Successful Treatment of Clonal Eosinophilia with FIP1L1-PDGFRA Rearrangement with Low Dose IMATINIB – A Case Report

Clonal eosinophilia with FIP1L1-PDGFRA rearrangement is a rare disorder which is almost exclusively seen in males. Targeted therapy with Imatinib has led to successful achievement of molecular remission of this disorder but no evidence exists for continuous or maintenance therapy or treatment free remission yet. This is a case of clonal eosinophilia with FIP1L1-PDGFRA rearrangement in a young man, who presented with very high eosinophil and neutrophil counts, moderate thrombocytopenia, hepatosplenomegaly and skin and lung involvement. Imatinib at 100mg daily was started after initial treatment with cytoreductive therapy and steroids. He responded well to low dose Imatinib with complete absence of symptoms and normalization of counts within 3 months and disappearance of molecular evidence of the disease following 2 years of therapy. Imatinib was then tailed off and he remains asymptomatic on a weekly dose of 100mg Imatinib. Workup towards a diagnosis of eosinophilia has been made easy with the new classification and inclusion of molecular evaluation. The high eosinophil count, presence of organomegaly and thrombocytopenia favoured a clonal aetiology .Low dose Imatinib gives excellent clinical, haematological and molecular remission and can be safely reduced thereafter to weekly maintenance.