Acute eosinophilic pneumonia: histopathologic findings in nine patients

Systematic Reporting of Eosinophils in Transbronchial Biopsies After Lung Transplantation Defines a Distinct Inflammatory Response

BACKGROUND

Descriptions of eosinophils in transbronchial biopsy (TBBx) pathology reports after lung transplantation (LTx) are associated with poor long-term outcomes. The absence of routine reporting and standardization precludes accurate assessment of this histologic predictor. A systematic reporting scheme for the presence of TBBx eosinophils after LTx was implemented. This report aims to assess this scheme by describing the presence, pattern, and gradation of TBBx eosinophils and clinical associations.

METHODS

A prospective cross-sectional study of all TBBx reports was performed including all patients presenting for a surveillance or diagnostic TBBx between January 2020 and June 2023. Each TBBx was systematically reported in a blinded manner. Mixed-effects logistic regression was performed to measure the association between concurrent clinical and histologic features, and the presence of TBBx eosinophils.

RESULTS

A total of 410 TBBx reports from 201 patients were systematically reported. In 43.8% recipients, any TBBx eosinophils were detected and in 17.1% recipients, higher-grade eosinophils (≥3 per high power field) were present. Adjusted analysis showed that retransplantation, A- and B-grade cellular rejection, positive bronchoalveolar lavage (BAL) bacterial microbiology, and elevated blood eosinophil count were independently associated with the presence of any TBBx eosinophils. Diagnostic "for-cause" procedures were independently associated with higher quantities of TBBx eosinophils.

CONCLUSIONS

Systematic reporting demonstrates that TBBx eosinophils are a distinct inflammatory response associated with rejection, infection, and peripheral eosinophilia. Although these findings require multicenter external validation, standardized reporting for TBBx eosinophils may assist in identifying recipients at risk of poor outcomes and provides a platform for mechanistic research into their role after lung transplantation.

Acute and chronic eosinophilic pneumonia: an overview

Acute and chronic eosinophilic pneumonia (AEP and CEP) include a group of rare interstitial lung diseases characterized by peripheral blood eosinophilia, increased eosinophils in bronchoalveolar lavage fluid, or eosinophilic infiltration of lung parenchyma. AEP is characterized by rapid onset, fast response to steroid treatment, and no relapse. CEP is characterized by marked tissue and peripheral blood eosinophilia, rapid response to steroid therapy, and tendency to disease recurrence. In addition, we briefly describe other eosinophilic lung diseases that must be considered in differential diagnosis of AEP and CEP. Eosinophilic pneumonias may be idiopathic or due to known causes such as medications or environmental exposure. At variance with previous reviews on this topic, a particular look in this overview was directed at pathological findings and radiological patterns.

Eosinophilic Lung Diseases

The eosinophilic lung diseases may manifest as chronic eosinophilic pneumonia, acute eosinophilic pneumonia, or as the Löffler syndrome (generally of parasitic etiology). The diagnosis of eosinophilic pneumonia is made when both characteristic clinical-imaging features and alveolar eosinophilia are present. Peripheral blood eosinophils are generally markedly elevated; however, eosinophilia may be absent at presentation. Lung biopsy is not indicated except in atypical cases after multidisciplinary discussion. The inquiry to possible causes (medications, toxic drugs, exposures, and infections especially parasitic) must be meticulous. Idiopathic acute eosinophilic pneumonia may be misdiagnosed as infectious pneumonia. Extrathoracic manifestations raise the suspicion of a systemic disease especially eosinophilic granulomatosis with polyangiitis. Airflow obstruction is frequent in allergic bronchopulmonary aspergillosis, idiopathic chronic eosinophilic pneumonia, eosinophilic granulomatosis with polyangiitis, and hypereosinophilic obliterative bronchiolitis. Corticosteroids are the cornerstone of therapy, but relapses are common. Therapies targeting interleukin 5/interleukin-5 are increasingly used in eosinophilic lung diseases.

Paraneoplastic acute eosinophilic pneumonia due to carotid angiosarcoma: A rare case

Key Clinical Message

This case report emphasizes that we should analyze a patient's signs and symptoms as a whole rather than relying exclusively on a common pattern to diagnose the condition and indicates that thorough histological investigation and sample collection are needed to accurately diagnose this malignancy.

Abstract

Angiosarcoma is a rare, fatal, and poorly understood malignant tumor of vascular endothelial cells which is a challenging disease to diagnose in the clinical settings and requires early diagnosis to achieve a favorable prognosis. Paraneoplastic syndromes associated with angiosarcoma can include hypercoagulability, thrombocytopenia, anemia, fever, weight loss, and night sweats. In some cases, the paraneoplastic syndrome can be the first sign of the underlying malignancy. Here, we present a 47-year-old individual with angiosarcoma over the right scapula accompanied by hemoptysis and other pulmonary complaints whom at first was thought to be metastatic polmunary involvement. However, the patient's dramatic response to corticosteroids, in addition to further imaging and paraclinical studies, led us to an acute eosinophilic pneumonia (AEP) diagnosis which is an eosinophilic infiltrations of alveolar spaces. The patient received chemotherapy for angiosarcoma and radiation, since the brachial nerve network was disrupted, leaving the tumor unresectable. After 3 years of continuous follow-up, the patient is now completely cured.

