Acute eosinophilic pneumonia. A summary of 15 cases and review of the literature

Drug-Induced Acute Eosinophilic Pneumonia With Pneumomediastinum: An Unusual Presentation

A 27-year-old female, with no significant past medical history, presented to the casualty department with a two-week history of progressive dyspnea, cough, and fever. She reported that she had recently started taking a non-conventional alternative medication for her irregular menstrual cycles. Chest radiography demonstrated bilateral alveolar opacities, and computed tomography (CT) of the chest revealed bilateral ground-glass opacities and pneumomediastinum. Laboratory testing showed peripheral blood eosinophilia, and bronchoscopy with bronchoalveolar lavage confirmed an elevated eosinophil count. Based on the clinical presentation, radiographic and laboratory findings, and exclusion of other etiologies, a diagnosis of drug-induced eosinophilic lung disease with pneumomediastinum was made. The alternative non-conventional drug was immediately discontinued and the patient was treated with systemic corticosteroids, leading to a rapid improvement in her symptoms and radiographic abnormalities. A repeat CT of the chest after 15 days revealed significant resolution of the ground-glass opacities and complete resolution of pneumomediastinum. This case highlights the importance of thorough medication history and vigilance for potential adverse effects of non-conventional treatments.

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.

Cryptogenic Organizing Pneumonia and Idiopathic Eosinophilic Pneumonia: A Case Report of Clinically Identical Entities

Cryptogenic organizing pneumonia (COP) and idiopathic eosinophilic pneumonia (IEP) are two forms of diffuse interstitial lung diseases (ILD) that lead to a rapid respiratory decline in young patients. Both conditions presented with similar clinical and radiological findings, making a clinical diagnosis challenging. They are both considered diagnoses of exclusion, and the treatment for both conditions is high-dose corticosteroids, leading to a quick recovery. Pathological specimens are often required prior to initiating appropriate treatment, leading to significant delays in appropriate therapy and a poorer prognosis. In this case report, we suggest that clinical pearls can be used to establish either diagnosis earlier, which leads to earlier treatment and better outcomes. Our patient presented with an acute respiratory distress syndrome (ARDS) picture, bilateral interstitial infiltrates with peripheral predominance, eosinophilia, and a negative initial infectious and cardiac workup. Based on these findings, we had a high initial suspicion that either COP or IEP was present. Our patient had a bronchoscopy done and was promptly started on steroid therapy soon after, which led to rapid clinical improvement. Pathological specimens were inconclusive, but the patient continued to improve, thereby confirming the presence of either form of ILD. The patient was subsequently discharged home with oxygen and recommended to follow up with a pulmonologist for further outpatient testing and management.

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.

Pneumothorax with Eosinophilia is an Important Diagnostic Clue for Distinguishing Paragonimiasis from Chronic Eosinophilic Pneumonia: A Case Report

The Paragonimus westermani infection is a parasitic foodborne infection that induces systemic symptoms with eosinophilia in humans. Here, we described pneumothorax in addition to pulmonary opacities with eosinophilia in a man with a positive P. westermani serology. He was misdiagnosed with chronic eosinophilic pneumonia (CEP) during the initial phase. Paragonimiasis can share similar clinical findings with CEP in cases where the worm is confined to the lungs. The findings of the current study suggest that paragonimiasis and CEP can be distinguished from each other by the presence of various symptoms. Notably, eosinophilia with pneumothorax should be an important diagnostic factor for paragonimiasis.

Seventeen Cases of Daptomycin-Induced Eosinophilic Pneumonia in a Cohort of Patients Treated for Bone and Joint Infections: Proposal for a New Algorithm

BACKGROUND

Daptomycin is increasingly used in the treatment of bone and joint infections (BJIs) and may be responsible for daptomycin-induced eosinophilic pneumonia (DIEP), a potentially severe adverse drug reaction. The aim of this study was to describe DIEP in patients treated at a referral center for the management of BJI, and to revisit current definitions of this disease.

METHODS

Patients treated from 1 January 2012 to 31 March 2021 were included in a prospective cohort (NCT02817711), in which all potential serious adverse events are prospectively recorded. Patients diagnosed with DIEP were retrospectively analyzed using different definitions.

