Abstract

Background: This study documents a rare case of lymphocytic variant hypereosinophilic syndrome (L-HES) [1], progressing to fatal hemophagocytic lymphohistiocytosis (HLH).
Methods: A 70-year-old female with eosinophilia (85.6%) underwent cytokine profiling, flow cytometry, and bone marrow examination.
Results: A Th2-to-Th1 cytokine shift (IL-5↓/IFN-γ↑) preceded HLH onset. Despite therapy, the patient succumbed to refractory disease.
Conclusions: Cytokine monitoring may predict L-HES-to-HLH transformation, suggesting JAK inhibitors for high-risk cases.

DOI: 10.7754/Clin.Lab.2025.250433