Acute erythroid leukemia: autopsy report of a rare disease

Abstract

Acute erythroid leukemia (AEL) is a rare subtype of acute myeloid leukemia
(AML), characterized by predominant erythroid proliferation. The 2008 World
Health Organization (WHO) classification of AML defined two AEL subtypes:
erythroleukaemia (EL), in which erythroid precursors account for 50% or more
of all nucleated bone marrow cells and myeloblasts account for 20% or more of
the nonerythroid cell population; and pure erythroid leukemia (PEL), in which
erythroid precursors account for 80% or more of all nucleated bone marrow
cells. We report the case of an elderly female patient with wasting syndrome
and pancytopenia without evidence of blasts in peripheral blood. A diagnosis
of PEL was established on the basis of bone marrow biopsy findings. The
patient died on postadmission day 20, and an autopsy was performed. We
reclassified the disease as EL on the basis of the autopsy findings, which
included myeloblasts accounting for more than 20% of the nonerythroid cells
in the bone marrow, as well as leukemic infiltration and myeloid metaplasia in
solid organs, such as the liver, spleen, kidneys, adrenal glands, and abdominal
lymph nodes. A rare disease, AEL accounts for less than 5% of all AMLs and is
practically a diagnosis of exclusion. Autopsy reports of AEL are extremely rare
in the literature. We demonstrate that in the case reported here, leukemia cells
tended to infiltrate solid organs with myeloid metaplasia. Our findings also
show that a larger neoplastic bone marrow sample is crucial to the correct
diagnosis of EL, which is based on morphological and quantitative criteria.