[Fluorescence in situ hybridization studies on a myeloid leukemia patient with ins(8;21)(q22;q22.1q22.3)].

Objective: To report a case of acute myeloid leukemia (AML) with the insertion (8;21)(q22;q22.1q22.3). A 33-year-old Chinese woman was referred to our hospital. Hematologic data showed WBC 42.7 x 10(9)/L with monocytosis (monocyte counts 7.296 x 10(9)/L). Bone marrow aspirate was hypercellular with 4.5% monoblasts and 7.5% promonocytes. At first she was diagnosed with chronic myelomonocytic leukemia (CMML) according to the FAB criteria. Initially the patient received supportive care only, but her general condition rapidly became worse three months later. The monoblasts and promonocytes in the bone marrow rose to 20.5%. After two cycles of combined chemotherapy she obtained complete remission.

Methods: Chromosome specimens were prepared by short-term culture of bone marrow cells. Karyotype analysis was carried out by R-banding technique. Three fluorescence in situ hybridization (FISH) analyses were performed using AML1-ETO dual color, dual fusion probe, whole chromosome painting 8 and 21 probes, and cen-8 and Tel 21qter probes, respectively. Reverse transcription polymerase chain reaction (RT-PCR) assay for detecting the AML1-ETO fusion transcript was also performed.

Results: Conventional cytogenetic analysis showed a karyotype of 46,XX,ins(8;21) (q22;q22.1q22.3)[7]/46,XX[3]. FISH tests confirmed the insertion. RT-PCR analysis detected the AML1-ETO fusion transcript.

Conclusion: We consider that this patient should be rediagnosed as acute myeloid leukemia according to the criteria proposed by World Health Organization (WHO) and that FISH and RT-PCR play an important role in verification of the ins(8;21).