Hypereosinophilia as Presenting Symptom of a Pre-B-ALL

Introduction

Pronounced eosinophilia may be a paraneoplastic phenomenon preceding or masking myeloproliferative malignancies. Commonly known in both lymphomas and metastatic cancer (G. K. Anagnostopoulos et al., J. Surg. Oncol. 2005, 89, 273–275), paraneoplastic eosinophilia has rarely been reported in pediatric ALL. Patients with eosinophilia can develop severe organ damage associated with poor prognosis and an early mortality rate up to 50%. Therefore it is of paramount importance to differentiate between paraneoplastic eosinophilia and primary, eosinophilic myeloproliferative disorders. In paraneoplastic conditions, the underlying disease requires rapid initiating of therapy to prevent further end-organ damage by eosinophilia.