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

Idiopathic Pulmonary Fibrosis: Diagnosis and Clinical Manifestations

Idiopathic pulmonary fibrosis (IPF) is a parenchymal lung disease characterized by progressive interstitial fibrosis. The clinical course of IPF can be unpredictable and may be punctuated by acute exacerbations. Although much progress is being made in unraveling the mechanisms underlying IPF, effective therapy for improving survival remains elusive. Longitudinal disease profiling, especially in terms of clinical manifestations in a large cohort of patients, should lead to proper management of the patients and development of new treatments for IPF. Appropriate multidisciplinary assessment in ongoing registries is required to achieve this. This review summarizes the current status of the diagnosis and clinical manifestations of IPF.

Clinical Impact of Emphysema Evaluated by High-Resolution Computed Tomography on Idiopathic Pulmonary Fibrosis Diagnosed by Surgical Lung Biopsy

BACKGROUND

The prognosis of combined cases of pulmonary fibrosis and emphysema is unresolved partially because radiological differentiation between usual interstitial pneumonia and nonspecific interstitial pneumonia is difficult in coexisting emphysema cases.

OBJECTIVE

The purpose of this study was to clarify the clinical impact of emphysema on the survival of patients with idiopathic pulmonary fibrosis (IPF).

METHODS

One hundred and seven patients with interstitial lung diseases were diagnosed by surgical lung biopsies between 2006 and 2012, and 47 patients were diagnosed with IPF through multidisciplinary discussion. Emphysema on high-resolution computed tomography scans was evaluated semiquantitatively by visual scoring.

RESULTS

Eight out of the 47 IPF patients showed a higher emphysema score (>3) and were diagnosed to have IPF-emphysema. The median survival time of patients with IPF-emphysema (1,734 days) from the initial diagnosis was significantly shorter than that of patients with IPF alone (2,229 days) by Kaplan-Meier analysis (p = 0.007, log-rank test). Univariate Cox proportional hazard regression analyses revealed that a higher total emphysema score (>3.0) was a significantly poor prognostic factor in addition to Krebs von den Lungen-6, surfactant protein-D, arterial oxygen tension, percent forced vital capacity, and percent diffusing capacity of carbon monoxide (%DLCO). Multivariate Cox proportional hazard regression analyses with the stepwise method showed that higher total emphysema score (>3) and %DLCO were significantly poor prognostic factors.

CONCLUSIONS

The prognosis of IPF-emphysema was significantly worse than that of IPF alone.

Factors associated with positive inhalation provocation test results in subjects suspected of having chronic bird-related hypersensitivity pneumonitis

BACKGROUND

Chronic bird-related hypersensitivity pneumonitis (BRHP) is often misdiagnosed as other interstitial lung diseases. While the utility of the inhalation provocation test (IPT) has been reported, the test is not commonly performed. In this study, we aimed to identify significant clinical variables associated with positive inhalation provocation test results in subjects suspected of having chronic BRHP. This would help clinicians decide whether to perform IPT in patients suspected of having chronic BRHP in real-life practice.

METHODS

We retrospectively evaluated 107 patients who underwent the IPT for suspected chronic BRHP. We used the IPT as the gold standard diagnostic tool for chronic BRHP.

RESULTS

Specific antibodies against pigeon dropping extract were documented in 52% of the IPT-positive patients but also in 38% of the IPT-negative patients (p=0.172). By using the logistic regression model, three significant predictors of IPT results were identified as follows: (1) a history of raising birds (odds ratio [OR] 3.112), (2) exposure to birds from the surrounding environment (OR 7.321), (3) white blood cell count (×10²/μl; OR 0.959).

CONCLUSIONS

This study demonstrates that current or past exposure to avian antigens is a positive predictor of positive IPT results in patients suspected of having chronic BRHP.

