Acute eosinophilic pneumonia as a reversible cause of noninfectious respiratory failure

Review of T Helper 2-Type Inflammatory Diseases Following Immune Checkpoint Inhibitor Treatment

Immune checkpoints are mechanisms that allow cancer cells to evade immune surveillance and avoid destruction by the body's immune system. Tumor cells exploit immune checkpoint proteins to inhibit T cell activation, thus enhancing their resistance to immune attacks. Immune checkpoint inhibitors, like nivolumab, work by reactivating these suppressed T cells to target cancer cells. However, this reactivation can disrupt immune balance and cause immune-related adverse events. This report presents a rare case of prurigo nodularis that developed six months after administering nivolumab for lung adenocarcinoma. While immune-related adverse events are commonly linked to T helper-1- or T helper-17-type inflammations, T helper-2-type inflammatory reactions, as observed in our case, are unusual. The PD-1-PD-L1 pathway is typically associated with T helper-1 and 17 responses, whereas the PD-1-PD-L2 pathway is linked to T helper-2 responses. Inhibition of PD-1 can enhance PD-L1 functions, potentially shifting the immune response towards T helper-1 and 17 types, but it may also influence T helper-2-type inflammation. This study reviews T helper-2-type inflammatory diseases emerging from immune checkpoint inhibitor treatment, highlighting the novelty of our findings.

A case of naltrexone-induced acute eosinophilic pneumonia

Acute eosinophilic pneumonia (AEP) is a rare cause of acute respiratory failure. Clinical presentations can range from dyspnoea, fever and cough, to rapidly progressive and potentially fulminant respiratory failure. While its exact cause is often unknown, associations with inhalational injuries and exposures to new medications have been described.We report a case of a middle-aged, non-smoking man with a history of alcohol use disorder. He presented with 4 days of shortness of breath that started hours after taking injectable naltrexone (Vivitrol). The patient had rapidly worsening hypoxaemia, necessitating emergent bronchoscopy with transbronchial biopsies and bronchoalveolar lavage which showed 66% eosinophils. The patient was intubated for the procedure and unable to get extubated due to worsening hypoxaemic respiratory failure with high fractional inspired oxygen requirements. Chest radiograph showed worsening lung infiltrates and with a high index of suspicion for AEP, he was started empirically on methylprednisolone. He had rapid improvement in his respiratory status and was extubated on day 5 of admission then discharged on day 8. Histopathological examination confirmed acute/subacute eosinophilic pneumonia. A 3-week post-discharge follow-up chest radiograph confirmed the full resolution of pulmonary infiltrates.Naltrexone-induced AEP is rare, with only six other cases reported in the literature. Careful history taking and prompt evaluation for AEP are important given the potential for rapid progression to acute hypoxic respiratory failure and the excellent response to steroid treatment.

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.

Smoking-related interstitial lung disease: A narrative review

Although smoking-related interstitial lung diseases (SR-ILD) are a relatively rare group of entities, they are a relevant public health problem of growing importance, both because they affect young adults and because of their increasing prevalence in recent years due to increased tobacco consumption. In patients who smoke and have non-specific respiratory symptoms, SR-ILD should be ruled out, a term that encompasses a group of different entities in which the basis for diagnosis is the smoking history together with compatible respiratory functional findings, radiology and/or histology. An association has been established between tobacco smoke and a group of diseases that include respiratory bronchiolitis-associated interstitial lung disease (2%-3% of all ILD), desquamative interstitial pneumonia (<1%), Langerhans cell histiocytosis (3%-5%) and acute eosinophilic pneumonia. Smoking is considered a risk factor for idiopathic pulmonary fibrosis which has also been called combined fibroemphysema (5%-10% of all ILD); however, the role and impact of smoking in its development, remains to be determined. The likely interconnection between the mechanisms involved in inflammation and pulmonary fibrosis in all these processes often results in an overlapping of clinical, radiological, and histological features. In the absence of robust scientific evidence on its management, smoking cessation is the first measure to be taken into account. Although most diseases have a benign clinical course after smoking cessation, some cases may progress to chronic respiratory failure.

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.

