Acute eosinophilic pneumonia: a hypersensitivity phenomenon?

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.

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.

Vaping Associated Acute Eosinophilic Pneumonia: A Clinical and Radiologic Mimicker of COVID-19

Acute eosinophilic pneumonia (AEP) is a rare cause of respiratory failure. It is primarily a disease of smokers, either a new smoker or an existing one with a recent increase in cigarette consumption. Other risk factors include toxic gas exposure, inhalational illicit drugs, and smoking marijuana. AEP has also been reported in patients with e-cigarette or vaping associated lung injury (EVALI). We present the case of a 20-year-old male who presented to the hospital with acute respiratory failure. The patient has been vaping heavily for the past three months and started smoking three days before presenting to the emergency department. He was hypertensive, tachycardic, tachypneic, and required high-flow nasal cannula to maintain SpO2 > 92%. His condition deteriorated in the first 24 hours following hospitalization requiring noninvasive positive pressure ventilation. Bronchoalveolar lavage revealed an eosinophil count of 36%. Bronchoalveolar lavage (BAL) cytology revealed lipid-laden macrophages. He was diagnosed with AEP due to EVALI, and the patient was treated with high dose corticosteroid with subsequent improvement. Before the bronchoscopic evaluation, the clinical and radiologic findings were consistent with COVID-19, and the patient was tested twice for SARS-CoV-2 PCR. In the appropriate clinical setting, AEP should be considered in the differential diagnoses of community-acquired pneumonia, acute respiratory distress syndrome (ARDS), and COVID-19, especially in this pandemic era.

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.

Acute eosinophilic pneumonia following inhalation of turpentine oil: A case report

Acute eosinophilic pneumonia (AEP) is an eosinophilic lung disease associated with environmental substances including smoking. Although the etiology of AEP has not been fully elucidated, it has been hypothesized that IL-33 plays a central role in the pathogenesis of AEP. Turpentine oil, from resins of pine trees, is not only used in paints, but also utilized in experimental animal models of inflammation because it leads to the production of inflammatory cytokines including IL-33. Here, we report the first case of AEP following turpentine oil inhalation. A 67-year-old woman reported using urushiol with turpentine oil to repair home goods. She had fever and persistent cough after turpentine inhalation over a very short period of time. The chest X-ray image showed consolidation in the upper right lung field. Laboratory findings indicated that there was no evidence of infection, collagen vascular diseases, and other allergic diseases that cause pneumonia, but analysis of the bronchoalveolar lavage fluid revealed 29% eosinophils with a small number of lipid-laden macrophages. With these findings, the diagnostic criteria of AEP was met. We rendered a diagnosis of AEP by inhalation of turpentine because no other cause for AEP was identified even with a structured questionnaire survey. The manifestations resolved immediately after steroid therapy. This is the first report of a case of AEP caused by the inhalation of turpentine oil.

Association between peripheral blood/bronchoalveolar lavage eosinophilia and significant oxygen requirements in patients with acute eosinophilic pneumonia

Background

We investigated the association between a combination of two markers, peripheral (PEC) and bronchoalveolar lavage (BAL) eosinophil percentage (BEP), and oxygen requirements in patients with acute eosinophilic pneumonia (AEP).

Methods

We retrospectively reviewed the medical records of patients with AEP treated at the Armed Forces Capital Hospital between May 2012 and May 2017. We used correlation analyses to assess the association between PEC/BEP and clinical outcomes in AEP patients. Receiver operating characteristic (ROC) curve analyses were used to calculate the cut-off value for BEP that categorised patients requiring a significant oxygen supply. The BAL/blood eosinophil (BBE) score was introduced to stratify patients with peripheral eosinophilia and elevated BEP. Clinical characteristics and outcomes were compared between the different groups. Multiple logistic regression was performed for significant oxygen requirements using two different models using age, C-reactive protein (CRP), smoking duration, and BBE score (model 1) and age, CRP, BEP, and PEC (model 2).

Results

Among the 338 patients, 99.7% were male, and their mean age was 20.4 ± 1.4 years. Only 0.6% of patients were never smokers and the mean number of smoking days was 26.2 ± 25.4. Correlation analyses revealed that both the PaO₂/FiO₂ ratio and duration of oxygen supply were associated with BEP. ROC curve analyses indicated a cut-off level of 41.5%. Patients with a high BBE score had favourable outcomes in terms of hypoxemia, hospital days, intensive care unit admission, oxygen supply days, and steroid treatment days. Multiple logistic regression revealed that BEP and BBE score tended to be associated with significant oxygen requirements.

