Hindawi Publishing Corporation Case Reports in Hematology Volume 2011, Article ID 670603, 3 pages doi:10.1155/2011/670603 Case Report CML Developing Three Years after Therapy Completion in a Child with Ph(−) Pre-B-ALL S. Hosseini,1, 2 G. H. Bahoush,1, 2 P. Vousogh,1, 2 Sh. Ansari,1, 2 Kh. Arjmandi,2 and M. Sabzechian2 1 Hematology Laboratory, Hematology Oncology Ward, Ali Asghar Children Hospital, Tehran, Iran 2 Tehran University of Medical Science, Tehran, Iran Correspondence should be addressed to S. Hosseini, hosseini.soudabeh@gmail.com and G. H. Bahoush, bahoush04@urocord.org Received 29 June 2011; Accepted 14 July 2011 Academic Editors: S. Aref and M.-C. Kyrtsonis Copyright © 2011 S. Hosseini et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We report a girl with a history of Ph(−) pre-B-ALL and three years of disease-free survival admitting to our hospital for regular end of treatment checkup with an increased white blood cell count which in follow-up studies and molecular detection of BCR- ABL (p210) fusions gene had been diagnosed as a Ph(+) typical CML. The upcoming question in this case scenario is whether developed CML is a secondary leukemia due to previous ALL chemotherapy or just a relapse case of primary leukemia. 1. Introduction Chronic myeloid leukemia (CML) is a Clonal Myeloprolif- erative expansion of transformed, primitive hematopoietic progenitor cells [1]. The Philadelphia (Ph) chromosome is the hallmark of CML and the most frequent cytogenetic abnormality known in human leukemia’s and can be detected in more than 95% of patients with chronic myeloid leukemia (CML) [2], in a range of 20% to 40% of adults with acute lymphoblastic leukemia (ALL), 2% to 5% of children with ALL, and in rare cases of acute myelogenous leukemia [3–5]. The Ph chromosome is a shortened chromosome 22 resulting from a reciprocal translocation, t (9; 22)-(q34; q11), between the long arms of chromosomes 9 and 22 [6]. The cytogenetic lesion in Ph(+) CML and Ph(+) ALL has been shown to diﬀer at the molecular level. In CML, the translocation is almost always associated with a breakpoint on Chromosome 22 that generally is known as the major breakpoint cluster region (M-BCR). This gives rise to a (P210) fusion protein in contrast to most cases of ALL which the break point is in the minor cluster region (m-BCR) and gives rise to (P190) fusion protein [7]. In pediatric Ph(+) ALL, nearly 90% of cases have the (p190) variant, but in adult ALL approximately 25% to 50% of cases have (p210) variant [8]. This speciﬁc chromosome translocation t (9; 22) (q34; q11), molecularly, generates the BCR-ABL fusion gene encoding a BCR-ABL protein with constitutively enhanced tyrosine kinase activity. The activated BCR-ABL tyrosine kinase has been shown to be a key factor in leukemic transformation in patients as in animal model or in vitro reviewed in Faderl et al. [9]. 2. Case Report A 12-year-old girl with a history of fever, fatigue, and pancytopenia had been referred to Ali Asghar’s Children Hospital from a clinic in Varamin (Tehran’s suburb) on September 2003. She had been admitted in infectious disease ward for workup of fever, pancytopenia, hepatosplenomegaly, and inguinal and cervical lymphadenopathy. The results of ﬁrst CBC taken in Ali Asghar’s laboratory were as follows. WBC: 1∗103/µL, RBC: 3.33 mil/uL, Hemoglobin: 8.7 g/dL, Platelet count: 54∗103/µL, Hematocrit: 20.1%, M.C.V: 78.9 fL, M.C.H: 26.3 pg, M.C.H.C: 33.6 g/dL. She had been taking antibiotic, and the bacterial culture results were all negative at the time of admission. Upon con- sultation with hematology oncology ward, a Bone Marrow aspiration (BM) had been scheduled, and on microscopic evaluation a hypercellular BM with complete replacement