RESULTS

In a total of 4664 patients included in the cohort during the study period, 1021 patients (21.9%) received daptomycin, of whom 17 (1.7%) were diagnosed with DIEP. Most patients were male (n = 11 [64.7%]), and periprosthetic joint infection was the commonest BJI (n = 12 [70.6%]). Only 1 patient had bronchoalveolar lavage (BAL) eosinophil count ≥25%, while most patients had peripheral blood eosinophilia (n = 15 [88.2%]). Chest computed tomography (CT) was compatible with eosinophilic pneumonia in 13 of 14 cases (92.9%). All patients recovered upon discontinuation of daptomycin. Using the different definitions available, only a minority of cases fulfilled existing criteria for DIEP. We propose a new algorithm that includes specific CT scan signs, and systemic instead of BAL eosinophilia.

CONCLUSIONS

DIEP is a rare event that requires prompt discontinuation of the causative antibiotic. Current criteria to diagnose definite DIEP are too restrictive and not easily applicable in clinical practice. A new algorithm is proposed here (Lyon algorithm) to facilitate the early identification of DIEP.

Diagnostic index for acute eosinophilic pneumonia without bronchoscopy in military smokers

BACKGROUND/AIMS

Acute eosinophilic pneumonia (AEP) is common among military smokers; however, bronchoscopy is required for the diagnosis. We aimed to derive and validate a scoring system to diagnose AEP without bronchoscopy.

METHODS

We conducted a retrospective study including patients diagnosed with AEP or any other pneumonia among military smokers hospitalized in the Armed Forces Capital Hospital from 15 November 2016 through 25 December 2019. The patients were divided into derivation and validation groups according to their admission day. Patient symptoms, laboratory findings, and computed tomography findings were candidate variables. Least absolute shrinkage and selection operator (LASSO) regression was used to calculate the scores for each variable.

RESULTS

Among 414 patients, AEP was confirmed in 54 of 279 patients (19.4%) in the derivation group and in 18 of 135 patients (13.3%) in the validation group. Ten variables were selected using LASSO regression: new-onset or a recently increased smoking (≤ 4 weeks) (8 points), interlobular septal thickening (5 points), absence of sputum (3 points), ground glass opacity (3 points), acute onset (≤ 3 days) (2 points), dyspnea (2 points), chest pain (2 points), leukocytosis (2 points), bronchovascular bundle thickening (2 points), and bilateral involvement (2 points). The area under the receiver-operating characteristic curve of the score to diagnose AEP was 0.997 (95% confidence interval, 0.992 to 1.000) in the derivation group and 0.985 (95% confidence interval, 0.965 to 1.000) in the validation group.

CONCLUSION

We introduce a scoring system that can distinguish AEP from other types of pneumonia in military smokers without the need for bronchoscopy.

CT patterns and differential criteria for acute eosinophilic pneumonia and COVID-19 pneumonia

Difficulties encountered in diagnosing and treating COVID-19 pneumonia and acute eosinophilic pneumonia during the pandemic from 2019 to 2021 led to the identification and study of the differential features of the two conditions.

Acute Eosinophilic Pneumonia Secondary to Menthol Cigarette Use: A Rare Phenomenon With a Review of Literature

Idiopathic acute eosinophilic pneumonia (AEP) is a very rare disease with fewer than 200 cases reported. It has been hypothesized to be a hypersensitivity reaction to an unidentified antigen. The clinical presentation typically involves fever, nonproductive cough, shortness of breath, and bibasilar inspiratory crackles within the first week of antigen exposure. Chest imaging usually reveals bilateral reticular and/or ground-glass opacities. Bronchoalveolar lavage demonstrates >25% eosinophils. Corticosteroids are the mainstay of treatment with good results; however, optimum dose and length of treatment are unclear. We present a case of a 31-year-old male who presented with 2 days of shortness of breath, cough, pleuritic chest pain, fevers, chills, nausea, and poor appetite in the setting of initiation of menthol-flavored cigarettes 2 weeks before presentation. He rapidly progressed to respiratory failure requiring intubation despite broad antibiotic coverage. His course was complicated by severe acute respiratory distress syndrome, circulatory shock, and renal failure. He underwent bronchoalveolar lavage testing that revealed 60% eosinophils. He was treated with steroids and was subsequently extubated and discharged. Eosinophilic counts in the blood peaked on the 10th day of admission to 34%. One week later, the patient was completely free of symptoms. The initiation of menthol cigarette use in this patient is the likely reason for ensuing acute eosinophilic pneumonia, hence adding to the sporadic reports on the role of menthol-flavored cigarettes. This case emphasizes a greater reliance on risk factors, as opposed to eosinophilic markers, for the diagnosis and treatment of acute eosinophilic pneumonia to prevent subsequent respiratory failure and intubation in such patients.