High-resolution computed tomography and histopathological findings in hypersensitivity pneumonitis: a pictorial essay

Hypersensitivity pneumonitis is a diffuse interstitial and granulomatous lung disease caused by the inhalation of any one of a number of antigens. The objective of this study was to illustrate the spectrum of abnormalities in high-resolution computed tomography and histopathological findings related to hypersensitivity pneumonitis. We retrospectively evaluated patients who had been diagnosed with hypersensitivity pneumonitis (on the basis of clinical-radiological or clinical-radiological-pathological correlations) and had undergone lung biopsy. Hypersensitivity pneumonitis is clinically divided into acute, subacute, and chronic forms; high-resolution computed tomography findings correlate with the time of exposure; and the two occasionally overlap. In the subacute form, centrilobular micronodules, ground-glass opacities, and air trapping are characteristic high-resolution computed tomography findings, whereas histopathology shows lymphocytic inflammatory infiltrates, bronchiolitis, variable degrees of organizing pneumonia, and giant cells. In the chronic form, high-resolution computed tomography shows traction bronchiectasis, honeycombing, and lung fibrosis, the last also being seen in the biopsy sample. A definitive diagnosis of hypersensitivity pneumonitis can be made only through a multidisciplinary approach, by correlating clinical findings, exposure history, high-resolution computed tomography findings, and lung biopsy findings.

Pitfalls in diagnosis and management of hypersensitivity pneumonitis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Thin-section computed tomography detects long-term pulmonary sequelae 3 years after novel influenza A virus-associated pneumonia

BACKGROUND

The aim of this research was to evaluate long-term pulmonary sequelae on paired inspiration-expiration thin-section computed tomography (CT) scans 3 years after influenza A (H1N1) virus-associated pneumonia, and to analyze the affecting factors on pulmonary fibrosis.

METHODS

Twenty-four patients hospitalized with H1N1 virus-associated pneumonia at our hospital between September 2009 and January 2010 were included. The patients underwent thin-section CT 3 years after recovery. Abnormal pulmonary lesion patterns (ground-glass opacity, consolidation, parenchymal bands, air trapping, and reticulation) and evidence of fibrosis (architectural distortion, traction bronchiectasis, or honeycombing) were evaluated on follow-up thin-section CT. Patients were assigned to Group 1 (with CT evidence of fibrosis) and Group 2 (without CT evidence of fibrosis). Demographics, rate of mechanical ventilation therapy, rate of intensive care unit admission, cumulative prednisolone-equivalent dose, laboratory tests results (maximum levels of alanine aminotransferase, aspartate transaminase [AST], lactate dehydrogenase [LDH], and creatine kinase [CK]), and peak radiographic opacification of 24 patients during the course of their illness in the hospital were compared between two groups.

RESULTS

Parenchymal abnormality was present in 17 of 24 (70.8%) patients and fibrosis occurred in 10 of 24 (41.7%) patients. Patients in Group 1 (10/24; 41.7%) had a higher rate of mechanical ventilation therapy (Z = -2.340, P = 0.019), higher number of doses of cumulative prednisolone-equivalent (Z = -2.579, P = 0.010), higher maximum level of laboratory tests results (AST [Z = -2.140, P = 0.032], LDH [Z = -3.227, P = 0.001], and CK [Z = -3.345, P = 0.019]), and higher peak opacification on chest radiographs (Z = -2.743, P = 0.006) than patients in group 2 (14/24; 58.3%).

CONCLUSIONS

H1N1 virus-associated pneumonia frequently is followed by long-term pulmonary sequelae, including fibrotic changes, in lung parenchyma. Patients who need more steroid therapy, need more mechanical ventilation therapy, had higher laboratory tests results (maximum levels of AST, LDH, and CK), and had higher peak opacification on chest radiographs during treatment are more likely to develop lung fibrosis.

Nonspecific interstitial pneumonia: survival is influenced by the underlying cause

Idiopathic, nonspecific interstitial pneumonia (NSIP) is most often associated with various clinical disorders, including connective tissue diseases (CTDs) and chronic hypersensitivity pneumonitis (cHP). Emerging evidence also suggests that “idiopathic” NSIP may be the lung manifestation of undifferentiated CTD (UCTD). However, whether or not NSIP outcome is influenced by the underlying cause remains uncertain.

This retrospective study included 127 biopsy-proven NSIP patients (65 women, mean±sd age 55±12 years). Survivals were estimated using a Kaplan–Meier curve and compared using the log-rank test. Multivariate analyses were based on a Cox model.

15 (11.8%) patients had cHP, 29 (22.8%) had CTD, 32 (25.2%) satisfied the Kinder criteria for UCTD and 51 (40.1%) had idiopathic NSIP. At the end of follow-up (mean±sd 64±54 months), a difference in survival was observed between aetiological groups (p=0.002). Survival was better for UCTD than for idiopathic NSIP (p=0.020) and similar to that observed for CTD. cHP survival tended to be poorer than that of idiopathic NSIP (p=0.087) and was an independent predictor of mortality (hazard ratio 2.17, 95% CI 1.05–4.47; p=0.035).

