An accurate diagnosis is one of the most important aspects of a person’s care. Obtaining a precise diagnosis will help the doctor
- 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.
A diagnosis of MDS requires that at least one of the following characteristics be found in the marrow:
- Blasts making up between 5 and 19 percent of the marrow cells
- Obvious changes to the structure or form of the marrow cells (dysplasia)
- Cytogenetic abnormalities (chromosomal damage to the DNA in the cells)
- “Simple” cytogenetics means fewer than three chromosomes are affected.
- “Complex” cytogenetics means three or more chromosomes are affected
The following tests will help your doctor make a diagnosis.
CBC with Differential. A doctor will order a complete blood count (CBC), which measures 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.
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.
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 (mature 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
Fluorescence in Situ Hybridization (FISH) or Karyotype
These are tests used to identify cells that contain chromosomal abnormalities. The tests can also help identify abnormal cells for diagnosis of disease, and can track and measure the effects of therapy. Chromosomal abnormalities are important factors in identifying specific subtypes of MDS, and they can sometimes help doctors determine the most effective treatment approach.
It is common for MDS cells to have abnormal chromosomes. Approximately 50 percent of patients have one or more chromosomal defects. There are different types of chromosome defects; for example, part of a chromosome or an entire chromosome may be missing. Or there may be an extra copy of a chromosome. Each chromosome is divided into two sections, or “arms.” The short arm of the chromosome is labeled the “p arm.” The long arm of the chromosome is labeled the “q arm.”
These tests look for mutations 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.
In recent years, research has identified several gene mutations among MDS patients. Some of these mutations can have an impact in outcome of the disease.
These are noteworthy because
- There are more than 40 genes that can be mutated in MDS.
- A large number of patients (over 80 percent) are likely to carry at least one mutation.
- Based on the functions of these mutated genes, researchers have learned about the molecular mechanisms responsible for the development of MDS.
- The specific pattern of mutations seen in MDS patients may partially explain the variability of their disease and will likely lead to newer classification systems based on these genetic abnormalities.
- A subset of mutations may have prognostic value. Mutations in specific genes have been associated with both better and worse prognoses than those predicted by the International Prognostic Scoring System (IPSS).