Chronic myelogenous leukemia at blast crisis with a T-cell phenotype (T-ALL CML-BC) at diagnosis, without any prior history of CML is extremely rare. After the introduction of tyrosine kinase inhibitors (TKIs), CML patients have a median survival comparable to general population and accelerated/blast crisis are rarely encountered. Most CML patients (80%) transform into acute myeloid leukemia and the rest into B-ALL. Anecdotal cases of Ph+ T-ALL, either de novo or in the context of CML-BC have been reported. Left shift in the blood, the presence of splenomegaly/extramedullary infiltration and the occurrence of BCR::ABL1 rearrangement in both the blastic population, as well as in the myeloid cell compartment are key points in differentiating de novo Ph+ T-ALL from T-ALL CML-BC. The latter is a rare entity, characterized by extramedullary disease, p210 transcript and clonal evolution. Lack of preceding CML does not rule out the diagnosis of T-ALL CML-BC. Prompt TKI treatment with ALL-directed therapy followed by allogeneic stem cell transplantation may offer long-term survival in this otherwise poor prognosis entity. In this paper, we describe a patient with T-ALL CML-BC at presentation, still alive 51 months after diagnosis and we offer a review of the literature on this rare subject. All clinical and laboratory features are provided in order to distinguish de novo Ph+ T-ALL from T-ALL CML-BC, underscoring the prognostic and therapeutic significance of such a differentiation.

1.
Hochhaus A, Baccarani M, Silver RT, Schiffer C, Apperley JF, Cervantes F, et al. European Leukemia Net 2020 recommendations for treating chronic myeloid leukemia. Leukemia. 2020;34(4):966–84.
2.
Jain P, Kantarjian H, Jabbour E, Kanagal-Shamanna R, Patel K, Pierce S, et al. Clinical characteristics of Philadelphia positive T-cell lymphoid leukemias-(De novo and blast phase CML). Am J Hematol. 2017;92(1):E3–4.
3.
Bower H, Björkholm M, Dickman PW, Höglund M, Lambert PC, Andersson T. Life expectancy of patients with chronic myeloid leukemia approaches the life expectancy of the general population. J Clin Oncol. 2016;34(24):2851–7.
4.
Hochhaus A, Larson R, Guilhot F, Radich JP, Branford S, Hughes TP, et al. Long-term outcomes of imatinib treatment for chronic myeloid leukemia. N Engl J Med. 2017;376(10):917–27.
5.
Kantarjian H, Hughes T, Larson R, Kim DW, Issaragrisil S, le Coutre P, et al. Long-term outcomes with frontline nilotinib versus imatinib in newly diagnosed chronic myeloid leukemia in chronic phase: ENESTnd 10-year analysis. Leukemia. 2021;35(2):440–53.
6.
Raanani P, Trakhtenbrot L, Rechavi G, Rosenthal E, Avigdor A, Brok-Simoni F, et al. Philadelphia-chromosome-positive T-lymphoblastic leukemia: acute leukemia or chronic myelogenous leukemia blastic crisis. Acta Haematol. 2005;113(3):181–9.
7.
Dorfman DM, Longtine JA, Fox EA, Weinberg DS, Pinkus GS. T–cell blast crisis in chronic myelogenous leukemia. Immunophenotypic and molecular biologic findings. Am J Clin Pathol. 1997;107(2):168–76.
8.
Lima M, Coutinho J, Bernardo L, dos Anjos Teixeira M, Casais C, Canelhas A, et al. Philadelphia-positive T-cell acute lymphoblastic leukemia with polymyositis, migratory polyarthritis and hypercalcemia following a chronic myeloid leukemia. Ann Hematol. 2002;81(3):174–7.
9.
Kim A, Goldstein S, Luger S, Van Deerlin V, Bagg A. Sudden Extramedullary T-lymphoblastic blast crisis in chronic myelogenous leukemia: a nonrandom event associated with imatinib?Am J Clin Pathol. 2008;129(4):639–48.
10.
Wei J, Huang M, Wang Y, Zhou J. Sudden extramedullary blast crisis of chronic myeloid leukemia manifesting as T-cell lymphoblastic lymphoma. Onkologie. 2013;36(3):119–22.
11.
Xu J, Li S. Unusual T-lymphoblastic blast phase of chronic myelogenous leukemia. Case Rep Hematol. 2014;2014:304359–5.
12.
Padhi P, Topalovski M, El Behery R, Cantu E, Medavarapu R. A rare case of chronic myelogenous leukemia presenting as T-cell lymphoblastic crisis. Case Rep Oncol Med. 2018;2018:1–4.
13.
Xia T, Yang Y, Li G, Chang J, Li J, Ren F, et al. T- cell blast crisis of chronic myelogenous leukemia presented with coexisting p210 and p190 BCR-ABL transcripts and t(10;11)(q11;p15). J Clin Lab Anal. 2020;34(6):e23241.
14.
Soverini S, Martinelli G, Rosti G, Bassi S, Amabile M, Poerio A, et al. ABL mutations in late chronic phase chronic myeloid leukemia patients with up-front cytogenetic resistance to imatinib are associated with a greater likelihood of progression to blast crisis and shorter survival: a study by the GIMEMA Working Party on Chronic Myeloid Leukemia. J Clin Oncol. 2005;23(18):4100–9.
15.
Grossmann V, Kohlmann A, Zenger M, Schindela S, Eder C, Weissmann S, et al. A deep-sequencing study of chronic myeloid leukemia patients in blast crisis (BC-CML) detects mutations in 76.9% of cases. Leukemia. 2011;25(3):557–60.
16.
Berger R. Differences between blastic chronic myeloid leukemia and Ph –positive acute leukemia. Leuk Lymphoma. 1993;11(Suppl 1):235–7.
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