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Slide submitted by Biswadip Hazarika, MD, Hematopathologist, Gulf Medical University, Ajman, UAE, biswa2006@yahoo.co.uk
Source: www.bloodmed.com

Peripheral blood film in acute monoblastic leukaemia (Jenner-Giemsa stain) The peripheral blood film shows presence of large blasts with slightly convoluted nuclei with dispersed chromatin and multiple prominent nucleoli. The cytoplasm is mildly basophilic with presence of fine, dusty granules with numerous cytoplasmic vacuoles of different sizes. Morphologically, the blasts are consistent with monoblasts/ promonocytes. Promonocytes have more convoluted nuclei and relatively more cytoplasm than the monoblasts. However, both monoblasts and promonocytes are counted as blasts in the WHO classification. A large cytoplasmic mass is seen attached to a blast (which is not a usual feature of monoblasts, though cytoplasmic blebs or projections are frequently noted). A small fragment of a monoblastic cytoplasmic mass is also noted at the lower right part of the image. Severe thrombocytopenia is noted with presence of a few microcytes and target cells. The leukaemia cells expressed non-specific esterase and, by flow cytometry, CD13, CD14 and CD117.


Bone marrow aspirate film in acute monoblastic leukaemia (Jenner-Giemsa stain) From Biswadip Hazarika, MD, Hematopathologist, Gulf Medical University, Ajman, UAE, biswa2006@yahoo.co.uk

The bone marrow aspirate shows intensely hypercellular marrowwith near-total replacement of the marrow by blasts. Morphologically, the blasts areconsistent with monoblasts, with a smaller population of promonocytes alsobeing present. Flow cytometric immunophenotyping showed an abnormal cell cluster comprising 96% of the total population with high forwards scatter (FSC) and low sideways scatter (SSC). Gating on the abnormal cluster using SSC/CD45 showed expression of CD13 and Cd117 but no expression of CD33, CD34, CD3, CD5, CD7, CD19 or CD22. CD14, a marker of monocytic differentiation, was strongly positive in the gated population. The leukaemic cells expressed non-specific esterase.
Non-specific esterase (NSE) in acute monoblastic leukaemia (substrate: alpha naphthyl acetate esterase) From Biswadip Hazarika, MD, Hematopathologist, Gulf Medical University, Ajman, UAE, biswa2006@yahoo.co.uk

NSE of a bone marrow film shows diffuse, intense positivity in the blasts which is consistent with monoblasts/promonocytes. A normal bone marrow smear with adequate number of megakaryocytes is used as a positive control for NSE staining, as the megakaryocytes normally shows diffuse, strong positivity for NSE.
Biswadip Hazarika
MD, Hematopathologist
Gulf Medical University, Ajman, UAE

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