Lymphocytic Variant Hypereosinophilic Syndrome Overlaps with Angioimmunoblastic T-Cell Lymphoma: A Case Report and Literature Review.

Introduction: Lymphocytic-variant of hypereosinophilic syndrome (L-HES) is a clonal T-cell disorder driven by an aberrant Th2 response, typically featuring CD3- CD4+ T-cell expansion, eosinophil-mediated tissue injury, most commonly skin lesions, and lymphadenopathy. Angioimmunoblastic T-cell lymphoma (AITL) is an aggressive peripheral T-cell lymphoma of follicular helper T-cell origin; it can present with similar clinical features such as lymphadenopathy, rash and eosinophilia. Histological and immunophenotypic features may also be common in both diseases, thus creating a diagnostic overlap. Case description: We report the case of a 53-year-old man with a medical history of allergic rhinitis who developed a diffuse, persistent maculopapular rash with pruritis. Physical examination revealed inguinal lymphadenopathy without organomegaly, laboratory investigations demonstrated marked eosinophilia, and hypergammaglobulinemia, while additional testing excluded any infectious or autoimmune aetiologies. Lymphocytic immunophenotyping on peripheral blood and skin biopsy revealed a high proportion of CD3-CD4+ cells exhibiting a classic TH2 phenotype, consistent with L-HES. However, lymph node histology demonstrated architectural remodelling with intrafollicular infiltration by atypical T lymphocytes showing a T-cell follicular helper phenotype, findings indicative of AITL. The coexistence of L-HES and AITL was established. The patient underwent polychemotherapy, resulting in rapid clinical improvement of skin lesions with sustained remission at 6 months of follow up. Conclusion: L-HES and AITL may coexist, or L-HES may precede overt lymphoma, suggesting clonal evolution within a shared biological spectrum. This case highlights diagnostic pitfalls and emphasizes the need for integrated clinical, pathological, flow cytometric and molecular evaluation. LEARNING POINTS: Lymphocytic-variant of hypereosinophilic syndrome (L-HES) may precede or be associated with T malignant lymphoproliferation.Physician awareness of L-HES conditions presenting with tumoral syndrome is necessary to rule out malignant lymphoproliferation.Histological samples and biological investigations are mandatory to distinguish L-HES from angioimmunoblastic T-cell lymphoma.