NSIP outcome is influenced by its cause. cHP exhibits the highest mortality. UCTD does not differ from CTD supporting the concept of autoimmune NSIP, with a prognosis that is better than that of idiopathic NSIP.

Age influence on hypersensitivity pneumonitis induced in mice by exposure to Pantoea agglomerans

Hypersensitivity pneumonitis (HP) represents the immunologically mediated lung disease induced by repeated inhalations of a wide variety of certain finely dispersed organic antigens. In susceptible subjects, these inhalations provoke a hypersensitivity reaction characterized by intense inflammation of the terminal bronchioles, the interstitium and the alveolar tree. The inflammation often organizes into granulomas and may progress to pulmonary fibrosis. Our previous work indicated that cell extract of gram-negative bacteria Pantoea agglomerans (SE-PA) causes, in young C57BL/6J mice, pulmonary changes that are very similar to the clinical manifestations of HP in men. The purpose of presented studies was to describe the response of mice immune system while exposed to SE-PA. Particular attention was paid to examine the age influence on SE-PA induced inflammation and fibrosis in lung tissue. We used 3- and 18-month-old C57BL/6J mice. Lung samples were collected from untreated mice and animals exposed to harmful agent for 7 and 28 days. HP development was monitored by histological and biochemical evaluation. Using ELISA tests, we examined concentration of pro- and anti-inflammatory cytokines in lung homogenates. Our study demonstrated again that SE-PA provokes in mice changes typical for the clinical picture of HP, and that successive stages of disease (acute, subacute and chronic) might be obtained by modulation of time exposure. Furthermore, we found that animals' age at the time of sensitization influences the nature of observed changes (cytokine expression pattern) and the final outcome (reaction intensity and scale of fibrosis).

Lung biopsy-proved hypersensitivity pneumonitis without known offending antigen: characteristics and follow-up

INTRODUCTION

Hypersensitivity pneumonitis (HP) without known offending antigen is hard to diagnose.

OBJECTIVES

The purpose of this study was to identify and analyze the clinical features of lung biopsy-proved HP.

METHODS

A retrospective cohort study was performed using a database from a 900-bed specialty hospital. Twenty-eight patients with the diagnosis of HP through lung biopsy were enrolled. Demographic data and clinical characteristics, radiologic characteristics, serologic and pulmonary function results, histopathologic changes, treatment and follow-up were analyzed.

RESULTS

Of all the patients, serum interleukin-1β, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), eosinophil cationic protein and immunoglobulin E (IgE) were increased in over 50% patients, but decreased significantly after corticosteroid therapy (P < 0.05). An initially reduced diffusion lung capacity for carbon monoxide was noted in 92.9% patients, while 39.3% patients had hypoxemia. Ground-glass opacities on the basis of interlobular septa thickening were observed in 71.4% cases. Histopathological findings demonstrated peribronchiolar lymphocytic infiltrates, poorly formed non-caseating granulomas fibrosis in all acute and subacute HP patients' lungs. Ninety-two percent of patients got improvement after corticosteroid therapy when assessed by computer tomography scans and pulmonary function tests.

CONCLUSIONS

For suspected HP patients who without known offending antigens, earlier diagnosed by lung biopsy and followed by corticosteroid therapy showed promising. It might prevent the disease progression to lung fibrosis.

Identifying an inciting antigen is associated with improved survival in patients with chronic hypersensitivity pneumonitis

BACKGROUND

The cornerstone of hypersensitivity pneumonitis (HP) management is having patients avoid the inciting antigen (IA). Often, despite an exhaustive search, an IA cannot be found. The objective of this study was to examine whether identifying the IA impacts survival in patients with chronic HP.

METHODS

We used the Kaplan-Meier method to display, and the log-rank test to compare, survival curves of patients with well-characterized chronic HP stratified on identification of an IA exposure. A Cox proportional hazards (PH) model was used to identify independent predictors in time-to-death analysis.

