Acute myeloid leukaemia with peculiar blast cell ... - Wiley Online Library

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showed absence of eosinophils and the presence of 40% blast ... showed blast cells to express myeloperoxidase (100%) and ... E-mail: [email protected].
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Acute myeloid leukaemia with peculiar blast cell inclusions and pseudo-eosinophilia

A 83-year-old man was admitted with a 4-week history of anorexia, weakness and night sweats. Physical examination did not show any relevant abnormality. An automatic blood cell count (Advia-120; Bayer, Leverkusen, Germany) showed leucocytosis (WBC: 43 · 109/l), mild anaemia (Hb: 10Æ4 g/ dl) and a normal platelet count. A peripheral blood film showed absence of eosinophils and the presence of 40% blast cells; these showed cytoplasmic granulation and a single large rectangular crystalline inclusion in some cells (Figures). Interestingly, the automated differential WBC suggested a very high percentage of eosinophils (35%). Cytochemical stains showed blast cells to express myeloperoxidase (100%) and fluoride-sensitive naphtol-AS-D chloroacetate-esterase (84%). Immunophenotyping showed expression of myeloid antigens (CD13, CD15 and CD66) by blast cells, with a weak coexpression of CD4. Markers of immaturity (CD34, HLA-DR and CD117) were negative. Cytogenetic analysis of a peripheral blood sample showed a normal karyotype. Molecular analysis

doi:10.1111/j.1365-2141.2005.05650.x

by reverse transcription polymerase chain reaction excluded the presence of PML-RARA, AML1-ETO and CBFB-MYH11 fusion transcripts. A diagnosis of acute myeloid leukaemia (AML) of FAB subtype M4 was made. Due to the advanced age of the patient, intensive chemotherapy was not administered and a palliative approach, with the cytoreductive agent 6mercaptopurine and supportive care, was taken. This case illustrates the presence of very unusual crystalline cytoplasmic inclusions in a case of AML with most blast cells being misidentified as eosinophils by the automated blood cell analyzer because of their strong myeloperoxidase activity. Anna Merino1 Jordi Esteve2 1

Hospital Clinic, Hemotherapy, CDB, Barcelona, Spain, and 2Hospital Clinic, Hematology Department, Barcelona, Spain. E-mail: [email protected]

ª 2005 Blackwell Publishing Ltd, British Journal of Haematology, 131, 286