Sertraline-Induced Acute Eosinophilic Pneumonia

Acute eosinophilic pneumonia (AEP) is a rare but severe respiratory syndrome characterized by fever, hypoxemic respiratory failure, diffuse pulmonary infiltrates, and pulmonary eosinophilia. The most common cause of AEP is idiopathic, but it can be associated with antidepressant medications like sertraline.

A 76-year-old female presented to our ED with acute hypoxemic respiratory failure. She had no history of smoking or prior lung disease. She did not improve after treatment with broad spectrum antibiotics so a trial of corticosteroids was initiated. Her work-up was negative for infectious or collagen vascular causes of the respiratory failure. She was diagnosed with AEP associated with sertraline. Her condition improved with corticosteroid therapy after discontinuation of sertraline. This case report highlights AEP as a possible adverse reaction of sertraline. Prompt discontinuation of the offending drug is necessary for early recovery.

Ustekinumab associated chronic eosinophilic pneumonia

INTRODUCTION

Ustekinumab-induced eosinophilic pneumonia is rare and to our knowledge, this is the fifth reported case of such an entity.

CASE STUDY

A 60-year-old female was admitted with worsening shortness of breath and a nonproductive cough for 4 months. Her past medical history was significant for Crohn's disease and psoriatic arthritis that was previously managed with adalimumab and switched to ustekinumab 2 months before symptoms. Initial diagnostic workup showed 10% peripheral eosinophilia and a CT chest showed numerous 5 mm nodules scattered throughout the lungs along with some peripheral reticulations. Her BAL fluid analysis showed abnormally high eosinophil count (67%), greatly limiting her potential diagnoses to eosinophilic pneumonia, EGPA, and tropical pulmonary eosinophilia (TPE). AEP typically causes more severe disease with a rapid onset, and there was low suspicion for TPE based on history, leaving EGPA and CEP. Based on her negative autoimmune serology, a negative biopsy of the nasal mucosa (no vasculitis/granulomata or eosinophils), and negative infectious workup, the patient was diagnosed with CEP secondary to ustekinumab and the drug was stopped. She was started on high dose prednisone and after a prolonged taper over 5 months, her symptoms and nodules and reticulations on her CT scan resolved.

DISCUSSION

This case exemplifies the importance of identifying drug-induced lung diseases which in many cases might not have a strong temporal association with the symptom onset. It also highlights that some drugs owing to their long elimination half-time can remain in the system for a prolonged period and continues to cause symptoms despite their cessation and require prolonged treatment and reassurance.

CONCLUSION

The association of eosinophilic pneumonia with ustekinumab, a drug used in the treatment of psoriasis and other autoimmune diseases, is rare and there is a paucity of literature regarding this association.

Bronchoalveolar lavage as a diagnostic procedure: a review of known cellular and molecular findings in various lung diseases

Bronchoalveolar lavage (BAL) is a commonly used procedure in the evaluation of lung disease as it allows for sampling of the lower respiratory tract. In many circumstances, BAL differential cell counts have been reported to be typical of specific lung disorders. In addition, more specific diagnostic tests including molecular assays such as polymerase chain reaction (PCR) or enzyme-linked immunosorbent assay, special cytopathologic stains, or particular microscopic findings have been described as part of BAL fluid analysis. This review focuses on common cellular and molecular findings of BAL in a wide range of lung diseases. Since the performance of the first lung irrigation in 1927, BAL has become a common and important diagnostic tool. While some pulmonary disorders have a highly characteristic signature of BAL findings, BAL results alone often lack specificity and require interpretation along with other clinical and radiographic details. Development of new diagnostic assays is certain to reinforce the utility of BAL in the future. Our review of the BAL literature is intended to serve as a resource to assist clinicians in the care of patients with lung disorders.