RESULTS

Of 142 patients, 67 (47%) had an identified IA, and 75 (53%) had an unidentified IA. Compared with survivors, patients who died (n = 80, 56%) were older, more likely to have smoked, had lower total lung capacity % predicted and FVC % predicted, had higher severity of dyspnea, were more likely to have pulmonary fibrosis, and were less likely to have an identifiable IA. In a Cox PH model, the inability to identify an IA (hazard ratio [HR], 1.76; 95% CI, 1.01-3.07), older age (HR, 1.04; 95% CI, 1.01-1.07), the presences of pulmonary fibrosis (HR, 2.43; 95% CI, 1.36-4.35), a lower FVC% (HR, 1.36; 95% CI, 1.10-1.68), and a history of smoking (HR, 2.01; 95% C1, 1.15-3.50) were independent predictors of shorter survival. After adjusting for mean age, presence of fibrosis, mean FVC%, mean diffusing capacity of the lung for carbon monoxide (%), and history of smoking, survival was longer for patients with an identified IA exposure than those with an unidentified IA exposure (median, 8.75 years vs 4.88 years; P = .047).

CONCLUSIONS

Among patients with chronic HP, when adjusting for a number of potentially influential predictors, including the presence of fibrosis, the inability to identify an IA was independently associated with shortened survival.

Radiographic fibrosis score predicts survival in hypersensitivity pneumonitis

BACKGROUND

It is unknown if the radiographic fibrosis score predicts mortality in persistent hypersensitivity pneumonitis (HP) and if survival is similar to that observed in idiopathic pulmonary fibrosis (IPF) when adjusting for the extent of radiographic fibrosis.

METHODS

We reviewed records from 177 patients with HP and 224 patients with IPF whose diagnoses were established by multidisciplinary consensus. Two thoracic radiologists scored high-resolution CT (HRCT) scan lung images. Independent predictors of transplant-free survival were determined using a Cox proportional hazards analysis. Kaplan-Meier survival curves were constructed, stratified by disease as well as fibrosis score.

RESULTS

HRCT scan fibrosis score and radiographic reticulation independently predicted time to death or lung transplantation. Clinical predictors included a history of cigarette smoking, auscultatory crackles on lung examination, baseline FVC, and FEV1/FVC ratio. The majority of HP deaths occurred in patients with both radiographic reticulation and auscultatory crackles on examination, compared with patients with only one of these manifestations (P &lt; .0001). Patients with IPF had worse survival than those with HP at any given degree of radiographic fibrosis (hazard ratio 2.31; P &lt; .01).

CONCLUSIONS

Survival in patients with HP was superior to that of those with IPF with similar degrees of radiographic fibrosis. The combination of auscultatory crackles and radiographic reticulation identified patients with HP who had a particularly poor outcome.

An official American Thoracic Society/European Respiratory Society statement: Update of the international multidisciplinary classification of the idiopathic interstitial pneumonias

BACKGROUND

In 2002 the American Thoracic Society/European Respiratory Society (ATS/ERS) classification of idiopathic interstitial pneumonias (IIPs) defined seven specific entities, and provided standardized terminology and diagnostic criteria. In addition, the historical "gold standard" of histologic diagnosis was replaced by a multidisciplinary approach. Since 2002 many publications have provided new information about IIPs.

PURPOSE

The objective of this statement is to update the 2002 ATS/ERS classification of IIPs.

METHODS

An international multidisciplinary panel was formed and developed key questions that were addressed through a review of the literature published between 2000 and 2011.

RESULTS

Substantial progress has been made in IIPs since the previous classification. Nonspecific interstitial pneumonia is now better defined. Respiratory bronchiolitis-interstitial lung disease is now commonly diagnosed without surgical biopsy. The clinical course of idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia is recognized to be heterogeneous. Acute exacerbation of IIPs is now well defined. A substantial percentage of patients with IIP are difficult to classify, often due to mixed patterns of lung injury. A classification based on observed disease behavior is proposed for patients who are difficult to classify or for entities with heterogeneity in clinical course. A group of rare entities, including pleuroparenchymal fibroelastosis and rare histologic patterns, is introduced. The rapidly evolving field of molecular markers is reviewed with the intent of promoting additional investigations that may help in determining diagnosis, and potentially prognosis and treatment.

CONCLUSIONS

This update is a supplement to the previous 2002 IIP classification document. It outlines advances in the past decade and potential areas for future investigation.

Usual interstitial pneumonia: typical and atypical high-resolution computed tomography features

The computed tomography appearances of usual interstitial pneumonia (UIP) are usually characteristic, with basal-predominant, peripheral-predominant reticular abnormality and honeycombing. Important complications that may be detected by the radiologist include pulmonary hypertension, lung cancer, and acute exacerbation. As the number of surgical lung biopsies performed for typical UIP declines, histologic findings of UIP are increasingly found in subjects with atypical computed tomographic features. Potential reasons for such discordance may include variability in pathologist interpretation, sampling error on biopsy, biopsy obtained from nonrepresentative site, coexistence of multiple pathologies within the same lung, and familial pulmonary fibrosis. Multidisciplinary diagnosis is critical in resolving these cases.

