OBJECTIVETo explore the characteristics of morphology, immunophenotype and cytogenetics (MIC) of myeloid surface antigen-expressing acute lymphoblastic leukemia (My+ ALL).

METHODSOne hundred and twenty untreated acute lymphoblastic leukemia (ALL) patients were diagnosed by standard bone marrow smear morphologic analysis and peroxidase staining. Flow cytometry and myeloid monoclonal antibodies (McAb) were used to analyze immunophenotype. Chromosome karyotypes were analyzed by R-band technique.

RESULTSOf 120 cases, 66 (55%) were My+ ALL, including 50 cases of My+ B-ALL (56.8% of B-ALL ), 14 cases of My T-ALL (50% of T-ALL) and 2 cases of My+ T and B-ALL (50% of T and BALL). Of 66 My+ ALL, 10 cases (15.1%) were misdiagnosed as acute non-lymphoblastic leukemia (ANLL), the other 54 My- ALL cases were correctly diagnosed. The inconsistent rate between morphological and immunophenotype classifications was higher in My+ ALL than in My- ALL , and there were more atypical morphology cases in My+ ALL than in My- ALL (P < 0.01). In My+ ALL cases 95.5% expressed CD13, 81.8% CD33, 77.3% CD13 and CD33 simultaneously, and 1.5% CD117, but none CD14, CD15 and MPO. CD34 expression rate in My+ ALL cases was significantly higher than that in My- ALL (P < 0.01 ). Cytogenetic abnormalities rates in My+ ALL and My- ALL were 72.3% and 66.7% (P > 0.05) respectively. t(9;22) and t(9;22) plus other cytogenetic abnormalities were detected more frequently in My+ LL cases than in My- B-ALL (P < 0. 01), and not in My+ T-ALL and My- T-ALL cases. The complete remission (CR) rates was 83.9% in My+ ALL and 79% in My- ALL(P > 0.05).

CONCLUSIONMy+ ALL had a specific characteristics in morphology, immunophenotype and cytogenetics. Some cases have a myeloid morphologic appearance and might be misdiagnosed as acute myeloid leukemia (AML). My+ ALL have a higher CD34 expression rate than My- ALL. t(9;22) abnormality was more frequently observed in My B-ALL than in My- B-ALL. There was no significant difference in CR rate between My+ ALL and My- ALL.