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.

Mimics of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) was first described in 1967 by Ashbaugh and colleagues. Acute respiratory distress syndrome is a clinical syndrome, not a disease, and has no ideal definition or gold standard diagnostic test. There are multiple causes and different pathways of pathogenesis as well as various histological findings. Given these variations, there are many clinical entities that can get confused with ARDS. These entities are discussed in this article as "Mimics of ARDS." It imperative to correctly identify ARDS and distinguish it from other diseases to implement correct management strategy.

Idiopathic acute eosinophilic pneumonia

A 44-year-old asthmatic male patient presented to the health centre with a 3-week history of coryzal symptoms, persistent productive sputum and shortness of breath. The chest X-ray (CXR) revealed symmetrical, perihilar airspace shadowed with peribronchial cuffing and bilateral reticular markings. The patient did not improve despite treatment, and hence a high resolution CT (HRCT) scan of the thorax was recommended. The HRCT showed smooth interlobular septal thickening, central perihilar soft tissue thickening and patches of ground glass changes. Both the CXR and HRCT findings, along with the symptoms and eosinophilia counts, were suggestive of idiopathic acute eosinophilic pneumonia (IAEP) which was confirmed on bronchoalveolar lavage. The patient was successfully treated with steroids. This case highlights the symptoms, diagnosis, management and treatment of IAEP. A rapid diagnosis of this rare disease is essential since it can be completely cured with correct management but can be fatal if left untreated. Once properly treated, this disease does not recur.

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.

Diagnostic pitfalls of acute eosinophilic pneumonia in an adolescent boy following cigarette smoking: A case report

RATIONALE

Acute eosinophilic pneumonia (AEP) is characterized by acute febrile respiratory symptoms, bilateral lung infiltrates, and pulmonary eosinophilia. AEP is closely related to cigarette smoking but is rarely suspected in pediatric cases despite the fact that there is a relatively high incidence of cigarette smoking among adolescents in Taiwan.

PATIENT CONCERNS

We report a case of a previously healthy 15-year-old boy who presented with fever and acute progressive dyspnea. Due to lack of awareness of cigarette smoking history in adolescents and the nonspecific signs and symptoms of AEP at early stages, the patient was initially treated as community-acquired pneumonia (CAP) but was unresponsive to antibiotics treatment.

DIAGNOSES

A combination of a recent onset smoking history and pulmonary eosinophilia on bronchoalveolar lavage confirmed the diagnosis of cigarette-induced AEP.

INTERVENTIONS

Corticosteroid treatment was prescribed.

OUTCOMES

The condition improved within 24 hours, with resolution of alveolar infiltrates on chest radiographs.

LESSONS

With the increasing incidence of smoking amongst adolescents in Taiwan, careful history questioning regarding cigarette smoking is necessary. Due to similarities in initial clinical and radiographic features of AEP and CAP, adolescents with suspected CAP who are unresponsive to antibiotic treatment but have a subsequent rise in peripheral eosinophils should raise the clinician's suspicion of AEP related to cigarette smoking.

Extracorporeal Membrane Oxygenation in Severe Acute Eosinophilic Pneumonia

Acute Eosinophilic Pneumonia (AEP) is a potentially fatal cause of hypoxemic respiratory failure characterized by fever, diffuse bilateral pulmonary infiltrates, and pulmonary eosinophilia. Shown to be associated with a number of environmental exposures and lifestyle choices, AEP has a good prognosis when diagnosed early and treated with corticosteroids. In this clinical case report, we detail the presentation, evaluation, diagnosis, and management of a 40-year old male who presented to the emergency department with dyspnea, chills, and diaphoresis. He had a history of pulmonary embolism 8 years prior but was otherwise healthy, though he had re-started smoking cigarettes a week prior to presentation. Initial chest CT scan revealed widespread mixed groundglass and solid airspace opacities; over the next 12 hours, he rapidly decompensated and after not responding to other invasive mechanical ventilation, was emergently cannulated for veno-venous extracorporeal membrane oxygenation (V-V ECMO). Bronchoalveolar lavage later revealed pulmonary eosinophilia, and after an infectious workup was negative, a diagnosis of AEP was reached and the patient was started on corticosteroids. To our knowledge, this is one of few published cases of AEP requiring V-V ECMO for clinical stabilization, highlighting the utility of this treatment modality in severe disease.