Treatments of refractory eosinophilic lung diseases with biologics

Biologics targeting the molecules associated with type 2 inflammation have significantly improved the outcomes of patients with severe eosinophilic asthma and chronic rhinosinusitis with nasal polyps (CRSwNP). Chronic eosinophilic airway/lung diseases including chronic eosinophilic pneumonia, allergic bronchopulmonary aspergillosis/mycosis, eosinophilic bronchitis, and eosinophilic granulomatosis with polyangiitis share clinical features with eosinophilic asthma and CRPwNP, which are mostly adult-onset and may develop simultaneously or consecutively. These eosinophilic airway/lung diseases respond well to initial treatment with systemic corticosteroids, but often recur when the corticosteroids are tapered. The management of these "refractory" cases is an unmet need for clinicians. We first reviewed the standard treatments for these chronic eosinophilic airway/lung diseases, followed by the definition and prevalence of refractory diseases and the role of biologics in their management. The available evidence varies from case reports and case series to randomized control trials, depending on the type of disease; however, these studies provide not only a direction for clinical practice, but also insights into the pathophysiology of each disease. Physicians should discuss the efficacy and costs of biologics in patients with refractory eosinophilic airway/lung diseases to minimize not only the current symptoms, but future risks as well.

Acute eosinophilic pneumonia in twins

The pathogenesis of eosinophilic pneumonia is currently poorly understood, and this disease has not been reported in twins since 1983. Herein, we report a case of acute eosinophilic pneumonia in twins, which appeared to be triggered by initial smoking at different times by both patients. One patient resumed smoking after recovering from eosinophilic pneumonia, with no observed recurrence. This study discussed the possibility of an association between susceptibility to eosinophilic pneumonia and genetic factors in twins.

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 caused by composter vapor inhalation: A case report

A 65-year-old woman presented to a local hospital with a 4-day history of cough, fever, and dyspnea. She had started using a composter and had been exposed to the vapor for 18 days before her first visit. She was diagnosed with acute eosinophilic pneumonia (AEP) based on her symptoms, the presence of bilateral pulmonary opacities on computed tomography, and alveolar eosinophilia confirmed by bronchoalveolar lavage. Inhalation of the composter vapor was thought to be the cause of AEP. Aspergillus fumigatus was cultured from the composter soil and the bronchoalveolar lavage fluid. She fully recovered without systemic corticosteroid administration by avoiding the composter.

Acute eosinophilic pneumonia caused by nicotine‐free vaping in an adolescent patient: A case report

An 18‐year‐old man was admitted to our hospital with pneumonia 4 days after he initiated vaping. The patient did not show improvement after ceftriaxone and azithromycin treatment. The cell count of the bronchoalveolar lavage fluid (BALF) revealed 64% eosinophils and 18% lymphocytes. Based on the BALF findings, the patient met the current diagnostic criteria and was diagnosed with vaping‐induced acute eosinophilic pneumonia (AEP). AEP caused by nicotine‐free vaping is rare in Japan. Thus, in cases of AEP, the patient's history of cigarette smoking as well as vaping should be considered.

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.

E-Cigarette Use: Device Market, Study Design, and Emerging Evidence of Biological Consequences

Electronic cigarettes are frequently viewed as a safer alternative to conventional cigarettes; however, evidence to support this perspective has not materialized. Indeed, the current literature reports that electronic cigarette use is associated with both acute lung injury and subclinical dysfunction to the lung and vasculature that may result in pathology following chronic use. E-cigarettes can alter vascular dynamics, polarize innate immune populations towards a proinflammatory state, compromise barrier function in the pulmonary endothelium and epithelium, and promote pre-oncogenic phenomena. This review will summarize the variety of e-cigarette products available to users, discuss current challenges in e-cigarette study design, outline the range of pathologies occurring in cases of e-cigarette associated acute lung injury, highlight disease supporting tissue- and cellular-level changes resulting from e-cigarette exposure, and briefly examine how these changes may promote tumorigenesis. Continued research of the mechanisms by which e-cigarettes induce pathology benefit users and clinicians by resulting in increased regulation of vaping devices, informing treatments for emerging diseases e-cigarettes produce, and increasing public awareness to reduce e-cigarette use and the onset of preventable disease.

