Myelodysplastic syndrome pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Nawal Muazam M.D.[2]
Overview
Cytogenetic abnormalities involved in the pathogenesis of myelodysplastic syndrome include isolated deletion of 5q, isolated deletion of 17p, monosomy 7, and monosomy 8.[1] There are no characteristic findings of myelodysplastic syndrome on gross pathology. On microscopic histopathological analysis, dyserythropoiesis, dysgranulopoiesis, and dysmegakaryocytopoiesis are findings of myelodysplastic syndrome.[1]
Pathophysiology
Pathogenesis
Myelodysplastic syndrome comprises a heterogeneous group of clonal bone marrow disorders characterized by various degrees of pancytopenia and morphological and functional abnormalities of hematopoietic cells and an increased risk of transformation into acute myeloid leukemia.[2]
Genetics
Cytogenetic abnormalities involved in the pathogenesis of myelodysplastic syndrome include:[1]
- Isolated deletion of 5q
- Isolated deletion of 17p
- Monosomy 7
- Monosomy 8
Associated conditions
Myelodysplastic syndrome may be associated with:[3]
- Fanconi syndrome
- Diamond-blackfan syndrome
- Shwachman-diamond syndrome
Gross Pathology
There are no characteristic findings of myelodysplastic syndrome on gross pathology.
Microscopic Pathology
On microscopic histopathological analysis, characteristic findings of myelodysplastic syndrome include:[1]
- Dyserythropoiesis
- Dysgranulopoiesis
- Dysmegakaryocytopoiesis
Dyserythropoiesis
- Abnormal red blood cell formation
Nuclear features
- Nuclear budding
- Intranuclear bridging (nuclei fail to separate post-division)
- Multinucleation
- Megablastoid change
- May be hard to see
- Karyorrhexis (nuclear fragmentation)
Cytoplasmic features
- Ring sideroblasts
- Rim of RBC has ring of iron
- Vacuolization
Dysgranulopoiesis
- Abnormal granulocyte formation
Nuclear features
- Nuclear hypolobation (pseudo Pelger-Huët)
- Hypersegmentation
- May be seen in vitamin B12 deficiency
Cytoplasmic features
- Cytoplasmic hypogranulation
- Pseudo-Chediak-Higashi granules
- Small size
Dysmegakaryocytopoiesis
- Abnormal megakaryocyte formation
Nuclear features
- Micromegakaryoctes with hypolobated nuclei
- Non-lobated nuclei of any size
- Multiple widely separated nuclear lobes
Gallery
Immunohistochemistry
On immunohistochemistry, characteristic findings of myelodysplastic syndrome include:
- CD34 - (myeloid) progenitor/precursor cells
- CD117 - (myeloid) progenitor/precursor cells, mast cells
- Tryptase - mast cells, immature basophils
- Uncommonly done
- CD61 - megakaryocytes
- CD42b - megakaryocytes
- CD20 - B cells
- CD3 - T cells
- Glycophorin A - erythroid cells
- Glycophorin C - erythroid cells
References
- ↑ 1.0 1.1 1.2 1.3 Cytogenetics of myelodysplastic syndromes. Librepathology (2015). http://librepathology.org/wiki/index.php/Myelodysplastic_syndromes. Accessed on December 8, 2015
- ↑ Corrêa de Souza, Daiane; de Souza Fernandez, Cecília; Camargo, Adriana; Apa, Alexandre Gustavo; Sobral da Costa, Elaine; Bouzas, Luis Fernando; Abdelhay, Eliana; de Souza Fernandez, Teresa (2014). "Cytogenetic as an Important Tool for Diagnosis and Prognosis for Patients with Hypocellular Primary Myelodysplastic Syndrome". BioMed Research International. 2014: 1–10. doi:10.1155/2014/542395. ISSN 2314-6133.
- ↑ Associations of myelodysplastic syndromes. Librepathology (2015). http://librepathology.org/wiki/index.php/Myelodysplastic_syndromes. Accessed on December 8, 2015