Evaluation and management of Idiopathic Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is a most common progressive interstitial lung disease (ILD) of unknown etiology, although majority of patients are elderly male smokers. The main pathogenesis is aberrant recovery of epithelial injury and collagen deposition. Fibrotic nonspecific interstitial pneumonia, connective tissue disease (CTD) especially rheumatoid arthritis (RA) associated ILD, and chronic hypersensitivity pneumonia(CHP) are important differential diagnosis. Main symptoms are non-productive cough and progressive exertional dyspnea. Crucial physical findings are scalene muscle hypertrophy, bibasilar fine crackles, and finger clubbing. The serum markers such as lactate dehydrogenase (LDH) and Krebs von den Lungen-6 (KL-6) are sensitive for ILD detection and activity. Both pulmonary function test (PFT) and the 6-minute walk test (6MWT) are useful tool for evaluation of disease progression of IPF. Serial changes of forced vital capacity (FVC) and 6MWT distance predict mortality in IPF effectively. Recently published international IPF guidelines highlight the importance of chest high resolution computed tomography (HRCT) findings such as honeycombing, traction bronchiectasis (TBE), and sub-pleural reticular opacity. IPF is chronic and progressive; therefore, tracking disease behavior is crucial. Unifying clinical, physiological, and imaging information over time is useful. With regard to its management, two anti-fibrotic drugs such as pirfenidone and nintedanib have been available. These drugs can slow the decline of FVC and prevent acute exacerbation (AE). In this review, I outline the clinical characteristics of IPF, physiological, imaging, pathological findings and review diagnosis process and management.

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.

Pathologic features of smoking-related lung diseases, with emphasis on smoking-related interstitial fibrosis and a consideration of differential diagnoses

Smoking-related interstitial fibrosis (SRIF) is frequently-seen and morphologically-distinctive finding in the lung tissue of cigarette smokers. It can be distinguished histologically from the idiopathic interstitial pneumonias and other causes of pulmonary interstitial fibrosis. SRIF is typified by dense thickening of the alveolar septa by thick collagen bundles with a hyalinized appearance, with the common admixture of bands of hyperplastic smooth muscle. Concomitant inflammation is minimal. SRIF predominates in the subpleural and centrilobular parenchyma, and is usually accompanied by the changes of centrilobular emphysema and respiratory bronchiolitis. Most patients with SRIF do not have clinical symptoms of the condition. This article reviews the pathologic features of SRIF and compares them with the appearances of other interstitial lung diseases, some of which are also related to cigarette smoking. Acute eosinophilic pneumonia is another lung disease that has an association with smoking, and its clinicopathologic features are considered here as well.

Acute respiratory distress syndrome mimics: the role of lung biopsy

PURPOSE OF REVIEW

Acute respiratory distress syndrome (ARDS) mimics is a condition looking like ARDS but that does not fulfill every criterion according to the recent Berlin definition. The purpose of this review is to better delineate ARDS mimics, to discuss why the complete diagnosis of ARDS is important, and to make a brief overview on the role of open lung biopsy in this setting.

RECENT FINDINGS

Recent autopsy and lung biopsy data from ARDS patients compared lung histologic findings with the new Berlin definition of ARDS. Among them, there are some limited data about two niches, namely open lung biopsy and ARDS mimics suggesting that lung histology is important for making the diagnosis and offering the accurate management. This includes specific new treatments or stopping some medications toxic to the lung. Finally, ARDS with diffuse alveolar damage could be a specific subphenotype of ARDS with poor prognosis.

SUMMARY

An ARDS mimic enhances the need of making ARDS diagnosis as comprehensive as possible. In some limited cases, open lung biopsy in skilled hands may have implications for management.

Acute eosinophilic pneumonia in the deployed military setting

RATIONALE

Acute eosinophilic pneumonia (AEP) is a rare but important cause of severe respiratory failure most typically caused by cigarette smoking, but can also be caused by medications, illicit drugs, infections and environmental exposures. There is growing evidence that disease severity varies and not all patients require mechanical ventilation or even supplemental oxygen.