Case Report: A Squamous Cell Lung Carcinoma Patient Who Responded to Neoadjuvant Immunochemotherapy but Died From Anastomosis Leakage or/and irAEs: Immune Microenvironment and Genomic Features Changes

Clinical trials indicated that PD-1/PD-L1 inhibitors significantly improve the survival rate of patients with advanced non-small cell lung cancer (NSCLC) and induce immune-related adverse events (irAEs). Thus, the molecular and immune characteristics during PD-1/PD-L1 inhibitor therapy are worth investigating further. We report the case of a 62-year-old male patient diagnosed with stage IIIA squamous cell lung carcinoma (SQCC) who responded to neoadjuvant and adjuvant nivolumab combined chemotherapy but died from anastomosis leakage or/and irAEs. In the pretreatment tumor biopsy, PD-L1 expression was negative and a few T cells, NK cells, and macrophages had infiltrated the tumor. Wild-type EGFR/STK11, mutant TP53, microsatellite stability, and low tumor mutational burden were also found at baseline. After neoadjuvant immunochemotherapy, the tumor was significantly reduced, PD-L1 expression levels were increased by 50%, and more CD8⁺ and CD8⁺ PD-1⁺ T cells had infiltrated the resected tumor tissue. Immune-related lung injury occurred during adjuvant immunochemotherapy, and serum levels of C-reactive protein, IL-13, IL-4, eotaxin, VEGF-A, IL-8, and IFN-gamma were increased. This case demonstrates a squamous cell lung carcinoma patient who responded to neoadjuvant immunochemotherapy that reshaped the tumor immune environment from “cold” to “hot.” Unfortunately, the patient eventually died from anastomosis leakage or/and irAEs during adjuvant immunochemotherapy.

Chest-CT mimics of COVID-19 pneumonia-a review article

Coronavirus disease 2019 (COVID-19) emerged in early December 2019 in China, as an acute lower respiratory tract infection and spread rapidly worldwide being declared a pandemic in March 2020. Chest-computed tomography (CT) has been utilized in different clinical settings of COVID-19 patients; however, COVID-19 imaging appearance is highly variable and nonspecific. Indeed, many pulmonary infections and non-infectious diseases can show similar CT findings and mimic COVID-19 pneumonia. In this review, we discuss clinical conditions that share a similar imaging appearance with COVID-19 pneumonia, in order to identify imaging and clinical characteristics useful in the differential diagnosis.

[Case report of severe acute eosinophilic pneumonia induced by amoxicillin]

INTRODUCTION

Acute eosinophilic pneumonia (AEP) is a rare and potentially severe disorder, characterized by an acute febrile respiratory illness with diffuse pulmonary infiltrates, pleural effusions and an eosinophilic alveolitis identified on broncho-alveolar lavage or lung biopsy. The condition can be idiopathic, or induced by the inhalation of toxic substances, by infections or by medications. The condition tends to respond rapidly to treatment with systemic steroids.

CASE REPORT

We report the case of a 16-year old patient who presented severe acute interstitial pneumonia with eosinophilia (1.17g/L). They had taken a seven-day course of amoxicillin treatment two weeks previously for a dental abscess. The patient initially required respiratory support by mechanical ventilation followed by extracorporeal membrane oxygenation due to severe refractory hypoxemia. After exhaustive investigation a diagnosis of amoxicillin-induced acute eosinophilic pneumonia was made. After steroid treatment was initiated the clinical response was rapidly favorable and remission was achieved. The patient has been advised to avoid beta lactam antibiotics for life.

CONCLUSION

This case illustrates a rare case of severe acute eosinophilic pneumonia induced by amoxicillin.

Tobacco Worker's Lung: A Neglected Subtype of Hypersensitivity Pneumonitis

Tobacco worker's lung (TWL) is a type of hypersensitivity pneumonitis (HP) affecting workers exposed to tobacco leaves and molds in the humidified environment of the tobacco production industry. Limited epidemiological data point to a prevalence of TWL that is not negligible and probably underestimated. As in other types of HP, an acute vs. chronic presentation depends on the pattern of the exposure. Therefore, the clinical presentation can vary from an acute influenza-like syndrome, mostly self-limiting with the removal of the exposure, to an insidious onset of cough, exertional dyspnea, fatigue and weight loss in chronic presentations, where fibrotic changes may be observed. The main treatment strategy is the removal of the exposure to tobacco dust and molds, while the main aim of corticosteroid therapy is to reduce morbidity and prevent complications, namely the development of pulmonary fibrosis and permanent lung dysfunction. Despite the fact that TWL is quite well described, preventive measures are not usually adopted in the tobacco production industry. We present here a state of the art review of this neglected, preventable, but still prevalent and occupational-related subtype of HP.

