Korean J Lab Med.  2006 Oct;26(5):338-342. 10.3343/kjlm.2006.26.5.338.

A Case of Acute Myeloid Leukemia with Masked t(8;21)

  • 1Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea. yonggoo@catholic.ac.kr
  • 2Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.


We report a case that revealed the characteristics of acute myeloblastic leukemia with maturation (AML-M2) on the morphology of the bone marrow biopsy and 45,X,-Y in conventional cytogenetic study, but was confirmed to have a typical AML1/ETO translocation by molecular studies using reverse transcriptase polymerase chain reaction and fluorescence in situ hybridization. Insertion of ETO gene on chromosome 8 into chromosome 21 in this patient resulted in the development of the chimeric gene, AML1/ETO, on the long arm of chromosome 21. Our final report on the patient's karyotype: 45,X,-Y.ish ins(21;8)(q22;q22q22)(AML1 +,ETO +;ETO +,AML1-). In case typical morphologic features compatible with recurrent cytogenetic abnormalities are shown, molecular studies in addition to conventional cytogenetic study might be required to confirm the diagnosis.


Masked t(8:21); AML-M2; t(8;21); Fluorescence in situ hybridization

MeSH Terms

Bone Marrow
Chromosome Aberrations
Chromosomes, Human, Pair 21
Chromosomes, Human, Pair 8
In Situ Hybridization
Leukemia, Myeloid, Acute*
Reverse Transcriptase Polymerase Chain Reaction


  • Fig. 1. Leukemic cells in (A) peripheral blood smear (×400) and in (B) bone marrow aspirate smear (×1,000, Wight Giemsa stain). They reveal large sized, round to oval shaped nuclei with or without nucleoli and moderate to abundant cytoplasm with azurophilic granules. Some leukemic cells show large azurophilic granules (abnormal fusion), and Auer rods are occasionally found. They also show cytoplasmic staining abnormalities, including homogenous pink colored cytoplasm.

  • Fig. 2. The G-banded karyotype of the patient's bone marrow cells showing 45,X,-Y.

  • Fig. 3. FISH analysis with LSI AML1 (orange)/ETO (green) dual color, dual fusion probe showed chromosome 8 (thick and thin orange arrows), one normal chromosome 21 (green arrow), and one fusion signal (white arrow) on chromosome 21, confirming the insertion of a fragment of ETO gene on chromosome 8 into the long arm of chromosome 21.

  • Fig. 4. RT-PCR for the AML1/ETO fusion transcript. SM, size marker; lane 3, patient. The black arrow indicates the AML1/ETO fusion transcript (393 bp) in the patient. The hollow arrow is the internal control band.

Cited by  3 articles

A Case of Masked t(8;21) in Acute Myeloid Leukemia with Cytogenetic Abnormality of 45,X,-Y,t(8;17)(q22;p13)
Hyeok Shim, Young-Jin Lee
Lab Med Online. 2011;1(3):168-171.    doi: 10.3343/lmo.2011.1.3.8.

Two Concurrent Chromosomal Aberrations Involving Three-way t(3;21;8)(p21;q22;q22) and Two-way t(2;11)(q31;p15) Translocations in a Case of de novo Acute Myeloid Leukemia
Gyun Cheol Park, Eun Hae Cho, Sung Ho Kang, Sook Jin Jang, Dae Soo Moon, Geon Park
Lab Med Online. 2016;6(4):246-249.    doi: 10.3343/lmo.2016.6.4.246.

Near-tetraploidy Acute Myeloid Leukemia with RUNX1-RUNX1T1 Rearrangement Due to Cryptic t(8;21)
Mijeong Im, Jin Kyung Lee, Dong Young Lee, Young Joon Hong, Seok-Il Hong, Hye Jin Kang, Yoon Hwan Chang
Korean J Lab Med. 2009;29(6):510-514.    doi: 10.3343/kjlm.2009.29.6.510.



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