Conclusions

In this study, we revealed that both peripheral and BAL eosinophilia is associated with favourable outcomes in AEP patients.

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.

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.

Long-term management and persistent impairment of pulmonary function in chronic eosinophilic pneumonia: A review of the previous literature

Chronic eosinophilic pneumonia (CEP) is an inflammatory disease characterized by accumulations of eosinophils in the lung with unknown etiology. Although corticosteroid treatment dramatically resolves these inflammations, relapse is common during the course of the disease. Approximately 50% of patients with CEP experience relapse. Subsequent to persistent disease and repeated relapse, and in cases of combined severe asthma, some CEP patients are administered corticosteroids indefinitely. Similar to patients with severe asthma who are often steroid dependent, a number of CEP patients exhibit prolonged persistent impairment of pulmonary function. Thus, CEP should be considered a potentially chronic disease requiring long-term management, rather than an acute or sub-acute disease requiring short-time therapy only. This review summarizes previous CEP studies, as well as our own cohort data, and discusses the long-term management of CEP with a particular focus on relapse, the prevalence of maintenance therapy, and persistent impairment of pulmonary function.

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.

Current Concepts in Pathogenesis, Diagnosis, and Management of Smoking-Related Interstitial Lung Diseases

Tobacco exposure results in various changes to the airways and lung parenchyma. Although emphysema represents the more common injury pattern, in some individuals, cigarette smoke injures alveolar epithelial cells and other lung cells, resulting in diffuse infiltrates and parenchymal fibrosis. Smoking can trigger interstitial injury patterns mediated via recruitment and inappropriate persistence of myeloid and other immune cells, including eosinophils. As our understanding of the role of cigarette smoke constituents in triggering lung injury continues to evolve, so does our recognition of the spectrum of smoking-related interstitial lung changes. Although respiratory bronchiolitis-interstitial lung disease, desquamative interstitial pneumonia, pulmonary Langerhans cell histiocytosis, and acute eosinophilic pneumonia have a well-established association with tobacco use, its role and impact on idiopathic pulmonary fibrosis, combined pulmonary fibrosis and emphysema, and connective tissue disease-related interstitial lung diseases is still ambiguous. Smoking-related interstitial fibrosis is a relatively newly appreciated entity with distinct histopathologic features but with unclear clinical ramifications. Increased implementation of lung cancer screening programs and utilization of CT scans in thoracic imaging have also resulted in increased identification of "incidental" or "subclinical" interstitial lung changes in smokers, the ensuing impact of which remains to be studied.

The Rare Complication and Diagnostic Challenges of Pulmonary Eosinophilia in Graft versus Host Disease Patients after Hematopoietic Stem Cell Transplantation

PURPOSE

Chronic graft versus host disease (cGvHD) is a common complication of hematopoietic stem cell transplantation (HSCT). Eosinophilic lung disease is a rare poorly understood complication in HSCT patients with cGvHD. These patients present similarly to those with Acute Eosinophilic Pneumonia (AEP). The purpose of this study is to better elucidate the presentation and potential treatment of this phenomenon.

METHODS

We reviewed over 170 bronchoscopies in post-HSCT patients with respiratory symptoms. Of these, four patients, whose course was complicated by cGvHD, presented with respiratory symptoms, diffuse ground-glass opacities (GGO) on chest computerized tomography (CT), bronchoalveolar lavage (BAL) eosinophilia, and no evidence of infection. The clinical course of these patients was reviewed.

RESULTS

Despite clinical presentation similar to AEP, not all patients had > 25% eosinophils on BAL, one criterion for AEP, however all improved with steroids. Steroid initiation was often delayed in favor of empiric antibiotics despite negative infectious workup. Several patients had recurrent episodes. Regarding possible associations, we examined but found no link between particular demographics, reason for HSCT, chemotherapy, immunosuppressants, or peripheral eosinophil count and pulmonary eosinophilia in these patients. GGO present on initial CT imaging became chronic in several of these patients.