Ceftaroline-related acute eosinophilic pneumonia

Ceftaroline fosamil is a novel 5^th generation broad-spectrum oxyimino-cephalosporin with activity against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), Streptococcus pneumoniae, Haemophilus influenzae, and Gram-negative bacteria. It has been approved by the United States Food and Drug Administration for the treatment of acute bacterial skin and skin structure infections and community-acquired bacterial pneumonia. There have been reported cases of successful treatment of MRSA bacteremia with this agent. Common adverse drug reactions from ceftaroline include skin rash, hives, neutropenia, thrombocytopenia, and anemia. Acute eosinophilic pneumonia is a rare untoward drug reaction associated with it. We report a case of fever and acute hypoxic respiratory failure with bilateral interstitial pulmonary infiltrates while on ceftaroline therapy for sternal osteomyelitis and ascending aortic graft infection secondary to MRSA. Laboratory studies revealed peripheral blood eosinophilia (>3000 cells/mm³). After exclusion of infectious, autoimmune, and other extrinsic allergic causes of pneumonia, ceftaroline-related acute eosinophilic pneumonia was suspected. Ceftaroline was discontinued and a therapeutic trial of high-dose steroid was initiated. Significant improvement of clinical symptoms and hypoxia was achieved after 24 h of steroid therapy. There was no recurrence of clinical symptoms after completing steroid course, which supported our suspicion of acute eosinophilic pneumonia from ceftaroline. Radiographic improvement of pulmonary infiltrates occurred 4 weeks later with complete resolution at 3 months from the initial event. The current case adds to this rarely reported adverse effect from this relatively newer antimicrobial agent. Increased awareness, early recognition, discontinuation of medication, and steroid therapy are key in favorable clinical outcome and recovery.

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.

[Daptomycin-induced eosinophilic pneumonia associated with an early endoprosthesis infection]

Acute eosinophilic pneumonia (AEP) is a rare disease characteristically involving eosinophilic infiltration of lung parenchyma as well as fever, dyspnea, and coughing. A differentiation is made between primary and secondary AEP depending on the underlying etiology. Substances that most frequently cause secondary AEP are antibiotics, such as the lipopeptide daptomycin. This is a case report about a 69-year-old female patient who underwent antibiotic treatment with daptomycin for an infection of a knee prosthesis. During the treatment, signs of pneumonia developed and included the increased dependence on mechanical ventilation of the previously intubated patient, infiltrates on a chest X‑ray, fever, and an increase in serum inflammation markers. Proof of bacteria as an underlying pathogen was not possible. A thoracic computed tomography (CT) scan showed opacities that are commonly seen in interstitial lung disease. Termination of daptomycin treatment due to renal failure led to an improvement of pulmonary symptoms. Re-exposure to daptomycin resulted in a recurrence of the symptoms. The diagnostic criteria for AEP according to Uppal et al. include 1) current exposure to daptomycin, 2) dyspnea with increased oxygen requirements or necessity for mechanical ventilation, 3) new infiltrates on chest X‑ray or CT scan, 4) bronchoalveolar lavage with eosinophilia >25%, 5) improvement of clinical symptoms following daptomycin withdrawal, and 6) fever. With 5 out of the 6 criteria by Uppal et al. positive-an eosinophilia >25% being the only unmet criteria-an AEP induced by daptomycin was diagnosed. Withdrawal of daptomycin as well as high-dose cortisol bolus treatment led to a rapid recovery.

Inhalation Toxicology of Vaping Products and Implications for Pulmonary Health

E-cigarettes have a liquid that may contain flavors, solvents, and nicotine. Heating this liquid generates an aerosol that is inhaled into the lungs in a process commonly referred to as vaping. E-cigarette devices can also contain cannabis-based products including tetrahydrocannabinol (THC), the psychoactive component of cannabis (marijuana). E-cigarette use has rapidly increased among current and former smokers as well as youth who have never smoked. The long-term health effects are unknown, and emerging preclinical and clinical studies suggest that e-cigarettes may not be harmless and can cause cellular alterations analogous to traditional tobacco smoke. Here, we review the historical context and the components of e-cigarettes and discuss toxicological similarities and differences between cigarette smoke and e-cigarette aerosol, with specific reference to adverse respiratory outcomes. Finally, we outline possible clinical disorders associated with vaping on pulmonary health and the recent escalation of acute lung injuries, which led to the declaration of the vaping product use-associated lung injury (EVALI) outbreak. It is clear there is much about vaping that is not understood. Consequently, until more is known about the health effects of vaping, individual factors that need to be taken into consideration include age, current and prior use of combustible tobacco products, and whether the user has preexisting lung conditions such as asthma and chronic obstructive pulmonary disease (COPD).

