The MDS Beacon™

MDS is difficult to diagnose, because symptoms are commonly shared with other diseases. MDS can only be confirmed after other causes are ruled out. In the sections below, a few of the tests used to help diagnose MDS are described.

Blood Tests

The first step in diagnosing MDS is a complete blood count (CBC). Red blood cells, white blood cells, and platelets are counted by an automatic cell counter. Abnormal cell counts may lead to manual inspection of the blood cells. In addition, cell shapes and sizes are noted. Both low blood cell counts (cytopenia) and abnormally shaped cells (dysplasia) are distinctive features of MDS.

Additional blood tests are done to rule out other causes of low red blood cell count (anemia), such as abnormal thyroid function, kidney failure, heart failure, HIV, lupus, hepatitis, and other cancers. All of these conditions commonly cause chronic tiredness or fatigue, shortness of breath, heart palpitations, pale skin, and chilled sensations. Nutrient, iron, and vitamin deficiencies must also be eliminated as sources of anemic symptoms. Last, blood tests help rule out myelodysplastic/myeloproliferative diseases, which cause similar symptoms as MDS by a higher than normal number of blasts that develop into blood cells. MDS is caused by a shortage of such cells.

Hemoglobin, an oxygen-carrying protein, and erythropoietin (EPO), a protein that stimulates red blood cell production, are also measured because low levels of either protein also cause anemic symptoms.

Bone Marrow Sample

As blood test results may be inconclusive, bone marrow tests can also be performed. Bone marrow analyses can help diagnose MDS by calculating a percentage of immature blood cells (blasts) and confirming defective blood cell formation (hematopoiesis).

There are two methods to obtain bone marrow samples – bone marrow trephine biopsy and bone marrow aspiration. In a bone marrow trephine biopsy, a thick needle is used to withdraw a sample of bony tissue from the bone marrow. In bone marrow aspiration, a thin needle is used to take a sample of bone marrow fluid. In both tests, local anesthesia is applied.

Bone marrow examinations usually do not require staying in a hospital overnight. The actual procedure takes less than an hour. After each procedure, the patient is asked to lie flat for 10 to 15 minutes, applying pressure to the wound. If there is no bleeding, normal activities may be resumed, though it is advised not to wash the area for 24 hours. Mild soreness is expected for two to three days. Worsening pain, redness, fever, or swelling may suggest a complication.

Bone marrow trephine biopsy and bone marrow aspiration samples provide different types of information, and sometimes both procedures are performed. With these samples, several laboratory tests can be performed.

Bone Marrow Laboratory Tests

Cytochemistry: Cells from the bone marrow sample are placed on glass microscope slides and exposed to dyes, which are attracted to specific chemicals. This causes a color change only in cells containing these chemicals.

Immunocytochemistry: Similar to cytochemistry, bone marrow cells are exposed to antibodies, which cause color change in cells that possess specific corresponding foreign substances (antigens), to which the antibodies bind. This test is helpful in diagnosing MDS by excluding other possible diseases and distinguishing the different types of MDS.

Cytogenetic Analysis: Cells from bone marrow aspirate are grown in laboratory dishes and the gene-containing structures (chromosomes) then viewed under a microscope. Cytogenetic tests examine these chromosomes for abnormalities, including missing, extra, and malformed structures, or interchanged (translocated) segments. Sixty percent of MDS cases have observable chromosomal irregularities. In MDS, the most common cytogenetic abnormalities include the complete loss of chromosome 5 or 7, an extra copy of chromosome 8, and deletion in the long arm of chromosomes 5, 7, or 20. Deletion of chromosome 5 has a better prognosis than deletion of chromosome 7.

Flow Cytometry: A sample of cells from bone marrow (or blood) is treated with antibodies and passed in front of a laser beam. Antibodies bind to cells that contain specific substances (antigens) whose presence indicates different stages of MDS. These cells give off light and are detected and counted by a computer. This test classifies MDS very accurately but is not required for all MDS patients.

Fluorescent In-Situ Hybridization (FISH): Abnormalities are located in chromosome segments with specific gene sequences. Fluorescent dyes that bind specifically to these sequences cause the areas to glow. FISH is not required for all patients, but is more sensitive than cytogenetic analysis and is helpful in giving an accurate prognosis.

Conclusion

If both blood tests and bone marrow tests reveal only mild dysplasia, i.e. less than five percent blasts and no cytogenetic abnormalities, then there is insufficient evidence to diagnose MDS. Patients are then monitored regularly with non-invasive procedures. In addition, genetic tests and immune cell examinations may be performed until the clinical criteria are met to diagnose MDS.

Patients diagnosed with MDS will be classified under the IPSS, WHO, and/or FAB system according to percentage of blasts in the blood, blood cell counts and morphology, and genetic findings. A patient’s individual health condition and specific classification are taken into account before proceeding with treatment.

Back to top

Prognosis »