CONCLUSION

We propose that in post-HSCT patients with GvHD presenting with respiratory symptoms, GGO on CT, BAL eosinophilia of > 10%, and negative respiratory cultures, an autoimmune eosinophilic process may be occurring. Earlier recognition and initiation of corticosteroids in these patients may improve their outcomes as an autoimmune diagnosis was often delayed in favor of antibiotics.

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.

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.

[A case of acute respiratory failure in an elderly patient with elderly asthma-COPD overlap syndrome (ACOS) is differentiated from acute eosinophilic pneumonia]

We report a case of acute respiratory failure in a 77-year-old male with chronic obstructive pulmonary disease (COPD) who showed marked eosinophilia (61.5% of the peripheral total white blood cells [WBCs]; 13,200/mm(3)). The patient was an ex-smoker, but he had started smoking again one month previously, His forced expiratory volume in one second (FEV1) was low and dyspnea symptom was observed. Although rhonchi were detected, wheezing chest sounds were not detected. Chest X-radiography and computed tomography of the lung revealed diffuse bilateral pulmonary infiltrates and emphysematous changes. He was given intravenous methyl prednisolone (1,000 mg) for 3 consecutive days. The abnormal shadows on the chest X-ray film improved remarkably and the eosinophils in his peripheral blood were reduced. Furthermore, it was no longer necessary to administer oxygen to treat his hypoxemia. The symptomatic and clinical course mimicked to a case of acute eosinophilic pneumonia (AEP). However, transbronchial lung biopsy specimens did not reveal eosinophilic infiltration in the alveolar septa. The fraction of eosinophils in the patient's bronchoalveolar lavage was 4.4% and not greater than 25%. After hospitalization, 5-15 mg of prednisolone administered orally in combination with bronchodilators to better manage his clinical symptoms. This case was thus determined to correspond to elderly asthma-COPD overlap syndrome (ACOS).

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.

Outcomes of rapid corticosteroid tapering in acute eosinophilic pneumonia patients with initial eosinophilia

BACKGROUND AND OBJECTIVE

Studies have shown that patients with acute eosinophilic pneumonia (AEP) and with initial eosinophilia have a milder disease than those with an initial normal peripheral eosinophil count (PEC). We investigated the effect of a rapid corticosteroid tapering strategy in AEP patients with initial eosinophilia.

METHODS

We performed a prospective cohort study in patients with AEP with initial eosinophilia (n = 14) who stopped corticosteroid treatment after achieving clinical stabilization compared with AEP patients with an initial normal PEC (n = 45) who received 2-week treatment with corticosteroid.

RESULTS

In total, 59 AEP patients were identified. The median duration of corticosteroid treatment was 4 days (interquartile ranges (IQR), 3-4) in patients with initial eosinophilia and 14 (IQR, 14-14) days in patients with initial normal PEC. No treatment failure occurred in the group with initial eosinophilia; one treatment failure case occurred in the group with an initially normal PEC. The median time to overall clinical stabilization was 3 days, and time to complete resolution of all symptoms and clinical instabilities from diagnosis was 4 days in AEP patients with initial eosinophilia. Both were significantly shorter than those) in the initially normal PEC group, which were 5 and 7 days respectively (both P < 0.001). Adverse effects were lower in AEP patients with initial eosinophilia, and additional medications to relieve adverse effects were only needed in AEP patients with initially normal PEC.

CONCLUSIONS

Rapid corticosteroid tapering may be an acceptable treatment strategy for managing AEP patients with initial eosinophilia.

Vitamin D Status in South Korean Military Personnel with Acute Eosinophilic Pneumonia: A Pilot Study

Background

A relationship between low vitamin D levels and the development or outcomes of respiratory diseases has been identified. However, there is no data on the vitamin D status in patients with acute eosinophilic pneumonia (AEP). We evaluated the vitamin D status in patients with AEP among South Korean military personnel.

Methods

We prospectively compared the serum levels of total 25-hydroxyvitamin D [25(OH)D], 25(OH)D3, and 25(OH)D2 among patients with AEP, pulmonary tuberculosis (PTB), and community-acquired pneumonia (CAP).