Acute eosinophilic pneumonia with sepsis-like symptoms of arthralgia, joint stiffness and lymph node enlargement: A case report

Background

Acute eosinophilic pneumonia (AEP) is an acute febrile disease with good prognosis. It is often manifested as cough, dyspnea and fever, and sometimes may also as myalgia. However, there are no reports of AEP with sepsis-like symptoms of arthralgia, joint stiffness, lymph node enlargement, transient rashes and abnormal liver function in the literature.

Case summary

A male patient with AEP was admitted to our hospital. He presented with fever, cough, arthralgia and joint stiffness, and also had transient rashes, lymph node enlargement and mild abnormal liver function. The counts of white blood cells and eosinophils were increased in peripheral blood. It seemed like sepsis, but his percutaneous lung biopsy suggested eosinophil inflammation, which had a good response to corticosteroids instead of antibiotics.

Discussion

AEP is easily misdiagnosed as bacterial pneumonia with sepsis when it presents with lung infiltration on CT and atypical manifestations such as arthralgia, joint stiffness, lymph node enlargement, transient rashes and abnormal liver function. In this case, if a lot more antibiotics do not work, some of possible diseases including AEP may be considered. Increased eosinophils in peripheral blood and lung biopsy are helpful for the diagnosis of the disease.

Possible Mechanisms of Eosinophil Accumulation in Eosinophilic Pneumonia

Eosinophilic pneumonia (EP), including acute EP and chronic EP, is characterized by the massive pulmonary infiltration of eosinophils into the lung. However, the mechanisms underlying the selective accumulation of eosinophils in EP have not yet been fully elucidated. We reported that bronchoalveolar lavage fluid (BALF) from EP patients induced the transmigration of eosinophils across endothelial cells in vitro. The concentrations of eotaxin-2 (CCL24) and monocyte chemotactic protein (MCP)-4 (CCL13), which are CC chemokine receptor (CCR) 3 ligands, were elevated in the BALF of EP patients, and anti-CCR3 monoclonal antibody inhibited the eosinophil transmigration induced by the BALF of EP patients. The concentration of macrophage inflammatory protein 1β (CCL4), a CCR5 ligand that induces eosinophil migration, was increased in the BALF of EP patients. Furthermore, the concentration of interleukin (IL) 5 was increased in the BALF of EP patients, and it has been reported that anti-IL-5 antibody treatment resulted in remission and the reduction of glucocorticoid use in some cases of chronic EP. The concentrations of lipid mediators, such as leukotriene (LT) B₄, damage-associated molecular pattern molecules (DAMPs), such as uric acid, or extracellular matrix proteins, such as periostin, were also increased in the BALF of EP patients. These findings suggest that chemokines, such as CCR3/CCR5 ligands, cytokines, such as IL-5, lipid mediators, such as LTB₄, DAMPs, and extracellular matrix proteins may play roles in the accumulation or activation of eosinophils in EP.

Unilateral antibiotic-induced acute eosinophilic pneumonia on the operative side after surgery for primary lung cancer: a case report

BACKGROUND

Acute eosinophilic pneumonia (AEP) is a rare idiopathic lung disease characterized by pulmonary eosinophilia. The epidemiology of AEP remains understudied; however, past reports have reported that AEP can be caused by an allergic reaction to medications, such as antibiotics or inhaled antigens, such as tobacco smoke. AEP usually occurs bilaterally. However, we encountered an unusual case of antibiotic-induced eosinophilic pneumonia showing unilateral consolidation just on the operative side, which was initially diagnosed as postoperative bacterial pneumonia and treated with antibiotic therapy. The prescribed antibiotics paradoxically provoked AEP and worsened the patient's condition. Here, we report this antibiotic-induced AEP case showing unilateral consolidation only on the operative side which could be triggered by surgery for primary lung cancer.

