{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T05:14:29Z","timestamp":1783401269575,"version":"3.54.6"},"reference-count":17,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"\n Background<\/jats:title>\n \n Philadelphia chromosome (Ph)-positive T-lymphoblastic leukemia (T-ALL) is exceptionally rare. Distinguishing\n de novo<\/jats:italic>\n Ph-positive T-ALL from T-lymphoid blast-phase chronic myeloid leukemia (BP-CML) can be highly challenging, yet this distinction has important therapeutic and prognostic implications. We report a pediatric patient initially diagnosed with\n de novo<\/jats:italic>\n Ph-positive T-ALL who subsequently developed CML following treatment discontinuation.\n <\/jats:p>\n <\/jats:sec>\n \n Case presentation<\/jats:title>\n \n A 14-year-old boy presented with fever, leukocytosis, and generalized lymphadenopathy. Bone marrow examination revealed 81% blasts, and flow cytometric immunophenotyping confirmed T-ALL (cytoplasmic CD3\n +<\/jats:sup>\n CD5\n +<\/jats:sup>\n CD7\n ++<\/jats:sup>\n ). Conventional cytogenetic analysis revealed a karyotype of 49,XY,\u22127,+8,t(9;22)(q34;q11.2),+15,+19,+mar[3], and real-time quantitative reverse-transcription polymerase chain reaction detected a b3a2\n BCR::ABL1<\/jats:italic>\n fusion transcript. A diagnosis of\n de novo<\/jats:italic>\n Ph-positive T-ALL was rendered, and the patient achieved complete remission following induction chemotherapy with VICP (vincristine, idarubicin, cyclophosphamide, prednisone) plus imatinib. The patient declined both allogeneic hematopoietic stem cell transplantation and escalation to a second-generation tyrosine kinase inhibitor (TKI). After self-discontinuing imatinib without medical advice for approximately 18 months, he developed CML.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusions<\/jats:title>\n \n This case highlights the diagnostic challenge of distinguishing\n de novo<\/jats:italic>\n Ph-positive T-ALL from T-lymphoid BP-CML at initial presentation, particularly in pediatric patients. Accurate classification is essential because it has important implications for therapeutic decision-making and long-term management in the TKI era. The subsequent development of CML following TKI discontinuation strongly supports that the initial presentation represented lymphoid BP-CML rather than\n de novo<\/jats:italic>\n Ph-positive T-ALL. This observation further underscores the importance of sustained TKI therapy and adherence in preventing disease recurrence and optimizing long-term clinical outcomes.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fonc.2026.1874606","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T04:21:44Z","timestamp":1783398104000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: Pediatric Philadelphia chromosome-positive T-lymphoblastic leukemia relapsing as chronic-phase CML after treatment discontinuation"],"prefix":"10.3389","volume":"16","author":[{"given":"Rongrong","family":"Dong","sequence":"first","affiliation":[{"name":"Department of Laboratory Medicine, Qingdao Women and Children\u2019s Hospital, Qingdao University","place":["Qingdao, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xinying","family":"Dai","sequence":"additional","affiliation":[{"name":"Department of Hematology, People\u2019s Hospital of Qianxinan Prefecture","place":["Xingyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuan","family":"Feng","sequence":"additional","affiliation":[{"name":"Department of Laboratory Medicine, People\u2019s Hospital of Qianxinan Prefecture","place":["Xingyi, Guizhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,7]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"44","DOI":"10.1186\/s13045-021-01055-9","article-title":"Third-line therapy for chronic myeloid leukemia: current status and future directions","volume":"14","author":"Cortes","year":"2021","journal-title":"J Hematol 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Philadelphia positive T-cell lymphoid leukemias-(De novo and blast phase CML)","volume":"92","author":"Jain","year":"2017","journal-title":"Am J Hematol"},{"key":"B13","doi-asserted-by":"publisher","DOI":"10.1159\/000445972","article-title":"Philadelphia chromosome-positive acute lymphoblastic leukemia is separated into two subgroups associated with survival by BCR-ABL fluorescence in situ hybridization of segmented cell nuclei: report from a single institution","volume":"136","author":"Kamoda","year":"2016","journal-title":"Acta Haematol"},{"key":"B14","first-page":"795","article-title":"Lineage involvement by BCR\/ABL in Ph+ lymphoblastic leukemias: chronic myelogenous leukemia presenting in lymphoid blast vs Ph+ acute lymphoblastic leukemia","volume":"10","author":"Anastasi","year":"1996","journal-title":"Leukemia"},{"key":"B15","doi-asserted-by":"publisher","DOI":"10.1002\/ajh.27210","article-title":"Recurrent lymphoid and myeloid relapses due to treatment cessations reveal natural 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