Myelodysplastic syndromes (MDS) diagnosis

Diagnostic criteria for MDS

The diagnosis of MDS is based on:

• At least one “cytopenia” (low blood cell count) in red blood cell, white blood cell, and/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 of “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).

Blood cell counts

A test called a “complete blood count (CBC)” is used to count the number of red blood cells, white blood cells and platelets in a sample of blood. Most patients with MDS have low blood cell counts, called “cytopenias.” Most often they have too few red blood cells. They may also have low white blood cell counts and/or low platelet counts. The CBC should include a "differential." This measures the different types of white blood cells in the sample.  

Learn more about blood tests.

Peripheral blood smear

In this test, a single drop of blood is spread on a glass slide, dried and then stained with a special dye. The sample is viewed under a microscope to examine the number, size, shape and appearance of the blood cells. In MDS, some blood cells have an abnormal shape or size, called dysplasia. A peripheral blood smear also checks for blast (immature) cells in the blood. Blast cells are not normally found in the blood.

Bone marrow tests

 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

View a 3D model of a bone marrow biopsy and aspiration. Click or tap the "Interact in 3D" button to begin.

View all 3D models.

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 

Learn more about bone marrow tests.

Cell examination  

At the laboratory, the cells from the blood and bone marrow samples are examined under a microscope. The types of cells and their shape and size are important findings. Another important finding is the percentage of immature MDS blast cells in the bone marrow and the blood.

Additional tests are done on the blood and bone marrow samples to determine the subtype of MDS.

Biomarker testing

These laboratory tests check for changes in the proteins, genes and chromosomes of the cancer cells. Each person’s cancer has a unique pattern of biomarkers. Biomarker testing is used to determine the MDS subtype and help plan treatment.

• Cytogenetic analysis (Karyotyping): Each cell in the body has chromosomes that carry genes. Genes give the instructions that tell each cell what to do. Cytogenetic analysis is used to look for abnormal changes in the chromosomes in the MDS cells.
• FISH (Fluorescence In situ hybridization): This test is used to examine genes and chromosomes in cells and tissues. Doctors use FISH to find certain abnormal changes in the chromosomes and genes of the MDS cells.
• Next-generation sequencing: This test looks for mutations in the genes of MDS cells. Certain mutations are markers that can help doctors identify a patients MDS subtype and predict how the disease will progress.

Learn more about blood tests.

MDS subtypes

There are several kinds (subtypes) of MDS. The subtype is determined by the results of the blood and bone marrow tests. It is important to know your MDS subtype because it can affect both your prognosis (outlook) and your treatment plan. If you are not sure of your MDS subtype, ask your doctor what it is and to explain how your MDS subtype affects your treatment plan. 

World Health Organization (WHO) classification

The current WHO classification guidelines, which were updated in 2022, groups MDS based on genetic abnormalities and morphologically defined features (the appearance and number of the cells under a microscope).

The subtypes are determined by the following: 

• Low blood cell counts (red blood cells, white blood cells and/or platelets)
• Dysplasia (cells that have an abnormal shape or size)
• The number of blast cells (immature blood cells) in the blood and bone marrow
• Changes to the chromosomes and genes in bone marrow cells that are associated with MDS

MDS with defining genetic abnormalities

• MDS with low blasts and isolated 5q deletion (MDS-5q)
• MDS with low blasts and SF3B1 mutation (MDS-SF3B1)
• MDS with biallelic TP53 inactivation (MDS-biTP53)

Morphologically defined MDS

• MDS with low blasts (MDS-LB)
• MDS with low blasts and ring sideroblasts (MDS-LB-RS)
• MDS, hypoplastic (MDS-h)
• MDS with increased blasts

International Prognostic Scoring Systems

A prognosis is a prediction of the likely outcome of a disease. Doctors often use scoring systems for people with MDS. The following scoring systems were created to predict overall survival and whether the disease will develop into a fast-growing cancer called acute myeloid leukemia (AML).  Scoring systems also help doctors determine appropriate treatment.

International Prognostic Scoring System (IPSS)  

The IPSS was the first widely used scoring system for MDS. A patient’s score is based on three factors:

• The percentage of blasts (immature cells) in the bone marrow
• The type of chromosomal abnormalities in the cancer cells
• Low blood cell counts  

Each factor is given a score. Then the scores are added up to place patients into four risk groups:  

• Low
• Intermediate-1
• Intermediate-2
• High

International Prognostic Scoring System-Revised (IPSS-R)

The revised IPSS, known as the “IPSS-R,” covers the same disease factors as the IPSS, but the factors are identified in a more detailed way. The IPSS-R shows five disease factors:

• The percentage of blasts (immature cells) in the bone marrow
• The type of chromosomal abnormalities in the cancer cells
• The level of red blood cells (measured as hemoglobin) in the blood
• The level of platelets in the blood
• The level of neutrophils (a type of white blood cell) in the blood  

Based on these factors, patients are placed into the following risk groups: 

• Very low
• Low
• Intermediate
• High
• Very high

International Prognostic Scoring System-Molecular (IPSS-M)

In 2022, the IPSS-R was updated to include MDS-associated gene mutations. The International Prognostic Scoring System-Molecular (IPSS-M) considers blood counts, such as anemia and low platelet counts, the percentage of bone marrow blasts and the presence of certain chromosomal abnormalities.

Unlike the IPSS-R, the IPSS-M also considers whether certain gene mutations are present and how many are mutated. The IPSS-M classifies MDS into six risk groups:

• Very low
• Low
• Moderate low
• Moderate high
• High
• Very high