Myelodysplasia - All About the Blood Disorder

What Is Myelodysplasia?

Myelodysplasia is also known as myelodysplastic syndrome. It is defined as a group of blood disorders caused by immature blood cells which do not proliferate into mature blood cells in the bone marrow and these unhealthy immature cells die early, even before entering the bloodstream. In general, bone marrow is the spongy tissue present in the center of the long bones of the body. The bone marrow consists of hematopoietic stem cells, fat cells, and supporting tissues. Bone marrow is of two types: red marrow and yellow marrow. The red marrow forms the blood cells like red blood cells, white blood cells, and platelets, whereas the yellow marrow consists of fats. The blood stem cells consist of myeloid and lymphoid stem cells. Myeloid stem cells form the red blood cells that carry the oxygen and other essential nutrients to the body, platelets help in blood clot formation to stop excessive blood loss, and granulocytes which are basically white blood cells, fight against the infection. The lymphoid stem cell proliferates into B-cells and T-cells, which are subtypes of white blood cells and function as an immune system of the body to fight against infection and inflammation. In myelodysplastic syndrome, the bone marrow fails to mature the blood cells into mature, healthy cells. These immature blood cells, called blasts, do not get mature and tend to fail to perform their functions and overcrowd the normal healthy cells. This leads to the development of other blood-related disorders like anemia, bleeding, and clotting problems.

What Are the Types of Myelodysplastic Syndrome?

Myelodysplastic syndrome is classified depending on the type of blood cells involved. The classification is given by the World Health Organization.

The subtype of myelodysplastic syndrome are the following -

• Myelodysplastic Syndrome with Single-Lineage Dysplasia -

It involves one type of blood cells, such as red blood cells, white blood cells, or platelets, that lead to a lower number and appear abnormal under the microscope.

• Myelodysplastic Syndrome with Multilineage Dysplasia -

It is a subtype of myelodysplastic syndrome involving two or three types of blood cells and leads to abnormal development of the cells.

• Myelodysplastic Syndrome with Ring Sideroblast -

This subtype of myelodysplastic syndrome involves a low number of one or more types of blood cells. The characterizing feature of this subtype is that the existing red blood cells in bone marrow have an extra iron ring in them.

• Myelodysplastic Syndrome with Isolated del (5q) Chromosome Abnormalities -

In this subtype, the affected individual has a low number of red blood cells, and the cells have a different DNA (deoxyribonucleic acid) mutation.

• Myelodysplastic Syndrome with an Excess Blast -

This subtype of myelodysplastic syndrome involves one type of blood cell either red blood cells, white blood cells, or platelets. It leads to a low number of blood cells and shows abnormal activities under microscopic examination. It is characterized by the excessive accumulation of immature (blast cells) cells present in blood and bone marrow.

• Myelodysplastic Syndrome, Unclassified -

It is a type of myelodysplastic syndrome associated with a low number of one or more types of blood cells with abnormal microscopic activities. Sometimes the blood appears to be normal, but some DNA (deoxyribonucleic acid) mutation is observed.

What Are the Symptoms of Myelodysplastic Syndrome?

The myelodysplastic syndrome may lead to asymptomaticity in the early stage meaning it does not show any characteristic features to detect the syndrome. As the disease progresses, the mild symptoms may get worse.

The following are the symptoms of myelodysplastic syndrome -

1. Shortness of breath.

2. Weakness and fatigue.

3. Skin appears pale.

4. Easily bleeding.

5. Easily bruising.

6. Petechiae (purple-blue small dark spot over the skin caused by the bleeding beneath the skin)

7. Recurrent infections.

What Are the Causes of Myelodysplastic Syndrome?

The cause of myelodysplastic syndrome is unknown. Still, it is believed that myelodysplastic syndrome is caused by exposure to certain chemicals, high-energy rays, chemotherapy, toxic substances like benzene, or some underlying causes.

What Are the Investigations for the Diagnosis of Myelodysplastic Syndrome?

Myelodysplastic syndrome is diagnosed by performing the following investigations -

1. Physical Examination - It is important to check the patient’s vitals, palpitations, auscultation, and inspection to understand the signs and symptoms of the disorders.

2. History taking is done to know the past medical and personal history of the patient.

3. Complete Blood Test - It is a blood investigation performed to determine the count of blood cells present in the given sample.

4. Peripheral Blood Smear - Small amount of blood sample is collected, and a slide is performed for microscopic examination to determine the number, size, shape, and presence of iron rings over the red blood cells.

5. Cytogenetic Analysis - It is a lab test performed to analyze the chromosomal changes like broken, missing, rearranged, or extra chromosomes in the given blood sample.

6. Blood Chemistry Studies - It is an investigation done to check the presence of substances like vitamin B12 and folate released in the blood. In disorders like this, the level of these substances is higher than normal.

7. Bone Marrow Aspiration and Biopsy - A sample from the hip bone or breast is taken for examination of the cells present in the bone marrow.

8. Immunocytochemistry or Immunophenotyping - It is performed by using antibodies to detect the cancerous or abnormal cells in the body.

9. Flow Cytometry - Flow cytometry is an investigation carried out for diagnosis and treatment planning in which a blood sample is taken and then stained with a fluorescent dye in a fluid and passed through a beam of light. The reaction of the cells passing through the beam of light is studied to determine the disorder.

10. FISH (Fluorescence in situ hybridization) - The FISH investigation is done by taking a blood sample and pieces of stained DNA with a fluorescent dye are added to it; then, the stained DNA pieces attach to the chromosome or genes of the blood sample, and they get charged and emit light.

What Are the Treatment Modalities for Myelodysplastic Syndrome?

Myelodysplastic syndrome is a treatable disorder. For the treatment of myelodysplastic syndrome, there are three different types of therapy depending upon the severity of the disorder.

Supportive Care

• Transfusion Therapy - Transfusion therapy is indicated for patients to increase the number of red blood cells, white blood cells, and platelets. Multiple blood transfusion leads to the development of iron overload and may damage other internal organs.

• Erythropoiesis-Stimulating Agents - Erythropoiesis-stimulating agents are indicated to increase the number of mature red blood cells.

• Antibiotic Therapy - Broad-spectrum antibodies are administered to the patient to fight against the infection.

Drug Therapy

• Lenalidomide - An individual affected with myelodysplastic syndrome associated with del (5q) chromosomal abnormality requires a blood transfusion with an indication of Lenalidomide to reduce the use of red blood cells.

• Immunosuppressive Therapy - Antithymocyte globulin is indicated to lessen the indication of blood transfusion.

• Azacitidine and Decitabine - These drugs are indicated to treat patients with myelodysplastic syndrome.

• Chemotherapy - It is indicated for patients who have myelodysplastic syndrome with acute myeloid leukemia.

Chemotherapy with Stem Cell Transplantation

Chemotherapy is indicated for cancer patients, and it may harm the normal and healthy cells; therefore, the healthy stem cells are removed from the body, and after the chemotherapy, the cells are injected back into the body to avoid damage to healthy cells.

Conclusion -

Myelodysplasia is a group of blood disorders caused by immature blood cells in the bone marrow. Generally, myelodysplastic syndrome is caused by some underlying disorder though it is a treatable disorder. An experienced team of oncologists, hematologists, pathologists, and general physicians is required for the diagnosis and treatment planning.