Abstract Introduction Chronic eosinophilic pneumonia (CEP) presents with subacute respiratory symptoms, along with radiographic findings that are bilateral, peripheral, and often migratory. Bronchoalveolar lavage (BAL) reveals ≥ 25% eosinophils or eosinophilic infiltration, and peripheral blood eosinophilia is also a common finding. However, differentiating CEP from other eosinophilic and autoimmune lung diseases, such as eosinophilic granulomatosis with polyangiitis (EGPA) or connective tissue disease-associated interstitial lung disease (CT-ILD) in patients with concomitant autoimmune illness, can be diagnostically challenging due to overlapping clinical and radiologic features. Case Presentation A 41-year-old female with aspirin sensitivity, recurrent nasal polyps and eosinophilic asthma presented to the clinic. A chest X-ray for shortness of breath in 2018 revealed diffuse interstitial changes in the lower lobes. Chest computerized tomography (CT) scan demonstrated scattered, indistinct pulmonary opacities, mostly ground-glass and reticular, prominently in the lower lobes. Labs were notable for positive anti-double stranded DNA antibody, but not diagnosed with systemic lupus erythematosus by rheumatology. Given peripheral eosinophilia, dupilumab was started for eosinophilic asthma. She continued to experience coughs provoked by exertion, laughter, and exertional dyspnea. Chest CT in December 2024 revealed multilobar ground-glass opacities and basilar fibrotic changes. Findings were consistent with fibrotic NSIP, but concomitant eosinophilic pneumonia could not be excluded in the context of peripheral eosinophilia that did not decrease after a year of dupilumab therapy, and ongoing respiratory symptoms. Further workup demonstrated negative antineutrophil cytoplasmic antibodies (ANCA) and Strongyloides serology. A bronchoscopy with BAL was performed, revealing 36% eosinophils, supporting the diagnosis of chronic eosinophilic pneumonia. The patient was initiated on corticosteroid therapy with symptomatic improvement and was transitioned from dupilumab to mepolizumab for long-term treatment. Discussion CEP is a challenging diagnosis due to its overlapping features with other conditions, necessitating careful testing to exclude other etiologies. Further confounding the diagnosis in a patient taking dupilumab with intermittent adherence is the expected transient increase in blood eosinophil level after medication initiation. A multidisciplinary approach is essential to interpret findings in context to arrive at the correct diagnosis. Furthermore, while most patients respond to corticosteroids, relapse rates are high, regardless of taper course. Long-term follow-up studies show that many patients remain corticosteroid-dependent for years. Emerging literature describes a “fibrosing CEP” phenotype where chronic eosinophilic inflammation leads to irreversible parenchymal remodeling, consistent with this patient’s basilar fibrosis. Although corticosteroids remain first-line therapy, biologics such as mepolizumab have shown efficacy as steroid-sparing agents in eosinophilic lung disease. This abstract is funded by: None
Hassan et al. (Fri,) studied this question.
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