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An accurate diagnosis is one of the most important aspects of a person’s care. Obtaining a precise diagnosis will help the doctor

  • Determine the MDS subtype 
  • Estimate how the disease will progress
  • Determine the most appropriate treatment

Since MDS can be a difficult disease to diagnose, you may want to get a second medical opinion by an experienced hematopathologist before you begin treatment.

Diagnostic Criteria

The diagnosis of MDS is based on:

  • At least one cytopenia (low blood cell count) in one or more of red blood cell, white blood cell or platelet counts
  • Dysplasia (cells that have an abnormal size or shape) in at least 10 percent or more of red blood cells, white blood cells or platelets on the blood smear or bone marrow examination
  • Less than 20 percent blasts (immature blood cells) in the blood and bone marrow
  • Specific MDS-associated cytogenetic (chromosome) abnormalities

In healthy people, there are usually no blast cells in the blood, and blast cells should make up less than 5 percent of all bone marrow cells. In MDS patients, blast cells may make up to 20 percent of cells in the bone marrow. A blast count of 20 percent or higher is considered acute myeloid leukemia (AML).

Complete Blood Cell Count with Differential. A doctor will order a complete blood count (CBC) with differential to measure the number of red cells, white cells and platelets in your blood. These measurements indicate the degree to which the MDS cells in the marrow are affecting normal blood cell development. Patients with MDS often have low numbers of one or more types of blood cells. The CBC should include a "differential." This measures the different types of white blood cells in the sample. 

A low red cell count means that you have anemia. If you have anemia, your doctor examines your red cells to find out whether your condition is caused by MDS or

  • Low iron, folate or B12
  • Another type of cancer or bone marrow problem
  • Another cause of anemia, such as kidney failure

Reticulocyte Count. Reticulocytes are precursor (immature) cells that develop into mature red blood cells. The reticulocyte count measures the number of reticulocytes in the circulating blood. It can show how quickly these cells are being made and released by the bone marrow and whether the bone marrow is functioning properly. When a person has anemia, the normal response is for the bone marrow to make more reticulocytes. A low reticulocyte count indicates that the bone marrow is not working well.

Peripheral Blood Smear. A peripheral blood smear is a test in which a hematopathologist examines a drop of blood under a microscope to identify unusual changes in the number, size, shape, appearance and maturity of various blood cells. In myelodysplastic syndromes, blood cells have an abnormal shape or size (dysplasia). The hematopathologist will also check a peripheral blood smear for the presence of blast cells. Blast cells are normally found in the bone marrow, but they are not typically found in the blood of healthy individuals. In some cases of MDS, a small number of blast cells can be found in the blood.

Serum Erythropoietin (EPO). Erythropoietin (EPO) is a substance made in the kidneys. EPO stimulates the bone marrow to produce more red blood cells. Measuring the amount of EPO in the blood can help determine the cause of anemia. A low EPO level can cause anemia and may be a sign of a health problem other than MDS. A low EPO level can also worsen anemia in a person with MDS. Most patients with MDS-related anemia have relatively low serum levels of EPO.

Lactate dehydrogenase (LDH). This test measures the level of lactate dehydrogenase (LDH) in the blood. LDH is a protein found in most cells. When a cell is damaged, LDH is released into the bloodstream. High levels of LDH in the blood may be caused by cancer and may also be a sign that the cancer is widespread. 

Bone Marrow Tests: Aspiration and Biopsy. These tests are used to confirm MDS. They are usually performed at the same time in a doctor's office or a hospital. After the samples are taken, a pathologist reviews the samples under the microscope to assess the type, size, appearance and maturity of the cells.

  • A bone marrow aspiration removes a small amount of liquid bone marrow from inside a bone.
  • A bone marrow biopsy removes a small piece of solid bone along with a small amount of bone marrow.

The following are signs of MDS:

  • Cells of abnormal size or shape (dysplasia)
  • Abnormal number (too many or too few) of any type of blood cell
  • An increased number of blast cells (immature bone marrow cells)
  • Abnormally low or high number of cells in the bone marrow
  • Red blood cells that have too much or too little iron

Cytogenetic Analysis. Cytogenetic analysis involves testing samples of tissue, blood or bone marrow to look for changes in chromosomes. In this test, a hematopathologist uses a microscope to examine the chromosomes inside of cells. Chromosomes are bundles of tightly coiled DNA that contain most of the genetic information in a cell. In patients with MDS, cytogenetic analysis is used to look for abnormal changes in the chromosomes of the cancer cells. Approximately 50 percent of people who have MDS have one or more chromosomal abnormalities, and 10 to 15 percent of patients have complex karyotypes (multiple chromosomal abnormalities). Cytogenetic testing is done using either a bone marrow or a blood sample.

Certain cytogenetic abnormalities are useful in predicting survival or progression to acute myeloid leukemia (AML) and are incorporated into the most common prognostic scoring systems for MDS. In some cases, cytogenetic analysis can also help guide treatment decisions.

Fluorescence In Situ Hybridization (FISH). This test uses special dyes that allow the hematopathologist to detect changes in a cell’s genes and chromosomes. This test identifies specific gene or chromosome changes that are common in MDS patients.

Molecular Testing. These tests look for mutations (changes) in genes that are associated with MDS. Sometimes, mutation testing results influence MDS treatment or its outcome. Molecular testing can be done on a sample of blood or bone marrow. It is performed in some patients with MDS to look for gene abnormalities. DNA sequencing is a type of molecular test that checks for specific gene mutations in cancer cells. Certain mutations are associated with a better or worse outcome. Doctors use the results of molecular testing to help plan treatment.

Testing for genetic mutations in myelodysplastic syndromes has progressed considerably in recent years and is becoming more widely available. This progress in the understanding of the genetic features of myelodysplastic syndromes will help doctors acquire a better understanding of a patient's individual disease to develop targeted treatments.

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