Hematological Neoplasms with Eosinophilia

Area of Science:

• Hematology
• Oncology

Background:

• Eosinophils constitute 0.3-5% of leukocytes, with elevated counts (≥0.5 × 10⁹/L) indicating eosinophilia and (≥1.5 × 10⁹/L) hypereosinophilia.
• Bone marrow eosinophilia is defined as >6% of total nuclear cells.
• Common causes of reactive eosinophilia include non-hematologic conditions (allergic, infectious, drug-induced, autoimmune) and solid tumors.

Purpose of the Study:

• To review the differential diagnosis of hematologic malignancies associated with eosinophilia.
• To explore the distinction between reactive and neoplastic eosinophilia in the context of hematologic cancers.

Main Methods:

• Literature review focusing on hematologic malignancies and eosinophilia.
• Analysis of diagnostic criteria for eosinophilia and hypereosinophilia.
• Discussion of reactive versus primary neoplastic eosinophilia in lymphoid and myeloid neoplasms.

Main Results:

• Eosinophilia associated with hematologic malignancy can be reactive (secondary to cytokines) or primary (neoplastic).
• Reactive eosinophilia is common in lymphoid neoplasms (e.g., Hodgkin lymphoma, T-cell neoplasms).
• Primary neoplastic eosinophilia typically arises in myeloid neoplasms or stem cell disorders.

Conclusions:

• Current cytological and cytometric methods lack definitive predictors for reactive versus clonal eosinophilia.
• Diagnosis often relies on indirect evidence and classification of the co-existing hematologic malignancy.
• Understanding the spectrum of hematologic malignancies associated with eosinophilia is crucial for accurate diagnosis and management.