Results

In total, 65 patients with respiratory diseases, including AEP (n=24), PTB (n=19), and CAP (n=22), were identified. Of the 24 patients with AEP, 2 (8%) had deficient total 25(OH)D levels (<10 ng/mL), 17 (71%) had insufficient total 25(OH)D levels (≥10 to <30 ng/mL), and only 5 (21%) had sufficient total 25(OH)D levels (≥30 to <100 ng/mL). The difference in the total 25(OH)D levels among patients with AEP, PTB, and CAP was not statistically significant (p=0.230). The median levels of total 25(OH)D, 25(OH)D3, and 25(OH)D2 were 22.84, 22.84, and 0.00 ng/mL, respectively, and no differences in the 25(OH)D level were present among patients with AEP, PTB, and CAP with the exception of the total 25(OH)D level between patients with AEP and PTB (p=0.042).

Conclusion

We have shown that low vitamin D levels are frequently found in patients with AEP and are comparable with those in patients with PTB and CAP.

Clinical implications of correlation between peripheral eosinophil count and serum levels of IL-5 and tryptase in acute eosinophilic pneumonia

BACKGROUND

The peripheral eosinophil count (PEC) tends to increase during the course of acute eosinophilic pneumonia (AEP), and an initially elevated PEC is associated with milder disease. However, there is a lack of data regarding these phenomena and inflammatory process of AEP.

METHODS

We prospectively evaluated serial changes in serum interleukin (IL)-5 levels and the correlation between the initial level of IL-5 and the PEC to investigate whether the initial PEC indicates a resolving state of inflammation. We also evaluated serum tryptase levels to investigate the possibility of involvement of mast cell activity in AEP.

RESULTS

Twenty-one AEP patients were included, and all patients improved within 10 days after corticosteroid treatment. The median initial serum IL-5 level among all patients was 561.0 pg/mL, which decreased to zero at 10 days of follow-up (n = 15, P < 0.001). The median initial serum tryptase level (detectable in 20 of 21 patients) was 3.7 ng/mL and decreased to a median of 1.1 ng/mL at 10 days of follow-up (n = 15, P < 0.001). The initial serum IL-5 and C-reactive protein levels were positively correlated (P = 0.009, r = 0.556), and the initial serum IL-5 level was inversely correlated with the initial PEC (P = 0.004, r = -0.603).

CONCLUSIONS

Our data suggest that IL-5 is an important cytokine involved in the recruitment of eosinophils from peripheral blood into the lungs, that an initially elevated PEC is associated with a resolving state of inflammation, and that mast cells are potentially involved in the inflammatory process of AEP.

Clinical implications of initial peripheral eosinophilia in acute eosinophilic pneumonia

BACKGROUND AND OBJECTIVE

The initial peripheral eosinophil count (PEC) is rarely elevated but tends to increase during the clinical course of acute eosinophilic pneumonia (AEP). We evaluated whether initial peripheral eosinophilia is an indicator of mild disease in patients with AEP.

METHODS

We retrospectively examined associations between initial peripheral absolute eosinophil count, inflammatory markers and clinical characteristics in 85 patients with AEP.

RESULTS

Of 85 patients, 24 (28%) had initial peripheral eosinophilia (>500/μL). Initial peripheral absolute eosinophil count was inversely correlated to white blood cell (WBC) count (ρ = -0.386, P < 0.001), neutrophil percentage (ρ = -0.645, P < 0.001) and C-reactive protein (CRP; ρ = -0.495, P < 0.001). During treatment, peripheral absolute eosinophil counts increased, while inflammatory markers (WBC, neutrophil percentage, and CRP) decreased. Patients with initial peripheral eosinophilia had a longer duration from onset of symptoms to admission (P = 0.006), had lower WBC counts, neutrophil percentages and CRP values (all P < 0.001), and higher oxygen saturation (P = 0.004) than patients with normal peripheral eosinophil counts. Oxygen requirements (P = 0.013), duration of oxygen administration (P = 0.028) and intensive care unit admission rates (P = 0.003) were lower in patients with initial peripheral eosinophilia. All patients survived and recovered fully after corticosteroid or conservative treatment.

CONCLUSIONS

Initial PEC may be related to a milder disease status on admission, compared with normal PEC in patients with AEP. This may help to stratify disease severity in AEP.

