A case of cigarette smoking-induced acute eosinophilic pneumonia showing tolerance

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.

Acute eosinophilic pneumonia following artenimol-piperaquine exposure

Acute eosinophilic pneumonia (AEP) has been reported following chloroquine or mefloquine exposure, both structurally related to piperaquine. We report a case of AEP with typical CT scan patterns, hypereosinophilia in blood (9.8 109/l), and bronchoalveolar lavage (78% of 600 000 cells/ml), 10 days after artenimol-piperaquine exposure in a 26-year-old man.

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.

Smoking-related interstitial lung diseases

Cigarette smoke, a toxic collection of thousands of chemicals generated from combustion of tobacco, is recognized as the primary causative agent of certain diffuse interstitial and bronchiolar lung diseases. Most patients afflicted with these disorders are cigarette smokers, and smoking cessation has been shown to be capable of inducing disease remission and should occupy a pivotal role in the management of all smokers with these diffuse lung diseases. The role of pharmacotherapy with corticosteroids or other immunomodulating agents is not well established but may be considered in patients with progressive forms of smoking-related interstitial lung diseases.

Eosinophilic pneumonias

Eosinophilic pneumonias (EP) encompass a wide spectrum of lung diseases characterized by peripheral blood eosinophilia (>1 x 10(9) eosinophils/l) and/or alveolar eosinophilia (>25%). Blood eosinophilia may be lacking, as in the early phase of idiopathic acute EP, or in patients already taking oral corticosteroids. EP may present with varying severity, ranging from almost asymptomatic infiltrates to the acute respiratory distress syndrome necessitating mechanical ventilation. Possible causes of EP must be thoroughly investigated, especially drugs and the variety of parasitic infections (considering history of travel or residence in areas of endemic parasitic infection). However, chronic EP remains idiopathic in many cases. When present, extrathoracic manifestations lead to suspect Churg-Strauss syndrome (CSS) or the hypereosinophilic syndrome (HES), the prognosis of which is dominated by cardiac involvement. Apart from the treatment of specific causes when possible, corticosteroids remain the cornerstone of symptomatic treatment for eosinophilic disorders, usually with a dramatic response, but frequent relapses when tapering or after stopping the treatment. The adjunction of immunosuppressants to corticosteroids is necessary in patients with CSS and poor prognosis factors. Imatinib has recently proven effective in the treatment of the myeloproliferative variant of the HES.

Idiopathic acute eosinophilic pneumonia: a study of 22 patients

Idiopathic acute eosinophilic pneumonia (IAEP) is characterized by acute febrile respiratory failure associated with diffuse radiographic infiltrates and pulmonary eosinophilia. We conducted a multicenter retrospective study to characterize this rare clinical entity further and to improve its diagnostic criteria. A total of 13 male and 9 female patients (mean age: 29 +/- 15.8 years) presented with severe hypoxemia (Pa(O2)/fraction of inspired oxygen ratio = 156 +/- 74.1) requiring mechanical ventilation in 14 cases. Bronchoalveolar lavage was performed on all patients and showed 54.4 +/- 19.2% eosinophils on differential cell count, but no open-lung biopsies were done. No clinical differences were found between patients seen at less than 7 days (n = 15) or at 7 to 31 days (n = 7) from the onset of IAEP. A total of 12 patients met the clinical criteria of acute lung injury, and eight of these patients met the criteria for acute respiratory distress syndrome. All patients recovered, either spontaneously (6) or on corticosteroid treatment (16). No relapses occurred. We conclude that: (1) diagnostic criteria of IAEP are compatible with a duration of symptoms for up to 1 month, but the response to corticosteroid treatment is not diagnostic because of possible spontaneous recovery; (2) IAEP should be considered as differential diagnosis of acute lung injury or acute respiratory distress syndrome; (3) bronchoalveolar lavage eosinophilia obviates the need for lung biopsy in IAEP.