images in haematology: Faggot cells in an HIV-positive patient with inv(16)/therapy-related acute myeloid leukaemia

A 32-year-old human immunodeficiency virus (HIV)-positive male presented with fever and some haemorrhagic vesicles on the soft palate. Three years previously, he had been diagnosed with stage IVB, nodular sclerosis Hodgkin lymphoma, treated with six cycles of doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD), and achieved complete remission. On admission, a full blood count showed: white cell count 67AE4 · 10/l, haemoglobin concentration 85 g/l and platelet count 10 · 10/l. Peripheral blood films showed 10% blasts (some with granules), 25% promonocytes and 6% eosinophils. A variable number of Auer rods were observed in some neutrophils and band forms, occasionally being numerous (top). A bone marrow aspirate showed blast cells, promonocytes, monocytes, eosinophils and eosinophil precursors. In addition there were faggot cells – maturing cells of neutrophil lineage containing bundles of Auer rods (bottom). Cytochemical studies showed a proportion of cells positive for myeloperoxidase, chloroacetate esterase and butyrate esterase. Periodic acid–Schiff (PAS) positivity was observed in some atypical eosinophils. Immunophenotypic analysis showed two abnormal populations: the first of these accounted for 15% of the events and showed a CD34+, CD117+, CD33+, CD13++, CD15±, HLA)DR+, CD45+, cMPO+ and lysozyme–phenotype; the second accounted for 60% and showed a CD34), CD117±, CD13+, CD15+, HLA-DR+, CD11b+, CD14+, CD64+, CD36+, CD45++, cMPO± and lysozyme+ phenotype. Interphase fluorescence in situ hybridization analysis revealed inv(16) and excluded t(15;17). Cytogenetic analysis showed 47,XY,+8,inv(16)(p13q22)[20]. Molecular analysis confirmed inv(16) (MYH11-CBFB/ABL1 ratio:12AE47). The final diagnosis was therapy related-acute myeloid leukaemia (AML) with +8 and inv(16). He received two cycles of induction chemotherapy without attaining complete remission. Faggot cells are very characteristic of acute promyelocytic leukaemia but, as illustrated by this patient, they cannot be regarded as specific. They are a very uncommon feature of AML associated with inv(16).