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 eosinophilic pneumonia leading to acute respiratory failure in a current systemic corticosteroid user

A 69-year-old female patient visited the emergency room with fever (38.3℃) and dyspnea. She had been taking prednisolone (5 mg once per day) and methotrexate (2.5 mg once per week) for rheumatoid arthritis for 2 years. Chest computed tomography (CT) showed bilateral, multifocal ground glass opacity with interlobular septal thickening. Peripheral blood leukocyte count was 6,520/mm(3) (neutrophils, 77.4%; eosinophils, 12.1%). During the night, mechanical ventilation was initiated due to the development of severe hypoxemia. Bronchoalveolar lavage fluid showed a high proportion of eosinophils (49%). Her symptoms improved dramatically after commencement of intravenous methylprednisolone therapy. This is the first report of idiopathic acute eosinophilic pneumonia developing in a current user of systemic corticosteroids.

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.

Cryptogenic Organizing Pneumonia in Tomm5–/– Mice

Almost all mitochondrial proteins are encoded in the nuclear DNA and synthesized in the cytosol as pre-proteins. There is a protein translocase located in the mitochondrial outer membrane that transports mitochondrial pre-proteins into mitochondria. The central component of this translocase of the outer mitochondrial membrane (TOMM) complex is TOMM40, and TOMM5 is one of three small subunits associated with TOMM40. Translocase of outer mitochondrial membrane 5 homolog ( Tomm5–/–) knockout mice demonstrated an unexpected lung-specific phenotype characterized by widespread intra-alveolar fibrosis. Although TOMM5-deficient mice tested normal in a very broad range of phenotyping assays, they displayed histopathological lesions in the lung that were consistent with those reported in humans with cryptogenic organizing pneumonia (COP), which is also known as bronchiolitis obliterans organizing pneumonia (BOOP). The lesions had a patchy distribution in the lung and were characterized by the presence of intraluminal fibrogenic buds consisting of fibroblasts and myofibroblasts embedded in a loose connective tissue matrix that occupied the lumina of alveoli and alveolar ducts, with preservation of underlying alveolar architecture. In addition to macrophages, which were numerous in affected and surrounding alveoli, eosinophils comprised the most common and widespread inflammatory cell. Taken together, the findings in Tomm5–/– mice provide yet another example of the value of histopathology as a baseline assay in high-throughput phenotyping systems.

Chronic eosinophilic pneumonia with mucous plugs in a child

Chronic eosinophilic pneumonia is a rare cause of chronic lung disease in children. A 7-year-old girl who attended our clinics with cough and sputum lasting for 5 years, has been evaluated for bilateral alveolar infiltration and ground-glass opacities. Peripheral eosinophilia was detected in total cell blood count. Flexible bronchoscopy showed mucous plugs. Bronchoalveolar lavage fluid and cell block of mucous plugs determined hypereosinophilia. Chronic eosinophilic pneumonia was confirmed after the elimination of other eosinophilic lung diseases and the case was accepted to be idiopathic. She showed a dramatic response to oral corticosteroids. This is the first reported case of chronic eosinophilic pneumonia presenting with mucous plugs in children described to date in the literature.

Osteopontin levels are elevated in patients with eosinophilic pneumonia

BACKGROUND AND OBJECTIVE

Osteopontin is a key cytokine involved in pro-inflammatory T helper type 1 (Th1)-associated immune responses, which has recently been implicated in allergic diseases. We investigated the pathogenic role of osteopontin in eosinophilic pneumonia.

METHODS

The concentrations of osteopontin and Th1- or Th2-associated cytokines were measured in BAL fluid (BALF) from 41 patients with eosinophilic pneumonia, including those with acute (AEP, n = 12), chronic (CEP, n = 16), or drug-induced eosinophilic pneumonia (DEP, n = 13). The results were compared with those from patients with other interstitial lung diseases. Immunocytochemistry and double immunofluorescence labelling were performed to determine the cellular source of osteopontin.

RESULTS

Osteopontin was significantly elevated in BALF from patients with eosinophilic pneumonia as compared with BALF from patients with drug-induced interstitial pneumonia, hypersensitivity pneumonitis, idiopathic interstitial pneumonia, or sarcoidosis, and also compared with BALF from healthy volunteers. Osteopontin concentrations elevated at the time of exacerbation decreased during clinical improvement, either spontaneously or as a result of corticosteroid therapy. Elevated concentrations of CXCL10, CCL17 and IL-10 were also detected in BALF from patients with eosinophilic pneumonia. Osteopontin concentrations in BALF of AEP patients were correlated with IL-5, as well as IL-10, CCL11, CCL17 and CXCL10 concentrations. In AEP and DEP patients, serum osteopontin concentrations were also elevated. Double immunofluorescence labelling showed that in patients with eosinophilic pneumonia, osteopontin was expressed in lung eosinophils.

