Acute leukaemia with a pure erythroid phenotype: under‐recognized morphological and cytogenetic signatures associated universally with primary refractory disease and a dismal clinical outcome

Aims Pure erythroid leukemia (PEL) is a very rare and aggressive subtype of acute myeloid leukemia defined by the World Health Organization (WHO) as a neoplastic proliferation of immature cells committed exclusively to the erythroid lineage comprising >80% of bone marrow cells and not meeting criteria of other well-defined myeloid neoplasms. The aim of this study was to describe the clinicopathologic features of acute leukemias with a pure erythroid phenotype (ALPEP) irrespective of their WHO classification and determine if ALPEP represents a distinct clinicopathologic entity. Methods and results We identified 7 cases of ALPEP in which immature cells fulfilled WHO morphologic and immunophenotypic criteria for PEL. All patients except for one were male with a median age of 60 years. Three cases represented de novo PEL, 3 were therapy-related myeloid neoplasms, and 1 was a blast phase of a myeloproliferative neoplasm. Extensive tumor necrosis was present in 5 cases (71%). Five cases with available modal karyotypes all demonstrated a complex karyotype involving the TP53 gene locus with 3 cases (60%) also showing a monosomy 5 or deletion 5q and additional material on chromosome 19q13. All patients died of their disease with a mean overall survival of 189 days and 64.7 days in cases without and with necrosis on the initial biopsy, respectively. Conclusions We describe previously unreported but relatively common findings of extensive tumor necrosis and recurring cytogenetic abnormalities in ALPEP. Our findings strongly suggest that ALPEP represents a distinct clinicopathologic entity regardless of its WHO classification. This article is protected by copyright. All rights reserved.