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.