CONCLUSIONS

Osteopontin is likely to contribute to the development of inflammation in patients with eosinophilic pneumonia.

Smoking-Induced Acute Eosinophilic Pneumonia in a 15-year-old Girl: A Case Report

Acute eosinophilic pneumonia is a very rare disease that is characterized by acute febrile respiratory failure, diffuse bilateral infiltrates on chest X-ray, and eosinophilia in bronchoalveolar lavage fluid in the absence of infection. We present the case of a 15-year-old girl diagnosed with smoking-induced acute eosinophilic pneumonia. A previously healthy young girl with a 1-day history of fever presented with cough, dyspnea, and diffuse bilateral infiltrates on chest X-ray. She had started smoking only 3 weeks before presentation. She was diagnosed by bronchoalveolar lavage fluid tests and lung biopsy and dramatically improved after steroid treatment. We emphasize that acute eosinophilic pneumonia must be considered when acute pneumonia does not respond to broad-spectrum antibiotics. Effective treatment and prompt institution of therapy can obviate unnecessary morbidity and mortality.

Emergency cesarean section as a result of acute eosinophilic pneumonia during pregnancy

Acute eosinophilic pneumonia is a disease of unknown etiology characterized by peripheral blood eosinophilia and pulmonary infiltrative shadows on radiography. Acute eosinophilic pneumonia follows an acute course within 1 week and the symptoms include fever, dyspnea, and cough. Acute eosinophilic pneumonia has a good prognosis and responds promptly to steroid treatments. Here we present a critical case of acute eosinophilic pneumonia during pregnancy, which led to emergency cesarean section because of fetal distress. The patient was a 24-year-old gravida at 34 + 6 weeks gestation, with fever, and an elevated CRP; thus antibiotics were started. At 35 + 1 weeks gestation, cardiotocography (CTG) revealed late decelerations, fetal distress was diagnosed, and an emergency cesarean section was performed. The pre-operative maternal blood gas analysis showed a low PaO(2) of 55.7 mmHg and a chest X-ray revealed ground-glass opacities and pleural effusions in the middle lower lung fields bilaterally. A male of 2,336 g in weight was delivered with Apgar scores of 8 and 8 at 1 and 5 min, respectively. Due to the clinical progress and the elevated eosinophil count (532/microl) in the peripheral blood differential leukocyte count, the diagnosis of acute eosinophilic pneumonia was made. With the administration of oxygen and steroid treatment, the patient's general condition recovered. Both the mother and the baby were discharged on the 10(th) post-operative day and the patient has been leading a normal life with no recurrence for > 3 years since delivery.

Acute eosinophilic pneumonia: A case report and review of the literature

OBJECTIVES

Since its original description in 1989, clinicians have documented many cases of acute eosinophilic pneumonia (AEP), but information regarding the appropriate timing of diagnostic testing and treatment continues to be lacking. As a cause of respiratory failure in relatively young individuals, AEP is one of the few diagnoses that will often dramatically alter the intensivist's current therapy. Evidence for effective therapy is anecdotal and may even suggest that the traditional treatment with steroids offers limited benefit. This review uses a patient with AEP to emphasize certain aspects of this illness and discusses the current literature regarding its features, diagnosis, and treatment.

DATA SOURCES

A PubMed search from 1989 to 2008 was conducted using the search terms acute eosinophilic pneumonia, respiratory failure, eosinophilic lung disease, bronchoalveolar lavage, and smoking.

DATA EXTRACTION

Twenty-two articles were included in this review and ranged from case reports to randomized controlled trials. These studies demonstrate our current knowledge of this disease and, more importantly, emphasize areas in which we are lacking.

CONCLUSIONS

The diagnostic criteria and treatment of AEP is currently based on data from limited case series. Although these criteria are rigid, a wide variation in symptoms, diagnostic findings, and treatments reported further emphasizes our lack of knowledge regarding the pathophysiology of this illness. Important questions remain regarding this disease, including predisposing factors in patients with AEP and the benefit of treating with steroids.