OBJECTIVES

To compare patients with AEP treated at Landstuhl Regional Medical Center (LRMC) to those in other published series, and to provide recommendations regarding diagnosis and treatment of AEP.

METHODS

A retrospective chart review was completed on forty-three cases of AEP which were identified from March 2003 through March 2010 at LRMC, Germany.

RESULTS

Tobacco smoking was reported by 91% of our patients. Only 33% of patients in our series had a fever (temperature > 100.4 °F) at presentation. Peripheral eosinophilia (>5%) was present in 35% on initial CBC, but was seen in 72% of patients during their hospital course. Hypoxemia, as measured by PaO2/FiO2 ratio, seemed to be less severe in patients with higher levels of bronchoalveolar (BAL) eosinophilia percentage.

CONCLUSIONS

Based on our experience and literature review, we recommend adjustments to the diagnostic criteria which may increase consideration of this etiology for acute respiratory illnesses as well as provide clinical clues we have found particularly helpful. Similar to recent reports of initial peripheral eosinophilia correlating with less severe presentation we found that higher BAL eosinophilia correlated with less severe hypoxemia.

Drug-induced eosinophilic pneumonia: A review of 196 case reports

BACKGROUND AND OBJECTIVE

Eosinophilic pneumonia (EP) is an important subset of patients who present with pulmonary infiltrates and eosinophilia (PIE). EP is classified by chronicity and etiology and drug-induced EP is the main cause of secondary EP. The primary goal of this review was to examine all the case reports published since the syndrome was defined in 1990. It remains unclear whether acute or chronic EP (AEP or CEP) represent different diseases, and the secondary goal of this review is to determine if there are factors that may help distinguish these 2 entities.

METHODS

PubMed (MEDLINE and Medical Subject Headings) was searched for case reports of drug-induced EP or PIE syndrome published between 1990 and 2017. Case reports were only included if the diagnostic criteria for AEP or CEP were fulfilled. For each case, data were extracted pertaining to age, sex, type of medication associated with the disease, time from the onset of symptoms to diagnosis, eosinophil counts in the blood, eosinophil fractions in bronchoalveolar lavage (BAL) fluid, initial chest radiograph and computed tomography results, use of mechanical ventilation, and use of steroid treatment and recurrence.

RESULTS

We found 196 case reports describing drug-induced EP. The leading cause was daptomycin. From our review, we found that AEP is more common in younger patients with no gender preference. Eosinophilia in the blood at the time of diagnosis characterized only the CEP patients (80% in CEP vs. 20% in AEP). Abnormal findings on radiographic imagine was similar in both syndromes. A significant portion of AEP patients (20%) presented with acute respiratory failure requiring mechanical ventilation. Most patients with EP were treated with steroids with a higher rate of relapse observed in patients with CEP.

CONCLUSION

AEP is a much more fulminant and severe disease than the gradual onset and slowly progressive nature of CEP. The pathogenesis of AEP and CEP remains unclear. However, there is significant clinical overlap among AEP and CEP that are associated with drug toxicity, suggesting the possibility that AEP and CEP are distinct clinical presentations that share a common pathogenic pathway.

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.

Acute Eosinophilic Pneumonia: Correlation of Clinical Characteristics With Underlying Cause

BACKGROUND

Acute eosinophilic pneumonia (AEP) is an uncommon disease, often indistinguishable from ARDS or community-acquired pneumonia at initial presentation. AEP can be idiopathic, but identifiable causes include medications and inhalational exposures, including cigarette smoke.

METHODS

Using a computer-assisted search, we retrospectively identified and reviewed the medical records of all patients diagnosed with AEP between January 1, 1998, and June 30, 2016, at our institution. Demographic and clinical data were extracted, including exposures (occupational, environmental, recreational, pharmacologic, and smoking), laboratory and radiologic findings, treatments, hospitalization (including ICU stay), and subsequent clinical course.

RESULTS

Among 36 consecutive patients with AEP, 11 were smoking-related cases, six were medication-related cases and 19 were idiopathic. Smoking-related AEP included six first-time smokers and five ex-smokers who had resumed smoking after a period of abstinence. Patients with smoking-related AEP were younger compared with both medication-related and idiopathic AEP cases (median age: 22 vs 47.5 vs 55 years, respectively; P = .004). Patients with smoking-related AEP were less likely to be associated with peripheral eosinophilia at presentation (36% vs 50% vs 58%; P = .52) but more likely to be hospitalized (100% vs 50% vs 63%; P = .039), including a longer ICU stay, compared with medication-related and idiopathic cases.

