The production of different blood cells takes place within the bone marrow. Stem cells lying within the marrow differentiate into various cell types along a spectrum of cell lineages. This process of differentiation is highly regulated predominantly by the genes. Therefore, mutations of these genes can disarray the entire process, causing a myriad of hematological disorders which are broadly categorized into two groups as myeloproliferative and myelodysplastic. In myeloproliferative disorders, there is an increase in the number of cells in different blood cell lineages. Myelodysplastic refers to the inability of the stem cells to mature into red blood cells, white blood cells, and platelets. Thus, the key difference between myeloproliferative and myelodysplastic is that in myeloproliferative disorders, there is an increase in the number of normal cells whereas, in myelodysplastic disorders, there is an increase in the number of abnormal immature cells.
CONTENTS
1. Overview and Key Difference
2. What is Myeloproliferative
3. What is Myelodysplastic
4. Similarity Between Myeloproliferative and Myelodysplastic
5. Side by Side Comparison – Myeloproliferative vs Myelodysplastic in Tabular Form
6. Summary
What is Myeloproliferative?
In myeloproliferative disorders, there is an increase in the number of cells in different blood cell lineages. The pathognomic feature of myeloproliferative conditions is the presence of a mutated and constitutively activated tyrosine kinase gene along with various aberrations in the signaling pathways that lead to growth factor independence.
Most myeloproliferative diseases originate from the multipotent myeloid progenitors and occasionally from the pluripotent stem cells.
Figure 01: Increased Reticulin in the Bone Marrow in Myeloproliferative Disorders
Common pathological changes observed in these disorders include,
- Increased proliferative drive in bone marrow
- Extramedullary hematopoiesis
- Marrow fibrosis along with peripheral blood cytopenias
- Transformation to acute leukemia
Following are the major varieties of myeloproliferative disorders:
- Chronic myelogenous leukemia
- Polycythemia vera
- Essential thrombocytopenia
- Primary myelofibrosis
- Systemic mastocytosis
- Chronic eosinophilic leukemia
- Stem cell leukemia
What is Myelodysplastic?
Myelodysplastic refers to the inability of the stem cells to mature into red blood cells, white blood cells and platelets. Consequently, the hemopoiesis is impaired and there is a higher risk of developing acute myeloid leukemia.
In these myelodysplastic conditions, the stem cells in the bone marrow are replaced by a variety of neoplastic multipotent stem cells that are capable of proliferating, but in an ineffective manner. Therefore, patients will have pancytopenia.
Myelodysplastic disorders can be due to acquired causes such as exposure to genotoxic radiation or idiopathic causes.
Figure 02: Megakaryocytes in Myelodysplastic Disorders
Morphological Changes
There is bone marrow hyperplasia, which is associated with disordered differentiation of granulocytes, megakaryocytes, erythroids, etc. In some cases, an increase in the myeloblasts can also be observed.
Clinical Features
- Usually, elderly people above 70 years of age are affected by this condition
- Recurrent infections
- Unexplained hemorrhages
- Weakness
Myelodysplatic disorders are classified into various subgroups for the purpose of assessing the disease prognosis. Patients usually die within 9-29 months from the onset of symptoms.
Treatments
- Allogeneic hemopoietic stem cell transplantation
- Antibiotics to control infections
- Blood product transfusion
What is the Similarity Between Myeloproliferative and Myelodysplastic?
- Both kinds of disorders are primarily due to the genetic mutations affecting the production of cells within the bone marrow.
What is the Difference Between Myeloproliferative and Myelodysplastic?
Myeloproliferative vs Myelodysplastic |
|
| In myeloproliferative disorders, there is an increase in the number of cells in different blood cell lineages. | Myelodysplastic refers to the inability of the stem cells to mature into red blood cells, white blood cells, and platelets. |
| Pathognomic Features | |
| The pathognomic feature of myeloproliferative conditions is the presence of a mutated and constitutively activated tyrosine kinase gene along with various aberrations in the signaling pathways that lead to growth factor independence. | In these myelodysplastic conditions, the stem cells in the bone marrow are replaced by a variety of neoplastic multipotent stem cells that are capable of proliferating but in an ineffective manner. |
| Common Pathological Changes | |
|
There is bone marrow hyperplasia, which is associated with disordered differentiation of granulocytes, megakaryocytes, erythroids, etc. In some cases, an increase in the myeloblasts can also be observed. |
Summary – Myeloproliferative vs Myelodysplastic
In myeloproliferative disorders, there is an increase in the number of cells in different blood cell lineages. Myelodysplastic refers to the inability of the stem cells to mature into red blood cells, white blood cells and platelets. In myeloproliferative disorders, there is an increase in the number of normal blood cells whereas in myelodysplastic disorders there is an increase in the number of abnormal immature cells. This is the major difference between myeloproliferative and myelodysplastic.
Reference:
1. Kumar, Vinay, Stanley Leonard Robbins, Ramzi S. Cotran, Abul K. Abbas, and Nelson Fausto. Robbins and Cotran pathologic basis of disease. 9th ed. Philadelphia, Pa: Elsevier Saunders, 2010. Print.
Image Courtesy:
1. “Increased Reticulin in Marrow in Myeloproliferative Disorder (3953335782)” By Ed Uthman from Houston, TX, USA -Uploaded by CFCF (CC BY 2.0) via Commons Wikimedia
2. “Megakaryocytes in MDS (RAEB and 5q-chromosome abnormality)” By The Armed Forces Institute of Pathology (AFIP) – PEIR Digital Library (Pathology image database). (Public Domain) via Commons Wikimedia