Distinct histopathology of acute onset or abrupt exacerbation of hypersensitivity pneumonitis

Disease trajectories in interstitial lung diseases - data from the EXCITING-ILD registry

BACKGROUND

Interstitial lung diseases (ILD) comprise a heterogeneous group of mainly chronic lung diseases with different disease trajectories. Progression (PF-ILD) occurs in up to 50% of patients and is associated with increased mortality.

METHODS

The EXCITING-ILD (Exploring Clinical and Epidemiological Characteristics of Interstitial Lung Diseases) registry was analysed for disease trajectories in different ILD. The course of disease was classified as significant (absolute forced vital capacity FVC decline > 10%) or moderate progression (FVC decline 5-10%), stable disease (FVC decline or increase < 5%) or improvement (FVC increase ≥ 5%) during time in registry. A second definition for PF-ILD included absolute decline in FVC % predicted ≥ 10% within 24 months or ≥ 1 respiratory-related hospitalisation. Risk factors for progression were determined by Cox proportional-hazard models and by logistic regression with forward selection. Kaplan-Meier curves were utilised to estimate survival time and time to progression.

RESULTS

Within the EXCITING-ILD registry 28.5% of the patients died (n = 171), mainly due to ILD (n = 71, 41.5%). Median survival time from date of diagnosis on was 15.5 years (range 0.1 to 34.4 years). From 601 included patients, progression was detected in 50.6% of the patients (n = 304) with shortest median time to progression in idiopathic NSIP (iNSIP; median 14.6 months) and idiopathic pulmonary fibrosis (IPF; median 18.9 months). Reasons for the determination as PF-ILD were mainly deterioration in lung function (PFT; 57.8%) and respiratory hospitalisations (40.6%). In multivariate analyses reduced baseline FVC together with age were significant predictors for progression (OR = 1.00, p < 0.001). Higher GAP indices were a significant risk factor for a shorter survival time (GAP stage III vs. I HR = 9.06, p < 0.001). A significant shorter survival time was found in IPF compared to sarcoidosis (HR = 0.04, p < 0.001), CTD-ILD (HR = 0.33, p < 0.001), and HP (HR = 0.30, p < 0.001). Patients with at least one reported ILD exacerbation as a reason for hospitalisation had a median survival time of 7.3 years (range 0.1 to 34.4 years) compared to 19.6 years (range 0.3 to 19.6 years) in patients without exacerbations (HR = 0.39, p < 0.001).

CONCLUSION

Disease progression is common in all ILD and associated with increased mortality. Most important risk factors for progression are impaired baseline forced vital capacity and higher age, as well as acute exacerbations and respiratory hospitalisations for mortality. Early detection of progression remains challenging, further clinical criteria in addition to PFT might be helpful.

Hospitalisation patterns in interstitial lung diseases: data from the EXCITING-ILD registry

BACKGROUND

Interstitial lung diseases (ILD) comprise a heterogeneous group of mainly chronic lung diseases with more than 200 entities and relevant differences in disease course and prognosis. Little data is available on hospitalisation patterns in ILD.

METHODS

The EXCITING-ILD (Exploring Clinical and Epidemiological Characteristics of Interstitial Lung Diseases) registry was analysed for hospitalisations. Reasons for hospitalisation were classified as all cause, ILD-related and respiratory hospitalisations, and patients were analysed for frequency of hospitalisations, time to first non-elective hospitalisation, mortality and progression-free survival. Additionally, the risk for hospitalisation according to GAP index and ILD subtype was calculated by Cox proportional-hazard models as well as influencing factors on prediction of hospitalisation by logistic regression with forward selection.

RESULTS

In total, 601 patients were included. 1210 hospitalisations were recorded during the 6 months prior to registry inclusion until the last study visit. 800 (66.1%) were ILD-related, 59.3% of admissions were registered in the first year after inclusion. Mortality was associated with all cause, ILD-related and respiratory-related hospitalisation. Risk factors for hospitalisation were advanced disease (GAP Index stages II and III) and CTD (connective tissue disease)-ILDs. All cause hospitalisations were associated with pulmonary hypertension (OR 2.53, p = 0.005). ILD-related hospitalisations were associated with unclassifiable ILD and concomitant emphysema (OR = 2.133, p = 0.001) as well as with other granulomatous ILDs and a positive smoking status (OR = 3.082, p = 0.005).

