Erythroleukemia shares biological features and outcome with myelodysplastic syndromes with excess blasts: a rationale for its inclusion into future classifications of myelodysplastic syndromes

A reevaluation of erythroid predominance in Acute Myeloid Leukemia using the updated WHO 2016 Criteria

The 2016 WHO update changed the diagnostic criteria for myeloid neoplasms with erythroid predominance, limiting the diagnosis of acute myeloid leukemia to cases with ≥20% blasts in the bone marrow or peripheral blood. Although acute myeloid leukemia with ≥50% erythroid cells has historically been presumed to represent acute myeloid leukemia with myelodysplasia-related changes, this hypothesis has never been systematically examined. We sought to investigate the clinicopathologic, cytogenetic, and molecular features of acute myeloid leukemia with erythroid predominance to subclassify cases as defined by the 2016 WHO. We retrospectively identified patients with ≥50% erythroid precursors and either ≥20% bone marrow blasts or ≥20% peripheral blood blasts at the time of initial diagnosis at seven major academic centers. Laboratory and clinical data were obtained. Patients were then reclassified according to 2016 WHO guidelines. A matched control group was also obtained. We identified 146 patients with acute myeloid leukemia with erythroid predominance (62% M, average age: 62 y, range: 5-93 y). Of these, 91 were acute myeloid leukemia with myelodysplasia-related changes, 20 (14%) were therapy-related myeloid neoplasm, 23 (16%) acute myeloid leukemia, not otherwise specified, and ten acute myeloid leukemia with recurrent cytogenetic/molecular abnormalities. The bone marrow blast count ranged from 9-41%. There was no difference in survival for patients with erythroid predominance compared to patients with acute myeloid leukemia without erythroid proliferations. In a multivariable analysis, cytogenetic risk was the only significant predictor of survival. We find a significantly lower rate of FLT3 and RAS pathway alterations in acute myeloid leukemia with erythroid predominance compared to controls. Our study is one of the first to apply the 2016 WHO guidelines for classification of acute myeloid leukemia. We find acute myeloid leukemia with erythroid predominance is a heterogeneous group and that erythroid richness has no impact on overall survival.

Re-evaluation of acute erythroid leukemia according to the 2016 WHO classification

In the recent update of WHO classification, the definition of myeloid neoplasms with erythroid predominance has been modified shifting the main criteria for calculating blast percentage from non-erythroid cells (NEC) to all nucleated marrow cells (ANC). Thus, the cases previously classified as erythroid/myeloid subtype of acute erythroid leukemia (AEL) based on the 2008 WHO will now be categorized either as myelodysplastic syndrome with excess blasts (MDS-EB) or acute myeloid leukemia, not otherwise specified (AML-NOS). However, the clinical significance of this new classification has not been demonstrated. Thus, we reviewed a leukemia database and reclassified 38 cases previously diagnosed as AEL, erythroid/myeloid subtype, with the consideration of 2016 revision criteria. Twenty seven (71%) of them had >20% blasts in NEC but less than 20% blasts in ANC, and 11 (29%) had >20% in both NEC and ANC. There was no significant difference in overall survivals (OS) among AEL, MDS-EB, and AML-NOS (non-erythroid predominance, NEP). However, AML with myelodysplasia-related changes showed significant shorter OS than AEL, MDS-EB and AML-NOS (NEP). Our results indicate that in myeloid neoplasm with erythroid predominance, patients with >20% blasts, of either NEC or ANC, share similar clinical laboratory features and survival outcomes with AML-NOS.

