Ph+ T-cell ALL or CML Presenting in T-cell Blast Phase? A Case Report and Diagnostic Challenge
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Description
Philadelphia (Ph) chromosome, the defining feature of chronic myeloid leukemia (CML), is characterized by BCR:ABL1 gene translocation resulting in two oncogenic proteins, p190 and p210 (1). CML accounts for 3% of pediatric leukemias with 1-2% of cases presenting in blast phase (2, 3). The p210 fusion transcript is classically associated with chronic phase CML(1). The p190 transcript is commonly found in Ph+ acute lymphoblastic leukemia but is seen in 1-2% of CML(1). This can elicit diagnostic challenges in patients presenting with Ph+ T-cell ALL, an exceptionally rare diagnosis with only 30 cases reported in the literature(4). This report describe a case of Ph+ T-cell ALL with concern for CML in blast phase and highlight minimal residual disease (MRD) discordance between flow cytometry and BCR:ABL real time PCR (RT-PCR).
A 16-year-old male with 6 weeks of fatigue, URI symptoms and cervical lymphadenopathy, presented with massive splenomegaly, hyperleukocytosis (434K/uL), anemia (hgb 4.9 g/dL), thrombocytopenia (42 K/uL), and 97% peripheral blasts. Peripheral blood flow cytometry was consistent with T-ALL. FISH testing revealed BCR:ABL/t(9;22) gene fusion in 96.5% of nuclei and deletion of TCRB (7q34) region in 22% of cells. BCR:ABL RT-PCR demonstrated only a minor breakpoint (p190) fusion. He started treatment on AALL 1631 with imatinib for Ph+ T-cell ALL. Due to persistent disease at end of induction 1B with a MRD by flow cytometry of 2.3% and 8.5% by BCR:ABL RT-PCR, he transitioned to T-cell targeted treatment, NECTAR therapy with dasatinib. Following cycle 1 of this therapy, he had persistent MRD discordance, 0.072% by flow cytometry and 0.46% by BCR:ABL RT-PCR. Cell sorting demonstrated BCR:ABL positivity in both CD3 and CD15 cells, suggesting possible CML in T-cell blast phase.
Ph+ leukemias are uncommon in the pediatric population and association with T-ALL at any age is exceedingly rare. This case report highlights the diagnostic uncertainty in differentiating CML in blast phase from Ph+ T-ALL.
Publication Date
5-8-2026
Disciplines
Pediatrics
Recommended Citation
Forschner C, Quigg T, Close A. Ph+ T-cell ALL or CML presenting in T-cell blast phase? A case report and diagnostic challenge. Presented at: Research Day Corewell Health West; 2026 May 8; Grand Rapids, MI.
Comments
2026 Research Day Corewell Health West, Grand Rapids, MI, May 8, 2026. Abstract 1915