CONCLUSION

Our results represent a crucial contribution in understanding predisposing factors for hospitalisation in ILD and its major impact on mortality. Further studies to characterize the most vulnerable patient group as well as approaches to prevent hospitalisations are warranted.

Feasibility and Outcomes of a Standardized Management Protocol for Acute Exacerbation of Interstitial Lung Disease

BACKGROUND AND OBJECTIVE

Despite the high mortality of acute exacerbations of interstitial lung disease (AE-ILD), there is minimal evidence to guide management decisions. We aimed to assess the feasibility and outcomes of a standardized management protocol for AE-ILD.

METHODS

We performed a retrospective cohort study of patients with AE-ILD admitted to hospital between January 2015 and August 2019. Patients were managed with a standardized protocol including chest computed tomography (CT) at diagnosis, pulse corticosteroid treatment, and a follow-up CT 7 days after corticosteroid pulse. The association between idiopathic pulmonary fibrosis (IPF) versus non-IPF diagnosis and transplant-free survival within 1-year of AE-ILD was assessed using adjusted Cox proportional hazards regression survival analysis. Associations with CT chest improvement 7 days after corticosteroid pulse were secondarily assessed.

RESULTS

89 patients with AE-ILD were identified. 1-year transplant-free and overall survival were 20.2 and 51.7%, respectively. Protocol adherence to pulse corticosteroids was high (95.5%). A diagnosis of IPF was associated with higher risk of death or transplant at 1-year versus a non-IPF diagnosis [hazard ratio (HR) 2.23, 95% CI 1.19-4.17, p = 0.012]. There were no significant associations with 7-day CT improvement; however, CT improvement was associated with higher transplant-free survival (p = 0.02) and a lower risk of in-hospital mortality (χ² = 7.06, p = 0.01) on unadjusted analysis.

CONCLUSIONS

IPF is associated with a higher risk of death or transplant at 1-year as compared to a non-IPF diagnosis in patients with AE-ILD managed using a standardized protocol. Improvement on CT chest 7 days after corticosteroid pulse is associated with better survival.

Pathology of Granulomatous Pulmonary Diseases

CONTEXT.—

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

OBJECTIVES.—

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

DATA SOURCES.—

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

CONCLUSIONS.—

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

Life-threatening hypersensitivity pneumonitis secondary to e-cigarettes

We report a case of hypersensitivity pneumonitis (HP) in a young person secondary to vaping. He presented with a putative diagnosis of asthma and required extracorporeal membrane oxygenationbecause of intractable respiratory failure. He developed a critical illness and steroid myopathy and required prolonged rehabilitation. Our patient fulfils diagnostic criteria for HP secondary to e-cigarettes with a positive exposure history, deterioration after skin prick testing, specific serum IgM antibodies against the implicated liquid raising the possibility that the relevant antigen was present in that liquid and radiological and histopathological features compatible with acute HP. There are two learning points. The first is always to consider a reaction to e-cigarettes in someone presenting with an atypical respiratory illness. The second is that we consider e-cigarettes as 'much safer than tobacco' at our peril.

Exposure assessment in hypersensitivity pneumonitis: a comprehensive review and proposed screening questionnaire

Hypersensitivity pneumonitis is an immune-mediated inflammatory lung disease characterised by the inhalation of environmental antigens leading to acute and chronic lung injury. Along with suggestive clinical and radiological findings, history and timing of suspected antigen exposure are important elements for diagnostic confidence. Unfortunately, many diagnoses remain tentative and based on vague and imprecise environmental or material exposure histories. To date, there has not been a comprehensive report highlighting the frequency and type of environmental exposure that might lead to or support a more systematic approach to antigen identification. We performed a comprehensive literature review to identify and classify causative antigens and their associated environmental contexts or source materials, with emphasis on the extent of the supportive literature for each exposure type. Eligible publications were those that reported unique inciting antigens and their respective environments or contexts. A clinical questionnaire was then proposed based on this review to better support diagnosis of hypersensitivity pneumonitis when antigen testing or other clinical and radiological variables are inconclusive or incomplete.

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.

Hospitalisation patterns of patients with interstitial lung disease in the light of comorbidities and medical treatment - a German claims data analysis

BACKGROUND

Interstitial lung disease (ILD) is a heterogeneous group of mainly chronic lung diseases differing in disease course and prognosis. For most subtypes, evidence on relevance and outcomes of hospitalisations is lacking.