Smoking-Related Interstitial Lung Diseases

Smoking-related interstitial lung diseases (ILDs) are a group of heterogeneous, diffuse pulmonary parenchymal disease processes associated with tobacco exposure. These disorders include pulmonary Langerhans cell histiocytosis, respiratory bronchiolitis-associated ILD, desquamative interstitial pneumonia, acute eosinophilic pneumonia, and combined pulmonary fibrosis and emphysema. This review summarizes the current evidence of pathogenesis, clinical manifestations, diagnostic approach, prognosis, and treatment modalities for these diseases. We also discuss the interstitial lung abnormalities incidentally detected in radiologic studies and smoking-related fibrosis identified on lung biopsies.

Loeffler's syndrome in a child: A rare radiological and histopathological diagnosis

Loffler syndrome is an uncommon, self-limited, benign pulmonary eosinophilia that usually lasts less than a month. Abnormal chest radiography occurs in 95% of patients; however, computed tomography findings are not well described. We present clinical features, radiological, and pathological findings of Loeffler's syndrome with secondary bacterial pneumonia in a child. He presented with dry cough, hemoptysis 2 times, chest pain for 1 week. Blood tests revealed high C-reactive protein levels and eosinophilia. On the initial computed tomography (CT) scan, a lesion was discovered at the upper edge of the right lung hilum. The lesion developed in size, together with right pleural effusion, on the repeated CT scan. A lung biopsy revealed a substantial number of inflammatory cells, including eosinophils and neutrophils. After ruling all other possibilities, Loffler's syndrome was confirmed. As a result of antibiotic treatment, favorable outcomes were confirmed by improving clinical symptoms and follow-up chest CT scans. A close combination of pulmonary symptoms, peripheral blood eosinophilia, abnormal chest imaging, and histopathological findings must be taken to confirm the diagnosis of Loeffler's syndrome.

CT Findings and Patterns of E-Cigarette or Vaping Product Use-Associated Lung Injury: A Multicenter Cohort of 160 Cases

BACKGROUND

E-cigarette and vaping-induced lung injury (EVALI) causes a spectrum of CT lung injury patterns. Relative frequencies and associations with vaping behavior are unknown.

RESEARCH QUESTION

What are the frequencies of imaging findings and CT patterns in EVALI and what is the relationship to vaping behavior?

STUDY DESIGN AND METHODS

CT scans of 160 subjects with EVALI from 15 institutions were retrospectively reviewed. CT findings and patterns were defined and agreed on via consensus. The parenchymal organizing pneumonia (OP) pattern was defined as regional or diffuse ground-glass opacity (GGO) ± consolidation without centrilobular nodules (CNs). An airway-centered OP pattern was defined as diffuse CNs with little or no GGO, whereas a mixed OP pattern was a combination of the two. Other patterns included diffuse alveolar damage (DAD), acute eosinophilic-like pneumonia, and pulmonary hemorrhage. Cases were classified as atypical if they did not fit into a pattern. Imaging findings, pattern frequencies, and injury severity were correlated with substance vaped (marijuana derives [tetrahydrocannabinol] [THC] only, nicotine derivates only, and both), vaping frequency, regional geography, and state recreational THC legality. One-way analysis of variance, χ² test, and multivariable analyses were used for statistical analysis.

RESULTS

A total of 160 patients (79.4% men) with a mean age of 28.2 years (range, 15-68 years) with EVALI underwent CT scan. Seventy-seven (48.1%), 15 (9.4%), and 68 (42.5%) patients admitted to vaping THC, nicotine, or both, respectively. Common findings included diffuse or lower lobe GGO with subpleural (78.1%), lobular (59.4%), or peribronchovascular (PBV) sparing (40%). Septal thickening (50.6%), lymphadenopathy (63.1%), and CNs (36.3%) were common. PBV sparing was associated with younger age (P = .02). Of 160 subjects, 156 (97.5%) had one of six defined patterns. Parenchymal, airway-centered, and mixed OP patterns were seen in 89 (55.6%), 14 (8.8%), and 32 (20%) patients, respectively. Acute eosinophilic-like pneumonia (six of 160, 3.8%), DAD (nine of 160, 5.6%), pulmonary hemorrhage (six of 160, 3.8%), and atypical (four of 160, 2.5%) patterns were less common. Increased vaping frequency was associated with more severe injury (P = .008). Multivariable analysis showed a negative association between vaping for > 6 months and DAD pattern (P = .03). Two subjects (1.25%) with DAD pattern died. There was no relation between pattern and injury severity, geographic location, and state legality of recreational use of THC.

INTERPRETATION

EVALI typically causes an OP pattern but exists on a spectrum of acute lung injury. Vaping habits do not correlate with CT patterns except for negative correlation between vaping > 6 months and DAD pattern. PBV sparing, not previously described in acute lung injury, is a common finding.

Electronic Cigarette or Vaping Product Use-Associated Lung Injury: A Case Report

Electronic cigarette (e-cigarette) or vaping product use-associated lung injury (EVALI) has emerged as a social issue as e-cigarette use is rapidly increasing worldwide and is related to many deaths in the United States. To our knowledge, this is the first case report of EVALI in South Korea of a 24-year-old man with acute respiratory symptoms and a history of e-cigarette use. Chest CT revealed diffuse bilateral ground-glass opacities with subpleural sparing, airspace consolidation, and centrilobular micronodules as typical patterns of EVALI with organizing pneumonia and diffuse alveolar damage. Infection was excluded with meticulous laboratory examinations, and the patients' illnesses were not attributed to other causes. EVALI was diagnosed by meeting the diagnostic criteria with consistent clinico-radiologic findings through a multidisciplinary approach. Radiologists should have good knowledge of EVALI radiologic findings and play a cardinal role in the proper diagnosis and management of EVALI.