CONCLUSIONS

AEP is associated with a good prognosis when recognized and treated promptly. Compared with medication-related and idiopathic AEP, smoking-related AEP was less likely to be associated with peripheral eosinophilia at presentation but was characterized by more severe disease manifestations.

A Review of Clinical and Imaging Findings in Eosinophilic Lung Diseases

OBJECTIVE

The purpose of this article is to review the clinical and imaging findings associated with eosinophilic lung diseases.

CONCLUSION

The spectrum of eosinophilic lung diseases comprises a diverse group of pulmonary disorders that have an association with tissue or peripheral eosinophilia. These diseases have varied clinical presentations and may be associated with several other abnormalities. Characteristic imaging findings are often detected with chest radiography, and CT best shows parenchymal abnormalities. The integration of clinical, radiologic, and pathologic findings facilitates diagnosis and directs appropriate treatment.

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.

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.

Non-infectious mimics of community-acquired pneumonia

Community-acquired pneumonia (CAP) is a common cause of presentation to healthcare facilities. The diagnosis of CAP is usually made in patients with suggestive symptoms, signs, and radiological features. A number of non-infectious conditions, including neoplastic lesions, pulmonary oedema, pulmonary embolism, drug-induced pneumonitis, diffuse alveolar haemorrhage syndromes, cryptogenic organising pneumonia and acute eosinophilic pneumonia, may present in a similar way and mimic CAP. These other conditions are often only thought of after patients that are being treated as CAP fail to respond to therapy. The non-infectious mimics of CAP require early diagnosis and appropriate treatment to decrease patient morbidity and mortality. This article is intended to create an awareness of the non-infectious mimics of CAP and highlight some of the more frequent conditions as well as those that require early diagnosis and treatment to prevent a poor outcome.

Imipenem/cilastatin-induced acute eosinophilic pneumonia

Drugs, toxins, and infections are known to cause acute eosinophilic pneumonia. Daptomycin and minocycline are the commonly reported antibiotics associated with acute eosinophilic pneumonia. In this study, we present a case of imipenem/cilastatin-induced acute eosinophilic pneumonia. The patient presented with fever, acute hypoxic respiratory distress, and diffuse ground-glass opacities on the chest CT a day after the initiation of imipenem/cilastatin. Patient also developed peripheral eosinophilia. A reinstitution of imipenem/cilastatin resulted in recurrence of the signs and symptoms. A bronchoscopy with bronchoalveolar lavage showed 780 nucleated cells/mm(3) with 15% eosinophil. The patient's clinical condition improved significantly after the discontinuation of imipenem/cilastatin therapy and the treatment with corticosteroid.

Acute eosinophilic pneumonia

We report the case of an 18-year-old woman who presented to an outside hospital in respiratory distress and was found to have pulmonary eosinophilia. She remained profoundly hypoxaemic despite maximal ventilatory strategies and underwent cannulation for veno-venous extra corporeal membrane oxygenation (ECMO). The respiratory failure improved with time, using corticosteroids, and the veno-venous ECMO helped in stabilisation of the patient in the setting of profound hypoxaemia.

Interstitial lung diseases in the hospitalized patient

BACKGROUND

Interstitial lung diseases (ILDs) are disorders of the lung parenchyma. The pathogenesis, clinical manifestations, and prognosis of ILDs vary depending on the underlying disease. The onset of most ILDs is insidious, but they may also present subacutely or require hospitalization for management. ILDs that may present subacutely include acute interstitial pneumonia, connective tissue disease-associated ILDs, cryptogenic organizing pneumonia, acute eosinophilic pneumonia, drug-induced ILDs, and acute exacerbation of idiopathic pulmonary fibrosis. Prognosis and response to therapy depend on the type of underlying ILD being managed.

