A patient with shortness of breath and bilateral pulmonary infiltrates

Eosinophilic disorders are rare and clinically challenging diagnoses. In part, the challenge comes from the fact that some classifications of eosinophilic diseases have been based on the site of eosinophilic infiltration whereas others have been based on the actual number of blood eosinophils present. We describe a 54-year-old woman who had a history of asthma and presented with shortness of breath and eosinophilia. The differential diagnosis is broad and includes infectious diseases, inflammatory conditions such as Churg–Strauss syndrome, and hematologic conditions such as hypereosinophilic syndrome. We describe the diagnostic challenges inherent in such a presentation and also the changing landscape of disease labels in light of our evolving ability to diagnose genetic abnormalities.