Clinical Outcomes of 217 Patients with Acute Erythroleukemia According to Treatment Type and Line: A Retrospective Multinational Study

Acute erythroleukemia (AEL) is a rare disease typically associated with a poor prognosis. The median survival ranges between 3-9 months from initial diagnosis. Hypomethylating agents (HMAs) have been shown to prolong survival in patients with myelodysplastic syndromes (MDS) and AML, but there is limited data of their efficacy in AEL. We collected data from 210 AEL patients treated at 28 international sites. Overall survival (OS) and PFS were estimated using the Kaplan-Meier method and the log-rank test was used for subgroup comparisons. Survival between treatment groups was compared using the Cox proportional hazards regression model. Eighty-eight patients were treated with HMAs, 44 front line, and 122 with intensive chemotherapy (ICT). ICT led to a higher overall response rate (complete or partial) compared to first-line HMA (72% vs. 46.2%, respectively; p ≤ 0.001), but similar progression-free survival (8.0 vs. 9.4 months; p = 0.342). Overall survival was similar for ICT vs. HMAs (10.5 vs. 13.7 months; p = 0.564), but patients with high-risk cytogenetics treated with HMA first-line lived longer (7.5 for ICT vs. 13.3 months; p = 0.039). Our results support the therapeutic value of HMA in AEL.

The uniqueness of morphological features of pure erythroid leukemia in myeloid neoplasm with erythroid predominance: A reassessment using criteria revised in the 2016 World Health Organization classification

We reviewed 97 consecutive cases of myeloid neoplasm with erythroid predominance (MN-EP) between 2000 and 2015. Following 2016 WHO classification, MN-EP patients were classified into four groups. Eight pure erythroid leukemia (PEL) (including t-MN and AML-MRC morphologically fulfilled criteria for PEL) patients had dismal outcomes (median OS: 1 month) and showed more bone marrow fibrosis, worse performance status (PS) and higher serum lactate dehydrogenase (LDH) at diagnosis than the other groups. In the univariate analysis, risks of death in MN-EP patients included the morphologic features of PEL, very poor cytogenetic risk by IPSS-R, bone marrow fibrosis, leukocytosis, anemia, hypoalbuminemia, high LDH, and poor PS. In the multivariate analysis, independent predictors of death were morphologic features of PEL (adjusted hazards ratio [HR] 3.48, 95% confidence interval [CI] 1.24–9.74, p = 0.018), very poor cytogenetic risk by IPSS-R (adjusted HR 2.73, 95% CI 1.22–6.10, p = 0.015), hypoalbuminemia (< 3.7 g/dl) (adjusted HR 2.33, 95% CI 1.10–4.91, p = 0.026) and high serum LDH (≥ 250 U/L) (adjusted HR 2.36, 95% CI 1.28–4.36, p = 0.006). Poor or unfavorable risk in different cytogenetic risk systems independently predicted death and UKMRC-R was the best model.

Study of clinical, haematological and cytogenetic profile of patients with acute erythroid leukaemia

Background

Acute erythroid leukaemia (AEL) is a rare subtype of acute myeloid leukaemia (AML), constituting <5% of all the cases of AML. The World Health Organization (WHO) in 2001 classified AEL into two types: (1) erythroid/myeloid leukaemia which required ≥50% erythroid precursors with ≥20% of the non-erythroid cells to be myeloid blasts and (2) pure erythroleukemia (pEL) with ≥80% erythroblasts. The WHO 2008 classification kept these subcategories, but made erythroleukemia a diagnosis of exclusion. There are very few studies on the clinico haematological and cytogenetic profile of this disease, considering the rarity of its occurrence and poor prognosis.

Materials and methods

This study was done by retrospective analysis of data from 32 case files of patients diagnosed with AEL. Clinical details noted down were the demographic profile, peripheral blood smear details and bone marrow examination details: (1) blasts-erythroblasts and myeloblasts, (2) dysplasia in the cell lineages and (3) cytogenetic abnormalities.

Results

The most common presenting symptom was fever. Pancytopenia at presentation was seen in 81.25% of patients. Dysplasia was observed in bone marrow in 100% of erythroblasts and in 40% of myeloblasts in erythroid/myeloid subtype. In pure myeloid subtype, myeloid and megakaryocytic dysplasias were not obvious. Complex karyotype was noticed only in patients of pEL.

Conclusion

AEL is a rare group of heterogeneous diseases with many neoplastic and non-neoplastic conditions mimicking the diagnosis. The clinical presentation and cytogenetics are also non-specific, presenting additional challenges to the diagnosis.