DISCUSSION

This opinion piece discusses approaches to differentiating ILDs in the hospitalized patient, emphasizing the role of bronchoscopy and surgical lung biopsy. We then consider pharmacologic treatments and the use of mechanical ventilation in hospitalized patients with ILD. Finally, lung transplantation and palliative care as treatment modalities are considered. The diagnosis of ILD in hospitalized patients requires input from multiple disciplines. The prognosis of ILDs presenting acutely vary depending on the underlying ILD. Patients with advanced ILD or acute exacerbation of idiopathic pulmonary fibrosis have poor outcomes. The mainstay treatment in these patients is supportive care, and mechanical ventilation should only be used in these patients as a bridge to lung transplantation.

Eosinophilia in Pulmonary Disorders

Lung disease associated with marked peripheral blood eosinophilia is unusual and nearly always clinically significant. Once recognized, it is generally easy to manage, albeit with long-term systemic corticosteroids. A failure to respond to oral steroids in the context of good compliance suggests a malignant cause for the eosinophilia. An important development is the introduction of antieosinophil therapies, particularly those directed against the interleukin 5 pathway, which is hoped to provide benefit in the full spectrum of eosinophilic lung disease as well as asthma, reducing the burden of side effects and resultant comorbidities.

Minocycline-induced acute eosinophilic pneumonia: A case report and review of the literature

Acute eosinophilic pneumonia (AEP) can be a challenging diagnosis and is often initially misdiagnosed as one of the more common pneumonia syndromes such as acute respiratory distress syndrome. Early bronchoalveolar lavage (BAL) is critical in distinguishing the diagnosis to initiate proper management. The etiology of AEP is unknown, though many drugs have been implicated, including minocycline. Minocycline is commonly used for pneumonia, acute bronchitis, urinary tract infections, and acne and is likely the cause of AEP in our patient. There are 26 case reports of minocycline-induced AEP. In most cases, outcomes were favorable and symptoms rapidly resolved upon discontinuation of minocycline, with 11 cases employing steroids, one case twelve hours of CPAP and another 5 days of intubation. None resulted in mortality. Although it is difficult to evaluate without further studies, steroids should be recommended for minocycline-induced AEP, especially for those with severe or persistent symptoms.

Clinical outcomes in patients with acute eosinophilic pneumonia not treated with corticosteroids

PURPOSE

The objective of this study was to evaluate the course of clinical stability in patients with acute eosinophilic pneumonia (AEP) who did not receive corticosteroid treatment.

METHODS

Secondary analysis included 19 consecutive patients with AEP who did not receive corticosteroid treatment from a cohort of 310 patients newly diagnosed with AEP between October 2007 and December 2013.

RESULTS

All patients presented with dyspnea, fever, or cough with diffuse pulmonary infiltration. All but one patient (95 %) had elevated C-reactive protein (CRP), and 11 (58 %) patients had peripheral eosinophilia at the time of diagnosis. During the follow-up period, the dyspnea improved within a median of 4 (3-6) days and defervescence occurred within a median of 5 (4-7) days. Median time to clinical stability (defined as disappearance of all initial presenting symptoms) was 9 (7-12) days. In addition, the majority of pulmonary infiltrates on chest radiographs completely disappeared within 14 days after diagnosis. However, the peripheral eosinophil count and the frequency of peripheral eosinophilia increased up to 10 days and then decreased during the follow-up period. All patients experienced peripheral eosinophilia during hospitalisation.

CONCLUSION

AEP-associated symptoms and radiographic abnormalities were resolved completely within 2 weeks after diagnosis even when corticosteroid treatment was not initiated. However, these findings might be limited to relatively mild cases of AEP.

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.

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.

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.

Idiopathic Acute Eosinophilic Pneumonia

Idiopathic acute eosinophilic pneumonia (IAEP) is characterized by febrile hypoxic respiratory failure with diffuse radiographic infiltrates and peripheral and pulmonary eosinophilia in a previously healthy child. Diagnosis is by exclusion, but promptness is imperative, as IAEP can lead to life-threatening acute lung injury and acute respiratory distress syndrome. Prognosis is usually good after steroid treatment with total recovery and absence of relapse in reported cases. We report a case of a previously healthy 14-year-old boy with this diagnosis who presented with acute hypoxia and characteristic radiographic and bronchoalveolar lavage findings. He had full recovery after corticosteroid treatment. This case report highlights the diagnostic approach to a patient with IAEP, an uncommon diagnosis, and one of the exclusions, in children.