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 leukaemia (PEL) is an extremely rare and aggressive subtype of acute myeloid leukaemia 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 the criteria of other well-defined myeloid neoplasms. The aim of this study was to describe the clinicopathological features of acute leukaemias with a pure erythroid phenotype (ALPEP) irrespective of their WHO classification and to determine if ALPEP represents a distinct clinicopathological entity.

METHODS AND RESULTS

We identified seven cases of ALPEP, in which immature cells fulfilled WHO morphological and immunophenotypical criteria for PEL. All patients except one were male, with a median age of 60 years. Three cases represented de novo PEL, three were therapy-related myeloid neoplasms and one was a blast phase of a myeloproliferative neoplasm. Extensive tumour necrosis was present in five cases (71%). Five cases with available modal karyotypes all demonstrated a complex karyotype involving the TP53 gene locus, with three 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 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 tumour necrosis and recurring cytogenetic abnormalities in ALPEP. Our findings suggest strongly that ALPEP represents a distinct clinicopathological entity regardless of its WHO classification.