Absence of Peripheral Eosinophilia on Initial Clinical Presentation Does Not Rule Out the Diagnosis of Acute Eosinophilic Pneumonia

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.

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.

Early diagnosis based on clinical history and BALF for successful management of smoking-induced acute eosinophilic pneumonia without unnecessary antibiotic usage: a case report

INTRODUCTION

Acute eosinophilic pneumonia (AEP) is a rapid onset and severe respiratory illness characterized by acute febrile respiratory insufficiency, eosinophilic infiltration in the lungs and unique findings on chest imaging. Difficulty in differentiating from other respiratory distress caused by community-acquired pneumonia may result in a delayed diagnosis or treatment with empirical antibiotics.

CASE STUDY

Sixteen-year-old boy who developed AEP with marked eosinophilia in bronchoalveolar lavage fluid (BALF, 36.6%), decreased diffusion capacity of the lung for carbon monoxide (62%) and unique radiological findings. Although he initially denied tobacco use, on repeated thorough clinical history questioning, he eventually admitted beginning smoking 19 days before the onset of symptoms with gradually increasing frequency.

RESULTS

His symptoms resolved quickly without use of antibiotics after cessation of tobacco and treatment with corticosteroids.

CONCLUSION

Careful clinical history taking regarding tobacco use combined with early examination of BALF and recognition of unique radiological findings are critical for proper management of AEP.