Chemotherapy-induced pulmonary complications in cancer: Significance of clinicoradiological correlation

Chemotherapy while revolutionizing cancer management by improving survival and quality of life; is also associated with several adverse effects. Lung is the most common organ affected in chemotherapy-related complications, due to either drug toxicity or more commonly due to infections caused by immunosuppression and less commonly due to immune-mediated injury. Radiology, when used in combination with clinical and lab data, can help reach the specific diagnosis or narrow down the differentials. The common radiological patterns of drug toxicity include pulmonary interstitial and airway infiltrates, diffuse alveolar damage, nonspecific interstitial pneumonia, eosinophilic pneumonia, cryptogenic organizing pneumonia, pulmonary hemorrhage, edema and hypertension. Cancer patients are immunosuppressed due to the underlying malignancy itself or due to therapy and are prone to a gamut of opportunistic infections including viral, bacterial, fungal and mycobacterial pathogens. Immune reconstitution inflammatory syndrome (IRIS), a well-known complication in HIV, is now being increasingly recognized in non-HIV patients with immunosuppression. Engraftment syndrome is specifically seen following hematopoietic stem cell transplant during neutrophil recovery phase. Pulmonary involvement is frequent, causing a radiological picture of noncardiogenic pulmonary edema. Thus, radiology in combination with clinical background and lab parameters helps in detecting and differentiating various causes of pulmonary complications. This approach can help alter potentially toxic treatment and initiate early treatment depending on the diagnosis.

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.

Eosinophilic pneumonia: A review of the previous literature, causes, diagnosis, and management

Eosinophilic pneumonia (EP) is a rare disorder, comprising several heterogeneous diseases. Two major types of EP are acute eosinophilic pneumonia (AEP) and chronic eosinophilic pneumonia (CEP), both of which are characterized by marked accumulation of eosinophils in lung tissues and/or BAL fluid. AEP and CEP share some similarities in terms of pathophysiology, radiological findings, and treatment response to corticosteroids. However, they distinctly differ in etiology, clinical manifestations, and the nature of disease course. Especially, although AEP and CEP respond well to corticosteroids, relapse frequently occurs in patients with CEP, but rarely in those with AEP. Although CEP occasionally persists and becomes corticosteroid dependent, most patients with AEP completely recover. This article reviews previous studies and discusses the etiology, clinical manifestations, and treatment of AEP and CEP.

Open Lung Biopsy in Nonresolving Acute Respiratory Distress Syndrome Commonly Identifies Corticosteroid-Sensitive Pathologies, Associated With Better Outcome

OBJECTIVES

Approximately half of the patients undergoing lung biopsy for nonresolving acute respiratory distress syndrome exhibit another histologic pattern than diffuse alveolar damage, with some of the pathologies characterized by a potential response to corticosteroids. This study aimed to assess whether open lung biopsy performed in the ICU for nonresolving acute respiratory distress syndrome was able to identify steroid-sensitive diseases and whether patients with a steroid-sensitive pathology experienced different clinical courses and outcomes.

DESIGN

Retrospective analysis.

SETTING

One 22-bed mixed ICU within a tertiary medical center.

PATIENTS

Patients age greater than or equal to 16 years old who met the Berlin definition for acute respiratory distress syndrome and underwent open lung biopsy from January 2007 to January 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

During the study period, 695 patients diagnosed with acute respiratory distress syndrome were identified, 51 (7%) of whom underwent open lung biopsy. An alternative diagnosis to diffuse alveolar damage was found in 29 patients (57%), and a steroid-sensitive pathology was identified in 19 (37%). In-hospital and 180-day mortality rates were 55% and 61%, respectively. There was a significant difference in hospital mortality and 180-day mortality rates between patients with steroid-sensitive pathology and those with steroid-resistant pathology (37% vs 65%; p < 0.045 and 37% vs 75%; p < 0.007, respectively). We did not identify any variable that could reliably predict a steroid-sensitive histologic pattern before open lung biopsy.

CONCLUSIONS

Open lung biopsy was able to identify a steroid-sensitive pathology in a significant proportion of nonresolving acute respiratory distress syndrome patients. These patients had a better outcome, with lower hospital mortality and 180-day mortality.

Acute Eosinophilic Pneumonia. Causes, Diagnosis, and Management

Acute eosinophilic pneumonia (AEP) is an uncommon acute respiratory illness of varying severity that includes presentation as acute respiratory distress syndrome with fatal outcome. AEP may be idiopathic, but identifiable causes include smoking and other inhalational exposures, medications, and infections. The pathogenesis of AEP is poorly understood but likely varies depending on the underlying cause. Airway epithelial injury, endothelial injury, and release of IL-33 are early events that subsequently promote eosinophil recruitment to the lung; eosinophilic infiltration and degranulation appear to mediate subsequent lung inflammation and associated clinical manifestations. Crucial for the diagnosis are the demonstration of pulmonary eosinophilia in the BAL fluid and the exclusion of other disease processes that can present with acute pulmonary infiltrates. Although peripheral blood eosinophilia at initial presentation may be a clue in suggesting the diagnosis of AEP, it may be absent or delayed, especially in smoking-related AEP. Optimal management of AEP depends on the recognition and elimination of the underlying cause when identifiable. The cessation of the exposure to the inciting agent (e.g., smoking), and glucocorticoids represent the mainstay of treating AEP of noninfectious origin. If AEP is recognized and treated in a timely manner, the prognosis is generally excellent, with prompt and complete clinical recovery, even in those patients manifesting acute respiratory failure.

