SARS-CoV-2 as a trigger of eosinophilic pneumonia

Resolution of Eosinophilic Pneumonia after Coronavirus Disease 2019 without Systemic Corticosteroids

Pulmonary and extrapulmonary complications after coronavirus disease 2019 (COVID-19) have been major public health concerns during the COVID-19 pandemic. Although post-COVID-19 pulmonary manifestations cover a wide spectrum, eosinophilic pneumonia (EP) has rarely been reported. To date, only four cases of EP potentially triggered by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been reported, all of which required systemic corticosteroid therapy. We herein report the first case of post-COVID-19 EP resolution without systemic corticosteroid therapy. We also review the literature regarding EP associated with SARS-CoV-2 infection and vaccination.

COVID-19-Induced Eosinophilic Lower Airway Inflammation in Those With Multiple COVID-19 Vaccinations

A 29-year-old woman was admitted with a diagnosis of ischemic enteritis. She had a coronavirus disease 2019 (COVID-19) infection four weeks before this visit and continued to experience a cough. Four months before, she received the third COVID-19 vaccine. Chest computer tomography revealed scattered ground-glass opacities in both upper lobes. Based on abnormalities in chest imaging, eosinophilia, and a high level of fractional exhaled nitric oxide, she was diagnosed with eosinophilic lower airway inflammation due to COVID-19. Since the visit, the patient had an intermittent fever and no radiological improvement, so systemic corticosteroid treatment was initiated, and the symptoms and clinical findings improved. Clinicians should know the potential association between COVID-19 and eosinophilic lower airway inflammation, which may still occur despite multiple vaccinations.

Respiratory virus infections of the lower respiratory tract elevate bronchoalveolar lavage eosinophil fraction: a clinical retrospective study and case review

BACKGROUND

Eosinophilic airway inflammation caused by respiratory virus infection has been demonstrated in basic research; however, clinical investigations are lacking. To clarify the extent to which respiratory virus infection induces airway eosinophilic inflammation, we reviewed the results of bronchoalveolar lavage (BAL) and respiratory virus testing performed at our hospital.

METHODS

Among the BAL procedures performed at the University of the Ryukyu Hospital from August 2012 to September 2016, we collected cases of acute respiratory disease in which multiplex polymerase chain reaction (PCR) was used to search for respiratory viruses. The effect of respiratory virus detection on BAL eosinophil fraction was analyzed using statistical analysis. A case study was conducted on respiratory virus detection, which showed an elevated BAL eosinophil fraction.

RESULTS

A total of 95 cases were included in this study, of which 17 were PCR-positive. The most common respiratory virus detected was parainfluenza virus (eight cases). The PCR-positive group showed a higher BAL eosinophil fraction than the PCR-negative group (p = 0.030), and more cases had a BAL eosinophil fraction > 3% (p = 0.017). Multivariate analysis revealed that being PCR-positive was significantly associated with BAL eosinophil fraction > 1% and > 3%. There were nine PCR-positive cases with a BAL eosinophil fraction > 1%, of which two cases with parainfluenza virus infection had a marked elevation of BAL eosinophil fraction and were diagnosed with eosinophilic pneumonia.

CONCLUSIONS

Cases of viral infection of the lower respiratory tract showed an elevated BAL eosinophil fraction. The increase in eosinophil fraction due to respiratory virus infection was generally mild, whereas some cases showed marked elevation and were diagnosed with eosinophilic pneumonia. Respiratory virus infection is not a rare cause of elevated BAL eosinophil fraction and should be listed as a differential disease in the practice of eosinophilic pneumonia.

A Case of Acute Eosinophilic Pneumonia Triggered by the SARS-CoV-2 Virus

We report a case of acute eosinophilic pneumonia (AEP) triggered by the coronavirus disease 2019 (COVID-19) infection. A 60-year-old male with chronic sinusitis and tobacco use presented to the emergency department (ED) with an acute onset of dyspnea, non-productive cough, and fever. A diagnosis of moderate SARS-CoV-2 infection with bacterial superinfection was made. He was discharged on antibiotic therapy. One month later, due to the persistence of symptoms, he returned to the ED. At this time, blood analysis showed eosinophilia and a chest computed tomography scan showed bilateral diffuse infiltrative changes. He was admitted to the hospital for the study of eosinophilic disease. A lung biopsy was performed, which showed eosinophilic pneumonia. Corticotherapy was started with symptoms and peripheral eosinophilia resolution, and imaging improvement.

Acute Eosinophilic Pneumonia Complicated with Venous Thromboembolic Disease—Diagnostic and Therapeutic Considerations

Acute Eosinophilic Pneumonia (AEP) is a rare idiopathic disease caused by an accumulation of eosinophils in the pulmonary alveoli and interstitial tissue of the lungs. The onset of symptoms is acute; some patients develop respiratory failure. The diagnosis is based on clinical symptoms, diffuse interstitial infiltrates in the lungs on imaging studies, and eosinophilia exceeding 25% on bronchoalveolar lavage or pleural fluid smear. Smokers are primarily at increased risk for the disease. We present a case of venous thromboembolic disease (VTE) that developed in the course of AEP in a previously healthy male smoker. Complete remission of the disease was achieved with anticoagulation therapy combined with a low dose of steroids. Surprisingly, further diagnostics revealed the presence of thrombophilia: antithrombin (AT) deficiency and increased homocysteine level. According to our knowledge, this is the first case of VTE diagnosed in the course of AEP combined with thrombophilia.