Acute Erythroid Leukemia (AEL): A Clinical, Morphological, Cytogenetic and Follow-Up Study of 69 Patients.

AEL is a uncommon type of acute leukemia. The subjects in this retrospective study were 69 patients diagnosed as having AEL to assess the incidence of different subtypes, detect prognostic factors, and compare there profile with others AML. 63 patients (82,5%) were diagnosed of erythroleukemia (EL) and 7 (17,5%) were pure erythroid leukemia according to WHO classification. 63,6% of EL presented erythroid maturation (immature/mature erythroid ratio <25%), and 36,4% >25%. Three of seven pure erythroid leukemia showed immature erythroid precursors identified by ultrastructural methods, and four had erythroid cells at all maturation stage. 49 (71%) were de novo AEL, only 3 pure erythroid leukemia, 9 (13%) were therapy related, in nine (13%) was preceded by a MDS, and 2 suffer a BC-CML, all of this later, pure erythroid leukemia. The three cases of pure erythroid proliferations with only immature precursors were two Down’s syndrome, both 2 years old, and one BC-CML. The chromosomal abnormalities were classified by SWOG and MRC. BC-CML were excluded from survival analyses. A p value <0.01 was considered significant. There were 38 males and 31 females. The median age was 62 years. The medians hemoglobin 80 g/l; white cell 3,8x10⁹/L; absolute neutrophil 1,0x10⁹/L and platelet 36,0x10⁹/L. Multilineage dysplasia were present in 74,5% (41/55). The overall incidence of chromosomal abnormalities was 79,7%(55/69). 35(50,7%) patients had complex karyotype, 26/49(53,1%) in de novo acute erythroid leukemia. Single abnormalities include 4 monosomy 7, 2 del(5q), two +8, two + 21. 39/64 patients (60,9%) received intensive chemotherapy (9 were consolidated with SCT) and 19/39 (48,7%) achieved CR. Remission rate was 83,3% for normal karyotype and 85,7% and 62,5% for intermediate cytogenetic groups according SWOG (p=0,003) and MCR(p=0,037). The median OS was 4 months with a projected actuarial DFS at 12 months 32,5%. Patients under 40 years (p=0,0001) with normal karyotype (p=0.0003) or intermediate SWOG (p=0.0002) or MRC (p=0.0019) citogenetic groups, who received intensive chemotherapy (p<0.0001) had a longer OS, and younger patients (p=0.0056) with normal karyotype (p=0.0038), or intermediate SWOG (p=0.0006) or MRC (p=0.039) citogenetic groups, consolidated with SCT (p=0.0023) showed the longest DFS. Multivariate analysis showed that only karyotype, is a powerful prognostic indicator both for OS and DFS, besides treatment for OS and age for DFS. The higher risk of relapse is for ≥65 years old patients (OR=2,84) with unknown (OR=7,86) or unfavourable (OR=4,29) SWOG groups and the higher risk of death is for unfavourable (OR=4,33) SWOG groups and those treat with supportive care (OR =3,31). When AEL were compared with a consecutive series of 339 de novo AML, 109 of them ≥ 65 years, and 68 therapy related AML, EL excluded, these series are similar for age and sex but AEL present more frequent multilineage dysplasia (p<0,001), and SWOG or MRC unfavourable citogenetic groups (p<0,001), beside the low remission rate, high risk of relapse and death, was similar at elderly patients AML and therapy related AML.