A Critical Evaluation of Safety Signal Analysis Using Algorithmic Standardised MedDRA Queries

INTRODUCTION

Algorithmic Standardised MedDRA^® Queries (aSMQs) are increasingly used to enhance the efficiency of safety signal detection. The manner that aSMQs affect capture of potential safety cases is unclear.

OBJECTIVES

Our objective was to characterise the performance of aSMQs with respect to their potential for double counting, the likelihood of events in aSMQ positive cases being clinically related, how frequently terms are used for algorithmically positive cases, and the face validity of positive cases based on the drug inducing events. We were also interested in what effect requiring symptoms to overlap temporally would have on performance.

METHODS

We reviewed adverse event (AE) datasets of New Drug Applications and Biological License Applications and compiled a database including preferred terms and corresponding SMQs, SMQ term categories, AE start day, AE duration, drug name, and Anatomical Therapeutic Chemical class. Two reviewers independently determined if the algorithm was met and, if so, whether the broad terms overlapped temporally.

RESULTS

A total of 107 marketing applications were reviewed, including 103,928 patients and 277,430 AEs. Use of algorithms condensed the number of AEs to between 5 and 8% and the incidence to about 1.5% relative to when the SMQs are used without the algorithm. Certain aSMQs exhibited a potential for overcounting. Requiring symptoms to temporally overlap helped to eliminate irrelevant cases.

CONCLUSIONS

Our findings demonstrate that algorithmic and temporal assessment increased specificity of case retrieval, though the reduction in the number of terms or incidence seemed excessive for certain aSMQs. Evaluating the day of AE onset and duration improve specificity through identification of outlying events. Identification of drug classes known to cause the aSMQ's clinical condition provides face validity for this tool, yet detection of cases associated with novel classes may provide new understanding of these disorders. Improvements in some of the SMQ term lists may improve the performance of SMQs in general.

Age distribution and seasonality in acute eosinophilic pneumonia: analysis using a national inpatient database

BACKGROUND

Acute eosinophilic pneumonia (AEP) is a rare inflammatory lung disease. Previous studies have shown that most patients with AEP are aged 20 to 40 years, whereas several case studies have included older patients with AEP. These studies also suggested that AEP is more prevalent in summer, but they were limited due to their small sample sizes. We therefore investigated the age distribution and seasonality among patients with AEP using a national inpatient database.

METHODS

Using the Japanese Diagnosis Procedure Combination database, we identified patients with a recorded diagnosis of AEP from 1 July 2010 to 31 March 2015. We examined patient characteristics and clinical practices including age, sex, seasonal variation, length of stay, use of corticosteroids, use of mechanical ventilation, and in-hospital mortality.

RESULTS

During the 57-month study period, we identified 213 inpatients with AEP. The age distribution of AEP peaked twice: at 15 to 24 years and 65 to 79 years. The proportion of patients with AEP was highest in summer for those aged < 40 years, whereas it was distributed evenly throughout the year for those aged ≥ 40 years. The interval from hospital admission to corticosteroid administration and the duration of corticosteroid use were significantly longer in the older than younger age group.

CONCLUSIONS

The age distribution of patients with AEP was bimodal, and seasonality was undetected in older patients. Older patients may be more likely to have delayed and prolonged treatment.

Smoking-Related Lung Disease

Smoke from cigarettes and other sources may induce a variety of patterns of lung injury. While smoking related lung diseases, in general, have a better prognosis than many other diffuse lung diseases, they may be a cause of significant symptoms and, in some cases, may even require lung transplantation. On histology, the manifestations of these patterns range from reversible inflammation to irreversible emphysema or fibrosis. High-resolution chest CT plays a critical role in the diagnosis of smoking related lung diseases. It has several roles including (1) helping determine diagnosis, (2) assessing the pattern of injury that is present, (3) evaluating the extent and severity of disease, and (4) determining the response to treatment. The practicing radiologist must have a knowledge of the clinical, pathologic, and imaging features of the differnent patterns of lung injury associated with smoke inhalation.

Traction bronchiectasis on high-resolution computed tomography may predict fatal acute eosinophilic pneumonia

BACKGROUND

Most patients with acute eosinophilic pneumonia (AEP) show rapid improvement. However, some cases of AEP prove fatal. The aims of this study were to determine the clinical, radiographic, and pathologic characteristics of patients in whom AEP has a fatal outcome and to identify predictors of a poor prognosis.

METHODS

We retrospectively identified the medical records of all patients diagnosed with AEP at our institution in Japan from July 2005 to July 2013.

RESULTS

There were four deaths among 41 patients diagnosed to have AEP during the study period. All the patients who died were male; three cases were idiopathic and one was medication-related. The median bronchoalveolar lavage eosinophil differential count was 59%. An autopsy was performed on the patient with medication-related AEP who died and the pathologic finding was diffuse alveolar damage with eosinophilic infiltration. Diffuse ground-glass attenuation and traction bronchiectasis (TBE) were identified on high-resolution computed tomography in the four patients with fatal AEP. TBE was observed in six patients (five with idiopathic AEP, one with medication-related AEP), and 67% of these patients died. None of the patients with smoking-related AEP had TBE; all these patients had better responses to treatment and survived.

CONCLUSIONS

We observed the characteristics of patients with fatal AEP who did not respond to treatment. TBE was observed in all fatal cases and may be associated with a poor prognosis.