METHODS

Using German claims data we investigated number of hospitalisations (zero-inflated-negative-binomial models providing rate ratios (RR)) and time to first hospitalisation (Cox proportional-hazard models providing hazard ratios (RR)) for nine ILD-subtypes. Models were stratified by ILD-related and non-ILD-related hospitalisations. We adjusted for age, gender, ILD-subtype, ILD-relevant comorbidities and ILD-medication (immunosuppressive drugs, steroids, anti-fibrotic drugs).

RESULTS

Among 36,816 ILD-patients (mean age 64.7 years, 56.2% male, mean observation period 9.3 quarters), 71.2% had non-ILD-related and 56.6% ILD-related hospitalisations. We observed more and earlier non-ILD-related hospitalisations in ILD patients other than sarcoidosis. Medical ILD-treatment was associated with increased frequency and in case of late initiation, earlier (non-)ILD-related hospitalisations. Comorbidities were associated with generally increased hospitalisation frequency except for COPD (RR = 0.90) and PH (RR = 0.94) in non-ILD-related and for lung cancer in ILD-related hospitalisations (RR = 0.89). Coronary heart disease was linked with earlier (ILD-related: HR = 1.17, non-ILD-related HR = 1.19), but most other conditions with delayed hospitalisations.

CONCLUSION

Hospitalisations are frequent across all ILD-subtypes. The hospitalisation risk might be reduced independently of the subtype by improved management of comorbidities and improved pharmacological and non-pharmacological ILD therapy.

Radiologic, Pathologic, Clinical, and Physiologic Findings of Electronic Cigarette or Vaping Product Use-associated Lung Injury (EVALI): Evolving Knowledge and Remaining Questions

Proposed as a safer alternative to smoking, the use of electronic cigarettes has not proven to be innocuous. With numerous deaths, there is an increasing degree of public interest in understanding the symptoms, imaging appearances, causes of, and treatment of electronic cigarette or vaping product use-associated lung injury (EVALI). Patients with EVALI typically have a nonspecific clinical presentation characterized by a combination of respiratory, gastrointestinal, and constitutional symptoms. EVALI is a diagnosis of exclusion; the patient must elicit a history of recent vaping within 90 days, other etiologies must be eliminated, and chest imaging findings must be abnormal. Chest CT findings in EVALI most commonly show a pattern of acute lung injury on the spectrum of organizing pneumonia and diffuse alveolar damage. The pathologic pattern found depends on when in the evolution of the disease process the biopsy sample is taken. Other less common forms of lung injury, including acute eosinophilic pneumonia and diffuse alveolar hemorrhage, have also been reported. Radiologists and pathologists help play an important role in the evaluation of patients suspected of having EVALI. Accurate and rapid identification may decrease morbidity and mortality by allowing for aggressive clinical management and glucocorticoid administration, which have been shown to decrease the severity of lung injury in some patients. In this review, the authors summarize the current state of the art for the imaging and pathologic findings of this disorder and outline a few of the major questions that remain to be answered.

Acute Lung Injury and Non-infectious Pneumonias

Lung injury can occur secondary to a myriad of causes, including infection, immunologic disorders, drug toxicity, or inhalational injury among others. Although the list of causative agents is long, the lung’s response to injury is limited resulting in similar patterns of disease irrespective of the cause. From a pathological perspective, acute lung injury refers to a group of entities that present with acute or subacute disease. These conditions are characterized by particular histological patterns including diffuse alveolar damage, acute fibrinous and organizing pneumonia, organizing pneumonia, and eosinophilic pneumonia and clinically correspond to the varying degrees of acute respiratory distress syndrome (Patel et al, Chest 125:197–202, 2004; Beasley et al, Arch Pathol Lab Med 126:1064–1070, 2002; Avecillas et al, Clin Chest Med 27:549–557, 2006; Cottin, Cordier, Semin Respir Crit Care Med 33:462–475, 2012; Ferguson et al, Intensive Care Med 38:1573–1582, 2012). In most cases, the underlying cause will not be apparent from the histological findings requiring close correlation with clinical history and laboratory findings to determine the etiology. Nevertheless, careful search for infectious organisms with application of histochemical and immunohistochemical stains should be performed in all cases in order to identify cases that benefit from more targeted treatment.

