Hypereosinophilic syndrome in the differential diagnosis of pulmonary infiltrates with eosinophilia

Objective: To describe key diagnostic considerations in patients with pulmonary infiltrates with eosinophilia, with a special emphasis on raising awareness of hypereosinophilic syndrome (HES), a disease that often involves the lungs and prompts investigation for clonal neoplastic processes that determine prognosis and treatment. Data Sources: Studies and review articles were selected from PubMed and Scopus for relevance to pertinent topics. Study Selections: The literature was screened for studies that described lung eosinophilia and HES. Studies relevant to the topic were included in this review. Results: Pulmonary eosinophil infiltrates in lung biopsy specimens present a broad differential diagnosis, including eosinophilic pneumonia; hypersensitivity reactions, such as allergic bronchopulmonary fungal disease; and pulmonary manifestations of systemic diseases, such as eosinophilic granulomatosis with polyangiitis. An additional important consideration in the differential diagnosis is pulmonary involvement by HES. HES is a rare syndrome that comprises a heterogeneous group of conditions characterized by persistent blood and/or tissue eosinophilia associated with organ dysfunction. Approximately one-third of HES cases are caused by neoplastic diseases, with the remaining cases classified as reactive or idiopathic. Lung involvement is seen in up to 67% of cases and may be the presenting manifestation of the disorder. Conclusion: The differential diagnosis of pulmonary eosinophilia is broad and requires a multidisciplinary approach with clinicopathologic-radiologic correlation. (C) 2018 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.