American Board of Internal Medicine (ABIM) Certification Practice Exam

How is hypereosinophilic syndrome diagnosed?

1. Elevated eosinophil count with fever

2. Elevated eosinophil count without organ involvement

3. Elevated eosinophil count with evidence of organ involvement

4. Normal eosinophil count with systemic symptoms

The correct answer is: Elevated eosinophil count with evidence of organ involvement

Hypereosinophilic syndrome is specifically characterized by an elevated eosinophil count accompanied by signs of organ involvement. The condition is defined by the presence of eosinophils in the blood, usually exceeding 1500 eosinophils per microliter, along with clinical evidence that suggests damage to one or more organs. This can manifest as symptoms related to the skin, lungs, heart, gastrointestinal tract, or nervous system. The critical element in diagnosing hypereosinophilic syndrome is not merely the elevated eosinophil count, but rather the presence of associated organ involvement, which differentiates it from other conditions involving eosinophilia. An elevated eosinophil count alone, without any clinical support indicating organ damage, does not fulfill the criteria for diagnosing hypereosinophilic syndrome. Thus, the finding of an elevated eosinophil count combined with objective evidence of organ damage is essential for a conclusive diagnosis of this syndrome.