Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 50 12 2012 12 15 827 830 EN Prasanna Kumari Department of Pathology, Cytogenetic Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Bidadi LingappaKavitha Department of Pathology, Cytogenetic Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Chintaparthi Obula Reddy Department of Pathology, Cytogenetic Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Maiana Mangalagowri Department of Pathology, Cytogenetic Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Danem Satienariana Madhumathi Department of Pathology, Hematology Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Madaiah Mahadeva Prasad Department of Pathology, Cytogenetic Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Hanumanthappa Vijay Raghavendra Department of Pathology, Hematology Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. Chennagiri Shinivasa Murthy Premalata Department of Pathology, Kidwai Memorial Institute of Oncology, Bangalore, India. Kuntejowdahalli Channaviriappa Lakshmaiah Department of Medical Oncology, Kidwai Memorial Institute of Oncology, Bangalore, 560029, India. Seyed Hashem Mir Mazloumi Department of Pathology, Cytogenetic Unit, Kidwai Memorial Institute of Oncology, Bangalore, India. 2015 09 28 Acute myeloid leukemia (AML) with t(8;21)(q22;q22) generating the AML1/ETO fusion gene on 8q22 is a distinct type of AML t(8;21) category (WHO)/AML-M2 (FAB), generally associated with a favourable prognosis. Variant additional chromosomal abnormalities are frequently reported. We report three adult cases of this category with unusual karyotype. Bone marrow cytogenetics of case no. 1: 45,X,-Y, t(8;21)(q13;q22) with a novel breakpoint of chromosome 8 at (q13). Case no. 2: 46,X,t(X;2)(q22;q37),t(3;7)(q21;q36),t(5;14)(p15;q11),del(8)(q22) a complex rearrangement without the involvement of chromosome 21. Case no. 3: 49,XX,+5, t(8;21)(q22;q22), +16, +der(21)t(8;21)(q22;q22) with additional der(21). Endometrial in this case which was positive for myeloperoxidase (MPO) and CD117 conforming the AML infiltration. All are morphologically AML with t(8;21). Relevant literature in cytogenetic of AML-M2 is reviewed. The molecular mechanism involved in unusual rearrangements and clinical significance of them are subjected for further studies. https://acta.tums.ac.ir/index.php/acta/article/view/4002 https://acta.tums.ac.ir/index.php/acta/article/download/4002/3977