# Case Report: Co-existence of BCR::PDGFRA gene fusion and PDGFRA variants in myeloid neoplasm with persistent leukocytosis, large splenomegaly, and eosinophilia

## TL;DR

A rare case of myeloid neoplasm with a BCR::PDGFRA gene fusion and PDGFRA mutations is reported, showing successful treatment with targeted therapy.

## Contribution

This is the first report of BCR::PDGFRA positive myeloid neoplasm coexisting with PDGFRA mutations and its response to targeted therapy.

## Key findings

- A patient with myeloid neoplasm had a t(4;22) translocation causing BCR::PDGFRA fusion and PDGFRA mutations.
- The patient showed persistent leukocytosis, splenomegaly, and eosinophilia, with successful treatment using imatinib.
- Genetic testing confirmed the BCR::PDGFRA fusion and PDGFRA mutations (c.1666G>A and c.1701A>G).

## Abstract

Persistent leukocytosis, massive splenomegaly, and eosinophilia are common manifestations in patients with myeloproliferative neoplasms (MPNs), particularly in those with chronic myeloid leukemia (CML). CML is characterized by the BCR::ABL fusion gene, typically associated with the t(9;22)(q34;q11) translocation. Herein, we report a case of myeloid neoplasm with a rare variant translocation, t(4;22)(q12;q11), involving the BCR::PDGFRA fusion gene and coexisting PDGFRA variants, accompanied by persistent leukocytosis, massive splenomegaly, and eosinophilia. Laboratory tests showed elevated white blood cell counts, with increased monocytes, neutrophils, and eosinophils. Bone marrow aspiration revealed a granulocytic-erythrocytic ratio of 189:1, marked granulocytic hyperplasia, and numerous immature granulocytes. Genetic testing confirmed an uncommon BCR::PDGFRA and coexisting PDGFRA mutations (c.1666G>A and c.1701A>G), confirming the diagnosis of myeloid neoplasm with BCR::PDGFRA rearrangement. Treatment with imatinib, a tyrosine kinase inhibitor, resulted in a continuous complete molecular response (CMR). To our knowledge, this is the first report to demonstrate the clinical and cytogenetic manifestations of BCR::PDGFRA positive myeloid neoplasm coexisting PDGFRA mutations. Furthermore, it emphasizes the effectiveness of targeted therapy and the significance of personalized management.