Clinical course and treatment outcomes of toxocariasis-related eosinophilic disorder

Blood eosinophilia is a common clinical finding. Helminthic infections, including toxocariasis, are a common cause of eosinophilia; however, the clinical course of toxocariasis associated with eosinophilia is not fully understood. Thus, controversies exist regarding treatment indications.To evaluate the clinical features and natural course of various types of eosinophilia, with a particular focus on toxocariasis, we retrospectively reviewed the medical records of 1000 patients with peripheral blood eosinophilia who were referred to the allergy clinic at Asan Medical Center between 2007 and 2012. Clinical parameters and imaging study findings were evaluated. The treatment response to albendazole and resulting changes in eosinophilia and imaging studies were analyzed in patients diagnosed with toxocariasis.Among the 1000 subjects, toxocariasis was the most common cause of eosinophilia (n = 534; 53.4%), followed by allergic disease and adverse drug reactions. The majority of patients with toxocariasis were men, and they were mostly asymptomatic. More than one-third of patients (n = 215; 40.3%) with toxocariasis exhibited organ involvement, particularly hepatic involvement. In most cases of eosinophilia and organ involvement due to toxocariasis, the symptoms normalized regardless of treatment.Most cases of eosinophilia related to toxocariasis displayed a self-remitting course regardless of treatment. With the exception of several clinical situations, including ocular involvement, the clinical need for anti-helminthic therapy in toxocariasis is not that significant.

Acute Lung Injury

A wide variety of insults can produce acute lung damage, inclusive of those that injure the lungs directly. The clinical syndrome of acute onset respiratory distress, dyspnea, and bilateral infiltrates is referred to as acute respiratory distress syndrome. The histologic counterpart of acute respiratory distress syndrome is diffuse alveolar damage, classically characterized by hyaline membranes. Other histologic features of acute lung injury include intraalveolar fibrin, organization, interstitial edema, and reactive pneumocytes. Diffuse alveolar damage and other histologic features of acute lung injury are nonspecific as to etiology, and once identified require the pathologist to search the biopsy for further features that may help identify a specific etiology. This chapter reviews the temporal sequence of acute lung injury and explores the large variety of specific etiologic causes with emphasis on helpful histologic features to identify.

Memory-type ST2+CD4+ T cells participate in the steroid-resistant pathology of eosinophilic pneumonia

The lung develops an unique epithelial barrier system to protect host from continuous invasion of various harmful particles. Interleukin (IL-)33 released from epithelial cells in the lung drives the type 2 immune response by activating ST2− expressed immune cells in various allergic diseases. However, the involvement of memory-type ST2⁺CD4⁺ T cells in such lung inflammation remains unclear. Here we demonstrated that intratracheal administration of IL-33 resulted in the substantial increase of numbers of tissue-resident memory-type ST2⁺CD4⁺ T cells in the lung. Following enhanced production of IL-5 and IL-13, eosinophilic lung inflammation sequentially developed. IL-33-mediated eosinophilic lung inflammation was not fully developed in T cell-deficient Foxn1^nu mice and NSG mice. Dexamethasone treatment showed limited effects on both the cell number and function of memory-type ST2⁺CD4⁺ T cells. Thus our study provides novel insight into the pathogenesis of eosinophilic lung disease, showing that memory-type ST2⁺CD4⁺ T cells are involved in IL-33-induced eosinophilic inflammation and elicited steroid-resistance.

A 53-year-old man with dyspnoea, respiratory failure, consistent with infliximab-induced acute interstitial pneumonitis after an accelerated induction dosing schedule

A 53-year-old man with ulcerative colitis (UC) suffered fatal acute interstitial pneumonitis (AIP) post completing an accelerated infliximab induction course. This is the first case reported in this setting. A literature review found four similar cases of infliximab-induced interstitial lung disease in the setting of treating patients with UC using standard infliximab regimens had successful treatment of the subjects post infliximab discontinuation. Unfortunately, the patient we are presenting, who had an accelerated infliximab induction course, did not survive. Although a prior small trial along more recent new small studies continue to show a benefit in reducing the need for early colectomy with the accelerated infliximab induction regimen as salvage therapy, it should be used cautiously until more safety data are available. Further larger trials are required to investigate rare side effects that may be associated with this regimen such as rapidly progressive lung toxicity as seen in this patient.

The Role of Infection in Interstitial Lung Diseases: A Review

Interstitial lung disease (ILD) comprises an array of heterogeneous parenchymal lung diseases that are associated with a spectrum of pathologic, radiologic, and clinical manifestations. There are ILDs with known causes and those that are idiopathic, making treatment strategies challenging. Prognosis can vary according to the type of ILD, but many exhibit gradual progression with an unpredictable clinical course in individual patients, as seen in idiopathic pulmonary fibrosis and the phenomenon of "acute exacerbation"(AE). Given the often poor prognosis of these patients, the search for a reversible cause of respiratory worsening remains paramount. Infections have been theorized to play a role in ILDs, both in the pathogenesis of ILD and as potential triggers of AE. Research efforts thus far have shown the highest association with viral pathogens; however, fungal and bacterial organisms have also been implicated. This review aims to summarize the current knowledge on the role of infections in the setting of ILD.