Eosinophilic Lung Disease

Eosinophilic lung diseases represent a group of disorders in which lung infiltrates seen on a chest radiograph, may or may not be accompanied by peripheral blood eosinophilia. The causes are varied, and range from drug ingestion, parasite or fungal infection, or else, may be idiopathic. The clinical manifestation of these disorders may be mild or severe, depending on the underlying condition. A full history and examination, along with radiological imaging, bronchoscopy, and serological tests are useful in reaching a diagnosis. Treatment with corticosteroids usually results in a good clinical outcome, if the diagnosis is suspected and made early. Early treatment with high dose corticosteroids may be life saving in some patients, whilst other patients require prolonged and sometimes recurrent courses of corticosteroids, due to the chronic relapsing nature of their condition.

[Acute respiratory failure revealing an idiopathic acute eosinophilic pneumonia: report of a pediatric case]

Eosinophilic pneumonias are a group of heterogeneous disorders, rarely reported in children. We describe a case of a 12-year-old boy hospitalized for an acute febrile respiratory failure. Chest radiograph showed bilateral diffuse infiltrates. A pulmonary eosinophilic infiltration was confirmed by a major blood eosinophilia at 33,800/mm(3) associated with increased eosinophilic rate (90%) on bronchoalveolar lavage fluid. Outcome improved markedly with mechanical ventilation and corticosteroid therapy. Laboratory screenings for parasitic or allergic disease were negative. Bone marrow smear and medullar caryotype eliminated an acute leukemia. No further visceral eosinophilic injury were found. Acute eosinophilic pneumonia should be included in etiological investigation of patients with acute respiratory distress syndrome (ARDS) even in young subjects.

Cigarette smoking-induced acute eosinophilic pneumonia: a case report including a provocation test

The mechanism and cause of acute eosinophilic pneumonia are largely unknown. Many factors including the smoking of cigarettes have been suggested, but none have been proven to directly cause acute eosinophilic pneumonia. The authors report a case of acute eosinophilic pneumonia in a young Asian male who recently started smoking. The diagnosis was made based on his clinical course and results of chest radiography, lung spirometry, bronchoalveolar lavage, and transbronchial lung biopsies. After administration of methylprednisolone, his clinical course rapidly improved. A provocation test was designed to establish a connection between cigarette smoking and the development of acute eosinophilic pneumonia. After the provocation test, the patient showed identical symptoms, increase in sputum eosinophils, and worsening of pulmonary function. The results of the provocation test suggest that smoking may directly cause acute eosinophilic pneumonia, and support previous reports of cigarette smoking-induced acute eosinophilic pneumonia.

Circulating thymus- and activation-regulated chemokine/CCL17 is a useful biomarker for discriminating acute eosinophilic pneumonia from other causes of acute lung injury

BACKGROUND

The presentation of acute eosinophilic pneumonia (AEP) closely resembles that of acute lung injury (ALI)/ARDS, including its idiopathic form, acute interstitial pneumonia (AIP). AEP usually lacks peripheral eosinophilia at the acute phase; therefore, the establishment of serum biomarkers for AEP would be clinically useful.

METHODS

We measured the levels of thymus- and activation-regulated chemokine (TARC)/CCL17, eotaxin/CCL11, KL-6, and surfactant protein-D (SP-D) in serum for patients with acute parenchymal lung diseases including AEP (n = 17), AIP (n = 13), pneumonia-associated ALI/ARDS (n = 12), and alveolar hemorrhage (n = 7). To evaluate diagnostic ability, each marker was estimated by measuring the area under the receiver operating characteristic curve (AUC).

RESULTS

Serum TARC/CCL17 levels of AEP patients were much higher than those of patients in other disease groups. More importantly, high circulating TARC/CCL17 levels were observed in AEP even at acute phase when peripheral eosinophilia was absent. TARC/CCL17 showed the largest AUC, and the TARC/CCL17 levels with cutoff points from 6,259 to 7,039 pg/mL discriminated AEP from other syndromes with sensitivity and specificity of 100%. The KL-6 level was low in most patients with AEP, and the sensitivity was 81.6% in cutoff with 100% specificity. The AUC for eotaxin/CCL11 and SP-D was small, with values of 0.73 (95% confidence interval [CI], 0.60 to 0.86) and 0.53 (95% CI, 0.31 to 0.64), respectively.