Recent advances in hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a pulmonary disease with symptoms of dyspnea and cough resulting from the inhalation of an allergen to which the subject has been previously sensitized. The diagnosis of HP most often relies on an array of nonspecific clinical symptoms and signs developed in an appropriate setting, with the demonstration of interstitial markings on chest radiographs, serum precipitating antibodies against offending antigens, a lymphocytic alveolitis on BAL, and/or a granulomatous reaction on lung biopsies. The current classification of HP in acute, subacute, and chronic phases is now challenged, and a set of clinical predictors has been proposed. Nonspecific interstitial pneumonitis, usual interstitial pneumonia, and bronchiolitis obliterans organizing pneumonia may be the sole histologic expression of the disease. Presumably, like in idiopathic interstitial pneumonia, acute exacerbations of chronic HP may occur without further exposure to the offending antigen. New offending antigens, such as mycobacteria causing hot tub lung and metalworking fluid HP, have recently been identified and have stimulated further research in HP.

Hypersensitivity pneumonia: role of surgical lung biopsy

Lung biopsy often plays a key role in identifying patients with hypersensitivity pneumonia, especially in the absence of a typical history. A 69-year-old woman with a 2-year history of unexplained dyspnea on exertion underwent surgical lung biopsy for diagnosis of diffuse lung disease thought to represent idiopathic pulmonary fibrosis. Her biopsy showed honeycomb change and fibroblast foci suggestive of usual interstitial pneumonia, but also showed areas of cellular interstitial pneumonia with chronic bronchiolitis and a pattern of granulomatous inflammation typical of hypersensitivity pneumonia. The classic features of hypersensitivity pneumonia in surgical lung biopsy are emphasized, including a bronchiolocentric cellular interstitial pneumonia, chronic bronchiolitis, and poorly formed nonnecrotizing granulomas. As illustrated in our patient, sometimes subtle histologic clues are key in separating hypersensitivity pneumonia from usual interstitial pneumonia and other forms of idiopathic interstitial pneumonia. Making the distinction is important given differences in treatment strategies and natural history.

Pathological differentiation of chronic hypersensitivity pneumonitis from idiopathic pulmonary fibrosis/usual interstitial pneumonia

AIMS

To evaluate the histological characteristics differentiating chronic hypersensitivity pneumonitis (chronic HP) with a usual interstitial pneumonia (UIP)-like pattern from idiopathic pulmonary fibrosis (IPF)/UIP.

METHODS AND RESULTS

Surgical lung biopsy specimens from 22 patients with chronic HP diagnosed as having a UIP-like pattern upon histological examination and 13 patients with IPF/UIP were examined and the incidences of bronchiolitis, perilobular fibrosis, centrilobular fibrosis, bridging fibrosis, organizing pneumonia, fibroblastic foci, honeycombing, granulomas, giant cells, lymphocytic alveolitis and lymphoid follicles were compared. Bronchiolitis, centrilobular fibrosis, bridging fibrosis, organizing pneumonia, granulomas, giant cells and lymphocytic alveolitis were significantly more frequent among patients with chronic HP than among patients with IPF (all P<0.01).

CONCLUSIONS

Centrilobular fibrosis, bridging fibrosis and organizing pneumonia, in addition to bronchiolitis, granulomas and giant cells, are characteristic features of chronic HP with a UIP-like pattern. These features are therefore important in differentiating chronic HP from IPF/UIP, as management strategies differ for the two disorders.

Chronic hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a complex syndrome caused by the inhalation of environmental antigens. Chronic HP may mimic other fibrotic lung diseases, such as idiopathic pulmonary fibrosis. Recognition of the antigen is important for diagnosis; avoidance of further exposure is critical for treatment. Fibrosis on biopsy or high-resolution computed tomography is a predictor of increased mortality. Additional research is needed to understand why the disease develops only in a minority of exposed individuals and why cases of chronic HP may progress without further antigen exposure.

Pulmonary hypertension in chronic hypersensitivity pneumonitis

BACKGROUND

The purpose of this study was to evaluate the prevalence and outcomes of pulmonary hypertension in chronic hypersensitivity pneumonitis and to examine the relationship between pulmonary function tests and pulmonary hypertension.