Prognostic differences among patients with idiopathic interstitial pneumonias with acute exacerbation of varying pathogenesis: a retrospective study

Background

Acute exacerbation of chronic fibrosing idiopathic interstitial pneumonias (AE-IIPs) is associated with a high mortality rate. In 2016, an international working group proposed a revised diagnostic criteria for AE-IIPs, suggesting that it be classified as idiopathic or triggered. Many factors are known to trigger AE-IIPs, including surgery, infection, and drugs. However, it is unknown which AE-IIPs triggers have a worse prognosis. We aimed to investigate the prognosis of patients with various clinical types of AE-IIPs, particularly infection-triggered, non-infection triggered, and idiopathic AE-IIPs.

Methods

We retrospectively collected data from 128 chronic fibrosing IIPs (CF-IIPs) patients who were hospitalized by respiratory failure between April 2009 and March 2019 at Juntendo University Hospital. Among these patients, we evaluated 79 patients who developed AE-IIPs and 21 who developed pneumonia superimposed on CF-IIPs. Patients with AE-IIPs were classified into three types: idiopathic, infection-triggered, and non-infection-triggered AE-IIPs. We analyzed differences in patient characteristics, examination findings; level of serum markers, results of pulmonary function, and radiological findings, prior treatment for baseline CF-IIPs, and prognosis. We then evaluated the risk factor for early death (death within 30 days from the onset of AE-IIPs) associated with AE-IIPs.

Results

Among the patients who developed AE-IIPs, 34 were characterized as having idiopathic, 25 were characterized as having infection-triggered, and 20 were categorized as having non-infection-triggered AE-IIPs. Survival time for pneumonia superimposed on IIPs was significantly longer than that for any AE-IIPs. Survival time for bacterial pneumonia superimposed on CF-IIPs was significantly longer than that for AE-IIPs (for each idiopathic and all triggered IIPs). Thereafter, survival time for infection-triggered was significantly longer than for idiopathic or non-infection-triggered AE-IIPs. The mortality rate was significantly lower in infection-triggered AE-IIPs than in other types of AE-IIPs. Furthermore, the incidence of infection-triggered AE-IIPs in winter was significantly higher than that in other seasons. Moreover, the clinical AE-IIPs types and radiological findings at AE-IIP onset were significant risk factors for AE-IIPs-induced early death.

Conclusions

Our findings suggest that patients with infection-triggered AE-IIPs can expect a better prognosis than can patients with other clinical types of AE-IIPs.

Update on Rare Idiopathic Interstitial Pneumonias and Rare Histologic Patterns

CONTEXT

- In 2013, the revised American Thoracic Society and European Respiratory Society classification of idiopathic interstitial pneumonias (IIPs) described 2 rare IIPs and 2 rare histologic patterns. Because of the rarity of the disease, there is limited evidence related to the histology. Because the rare histologic patterns are provisional criteria, no unanimous consensus on histologic diagnostic criteria has yet been reached.

OBJECTIVE

- To review the histologic features for rare IIPs and rare histologic patterns, and to provide diagnostic aids and discuss the differential diagnosis.

DATA SOURCES

- Published peer-reviewed literature and the authors' personal experience.

CONCLUSIONS

- Following the publication of the international consensus classification, evidence regarding rare IIPs and rare histologic patterns has accumulated to some extent, although to date the amount remains insufficient and further evidence is required. Because the diagnosis is sometimes challenging, a multidisciplinary approach represents the gold standard in reaching an accurate diagnosis for these rare disorders.

[Hypersensitivity pneumonitis in children]

Hypersensitivity pneumonitis (HP) is an interstitial lung disease caused by an immune response to a variety of antigens to which patients have been previously sensitised. It can occur at any age. In children, it is a rare disease, probably under-diagnosed, with an estimated prevalence of 4 per million. The paediatric forms are not really different from those of adults but present some particularities. Avian exposure is by far the most frequent cause of HP, accounting for nearly two-thirds of cases. Although there is no current recommendation for the diagnosis of HP, it is commonly considered that the diagnosis can be made with confidence on the combination of (1) compatible respiratory symptoms, (2) exposure to a known offending antigen, (3) lymphocytic alveolitis, (4) decreased transfer factor for carbon monoxide or hypoxia on exertion and (5) compatible radiologic features. The treatment is based on antigen avoidance that must be complete and definitive. Corticosteroids can be necessary in severe forms. The prognosis of HP in children is better than in adults, with a full clinical and functional recovery in the majority of cases after complete antigenic withdrawal.

