CML-216 Hypereosinophilia Syndrome With FIP1L1-PDGFRA Transcript Revealed by Cardiac Involvement.

INTRODUCTION: Hypereosinophilic syndrome (HES) is defined by eosinophilia greater than 1.5 G/L persisting for more than 6 months and associated with specific visceral damage (cardiac, neurological, pulmonary, etc.), after elimination of "classic" causes of hypereosinophilia. A myeloproliferative variant of HES is associated with the fusion of the FIP1L1 and PGDFRα genes, resulting in the constitutive activation of a receptor with tyrosine kinase activity. We report a case revealed unexpectedly by cardiac involvement (a mitral valve disease).

OBSERVATION: A 25-year-old man with no particular history, allergies, or cardiovascular risk factors was hospitalized in the cardiology department for sudden-onset precordialgia associated with low-grade fever. The clinical examination: a general state preserved asthenic, nocturnal fever with precordialgia, and stage IV splenomegaly. ECG: unremarkable; heart echo: a thickened mitral valve with moderate mitral leakage, with rupture of the chords giving moderate grade II mitral insufficiency. Three blood cultures taken at the time of the fever peak came back sterile. FNS: anemia reduced to 9 g/dL normochromic normocytic aregenerative, activated thrombocytopenia to 124 G/L, hyperleukocytosis to 65,000/mm3, including 81% of eosinophilic polynuclear cells (52,650 elements/mm3 ) without myelemia. Myelogram: a very rich smear with eosinophilic hyperplasia at all stages of maturation. A thoraco-abdominopelvic CT scan showed heterogeneous splenomegaly with parenchymal involvement in centro-lobular ground glass, predominantly apical with areas of geographical somatic vertebral bone condensation staged in the dorsolumbar and pelvis. A corticosteroid test was negative, and a molecular cytogenetic study revealed the FIP1L1-PDGFRA fusion transcript in 88% of cells with a rearrangement of the locus at 4q12. The patient was put on imatinib 100 mg/day for 15 days then 200 mg/day with prophylactic anticoagulation. The evolution was favorable with a normalization of the FNS after 20 days. After 6 months of treatment, a FISH was requested, having objectified the complete disappearance of the cytogenetic anomaly.

CONCLUSIONS: Chronic eosinophilic leukemia with FIP1L1-PDGFRA can be serious and fatal in the event of diagnostic delay and the nature of the affected organ. Patients with clinical manifestations consistent with HES should be investigated for evidence of clonality of hematopoiesis and a search for a T-lymphocyte population for treatment decisions.