Cardiopulmonary and Gastrointestinal Manifestations of Eosinophil- associated Diseases and Idiopathic Hypereosinophilic Syndromes: Multimodality Imaging Approach

Eosinophil-associated diseases (EADs) are a diverse group of disorders characterized by an increase in circulating or tissue eosinophils. Cardiopulmonary and gastrointestinal system involvement can be due to primary EAD with no known cause or can be secondary to known systemic disease. The cardiopulmonary spectrum of EADs comprises simple pulmonary eosinophilia, acute eosinophilic pneumonia, chronic eosinophilic pneumonia, Churg-Strauss syndrome, allergic bronchopulmonary aspergillosis, bronchocentric granulomatosis, parasitic infections, and idiopathic hypereosinophilic syndrome. Eosinophilic gastrointestinal disorders include eosinophilic esophagitis, eosinophilic gastroenteritis, and eosinophilic colitis. Diagnosis is often challenging and requires a combination of clinical and imaging features along with laboratory findings. The absolute eosinophil count in peripheral blood and the percentage of eosinophils in bronchoalveolar lavage fluid are crucial in evaluation of various eosinophilic lung diseases. Although chest radiography is the initial imaging modality used in suspected cases of pulmonary EAD, multidetector computed tomography may demonstrate more characteristic pulmonary patterns, nodules, and subtle parenchymal abnormalities. Barium esophagography is used to assess mucosal abnormalities and the length and diameter of esophageal strictures. Magnetic resonance imaging is superior in providing valuable information in select patients, especially in evaluation of cardiac and gastrointestinal system involvement. Many patients require a multimodality imaging approach to enable diagnosis, guide treatment, and assess treatment response. Knowledge of the clinical features and imaging findings of the spectrum of EADs involving the lungs, heart, and gastrointestinal tract permits optimal patient care.

Spectrum of Smoking-related Lung Diseases: Imaging Review and Update

There is increased awareness of smoking-related lung diseases other than lung cancer and chronic obstructive pulmonary disease. Concurrently, there is general acceptance that there is difficulty in establishing a specific diagnosis of smoking-related interstitial lung disease (ILD), as many patients may not undergo biopsy to facilitate a specific histopathologic diagnosis. Cases that do proceed to biopsy may demonstrate multiple abnormalities, and histologic overlap between different disease processes may confound the picture. This review outlines the key aspects of smoking-related lung disease, including entities secondary to smoking-related lung inflammation such as respiratory bronchiolitis-ILD, desquamative idiopathic pneumonia, and pulmonary Langerhans cell histiocytosis, as well as chronic fibrosing lung diseases strongly associated with cigarette smoke including idiopathic pulmonary fibrosis, combined pulmonary fibrosis and emphysema, nonspecific interstitial pneumonia, and rheumatoid arthritis-ILD. The focus will be on incorporation of clinical findings, key pulmonary function testing parameters, high-resolution computer tomography (HRCT) findings, and pathologic correlates in refining the differential diagnosis and differentiating between the various entities.

Interstitial Lung Diseases

The term interstitial lung diseases (ILD) comprises a diverse group of diseases that lead to inflammation and fibrosis of the alveoli, distal airways, and septal interstitium of the lungs. The ILD consist of disorders of known cause (e.g., collagen vascular diseases, drug-related diseases) as well as disorders of unknown etiology. The latter include idiopathic interstitial pneumonias (IIPs), and a group of miscellaneous, rare, but nonetheless interesting, diseases. In patients with ILD, MDCT enriches the diagnostic armamentarium by allowing volumetric high-resolution scanning, i.e., continuous data acquisition with thin collimation and a high spatial frequency reconstruction algorithm. CT is a key method in the identification and management of patients with ILD. It not only improves the detection and characterization of parenchymal abnormalities, but also increases the accuracy of diagnosis. The spectrum of morphologic characteristics that are indicative of interstitial lung disease is relatively limited and includes the linear and reticular pattern, the nodular pattern, the increased attenuation pattern (such as ground-glass opacities and consolidation), and the low attenuation pattern (such as emphysema and cystic lung diseases). In the correct clinical context, some patterns or combination of patterns, together with the anatomic distribution of the abnormality, i.e., from the lung apex to the base, or peripheral subpleural versus central bronchovascular, can lead the interpreter to a specific diagnosis. However, due to an overlap of the CT morphology between the various entities, the final diagnosis of many ILD requires close cooperation between clinicians and radiologists and complementary lung biopsy is recommended in many cases.

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.

Clinical-Radiologic-Pathologic Correlation of Smoking-Related Diffuse Parenchymal Lung Disease

The direct toxicity of cigarette smoke and the body's subsequent response to this lung injury leads to a wide array of pathologic manifestations and disease states that lead to both reversible and irreversible injury to the large airways, small airways, alveolar walls, and alveolar spaces. These include emphysema, bronchitis, bronchiolitis, acute eosinophilic pneumonia, pulmonary Langerhans cell histiocytosis, respiratory bronchiolitis, desquamative interstitial pneumonia, and pulmonary fibrosis. Although these various forms of injury have different pathologic and imaging manifestations, they are all part of the spectrum of smoking-related diffuse parenchymal lung disease.

Imaging of Acute Lung Injury

Acute lung injury (ALI) is the clinical syndrome associated with histopathologic diffuse alveolar damage. It is a common cause of acute respiratory symptoms and admission to the intensive care unit. Diagnosis of ALI is typically based on clinical and radiographic criteria; however, because these criteria can be nonspecific, diagnostic uncertainty is common. A multidisciplinary approach that synthesizes clinical, imaging, and pathologic data can ensure an accurate diagnosis. Radiologists must be aware of the radiographic and computed tomographic findings of ALI and its mimics. This article discusses the multidisciplinary diagnosis of ALI from the perspective of the imager.

Eosinophilic Lung Diseases

Eosinophilic lung diseases especially comprise eosinophilic pneumonia or as the more transient Löffler syndrome, which is most often due to parasitic infections. The diagnosis of eosinophilic pneumonia is based on characteristic clinical-imaging features and the demonstration of alveolar eosinophilia, defined as at least 25% eosinophils at BAL. Peripheral blood eosinophilia is common but may be absent at presentation in idiopathic acute eosinophilic pneumonia, which may be misdiagnosed as severe infectious pneumonia. All possible causes of eosinophilia, including drug, toxin, fungus related etiologies, must be thoroughly investigated. Extrathoracic manifestations should raise the suspicion of eosinophilic granulomatosis with polyangiitis.