Biopsy-proven recurrent, acute, familial hypersensitivity pneumonitis: A case report and literature review

Hypersensitivity pneumonitis (HP) is characterized by inflammation of the lung parenchyma that is induced by exposure to an inhaled organic antigen. We present a case of recurrent, acute HP caused by repeated transient exposure to a down sleeping bag in a patient with a family history of chronic bird-associated hypersensitivity pneumonitis. The patient's recurrent symptoms, changes in physiology, and radiographic findings coincided with repeated exposure to this source. It was later confirmed that the patient's sister had also developed chronic HP from recurrent exposure to household birds. This case highlights recent studies implicating gene-exposure interactions in the development of HP.

Early immunopathological events in acute model of mycobacterial hypersensitivity pneumonitis in mice

Prolonged exposure to antigens of non-tuberculous mycobacteria species colonizing industrial metalworking fluid (MWF), particularly Mycobacterium immunogenum (MI), has been implicated in chronic forms of hypersensitivity pneumonitis (HP) in machinists based on epidemiology studies and long-term exposure of mouse models. However, a role of short-term acute exposure to these antigens has not been described in the context of acute forms of HP. This study investigated short-term acute exposure of mice to MI cell lysate (or live cell suspension) via oropharyngeal aspiration. The results showed there was a dose- and time-dependent increase (peaking at 2 h post-instillation) in lung immunological responses in terms of the pro- (TNFα, IL-6, IL-1β) and anti-inflammatory (IL-10) cytokines. Bronchoalveolar lavage and histology showed neutrophils as the predominant infiltrating cell type, with lymphocytes <5% at all timepoints or concentrations. Granulomatous inflammation peaked between 8 and 24 h post-exposure, and resolved by 96 h. Live bacterial challenge, typically encountered in real-world exposures, showed no significant differences from bacterial lysate except for induction of appreciable levels of interferon (IFN)-γ, implying additional immunogenic potential. Collectively, the short-term mycobacterial challenge in mice led to a transient early immunopathologic response, with little adaptive immunity, which is consistent with events associated with human acute forms of HP. Screening of MWF-originated mycobacterial genotypes/variants (six of MI, four of M. chelonae, two of M. abscessus) showed both inter- and intra-species differences, with MI genotype MJY10 being the most immunogenic. In conclusion, this study characterized the first short-term mycobacterial exposure mouse model that mimics acute HP in machinists; this could serve as a potentially useful model for rapid screening of field MWF-associated mycobacteria for routine and timely occupational risk assessment and for investigating early biomarkers and mechanisms of this understudied immune lung disease.

Pneumonia

The lung is constantly exposed to airborne infectious agents due to the large surface area of approximately 100 m². Therefore pneumonia is one of the most common lung diseases. Understanding infection requires understanding the routes of infections, the way invading organisms infect epithelial cells, as well as defense mechanisms of the lung tissue acquired during evolution.

 Different variants of infectious and non-infectious pneumonias are discussed; special types of pneumonias such as granulomatous and fibrosing pneumonias are presented under separate sections. Causing organisms and other causes of pneumonias are included, and their mode of action is included as far as understood.

Pulmonary Manifestations of Acute Lung Injury: More Than Just Diffuse Alveolar Damage

CONTEXT

- Acute pulmonary injury may occur as a result of myriad direct or indirect pulmonary insults, often resulting in hypoxemic respiratory failure and clinical acute respiratory distress syndrome. Histologically, most patients will exhibit diffuse alveolar damage on biopsy, but other histologic patterns may be encountered, such as acute eosinophilic pneumonia, acute fibrinous and organizing pneumonia, and diffuse alveolar hemorrhage with capillaritis.

OBJECTIVE

- To review the diagnostic features of various histologic patterns associated with a clinical picture of acute lung injury, and to discuss key features in the differential diagnosis.

DATA SOURCES

- The review is drawn from pertinent peer-reviewed literature and the personal experience of the authors.

CONCLUSIONS

- Acute pulmonary injury is a significant cause of morbidity and mortality. In addition to diffuse alveolar damage, pathologists should be aware of alternate histologic patterns of lung disease that may present with a similar clinical presentation because this may impact treatment decisions and disease outcome.

Imaging of Hypersensitivity Pneumonitis

The management of hypersensitivity pneumonitis (HP) depends on early identification of the disease process, which is complicated by its nonspecific clinical presentation in addition to variable and diverse laboratory and radiologic findings. HP is the result of exposure and sensitization to myriad aerosolized antigens. HP develops in the minority of antigenic exposures, and conversely has been documented in patients with no identifiable exposure, complicating the diagnostic algorithm significantly. Prompt diagnosis and early intervention are critical in slowing the progression of irreversible parenchymal damage, and additionally in preserving the quality of life of affected patients.

