Myelodysplastic Syndrome

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07/04/23

Myelodysplastic syndromes are a group of several related disorders characterized by bone marrow dysplasia and dysfunction associated with peripheral blood anemia, thrombocytopenia and/or leukopenia
Anemia is the most common finding in patients with myelodysplastic syndrome. The peripheral blood smear can show macrocytosis of the red cells and hypogranular neutrophils. The neutrophils can also show Pelger-Huët nuclei and other abnormal nuclear patterns. Rarely you can see circulating micromegakaryocytes.
The myelodysplastic disorders can evolve over time into acute leukemia. There are 9 defined myelodysplastic syndromes.
Age is a very important risk factor for the development of myelodysplastic syndrome.
Smoking is associated with a 3-5 fold increase in occurrence of myelodysplastic syndrome.
Myelodysplastic syndrome is a disease of the elderly. It is a rare in people less than 50 years old. Myelodysplastic syndrome presents most commonly with symptoms of anemia.
The bone marrow in patients with myelodysplastic syndrome is typically hypercellular which points to ineffective hematopoiesis as a cause of low cell counts.
Approximately 50% of patients with myelodysplastic syndrome have RAS mutations.
Approximately 15% of patients with myelodysplastic syndrome will have a monoclonal gammopathy.
Refractory anemia is a type of myelodysplastic syndrome that is characterized by isolated anemia with a normal white blood cell count and platelet count. There are less than 5% blasts in the bone marrow. This is considered a low risk myelodysplastic syndrome.
Refractory anemia with ringed sideroblasts is a myelodysplastic syndrome that is similar to refractory anemia accept that at least 15% of marrow Red cell precursors are ringed sideroblasts. This is a low risk of myelodysplastic syndrome.
Refractory anemia with excess blasts is characterized by disordered myelopoiesis, megakaryopoiesis and erythropoiesis. This is categorized into RAEB 1 and RAEB 2. RAEB 1 is characterized by 5 to 9% blasts in the bone marrow and less than 5% blasts in the peripheral blood. RAEB 2 is characterized by 10 to 19% blasts in the bone marrow. Both categories of RAEB are considered high risk myelodysplastic syndrome.
The blast count in MDS may vary from less than 5% and refractory anemia to more than 5% and refractory anemia with excess blasts. A blast cells greater than 20% in the bone marrow defines a condition of acute leukemia.
Refractory cytopenia with multilineage dysplasia is characterized by bicytopenia or pancytopenia. Dysplastic changes are present in 10% or more of the cells and 2 or more myeloid cell lines. There are at least 1% blasts in the blood and less than 5% blasts in the bone marrow. Auer rods are not present. Monocytes in the blood are less than 1×10 to the ninth. Refractory cytopenia with multilineage dysplasia and ringed sideroblasts is a subcategory characterized by more than 15% erythroid precursors in the bone marrow being ringed sideroblasts.
Refractory cytopenia with uni-lineage dysplasia is characterized by a single cytopenia involving either erythrocytes, neutrophils or platelets. In addition, dysplastic changes are present in 10% or more of the cells 2 or more myeloid cell lines. There are less than 1% blasts in the blood and less than 5% blasts in the bone marrow. Auer rods are not present. Monocytes in the blood are less than 1×10 to the ninth
The 5 q. minus myelodysplastic syndrome has a female predominance and often presents with macrocytic anemia, thrombocytosis, preserved neutrophil count and increasing number of hypo-lobulated and micromegakaryocytes
Therapy related myelodysplastic syndrome has a 75% chance of progression to acute leukemia. The delay from exposure to chemotherapy or radiation to the development of therapy-related myelodysplastic syndrome is typically 2 to 10 years.
Therapy related myelodysplastic syndrome is seen in patients who were previously treated with chemotherapy or radiation therapy for other cancers and in him there is a clinical suspicion that the prior therapy caused a myeloid neoplasm. Associated chemotherapies include alkylating agents, Toprol summaries inhibitors and purine analogs.
Alkylating agents like cyclophosphamide are associated with the lesions on chromosomes 5 and or 7Topoisomerase II inhibitors like etoposide are associated with 11 q. 23 abnormalities and have a shorter delay than alkylating agents from exposure to diagnosis of myelodysplastic syndrome
Topoisomerase II inhibitors like etoposide are associated with 11 q. 23 abnormalities and have a shorter delay than alkylating agents from exposure to diagnosis of myelodysplastic syndrome
Chronic myelomonocytic leukemia is assigned to a group of overlap myelodysplastic/myeloproliferative neoplasms.
Myelodysplastic syndromes with abnormalities in chromosome 7 and complex karyotype are prominent high risk features that predispose to evolution to acute myelogenous leukemia.