Laboratory Aspects and Diagnostic Challenges in a Case of Hypereosinophilic Syndrome.

Hypereosinophilia is defined by a persistent increase in eosinophil levels and can lead to multi-organ damage with highly variable symptoms. The most common manifestations involve the skin, lungs, and gastrointestinal tract, while cardiac and neurological complications can be particularly severe and sometimes fatal. Within this context, we describe the case of a 35-year-old woman with hypereosinophilic syndrome (HES), whose symptoms began during pregnancy. Three months after giving birth, she contracted SARS-CoV-2, which resolved without complications. However, shortly thereafter, laboratory tests revealed marked leukocytosis accompanied by a rapid clinical deterioration. At admission, the patient displayed severe hypereosinophilia associated with systemic inflammation, liver injury, myocardial necrosis, and multi-organ involvement affecting the kidneys, brain, heart, and lungs. As her neurological condition worsened, she required admission to the intensive care unit, where she unfortunately died four days later. The aim of this case report is to raise awareness among clinicians and laboratory professionals about the crucial role of the laboratory finding in assessing disease severity and guiding the diagnostic challenges of idiopathic syndrome (I-HES). The exclusion of secondary causes confirmed the idiopathic nature of the condition. Finally, the case highlights the importance of early recognition of unexplained eosinophilia and systemic symptoms, as timely intervention may be life-saving in rapidly progressive presentations.