Acute and subacute idiopathic interstitial pneumonias

Idiopathic interstitial pneumonias (IIPs) may have an acute or subacute presentation, or acute exacerbation may occur in a previously subclinical or unrecognized chronic IIP. Acute or subacute IIPs include acute interstitial pneumonia (AIP), cryptogenic organizing pneumonia (COP), nonspecific interstitial pneumonia (NSIP), acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) and AE-NSIP. Interstitial lung diseases (ILDs) including connective tissue disease (CTD) associated ILD, hypersensitivity pneumonitis, acute eosinophilic pneumonia, drug-induced lung disease and diffuse alveolar haemorrhage need to be differentiated from acute and subacute IIPs. Despite the severe lack of randomized controlled trials for the treatment of acute and subacute IIPs, the mainstream treatment remains corticosteroid therapy. Other potential therapies reported in the literature include corticosteroids and immunosuppression, antibiotics, anticoagulants, neutrophil elastase inhibitor, autoantibody-targeted treatment, antifibrotics and hemoperfusion therapy. With regard to mechanical ventilation, patients in recent studies with acute and subacute IIPs have shown better survival than those in previous studies. Therefore, a careful value-laden decision about the indications for endotracheal intubation should be made for each patient. Noninvasive ventilation may be beneficial to reduce ventilator associated pneumonia.

Pathology of Idiopathic Interstitial Pneumonias

The updated classification of idiopathic interstitial pneumonias (IIPs) in 2013 by American Thoracic Society/European Respiratory Society included several important revisions to the categories described in the 2002 classification. In the updated classification, lymphoid interstitial pneumonia (LIP) was moved from major to rare IIPs, pleuroparenchymal fibroelastosis (PPFE) was newly included in the rare IIPs, acute fibrinous and organizing pneumonia (AFOP) and interstitial pneumonias with a bronchiolocentric distribution are recognized as rare histologic patterns, and unclassifiable IIP (UCIP) was classified as an IIP. However, recent reports indicate the areas of concern that may require further evaluation. Here, we describe the histopathologic features of the updated IIPs and their rare histologic patterns and also point out some of the issues to be considered in this context.

A case of acute fibrinous and organizing pneumonia during early postoperative period after lung transplantation

Acute fibrinous and organizing pneumonia (AFOP) is a distinct histologic pattern usually classified under the term chronic lung allograft dysfunction. We present a 48-year-old female patient who experienced AFOP during the 2nd week of double lung transplantation for pulmonary Langerhans cell histiocytosis and secondary pulmonary hypertension. During the 8th day after transplantation, fever and neutrophilia developed together with bilateral consolidation. Infection markers were elevated. Despite coverage of a full antimicrobial spectrum, the situation progressed. The patient was diagnosed with AFOP with transbronchial biopsy. The infiltration resolved and the patient improved dramatically with the initiation of pulse corticosteroid treatment. AFOP should be suspected when there is a pulmonary consolidation after lung transplantation, even in the very early post-transplantation period. Several causes, such as alveolar damage and drug reactions, should be considered in the differential diagnosis.

Patients With Fibrotic Interstitial Lung Disease Hospitalized for Acute Respiratory Worsening: A Large Cohort Analysis

BACKGROUND

Acute respiratory worsening (ARW) requiring hospitalization in patients with fibrotic interstitial lung disease (f-ILD) is common. Little is known about the frequency and implications of ARW in IPF and non-IPF ILD patients hospitalized for acute exacerbation (AE) vs known causes of ARW.

METHODS

All consecutive patients with f-ILD hospitalized with ARW at our institution from 2000 to 2014 were reviewed. ARW was defined as any worsening of respiratory symptoms with new or worsened hypoxemia or hypercapnia within 30 days of admission. Suspected AE was defined using modified 2007 American Thoracic Society/European Respiratory Society criteria. Known causes of ARW were reviewed and collated along with in-hospital and all-cause mortality postdischarge.