METHODS

We conducted a retrospective review of 120 patients with hypersensitivity pneumonitis seen at two centers for pulmonary diseases over a 5-year interval and identified patients with chronic hypersensitivity pneumonitis for whom both pulmonary function tests and Doppler echocardiography data were available.

RESULTS

Chronic hypersensitivity pneumonitis was identified in 83 patients and Doppler echocardiography data were available for 73 of them. Pulmonary hypertension (sPAP ≥ 50 mmHg) was detected in 14 patients (19%), and was associated with a greater risk of death (median survival = 23 months vs. 98 months; P=0.003). Patients with pulmonary hypertension were older and had a significantly decreased PaO(2). There was a weak correlation between pulmonary function parameters and the underlying sPAP, with significance for FVC, FEV(1), and PaO(2) and inversely with PaCO(2).

CONCLUSIONS

Using Doppler echocardiography for evaluation, pulmonary hypertension seems to be common in patients with chronic hypersensitivity pneumonitis, significantly impacts survival, and correlates with FVC, FEV(1), and PaO(2) and inversely with PaCO(2).

Hypersensitivity pneumonia: the role of lung biopsy in diagnosis and management

Hypersensitivity pneumonia is a form of diffuse interstitial lung disease resulting from sensitization to an inhaled antigen. Clinical and radiological features are relatively nonspecific, overlapping significantly with other forms of diffuse interstitial lung disease. Establishing the diagnosis in the absence of lung biopsy is challenging and is heavily dependent on being able to identify a specific antigenic exposure. Lung biopsy is especially important in diagnosing hypersensitivity pneumonia in patients for whom no incriminating exposure has been elucidated. Surgical lung biopsies show a classical combination of findings in the majority of patients, which include an airway-centered, variably cellular chronic interstitial pneumonia, a lymphocyte-rich chronic bronchiolitis, and poorly formed non-necrotizing granulomas distributed mainly within the peribronchiolar interstitium. The bronchiolitis may include variable degrees of peribronchiolar fibrosis and hyperplasia of the bronchiolar epithelium ('peribronchiolar metaplasia'), a characteristic but a nonspecific finding. In some patients, granulomatous inflammation may be lacking, resulting in a histological appearance resembling nonspecific interstitial pneumonia. Late-stage fibrotic hypersensitivity pneumonia results in clinical, radiological, and histological findings that closely mimic usual interstitial pneumonia. The presence of established collagen fibrosis, especially when associated with architectural distortion in the form of honeycomb change, is associated with shorter survivals.

Serial high-resolution computed tomography findings of acute and chronic hypersensitivity pneumonitis induced by avian antigen

PURPOSE

The purpose of this study was to evaluate serial changes and the prognostic value of high-resolution computed tomographic (HRCT) findings in hypersensitivity pneumonitis (HP).

METHOD

The medical records of 112 patients with bird-related HP (17 acute, 33 recurrent, and 62 insidious) were retrospectively reviewed. High-resolution computed tomographic findings at the time of diagnosis and at follow-up were retrospectively interpreted.

RESULTS

Ground-glass opacities and centrilobular nodules were predominant findings in acute and recurrent HP, whereas honeycombing was the outstanding feature in insidious HP. Areas of ground-glass opacities and centrilobular nodules decreased in all groups over a long-term follow-up. Areas of honeycombing, on the other hand, increased in chronic HP, especially in the insidious cases. Cox regression models revealed a higher mortality risk in cases with airspace consolidation and honeycombing on HRCT.

CONCLUSION

Acute, recurrent, and insidious HP all have characteristic features on CT. Characteristic HRCT findings can predict the prognosis of chronic HP.

Occupational lung disease

Despite federally mandated safety standards, occupational lung disease remains one of the most common work-related injuries. Inhaled dust can result in a range of tissue injury in the lung and can lead to significant respiratory insufficiency causing death. Although silicosis and coal worker's pneumoconiosis are becoming less common, hypersensitivity pneumonitis is increasingly recognized as an occupational lung disease with new antigens being introduced annually. Imaging, particularly high-resolution computed tomography, is central to the management of occupational lung disease and is useful in diagnosis, assessment of disease activity, and evaluating response to therapy.

Subacute and chronic hypersensitivity pneumonitis: histopathological patterns and survival

BACKGROUND

In hypersensitivity pneumonitis (HP), survival can be predicted on the basis of the severity of fibrosis in surgical lung biopsy, but few data are available on the influence of clinical, functional, tomographic and histologic findings on prognosis.

