FIP1L1 and Chronic Eosinophilic Leukemia, Not Otherwise Specified: The severity of the prognosis depends on the location of involvement in the heart.7 The prognostic outcome in Loeffler endocarditis is closely tied to the successful management and control of eosinophilia.12 The introduction of targeted therapies, notably tyrosine kinase inhibitors like imatinib, has significantly altered the treatment paradigm for CEL with FIP1L1-PDGFRA rearrangement.