Acute myeloid leukemia with t(4;12)(q12;p13): report of 2 cases

which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Acute myeloid leukemia with t(4;12)(q12;p13): report of 2 cases TO THE EDITOR: Acute myeloid leukemia (AML) with t(4;12) is rare, but its unique morphologic and clinical characteristics have been described in several reports [1-8]. Most cases show CD7 expression, low or absent myeloperoxidase activity, basophilia, unique blast morphology, dysplastic features , and poor prognosis [1-8]. Harada et al. reported that the incidence among adults is 0.6% [1, 2]. ETV6, at 12p13, and CHIC2, at 4q12, have been reported to be involved in AML [5, 8]. Here, we report 2 cases of AML with t(4;12) (q12;p13) which showed the common characteristics of AML with t(4;12). A 53-year-old male underwent a bone marrow (BM) examination following detection of circulating blasts. His initial complete blood count was hemoglobin 12.4 g/dL, white blood cell count 44.57×10 9 /L (differential count: myeloblasts 99%, atypical lymphocytes 1%), and platelets 120×10 9 /L. BM aspirates revealed 84% myeloblasts and dysmegakar-yopoiesis, such as multinucleation and nuclear hypoloba-tion. Myeloblasts were large and showed a fine and blocky chromatin pattern (Fig. 1A). Flow cytometric analysis revealed CD34, CD13, CD33, CD117, HLA-DR, and CD7 expression but was negative for myeloperoxidase. The kar-yotype was 46,XY,t(4;12)(q12;p13),del(5)(q22q35) in 20 metaphases (Fig. 1B). FISH analysis using a Vysis LSI 4q12 tricolor probe (Abbott Molecular, Des Plaines, IL, USA) showed 1 tri-color fusion, 1 orange/green fusion, and 1 aqua signal in 89% of cells. These results confirmed that the break point is at 4q12 and suggested that PDGFRA or CHIC2 may be involved (Fig. 1C). FISH analysis using a Vysis LSI ETV6/RUNX1 ES dual-color translocation probe (Abbott Molecular) showed 3 green signals in metaphase cells, suggesting an ETV6 gene rearrangement (Fig. 1D). The patient did not achieve complete remission after standard induction chemotherapy (idarubicin and cytarabin). Post-induction, 24% of all marrow nucleated cells were myeloblasts and the karyotype was 46,XY,t(4;12)(q12;p13), del(5)(q22q35)[2]/46,XY[2]. After reinduction using high-dose cytarabin and daunorubicin, blasts were not increased and a normal karyotype was detected (46,XY[17]). The patient underwent allogenic hematopoietic stem cell trans-plantation from an unrelated matched donor and has been in complete remission for 52 months. A 74-year-old male with a history of acute myocardial infarction presented at a local clinic complaining of melena. He was referred to the tertiary hospital following detection of myeloblasts on a peripheral blood smear. His initial complete …