OBJECTIVETo investigate the clinical and biological characteristics of childhood acute myeloid leukemia(AML)with 8;21 translocation.

METHODSA retrospective analysis including clinical information, cell morphology, chromosome, immunophenotype and molecular biology was performed on 41 cases of childhood t(8;21)AML. The control group included 19 cases of AML without t(8;21) translocation detected during the same period.

RESULTSThe 41 cases of t(8;21)AML accounted for 68.3% of 60 continuous childhood AML patients. Among them, classical t(8;21) translocation was seen in 29 cases; variant t(8;21) translocation, simple 8q-, near-tetraploidy characterized by the duplication of t(8;21) translocation each came into view in 2 cases; and cryptic t(8;21) translocation was seen in 6 cases. Thirty seven cases (80.4%) belonged to M2 subtype of AML. Most of them had the morphological changes such as the leukemia cells' indent nucleus with a light stain region of perinucleus, basophilic cytoplasm, differentiation with maturation, megaloblastoid changes and nuclear-cytoplasm imbalance; the high expression of CD13 antigen; and the AML1/ETO fusion transcript in 23 cases examined by reverse transcription-polymerase chain reaction (RT-PCR) assay, including 6 cases with normal karyotype. The difference in complete remission rate between t(8;21) positive patients group and t(8;21) negative patients group was not significant in statistics (82.4% vs 75%, P>0.05). However the difference in recurring rate of the leukemia was statistically significant (10.7% vs 41.7%, P<0.05).

CONCLUSIONt(8;21)AML is the most frequent type of childhood AML. It is predominantly associated with M2 subtype of AML and has unique morphological, immunological prognostic features .