What are the morphologic features of acute myeloid leukemia (AML) with myelodysplasia-related changes (AML-MRC)?

Updated: Feb 25, 2018
  • Author: Angie Duong, MD; Chief Editor: Christine G Roth, MD  more...
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Answer

Answer

AML with multilineage dysplasia is established by demonstrating at least 20% blasts and by identifying dysplastic features in at least 50% of cells in at least two bone marrow (BM) cell lines (ie, dysgranulopoiesis, dyserythropoiesis, or dysmegakaryopoiesis). [6] Features of dysgranulopoiesis include hypogranularity, hyposegmentation of granulocytes (ie, pseudo-Pelger-Huet forms), abnormal granularity (pseudo-Chediak-Higashi granules), or abnormally segmented nuclei (see the images below). As such, cytochemical staining, especially with myeloperoxidase (MPO), may be aberrant, because patients may develop an acquired MPO deficiency as part of the dysplastic process. [9, 10, 11]

Dysplastic promyelocyte with cytoplasmic vacuole ( Dysplastic promyelocyte with cytoplasmic vacuole (left), blast (center), and dysplastic neutrophil with pseudo-Pelger-Huet anomaly and hypogranularity (right).
Dysplastic neutrophil with large pseudo-Chediak-Hi Dysplastic neutrophil with large pseudo-Chediak-Higashi granules.

Features of dyserythropoiesis include megaloblastoid forms, nuclear budding, irregular nuclear contours, nuclear fragmentation, multinucleation, karyorrhexis, mitoses within erythroid forms, ring sideroblasts, and cytoplasmic vacuolization (see the following images).

A dysplastic red blood cell with budding nuclei (l A dysplastic red blood cell with budding nuclei (left) is seen with a monocyte (center), and a blast (right).
Numerous dysplastic erythroid cells are seen inclu Numerous dysplastic erythroid cells are seen including nuclear budding, irregular nuclear contours, and multinucleation.

Features of dysmegakaryopoiesis include small size, nuclear hypolobation, nuclear hypersegmentation, and separated nuclear lobes (see the image below).

A cluster of dysplastic megakaryocytes is seen.  S A cluster of dysplastic megakaryocytes is seen. Several small and hypolobate megakaryocytes are present.

Rare cases of AML-MRC demonstrating basophilic differentiation [12] or mixed-lineage phenotype [13] have been reported.


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