micromegakaryocyte

micromegakaryocyte

A small platelet precursor with agranular cytoplasm, hyalinoplasmic zones (pseudopods), a rounded, dense nucleus and 1–3 small nucleoli, which is associated with large atypical platelets. Micromegakaryocytes often indicate abnormal megakaryopoiesis and associated myeloproliferative disorders, such as chronic idiopathic myelofibrosis (agnogenic myeloid metaplasia), a blast crisis of CML.
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Identification of cell abnormalities--such as the large azurophilic granules in toxic granulation, asynchronous maturation, micromegakaryocyte identification or quantitating variant lymphs--still requires a skilled human eye.
Bone marrow biopsies show increased reticulin fibrosis and increased numbers of dysplastic megakaryocytes, including micromegakaryocytes and/or hypolobated megakaryocytes.
Dysplastic features include nuclear hypolobation (a) and micromegakaryocytes (b).
Young forms of megakaryocytes and rare micromegakaryocytes were observed as well as mature forms.
Inthebonemarrowbiopsy, 30% cellularity, a small number of micromegakaryocytes, decreased erythroid and myeloid series elements, significantly increased eosinophilic precursors, and hypocellularity were observed, but there was no increase in the blastic series (Figure 1).
Another key characteristic of MDS is the presence of micromegakaryocytes. In the bone marrow, nuclearcytoplasmic asynchrony can also be seen.
Bone marrow at that time showed mildly hypocellular bone marrow with dyserythropoesis in more than 10% of erythroid precursors and presence of micromegakaryocytes, consistent with refractory cytopenia according to WHO classification.
In bone marrow, megaloblastoid changes, multinuclearity, nuclear budding and bridging in erythroblasts, hypogranulation in granulocytic series, micromegakaryocytes, uninucleated and binucleated forms, and cytoplasmic vacuolation in megakaryocytes were the common dysplastic features.
Micromegakaryocytes were hypolobated (Figure 1(c)).
In this 58-year-old man with AML harboring inv(3)(q21q26), the megakaryocytes exhibit dysplasia (micromegakaryocytes; A), and the myeloid blasts have expression of CD56 (B) (hematoxylin-eosin, original magnification X400).
A few things to consider: RBC results and MCV may be falsely elevated due to the WBCs being counted simultaneously with RBCs and platelets; a spun hematocrit is approximately 2% to 5% higher than a calculated hematocrit; Hemoglobin may be falsely elevated due to turbidity; MCH and MCHC values may be inaccurate due to the affected parameters from which they're calculated; falsely elevated WBC values may be seen in samples with cryofibrinogen, cryoglobulins, nucleated red blood cells, micromegakaryocytes, or any particle sized in the range that is counting WBCs.
A few things to consider: RBC results and MCV may be falsely elevated due to the WBCs being counted simultaneously with RBCs and platelets; a spun hematocrit is approximately 2% to 5% higher than a calculated hematocrit; hemoglobin may be falsely elevated due to turbidity; MCH and MCHC values may be inaccurate due to the affected parameters from which they're calculated; and falsely elevated WBC values may be seen in samples with cyofibrinogen, cryoglobulins, nucleated red blood cells, micromegakaryocytes, or any particle sized in the range that is counting WBCs.