OBJECTIVES

To describe the impact on survival of clinical data, histological patterns, and HRCT findings in subacute/chronic HP.

METHODS

A retrospective analysis of 103 patients diagnosed with HP submitted to surgical lung biopsy. Chronic HP was characterized by HRCT findings indicative of fibrosis (n=76).

RESULTS

The most relevant exposures were to molds and birds. Lung biopsies revealed typical HP with granulomas in 46 patients, bronchiolocentric interstitial pneumonia in 27, and non-specific interstitial pneumonia (NSIP) in 16. By univariate analysis, several findings were predictors of mortality: older age, male sex, velcro crackles, higher FEV(1)/FVC ratio, lower oxygen saturation during exercise, and absence of mosaic pattern/air trapping and presence of fibrosis on HRCT. By multivariate analysis, remained significant: age (p=0.007), oxygen saturation during exercise (p=0.003), and mosaic pattern/air trapping on HRCT (p=0.004). Patients with NSIP had a greater survival than did those with typical histology and those with bronchiolocentric pneumonia (p=0.033).

CONCLUSIONS

A wide range of histological features are found in HP. Typical findings are seen in 45% of cases. Other common patterns are NSIP and centriacinar lesions. Survival is better in patients with NSIP and worse in those with older age, desaturation during exercise, and absence of mosaic pattern/air trapping on HRCT.

Pathologic patterns and survival in chronic hypersensitivity pneumonitis

The objective of the study was to examine the relationship of pathologic pattern and prognosis in hypersensitivity pneumonitis (HP). We analyzed 24 cases of subacute (cellular, nonfibrotic) and 25 cases of chronic (fibrotic) HP. Nineteen (79%) of the subacute cases showed a pattern of bronchiolocentric interstitial pneumonia and 5 (21%) a pattern mimicking cellular nonspecific interstitial pneumonia (NSIP). Giant cells or granulomas or Schaumann bodies were present in 19 cases (79%). Eighteen (72%) chronic cases showed a pattern resembling usual interstitial pneumonia (UIP), but, in most cases, with more peribronchiolar fibrosis than one would expect in UIP. Three fibrotic cases (12%) had only peribronchiolar fibrosis, whereas 4 (16%) resembled fibrotic NSIP. Giant cells or granulomas or Schaumann bodies were present in 22 (88%) cases. Areas of subacute HP were present in 12 cases with a UIP-like pattern. Only 2 UIP-like cases could not be morphologically distinguished from idiopathic UIP. The median survival for patients who had no fibrosis was 22.4 years; for patients with a fibrotic NSIP pattern was 2.1 years; and for those with a UIP-like pattern 2.8 years (not statistically different). Patients with a pattern of only peribronchiolar fibrosis had a median survival of 11.3 years. These data confirm that the presence of fibrosis is associated with a generally poor prognosis in patients with HP, and suggest that pure peribronchiolar fibrosis may portend a longer survival than does a UIP-like or fibrotic NSIP-like pattern of fibrosis. Most cases of chronic HP have distinctive pathologic features, but a small percentage of cases cannot be pathologically distinguished from UIP.

Angiostatic versus angiogenic chemokines in IPF and EAA

BACKGROUND

Extrinsic allergic alveolitis (EAA) and idiopathic pulmonary fibrosis (IPF) share the presence of varying degree interstitial involvement and fibrosis. Vascular changes were often reported to accompany the development of fibrosis.

OBJECTIVES

The aim of our study was to examine the differences in angiostatic and angiogenic chemokine milieu in both diseases. Correlations between chemokine levels in bronchoalveolar lavage fluid (BALF), expression of chemokine receptors on CD4+ T cells (CXCR2, CXCR3) in BALF and HRCT pattern of the diseases were investigated.

METHODS

Sixteen patients with chronic EAA and 8 with IPF were enrolled to the study. Concentrations of interleukin (IL)-8, epithelial neutrophil activating protein (ENA)-78, interferon-gamma-inducible protein (IP)-10 and interferon-inducible T cell alpha chemoattractant (I-TAC) in BALF supernatants were quantified using Fluorokine MultiAnalyte profiling.

RESULTS

There was no significant difference in the BALF chemokine levels between the EAA and IPF group. IL-8 BALF concentrations correlate with the extent of fibrosis in both EAA and IPF (p<0.01). The IP-10 BALF concentrations do not correlate either with the HRCT alveolar or interstitial score and should be evaluated in the relationship with the disease course.