CASE PRESENTATION

A 74-year-old man underwent right upper lobectomy for lung adenocarcinoma. On postoperative day (POD) 9, an interstitial shadow appeared in the right lower lung field of the chest radiographs, along with a fever of 38.5 °C, dyspnea needing oxygen supplementation, and increased purulent sputum production, suggesting postoperative bacterial pneumonia. Despite administration of the broad-spectrum antibiotic, meropenem, the fever did not improve, and pulmonary opacity gradually worsened. Blood analysis showed increased peripheral eosinophils at 1182/mm³. The meropenem treatment was discontinued and bronchoscopy was performed for further evaluation, and the bronchoalveolar lavage fluid assessment showed a remarkable increase in the eosinophil population (51%). The drug lymphocyte stimulation test (DLST) for meropenem was positive. We diagnosed the patient with antibiotic-induced unilateral AEP, after which corticosteroid treatment was initiated. The patient subsequently improved and the infiltration in the right lower lung field completely disappeared. The patient was discharged on POD 43 without oxygen supplementation and is doing well without tumor recurrence 16 months after the surgery.

CONCLUSIONS

Unilateral drug-induced AEP is rare. Nonetheless, it should be recognized as a differential diagnosis of postoperative pneumonia even in cases of a unilateral radiographic infiltration, because the lung operation itself could trigger this type of AEP.

Effects of Cigarette Smoke on the Nasal Respiratory and Olfactory Mucosa in Allergic Rhinitis Mice

Objective

Cigarette smoke (CS) exposure reportedly enhances allergic airway inflammation. However, some studies have shown an association between current cigarette smoke exposure and a low risk for allergic rhinitis. Thus, the impact of CS exposure on allergic rhinitis remains poorly understood. The purpose of this study was to investigate the effects of CS on the respiratory mucosa (RM) and the olfactory epithelium (OE) of mice with allergic rhinitis, as the effects may differ depending on the nasal histological compartments.

Methods

Eight-week-old male BALB/c mice were used for this study. We developed a mouse model of smoking by intranasally administering 10 doses of a CS solution (CSS), and a mouse model of allergic rhinitis by sensitization with intraperitoneal ovalbumin (OVA) injection and intranasal challenge with OVA. We examined the effects of CS on the nasal RM and OE in mice with or without allergic rhinitis using histological, serum, and genetic analyses. First, we examine whether CSS exposure induces allergic responses and then, examined allergic responses in the OVA-sensitized allergic rhinitis mice with or without CSS exposure.

Results

Short-term CSS administration intensified allergic responses including increased infiltration of eosinophils and inflammatory cells and upregulation of interleukin-5 expression in the nasal RM of OVA-immunized mice, although only CSS induced neither allergic responses nor impairment of the RM and OE. Notably, repetitive OVA-immunization partially impaired the OE in the upper-lateral area, but CSS administration did not reinforce this impairment in OVA-induced allergic mice.

Conclusion

Short-term CSS exposure strengthened allergic responses in the nasal RM and did not change the structure of the OE. These results suggest that patients with allergic rhinitis could experience exacerbation of allergic symptoms after CS exposure.

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.

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.

[Acute eosinophilic pneumonia and illicit psychoactive substance use]

Illicit psychoactive substance (IPAS) use can lead to a number of respiratory complications, including acute eosinophilic pneumonia (AEP). Systematic literature review of data on AEP in IPAS users (cannabis, cocaine, heroin and amphetamine). Of two cases of cannabis and tobacco users reported to have developed AEP, one, a teenage15 year old boy presented with acute respiratory distress syndrome (ARSD) which necessitated extracorporeal membrane oxygenation (ECMO). Five cases of AEP in cocaine smokers (crack) are reported, one of which was fatal. The patient presented with acute pulmonary edema and ARDS which progressed to ventricular fibrillation and asystole. A 24-year-old woman presented with AEP after repeated inhalation of heroin. Finally, a case of an amphetamine abuser who developed AEP and ARDS after amphetamine inhalation is reported. The time between the first IPAS use and admission in cases reported ranged from 7 days to 4 years, while time between the last IPAS use and admission was short (less than 15 days). IPAS use must be sought in case of AEP, especially in young adults, and practitioners must advise and help users to stop their consumption.