RESULTS

A total of 220 patients (100 with IPF and 120 non-IPF) composed 311 admissions for ARW. Suspected AE (SAE) comprised 52% of ARW admissions, followed by infection (20%), and subacute progression of disease (15%). In-hospital mortality was similar in patients with IPF vs patients without (55 vs 45%, P = .18), but worse in suspected AE admission types (OR, 3.1 [1.9-5.14]). One-year survival after last ARW admission for the whole cohort was 22%, despite only 27% of patients presenting with baseline oxygen requirement at admission and a mean admission Charlson Comorbidity Index score of 5.4 (expected 1-year survival, 89%). Survival after discharge was similar between SAE and secondary ARW admission types in both IPF and non-IPF patients.

CONCLUSIONS

Among patients with f-ILD, hospitalization for ARW appears associated with significant in-hospital and postdischarge mortality regardless of underlying fibrotic lung disease or non-AE cause of acute respiratory decline.

Worsening of pulmonary sarcoidosis

PURPOSE OF REVIEW

Despite the frequent occurrence of worsening pulmonary symptoms in pulmonary sarcoidosis patients, there is little available information concerning this topic.

RECENT FINDINGS

In this review, we outline the various causes for these symptoms. We propose to partition the various causes for these symptoms into specific categories.

SUMMARY

We believe that these categories will provide the clinician a framework to evaluate pulmonary sarcoidosis patients with such symptoms in a rigorous way that may be useful in optimizing their care.

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.

Lymphangiogenic factors are associated with the severity of hypersensitivity pneumonitis

Background

Antigen presenting cells play a pivotal role in the adaptive immune response in hypersensitivity pneumonitis (HP). It was hypothesised that lymphangiogenesis is involved in the pathophysiology of HP via cell transport.

Objective

To determine the clinical significance of lymphangiogenic factors in HP.

Methods

Levels of vascular endothelial growth factors (VEGF)-A, VEGF-C, VEGF-D and CCL21 in the serum and bronchoalveolar lavage fluid (BALF) were measured in 29 healthy volunteers, 14 patients with idiopathic pulmonary fibrosis (IPF) and 26 patients with HP by ELISA. Additionally, immunohistochemical analyses were performed using lung specimens of patients with HP (n=8) and IPF (n=10).

Results

BALF VEGF-D levels were significantly elevated in patients with HP compared to the other groups. BALF VEGF–D levels in patients with HP correlated significantly with the BALF total cell and lymphocyte counts (r=0.485, p=0.014 and r=0.717, p<0.0001, respectively). BALF VEGF-C and CCL21 levels were increased in patients with HP compared to healthy volunteers, but not patients with IPF. BALF CCL21 levels were negatively correlated with the forced expiratory volume in 1 s percentage and diffuse capacity of the lung for carbon monoxide (r=−0.662, p=0.007 and r=−0.671, p=0.024, respectively). According to the immunohistochemical analyses, CCL21 was expressed in the lymphatic endothelium in both conditions and CCR7⁺ cells were aggregated around lymphatics in patients with HP, but not in patients with IPF.

Conclusions

Lymphangiogenic factors might be associated with the inflammatory and functional severity of HP. The increased BALF VEGF-D levels were associated with lymphatic alveolitis intensity, and CCL21 with lung function impairment.

From the radiologic pathology archives: organization and fibrosis as a response to lung injury in diffuse alveolar damage, organizing pneumonia, and acute fibrinous and organizing pneumonia

Organization, characterized by fibroblast proliferation, is a common and nearly universal response to lung injury whether it is focal or diffuse. Despite the vast range of injurious agents, the lung's response to injury is quite limited, with a similar pattern of reaction seen radiologically and histologically regardless of the underlying cause. Although there is a tendency to divide organization into distinct entities, the underlying injury to the alveolar epithelial basement membrane is a uniting factor in these processes. This pattern of lung injury is seen in the organizing phase of diffuse alveolar damage, organizing pneumonia (OP), acute fibrinous and organizing pneumonia, and certain types of fibrotic lung disease. In addition, although organization can heal without significant injury, in some instances it progresses to fibrosis, which can be severe. When fibrosis due to organization is present, other histologic and imaging patterns, such as those seen in nonspecific interstitial pneumonia, can develop, reflecting that fibrosis can be a sequela of organization. This article reviews the histologic and radiologic findings of organization in lung injury due to diffuse alveolar damage, OP, and acute fibrinous and organizing pneumonia and helps radiologists understand that the histologic and radiologic findings depend on the degree of injury and the subsequent healing response.

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.

