expert commentary: Mosaic attenuation is a prominent feature of this disease, but air trapping in chronic HP seems overestimated. Quantitative analysis has the potential to estimate the involvement of the pulmonary parenchyma more accurately and could correlate better with pulmonary function results.

Interstitial Lung Disease in India. Results of a Prospective Registry

RATIONALE

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

OBJECTIVES

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

METHODS

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

MEASUREMENTS AND MAIN RESULTS

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

CONCLUSIONS

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

Diagnostic implications of positive avian serology in suspected hypersensitivity pneumonitis

BACKGROUND

The diagnostic evaluation of patients with interstitial lung disease (ILD) often involves serologic assessment for identifiable causes such as hypersensitivity pneumonitis (HP). While not on its own defining of HP, precipitin serologies are often obtained to support clinical suspicion if other findings are inconclusive. We studied the clinical relevance of positive avian serology in patients undergoing ILD evaluation.

MATERIAL AND METHODS

We identified individuals with positive avian serology (>53.3 mg/L) and undifferentiated ILD seen at our institution over a three-year period. Clinical, laboratory, pathologic, and radiologic findings were evaluated for consensus HP diagnosis by two expert pulmonologists, blinded to presenting serology levels.

RESULTS

Ninety-one ILD subjects with positive avian serology were identified; mean age was 62.7 ± 15.3 years with a slight male predominance (56%). Forty-nine (54%) received a consensus HP diagnosis. Those with HP had higher mean avian serology titer (95.0 ± 38.7 mg/L vs. 68.3 ± 16.7, (P < 0.0001). Never-smokers also had higher titers compared to prior or active smokers (P = 0.0008). Positive avian protein exposure (P < 0.0001, OR 21.3 (6.4-87)), DLCO% (P = 0.04, unit OR 0.96 (0.92-0.99)), and increasing serology titer (P < 0.015, unit OR 1.03 [1.01-1.06]) were independent predictors of HP diagnosis.

CONCLUSION

Among patients with positive avian serology, those with higher titers were more likely to have HP diagnosis. Nonsmokers also manifested higher titers compared to those with smoking history. These results may guide the usage and interpretation of avian serology screening in the initial assessment of suspected HP.

Pathologic Findings and Prognosis in a Large Prospective Cohort of Chronic Hypersensitivity Pneumonitis

BACKGROUND

The ability of specific histopathologic features to predict mortality or lung transplantation in patients with chronic hypersensitivity pneumonitis (HP) is unknown.

METHODS

Patients with chronic HP diagnosed by surgical lung biopsy were identified from an ongoing longitudinal cohort. The surgical lung biopsy slides were evaluated prospectively by an experienced thoracic pathologist using a standardized checklist to differentiate the major pathologic patterns and score the presence of specific histopathologic features. Cox proportional hazard analysis was used to identify independent predictors of transplant-free survival, and Kaplan-Meier analysis was used to visualize outcomes.

RESULTS

One hundred nineteen patients were identified. Patients with a fibrotic nonspecific interstitial pneumonia (f-NSIP) pattern, bronchiolocentric fibrosis (BF) pattern, or usual interstitial pneumonia (UIP) pattern had significantly worse transplant-free survival than did those with a cellular NSIP (c-NSIP) pattern or peribronchiolar inflammation with poorly formed granulomas (PI-PFG) pattern. No survival difference among patients with an f-NSIP pattern, a BF pattern, or a UIP pattern was found. Fibroblastic foci were identified in a subset of biopsy samples from all pathologic patterns. Peribronchiolar fibrosis was noted in all UIP cases. Independent predictors of time to death or transplantation included the presence of fibroblast foci or dense collagen fibrosis.

CONCLUSIONS

Histopathologic patterns of c-NSIP and PI-PFG had a better transplant-free survival than did patterns of UIP, f-NSIP, and BF. The presence of fibroblast foci or dense collagen fibrosis correlated with progression to death or lung transplantation. Identification of fibroblast foci on biopsy samples, regardless of the underlying histopathologic pattern, may be a clinically useful predictor of survival in patients with HP.

Multidisciplinary Approach to Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) may be a challenging diagnosis given the wide variability of its clinical, radiographic, and pathologic manifestations. A multidisciplinary approach to diagnosis is critical in maintaining a high specificity for HP. An in-depth knowledge of all 3 arms of the multidisciplinary approach helps clinicians, radiologists, and pathologists interpret their own findings in the context of the entire presentation. In some cases, the combination of clinical findings (ie, an identifiable exposure) and typical findings on high-resolution computed tomography is considered diagnostic of HP, and pathologic confirmation is not necessary. As many as 50% of patients do not have a clear exposure, however. These patients may be difficult to distinguish from idiopathic disorders. In these cases, high-resolution computed tomography and pathology are the primary data points that may suggest the correct diagnosis. The goal of this paper is to discuss recent advances in HP and to present the spectrum of clinical, radiographic, and pathologic findings.