A Fatal Case of Chronic Eosinophilic Leukemia Not Otherwise Specified (CEL-NOS) in a 19-Year-Old Male with Acute Transformation into Blast Crisis

Abstract

Chronic eosinophilic leukemia (CEL) is a rare disorder that is characterized by hypereosinophilia with increased number of blood or marrow blasts (>5% and <20%). CEL is distinguished from hypereosinophilic syndrome (HES) by the presence of eosinophilic clonality. Chronic eosinophilic leukemia not otherwise specified (CEL-NOS) diagnosis is made when no fusion genes are detected by most modern molecular testing, particularly the most common fusion gene FIP1L-1/PDGFRA (Factor Interacting with PAP like-1/Platelet-Derived Growth Factor Receptor Alpha). This disease is very rare, and its description in the literature is not well characterized. We report a fetal case of severe CEL-NOS in a 19-year-old male who presented with a plethora of clinical features consists of constitutional symptoms, pancytopenia, intravascular thrombosis, acute stroke and endomyocardial infiltrates. The course of his disease was aggressive and resistant to conventional treatment. After a short period of improvement, an acute transformation into blast crisis (BC) had occurred. The diagnosis was confirmed by morphology and immunophenotyping of bone marrow biopsy. The patient eventually died of heart failure and sepsis. To our knowledge this is the first case report of fatal CEL-NOS transforming into severe blast crisis.