CONCLUSIONS

Both IL-8 and ENA-78 probably play a different role in IPF and chronic EAA pathogenesis. While we suggest ENA-78 as the marker of at least partial reversibility of the lung impairment in the EAA patients, IL-8 could be rather an indicator of continuous exposition to provoking agent in EAA patients. IL-8 might serve as a potential marker of early phase of IPF.

Pathology of hypersensitivity pneumonitis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Diagnosis of usual interstitial pneumonia and distinction from other fibrosing interstitial lung diseases

Usual interstitial pneumonia is an almost uniformly fatal form of fibrosing interstitial lung disease. It is the most common idiopathic interstitial pneumonia, and currently, there is no effective therapy. Lung biopsy is often needed for diagnosis, and pathologists must be able to recognize its features and distinguish it from other interstitial lung diseases that have a better prognosis and a more favorable response to therapy. This review is an attempt to clarify the diagnostic pathologic features of usual interstitial pneumonia and to provide guidelines for its distinction from other interstitial lung diseases that enter the differential diagnosis.

High-resolution CT findings of parenchymal fibrosis correlate with prognosis in hypersensitivity pneumonitis

BACKGROUND

Histopathologic evidence of fibrosis on surgical lung biopsy has been associated with reduced survival in patients with hypersensitivity pneumonitis (HP). Changes of pulmonary fibrosis detected on CT may also correlate with prognosis in patients with HP.

METHODS

We identified 69 consecutive patients with HP diagnosed between January 1997 and December 2002 at Mayo Clinic, Rochester, MN. Patients were stratified into fibrotic and nonfibrotic groups based on the CT findings. Fibrosis was defined by the presence of irregular linear opacities, traction bronchiectasis, or honeycombing.

MEASUREMENTS AND MAIN RESULTS

Of 69 patients, 26 were classified as fibrotic and 43 as nonfibrotic. Patients in the fibrotic group were older, had longer symptom duration, were more likely to have crackles on auscultation, more likely to be exposed to avian antigen, and had greater restrictive lung impairment (p<0.05 for all comparisons). There were 11 deaths in the fibrotic group and 1 death in the nonfibrotic group (p<0.0001). In the regression analysis, CT evidence of fibrosis, more severe pulmonary function abnormalities, and the presence of crackles on auscultation were predictive of reduced survival (p<0.05 for all). The presence as well as the extent of fibrosis on CT was associated with increased mortality. The age-adjusted hazard ratio for mortality in patients with fibrosis was 4.6 (95% confidence interval, 2.0 to 20.1; p<0.0001).

CONCLUSION

CT findings of parenchymal fibrosis are associated with reduced survival in patients with HP and may serve as a useful prognostic indicator.

Role of surgical lung biopsy in separating chronic hypersensitivity pneumonia from usual interstitial pneumonia/idiopathic pulmonary fibrosis: analysis of 31 biopsies from 15 patients

BACKGROUND

Lung biopsy has been proposed as a criterion for diagnosis of chronic hypersensitivity pneumonia (HP), especially in patients without proven antigen exposure. Histologic findings in some suspected HP patients overlap with usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP). We reviewed our experience to determine the specificity of histologic findings in surgical lung biopsies from patients with clinical diagnoses of HP.

METHODS

Surgical lung biopsies from patients with chronic HP, idiopathic pulmonary fibrosis, and idiopathic NSIP were reviewed retrospectively without knowledge of the clinical diagnosis. Each specimen was assigned a histologic diagnosis, and selected histologic findings were tabulated. Clinical data were abstracted from medical records.

RESULTS

Fifteen patients with clinical diagnoses of chronic HP underwent biopsy of one to three lobes. Ten showed features diagnostic of HP in all specimens. Two had discordant findings that included HP in one specimen and UIP or nonspecific changes in others. Biopsies from two showed only UIP, and one showed NSIP. Diagnostic features were present in all samples from 9 of the 11 patients with more than one biopsy site (81.8%). Three patients died of disease, including both patients from whom biopsies showed only UIP.

CONCLUSIONS

Most patients with a clinical diagnosis of chronic HP have supportive histologic findings in surgical lung biopsies. A subset of HP patients has findings indistinguishable from UIP. Sampling from more than one lobe may be helpful in separating HP from idiopathic pulmonary fibrosis.