A 45-year-old woman presents with splenomegaly, eosinophilia, and WBC 80,000/μL with 15% myeloblasts. FISH reveals FIP1L1-PDGFRA fusion. Which statement about this condition and its management is MOST accurate?

• A This represents CML blast crisis and requires bone marrow transplantation as first-line therapy
• B This is hypereosinophilic syndrome and requires corticosteroids plus hydroxyurea; imatinib is contraindicated
• C This represents CMML with eosinophilia; azacitidine is the standard of care
• D This is a myeloid/lymphoid neoplasm with PDGFRA rearrangement; first-line treatment is imatinib, which achieves durable molecular remission ✓

Explanation

FIP1L1-PDGFRA fusion (resulting from cryptic 4q12 deletion) defines a WHO-recognized entity — myeloid/lymphoid neoplasm with PDGFRA rearrangement — presenting with eosinophilia, splenomegaly, and variable blast percentage. Imatinib (at low doses, 100 mg/day) is highly effective, achieving complete cytogenetic and molecular remission in virtually all patients. This is not CML (BCR-ABL1 negative) and not idiopathic hypereosinophilic syndrome. Distinguishing this entity from idiopathic HES is critical because imatinib is curative in PDGFRA-rearranged disease but ineffective in true HES.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.