Resolvin D1 prevents smoking-induced emphysema and promotes lung tissue regeneration

Purpose

Emphysema is an irreversible disease that is characterized by destruction of lung tissue as a result of inflammation caused by smoking. Resolvin D1 (RvD1), derived from docosahexaenoic acid, is a novel lipid that resolves inflammation. The present study tested whether RvD1 prevents smoking-induced emphysema and promotes lung tissue regeneration.

Materials and methods

C57BL/6 mice, 8 weeks of age, were randomly divided into four groups: control, RvD1 only, smoking only, and smoking with RvD1 administration. Four different protocols were used to induce emphysema and administer RvD1: mice were exposed to smoking for 4 weeks with poly(I:C) or to smoking only for 24 weeks, and RvD1 was injected within the smoking exposure period to prevent regeneration or after completion of smoking exposure to assess regeneration. The mean linear intercept and inflammation scores were measured in the lung tissue, and inflammatory cells and cytokines were measured in the bronchoalveolar lavage fluid.

Results

Measurements of mean linear intercept showed that RvD1 significantly attenuated smoking-induced lung destruction in all emphysema models. RvD1 also reduced smoking-induced inflammatory cell infiltration, which causes the structural derangements observed in emphysema. In the 4-week prevention model, RvD1 reduced the smoking-induced increase in eosinophils and interleukin-6 in the bronchoalveolar lavage fluid. In the 24-week prevention model, RvD1 also reduced the increased neutrophils and total cell counts induced by smoking.

Conclusion

RvD1 attenuated smoking-induced emphysema in vivo by reducing inflammation and promoting tissue regeneration. This result suggests that RvD1 may be useful in the prevention and treatment of emphysema.

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.

Spectrum of Eosinophilic End-Organ Manifestations

Eosinophil-associated disorders can affect practically all tissues and organs in the body, either individually or in combination. This article provides an overview of end-organ manifestations of eosinophilia and discusses selected organ systems, including the upper and lower respiratory, cardiovascular, gastrointestinal, nervous, dermatologic, and renal systems. Mechanisms by which eosinophilia leads to end-organ damage are also considered.

Eosinophilic Pneumonia

Eosinophilic pneumonia may manifest as chronic or transient infiltrates with mild symptoms, chronic idiopathic eosinophilic pneumonia, or the frequently severe acute eosinophilic pneumonia that may be secondary to a variety of causes (drug intake, new onset of tobacco smoking, infection) and that may necessitate mechanical ventilation. When present, blood eosinophilia greater than 1 × 10⁹ eosinophils/L (and preferably greater than 1.5 × 10⁹/L) is of considerable help for suggesting the diagnosis, however it may be absent, as in the early phase of idiopathic acute eosinophilic pneumonia or when patients are already taking corticosteroids. On bronchoalveolar lavage, high eosinophilia (>25 %, and preferably >40 % of differential cell count) is considered diagnostic of eosinophilic pneumonia in a compatible setting, obviating the need of video-assisted thoracic surgical lung biopsy, which is now performed only on very rare occasions with inconsistency between clinical, biological, and imaging features. Inquiry as to drug intake must be meticulous (www.pneumotox.com) and any suspected drug should be withdrawn. Laboratory investigations for parasitic causes must take into account the travel history or residence and the epidemiology of parasites. In patients with associated extrathoracic manifestations, the diagnosis of eosinophilic granulomatosis with polyangiitis or of the hypereosinophilic syndromes should be raised. Presence of airflow obstruction can be found in hypereosinophilic asthma, allergic bronchopulmonary aspergillosis, idiopathic chronic eosinophilic pneumonia, eosinophilic granulomatosis with polyangiitis, or in the recently identified syndrome of hyperosinophilic obliterative bronchiolitis. Corticosteroids remain the cornerstone of symptomatic treatment for eosinophilic pneumonias, with a generally dramatic response. Relapses are common when tapering the doses or after stopping treatment especially in idiopathic chronic eosinophilic pneumonia. Cyclophosphamide is necessary only in patients with eosinophilic granulomatosis with polyangiitis and poor-prognostic factors. Imatinib is very effective in the treatment of the myeloproliferative variant of hypereosinophilic syndromes. Anti-interleukin-5 monoclonal antibodies are promising in the spectrum of eosinophilic disorders.

Histologic Patterns of Acute Lung Injury and Issues in Forensic Medicine

Context

Acute lung injury and acute respiratory distress syndrome are significant causes of pulmonary morbidity and are frequently fatal. These two entities have precise definitions from a clinical standpoint. Histologically, cases from patients with clinical acute lung injury typically exhibit diffuse alveolar damage, but other histologic patterns may occasionally be encountered such as acute fibrinous and organizing pneumonia, acute eosinophilic pneumonia, and diffuse hemorrhage with capillaritis.

Objective

To review the diagnostic criteria for various histologic patterns associated with a clinical presentation of acute lung injury and to provide diagnostic aids and discuss the differential diagnosis.

Data Sources

The review is drawn from pertinent peer-reviewed literature and the author's personal experience.

Conclusions

Acute lung injury remains a significant cause of morbidity and mortality. The pathologist should be aware of histologic patterns of lung disease other than diffuse alveolar damage which are associated with a clinical presentation of acute lung injury. Identification of these alternate histologic findings as well as identification of potential etiologic agents, especially infection, may impact patient treatment and disease outcome.