Pediatric Acute Respiratory Distress Syndrome and Hypersensitivity Pneumonitis Related to E-cigarette Vaping

In recent years, electronic cigarettes (e-cigs) have been falsely advertised as safe alternatives to conventional smoking. We report a case involving a 16-year-old female who presented with fever, nonproductive cough, and shortness of breath after vaping e-cig/tetrahydrocannabinol dab pen. Her symptoms rapidly deteriorated and met diagnostic criteria for pediatric acute respiratory distress syndrome. Chest radiograph revealed extensive patchy airspace disease and computed tomography scan showed bilateral ground glass opacities. Bronchoalveolar lavage fluid revealed increased neutrophils, lymphocytosis, but absent eosinophilia. After the results of a comprehensive workup for infectious etiology returned negative, she was diagnosed with hypersensitivity pneumonitis and started on systemic corticosteroids.

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

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

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.

Critical role of CCL4 in eosinophil recruitment into the airway

BACKGROUND

Excessive eosinophil airway infiltration is a clinically critical condition in some cases. Eosinophilic pneumonia (EP) is a pulmonary condition involving eosinophil infiltration of the lungs. Although several chemokines, including eotaxin-1 (CCL11), RANTES (CCL5) and macrophage inflammatory protein 1β (MIP-1β or CCL4), have been detected in bronchoalveolar lavage fluid (BALF) from patients with EP, the pathophysiological mechanisms underlying EP, including potential relationships between eosinophils and CCL4, have not been fully elucidated.

OBJECTIVE

To examine the involvement of CCL4 in eosinophilic airway inflammation.

METHODS

We analysed supernatants of activated eosinophils and BALF from 16 patients with eosinophilic pneumonia (EP). Further, we examined the effects of CCL4 on eosinophil functions in vitro and those of anti-CCL4 neutralizing antibody in an in vivo model.

RESULTS

We found that purified human eosinophils stimulated with IL-5 predominantly secreted CCL4 and that patients with EP had elevated CCL11 and CCL4 levels in BALF compared with samples from individuals without EP. Because CCL4 levels were more strongly correlated with eosinophil count and expression of eosinophil granule proteins than CCL11, in vitro experiments using purified eosinophils concentrated on the former chemokine. Interestingly, CCL4 acted as a chemoattractant for eosinophils. In a mouse model, administration of a CCL4-neutralizing antibody attenuated eosinophilic airway infiltration and airway hyperresponsiveness.

CONCLUSIONS AND CLINICAL RELEVANCE

Overall, these findings highlight an important role of CCL4 in the mechanisms underlying eosinophil recruitment into the airway and may provide a novel insight into this potential therapeutic target.

Acute eosinophilic pneumonia following electronic cigarette use

Electronic cigarette (e-cigarette) use, or vaping, is gaining widespread popularity among adults aged 18–35. Vaping is commercially promoted as a safer alternative to traditional cigarette smoking. Previous studies have reported a close relationship between conventional cigarette smoking and acute eosinophilic pneumonia (AEP), but only one case report to date associates vaping with AEP in a male patient. We present the first case of AEP involving a young female after use of e-cigarettes. Clinicians should consider AEP when evaluating young patients with hypoxic respiratory failure and a recent history of e-cigarette use. This case highlights the need for more research into the relationship between e-cigarettes and AEP.

Cigarette smoking-induced acute eosinophilic pneumonia: A case report

RATIONALE

Acute eosinophilic pneumonia (AEP) is a rare pulmonary disease, which is characterized by diffuse pulmonary eosinophilia. The pathogenesis remains unknown. Here we report a patient with AEP following a recently acquired habit of smoking.

PATIENT CONCERNS

A 21-year-old female presented with fever, dry cough, and acute hypoxic respiratory distress for 2 days. Chest computed tomography showed bilateral ground glass opacities, patchy nodules, and pleural effusions. Blood tests showed a gradually raised peripheral eosinophils level.

DIAGNOSES

Bronchoalveolar lavage fluid revealed marked elevation of eosinophils. She was diagnosed with AEP.

INTERVENTIONS

Systemic methylprednisolone was immediately used for treatment.

OUTCOMES

Her clinical symptoms and chest radiographs improved promptly after treatment.

LESSONS

Cigarette smoking might be an underlying triggering factor of AEP. Diffuse alveolar infiltrates and a gradually increasing peripheral eosinophilia should raise the concern especially in recent smoking patients.

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.

Elevated Periostin Concentrations in the Bronchoalveolar Lavage Fluid of Patients with Eosinophilic Pneumonia

BACKGROUND

Eosinophilic pneumonia (EP) is characterized by massive pulmonary infiltration by eosinophils. Although serum periostin is a novel marker for eosinophil-dominant asthma, the upregulation of periostin in the airway of asthmatics is controversial. In this study, we examined whether periostin concentrations are elevated in the bronchoalveolar lavage fluid (BALF) of patients with EP.

