It is important to begin with by stating that not every case of cytopenia and/or myeloid dysplasia will be considered as a MDS, or even caused by clonal disorder at all. There are many factors, most already mentioned in this course, which contribute to the diagnosis of MDS.
In some cases, MDS can be easily diagnosed when the blasts in the blood or bone marrow are increased and the presence of abnormal cytogenetics is discovered. Other cases may require a thorough history of exposure to drugs, chemotherapeutic agents, radiation, or chemicals. Further testing, typically including repeated bone marrow biopsies with cytogenetic evaluations over a period of several months, is recommended to establish the MDS diagnosis.
Some of the cellular abnormalities demonstrated in MDS can be explained by other factors, such as:
- Nutritional: vitamin B12 or folic acid deficiency
- Causes megaloblastic changes and cytopenia
- Exposure to heavy metal or toxins (examples: arsenic compounds, alcohol, lead, benzene, zinc, isoniazid)
- May cause dyserythropoiesis
- Antibiotics such as cortrimoxazol
- May cause granulocytic dysplasia
- Congenital dyserythropoietic anemia
- May cause dysplastic normoblast development
- Parvo-virus infection
- May cause temporary suppression of the bone marrow erythroid cells and megaloblastoid changes
- Immunosuppressive agents given to organ transplant patients (example: Mycophenolate)
- May cause dysplastic granulocytes and/or erythroid cells
- Chemotherapeutic agents
- Granulocyte colony stimulating factor (GCSF) treatments
- May cause bone marrow hyperplasia, granulocytic hyper-granulation, and increased blast counts
Each of the factors listed above are non-clonal in origin and may also cause cytopenia and/or dysplasia. Therefore, they must be ruled-out before establishing the diagnosis of MDS.