Hypersensitivity pneumonitis: a review and update of histologic findings

Hypersensitivity pneumonitis (HSP) is a poorly understood entity typically caused by exposure to an inciting antigen such as fungi, thermophilic bacteria or animal protein. Clinically, HSP is often divided into acute, subacute and chronic forms. While the subacute form is best described from a pathologic standpoint, the pathology of chronic HSP has only been critically evaluated in the past decade and the pathology of acute HSP is poorly described. The aim of this review is to summarise the current knowledge of pathogenetic theories of HSP and to review the current knowledge of the pathology of each stage of HSP and the main entities in the differential diagnosis.

Management of hypersensivity pneumonitis

Hypersensitivity pneumonitis (HP) is an interstitial lung disease due to a combined type III and IV reaction with a granulomatous inflammation, caused by cytotoxic delayed hypersensitivity lymphocytes, in a Th1/Th17 milieu, chaperoned by a deficient suppressor function of T regulatory cells. Skewing toward a Th2 phenotype is reported for chronic HP. Phenotypic expression and severity depends on environmental and/or host genetic and immune co-factors. The wide spectrum of causative antigens is continuously up-dated with new sources of airborne organic particles and drug-induced HP. The diagnosis requires a detailed history, measurement of environmental exposure, pulmonary function tests, imaging, detection of serum specific antibodies, broncho-alveolar lavage, antigen-induced lymphocyte proliferation, environmental or laboratory-controlled inhalation challenge and lung biopsy. Complete antigen avoidance is the best therapeutic measure, although very difficult to achieve in some cases. Systemic steroids are of value for subacute and chronic forms of HP, but do not influence long term outcome. Manipulation of the immune response in HP holds future promise.

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.

Hypersensitivity pneumonitis: insights in diagnosis and pathobiology

Hypersensitivity pneumonitis (HP) is a complex syndrome resulting from repeated exposure to a variety of organic particles. HP may present as acute, subacute, or chronic clinical forms but with frequent overlap of these various forms. An intriguing question is why only few of the exposed individuals develop the disease. According to a two-hit model, antigen exposure associated with genetic or environmental promoting factors provokes an immunopathological response. This response is mediated by immune complexes in the acute form and by Th1 and likely Th17 T cells in subacute/chronic cases. Pathologically, HP is characterized by a bronchiolocentric granulomatous lymphocytic alveolitis, which evolves to fibrosis in chronic advanced cases. On high-resolution computed tomography scan, ground-glass and poorly defined nodules, with patchy areas of air trapping, are seen in acute/subacute cases, whereas reticular opacities, volume loss, and traction bronchiectasis superimposed on subacute changes are observed in chronic cases. Importantly, subacute and chronic HP may mimic several interstitial lung diseases, including nonspecific interstitial pneumonia and usual interstitial pneumonia, making diagnosis extremely difficult. Thus, the diagnosis of HP requires a high index of suspicion and should be considered in any patient presenting with clinical evidence of interstitial lung disease. The definitive diagnosis requires exposure to known antigen, and the assemblage of clinical, radiologic, laboratory, and pathologic findings. Early diagnosis and avoidance of further exposure are keys in management of the disease. Corticosteroids are generally used, although their long-term efficacy has not been proved in prospective clinical trials. Lung transplantation should be recommended in cases of progressive end-stage illness.

Is there a regulatory role of immunoglobulins on tissue forming cells relevant in chronic inflammatory lung diseases?

Epithelial cells, fibroblasts and smooth muscle cells together form and give structure to the airway wall. These three tissue forming cell types are structure giving elements and participate in the immune response to inhaled particles including allergens and dust. All three cell types actively contribute to the pathogenesis of chronic inflammatory lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). Tissue forming cells respond directly to allergens through activated immunoglobulins which then bind to their corresponding cell surface receptors. It was only recently reported that allergens and particles traffic through epithelial cells without modification and bind to the immunoglobulin receptors on the surface of sub-epithelial mesenchymal cells. In consequence, these cells secrete pro-inflammatory cytokines, thereby extending the local inflammation. Furthermore, activation of the immunoglobulin receptors can induce proliferation and tissue remodeling of the tissue forming cells. New studies using anti-IgE antibody therapy indicate that the inhibition of immunoglobulins reduces the response of tissue forming cells. The unmeasured questions are: (i) why do tissue forming cells express immunoglobulin receptors and (ii) do tissue forming cells process immunoglobulin receptor bound particles? The focus of this review is to provide an overview of the expression and function of various immunoglobulin receptors.