METHODS

BAL was performed in healthy volunteers and in patients with acute eosinophilic pneumonia (AEP), chronic eosinophilic pneumonia (CEP), and sarcoidosis. The periostin concentrations in the BALF were measured.

RESULTS

The periostin concentration in the BALF increased significantly with pulmonary eosinophil ia and was higher in AEP and CEP patients than in healthy volunteers and sarcoidosis patients, even after adjusting the albumin concentration. In pulmonary eosinophilia, the periostin concentration correlated with the eosinophil and lymphocyte counts, the concentration of albumin, and the concentration of cytokines such as IL-5, IL-13, and transforming growth factor β1.

CONCLUSIONS

Although some blood leakage may be involved in the elevation of periostin in the BALF of EP, periostin can be induced locally, at least in part. Therefore, periostin may play a role in the development of EP.

Heat-not-burn cigarettes induce fulminant acute eosinophilic pneumonia requiring extracorporeal membrane oxygenation

Background

Although the cause of acute eosinophilic pneumonia (AEP) has not yet been fully clarified, cigarette smoking is reported to be a risk factor for developing AEP. The heat-not-burn cigarette (HNBC) was developed to reduce the adverse effects of smoke on the user's surroundings. However, the health risks associated with HNBCs have not yet been clarified. We report a successfully treated case of fatal AEP presumably induced by HNBC use.

Presentation of case

A 16-year-old man commenced HNBC smoking two weeks before admission and subsequently suffered from shortness of breath that gradually worsened. The patient was transferred to emergency department and immediately intubated because of respiratory failure. Computed tomography showed mosaic ground-glass shadows on the distal side of both lungs with a PaO₂/F_IO₂ ratio of 76. The patient required veno-venous extracorporeal membrane oxygenation (ECMO) for severe respiratory failure. He was diagnosed with AEP by clinical course and detection of eosinophils in sputum; thus, methylprednisolone was administrated. The patient was weaned off ECMO four days after initiation and extubated the day after. He fully recovered without sequelae.

Conclusion

As far as we know, our patient is the first case of AEP induced by HNBC use successfully treated with ECMO. Emergency physicians must be aware that HNBCs can induce fatal AEP.

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The use of heat-not-burn cigarettes has been increasing in recent years.

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The effects of heat-not-burn cigarettes on health have not yet been clarified.

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Heat-not-burn cigarettes possibly induce acute eosinophilic pneumonia.

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Extracorporeal membrane oxygenation was effective in a patient with a severe case of acute eosinophilic pneumonia.

A potential mechanism of the onset of acute eosinophilic pneumonia triggered by an anti-PD-1 immune checkpoint antibody in a lung cancer patient

INTRODUCTION

The impact of immune checkpoint blockade on immunity in cancer patients is not completely elucidated due to the complexity of the immune network. Recent studies have revealed a significant role of programed cell death-ligand 2 (PD-L2) in negatively controlling the production of CD4+ T helper type 2 (Th2) cytokines and airway hypersensitiveness, suggesting hypo-responsive Th2 cells via the PD-1/PD-L2 inhibitory pathway in lung could be reawaken by PD-1 blockade therapy.

METHODS

We describe the first report of acute eosinophilic pneumonia (AEP), which is known as Th2-associated pulmonary disease, triggered by nivolumab, an anti-PD-1 antibody, in an advanced non-small cell lung cancer patient. Based on the current case report and literature, the present study proposes a potential mechanism of the onset of AEP as an immune-related adverse event (irAE).

RESULTS

A 62-year-old man was diagnosed with lung adenocarcinoma and nivolumab was selected as the third-line regimen. After three cycles of nivolumab treatment, chest computed tomography revealed pulmonary infiltrates in both lungs. The patient was diagnosed with AEP based on the diagnostic criteria for AEP. Nivolumab was suspended and the patient was started on oral prednisolone. His symptoms and radiological findings had rapidly improved.

CONCLUSIONS

Given the increasing frequency of the use of anti-PD-1 antibodies, clinicians should be aware of the risk of AEP as a potential irAE. This study may improve our understanding of the pathophysiology underlying Th2-associated irAEs and AEP.