COVID-19 Pneumonia or Hypereosinophilic Syndrome?

Hypereosinophilic syndromes (HESs) are a group of disorders characterized by pathological proliferation of eosinophils. Diagnostic criteria include eosinophil count of 1,500/mm(3) or higher, presence of organ involvement and exclusion of other causes of eosinophilia for at least 6 months. A 69-year-old male patient was referred to the pandemic clinic with a preliminary diagnosis of coronavirus disease 2019 (COVID-19) with fever and dyspnea. Computed tomography (CT) was compatible with COVID-19, nasopharyngeal swab polymerase chain reaction (PCR) was negative for two times. He had 20,000/mm(3) eosinophilia and retrospective examinations showed that he have had eosinophilia for more than 1 year. Platelet-derived growth factor receptor alpha (PDGFRα) resulted positively. After starting parenteral methylprednisolone with a dose of 1 mg/kg, he was discharged with oral maintenance therapy. In outpatient follow-up, it was observed that eosinophilic pneumonia completely regressed. HES may occur with multiple system and organ involvement and findings. In the differential diagnosis of patients presenting with heart failure, pulmonary involvement and eosinophilia, HES must definitely be considered.