A retrospective study of absence of expression of HLA-DR in acute myeloid leukaemia

Abstract

Aims To investigate whether absence of expression of HLA-DR on myeloblasts has a predictive value in the diagnosis of acute pro-myelocytic leukaemia (APML) and other subtypes of acute my-eloid leukaemia (AML). Background From 2000 to 2008, 142 new cases of AML were diagnosed in Tasmania, of which 10–20% are expected to be of the APML subtype according to the Tasmania Cancer Registry. APML has one of the worst prognoses among the AML subtypes on presentation, however with rapid diagnosis and treatment it is the most curable form of AML. Methods The immunophenotype results from the Flow Cytom-etry Department of the Royal Hobart Hospital (RHH) of all patients diagnosed with AML in Tasmania from 2000 to 2008 was reviewed and patients were categorised into respective French-American-British classification (FAB) AML subtypes using this data. Confirmation of true APMLs were obtained from the cytoge-netics department of the RHH. Results A total of 110 patients were diagnosed with AML based upon flow cytometry results. There were nine suspected with APML, of which four were confirmed to be APML by cytogenetics. HLA-DR expression was negative on 18 patients, of which only one was an APML. In fact nine (50%) were classified as M2. Conclusions Preliminary results suggest that absence of expression of HLA-DR does not correlate with a diagnosis of APML; rather it may suggest a diagnosis of AML with maturation (M2).