Idiopathic acute eosinophilic pneumonia: A retrospective case series and review of the literature

Introduction

Idiopathic acute eosinophilic pneumonia (AEP) is characterized by hypoxemia, pulmonary infiltrates and pulmonary eosinophilia. Data is limited and the purpose of this study is to better understand this disorder.

Methods

A search of the computerized patient records from January 1, 1997 to October 15, 2010 for patients with suspicion of “eosinophilic pneumonia” was conducted. Included patients were 18 years or older with an acute febrile illness, hypoxemia, diffuse pulmonary infiltrates on imaging, and pulmonary eosinophilia. Patients were excluded with other known causes of pulmonary eosinophilia.

Results

Of 195 patients with pulmonary eosinophilia, 8 patients had “definite” or “probable” and 4 patients had “possible” idiopathic AEP. Three patients were categorized as “probable” idiopathic AEP due to exceeding expected maximal 30-day symptom duration and/or a maximal recorded temperature less than 38 °C. Four patients were defined as “possible” idiopathic AEP given histories of polymyalgia rheumatica, eczema or allergic rhinitis. Of the 8 included patients, 63% were male with a median age of 53. Median duration of symptoms was 21 days. Median nadir oxygen saturation was 83%. Median eosinophil count on bronchoalveolar lavage was 36%. Two patients required intubation. Two patients were current smokers, one of whom had reported a change in smoking habits. All patients were treated with steroids (median of two months).

Conclusions

As diagnostic methods and pharmacologic knowledge improve, the number of patients meeting criteria for idiopathic AEP remains small. Much remains to be learned about this truly rare condition, and current criteria may exclude milder presentations of the disease.

Acute pulmonary injury: high-resolution CT and histopathological spectrum

Acute lung injury usually causes hypoxaemic respiratory failure and acute respiratory distress syndrome (ARDS). Although diffuse alveolar damage is the hallmark of ARDS, other histopathological patterns of injury, such as acute and fibrinoid organising pneumonia, can be associated with acute respiratory failure. Acute eosinophilic pneumonia can also cause acute hypoxaemic respiratory failure and mimic ARDS. This pictorial essay reviews the high-resolution CT findings of acute lung injury and the correlative histopathological findings.

Eosinophilic pneumonia associated with concomitant cigarette and marijuana smoking

A 29-year-old Caucasian man presented for the evaluation of a new onset of shortness of breath associated with cough and wheeze for 1 day. The history was significant for a recent travel of 20 h duration to Houston, a new onset of cigarette smoking for 2 weeks and marijuana smoking. The patient was afebrile and did not have any leg swelling; initial diagnosis of community-acquired pneumonia was made and the patient was started on antibiotics. Despite being on antibiotics, his medical condition continued to deteriorate and extensive diagnostic workup for infectious and autoimmune aetiology including bronchoalveolar lavage was completed and was inconclusive. Ultimately, the patient underwent video-assisted thoracoscopic lung biopsy which led to the diagnosis of acute eosinophilic pneumonia. Steroids were started with a good treatment response. The patient was discharged on a tapering dose of steroids; a follow-up chest x ray at 6 weeks was within normal limits.

Acute eosinophilic pneumonia

Acute eosinophilic pneumonia is a severe and rapidly progressive lung disease that can cause fatal respiratory failure. Since this disease exhibits totally different clinical features to other eosinophilic lung diseases (ELD), it is not difficult to distinguish it among other ELDs. However, this can be similar to other diseases causing acute respiratory distress syndrome or severe community-acquired pneumonia, so the diagnosis can be delayed. The cause of this disease in the majority of patients is unknown, even though some cases may be caused by smoke, other patients inhaled dust or drugs. The diagnosis is established by bronchoalveolar lavage. Treatment with corticosteroids shows a rapid and dramatic positive response without recurrence.

Eosinophilic pneumonias

This review starts with discussions of several infectious causes of eosinophilic pneumonia, which are almost exclusively parasitic in nature. Pulmonary infections due specifically to Ascaris, hookworms, Strongyloides, Paragonimus, filariasis, and Toxocara are considered in detail. The discussion then moves to noninfectious causes of eosinophilic pulmonary infiltration, including allergic sensitization to Aspergillus, acute and chronic eosinophilic pneumonias, Churg-Strauss syndrome, hypereosinophilic syndromes, and pulmonary eosinophilia due to exposure to specific medications or toxins.

Smoking-related interstitial lung diseases

Cigarette smoke, a toxic collection of thousands of chemicals generated from combustion of tobacco, is recognized as the primary causative agent of certain diffuse interstitial and bronchiolar lung diseases. Most patients afflicted with these disorders are cigarette smokers, and smoking cessation has been shown to be capable of inducing disease remission and should occupy a pivotal role in the management of all smokers with these diffuse lung diseases. The role of pharmacotherapy with corticosteroids or other immunomodulating agents is not well established but may be considered in patients with progressive forms of smoking-related interstitial lung diseases.

Eosinophilic lung diseases

Accurate diagnosis of eosinophilic lung diseases is essential to optimizing patient outcomes, but remains challenging. Signs and symptoms frequently overlap among the disorders, and because these disorders are infrequent, expertise is difficult to acquire. Still, these disorders are not rare, and most clinicians periodically encounter patients with one or more of the eosinophilic lung diseases and need to understand how to recognize, diagnose, and manage these diseases. This review focuses on the clinical features, general diagnostic workup, and management of the eosinophilic lung diseases.