CONCLUSIONS

This study indicates that the measurement of circulating TARC/CCL17 and KL-6 is useful for discriminating AEP from other causes of ALI.

Pulmonary Eosinophilic Syndromes

Acute eosinophilic pneumonia, chronic eosinophilia, Churg-Strauss syndrome, and the hypereosinophilic syndrome are pulmonary eosinophilic syndromes characterized by an increased number of eosinophils in peripheral blood, in lung tissue, in sputum, in bronchoalveolar lavage fluid, or in all of these. These pulmonary eosinophilic syndromes generally are characterized by increased respiratory symptoms, abnormal radiographic appearance, and the potential for systemic manifestations. It is critical to exclude other causes of eosinophilia in patients who have lung disease, to make a quick diagnosis, and to treat aggressively with corticosteroids and other therapies to prevent long-term sequelae.

Flavored Cigar Smoking Induces Acute Eosinophilic Pneumonia

Two cases of acute eosinophilic pneumonia (AEP) following smoking of flavored cigars were analyzed for characteristic features. None of our patients had a history of smoking flavored cigars/cigarettes in the past. One of them had never smoked, and the second patient was an ex-smoker who quit 17 years ago. Both patients presented with community-acquired pneumonia-like symptoms that did not respond to treatment with antibiotics. Their chest radiographs revealed bilateral diffuse infiltrates. The diagnosis of AEP was established based on the clinical picture, BAL that revealed an average eosinophil count > 45%, and immediate clinical improvement after introducing corticosteroids. All other possible causes were excluded during the initial workup.

Eosinophilic pneumonia induced by daptomycin

We present a case of drug-induced eosinophilic pneumonia resulting from intravenous daptomycin being used as therapy for recurrent methicillin-sensitive Staphlococcus aureus endocarditis. The patient developed hypoxic respiratory failure requiring intubation and mechanical ventilation. Daptomycin therapy was discontinued immediately, and the patient improved significantly after the administration of intravenous corticosteroids allowing for extubation 3 days later.

Idiopathic acute eosinophilic pneumonia

Idiopathic acute eosinophilic pneumonia (IAEP) is a rare disease but of clinical importance because of its good prognosis if treated promptly and appropriately. The etiology remains unknown and the temporal relationship between IAEP and a history of resent onset of cigarette smoking has been described. We report a typical case of a 21-year-old male with recent onset of smoking, who presented with acute febrile hypoxemic respiratory failure. High-resolution chest computed tomography scan revealed patchy ground glass opacity and ill-defined nodules, diffuse interlobar and interlobular septal thickening, and bilateral small amount of pleural effusion, which mimicked congestive heart failure except that the heart size was within normal limits. Bronchoalveolar lavage (BAL) was performed soon after the patient was admitted and remarkable eosinophilia was noted in BAL fluid. Clinical condition and chest radiographs improved dramatically after corticosteroid treatment. Because effective treatment and prompt institution of therapy can obviate unnecessary morbidity and mortality, IAEP should be kept in mind when treating patients presenting with diffuse parenchymal lung disease and acute respiratory failure. In that case, BAL is valuable and should be performed as soon as possible.

Hypersensitivity pneumonitis: beyond classic occupational disease-changing concepts of diagnosis and management

OBJECTIVE

To review inhaled antigens in home environments that cause hypersensitivity pneumonitis (HP) of varied clinical expressions and histopathologic patterns.

DATA SOURCES

Computer-assisted MEDLINE and manual searches for articles concerning HP, interstitial lung disease (ILD), epidemiology of HP and ILD, challenge procedures of HP, and indoor fungi.

STUDY SELECTION

Published articles concerning inhaled antigens in home environments and HP were selected.

RESULTS

Current criteria for the diagnosis of HP are too restrictive, because most apply only to the classic acute presentation and are of limited value in the subacute and insidious forms. Clinical expressions vary across the gamut of respiratory tract signs and symptoms. Patterns on lung biopsy may include all histopathologic descriptions of idiopathic ILD. The home is the likely causative environment rather than the workplace. Exposures may be occult and require in-depth environmental histories and on-site investigations to detect antigens and sources.

CONCLUSIONS

Natural or environmental challenges have become an important tool for diagnosing HP and determining effectiveness of remediation. Early diagnosis and effective remediation of the cause lead to a high survival rate, whereas diagnosis in advanced stages leads to disability and/or premature death.