myelodysplastic syndromes
Meaning of myelodysplastic syndromes: The marrow is busy but unproductive, making faulty cells that die before reaching the blood, so counts fall while the marrow stays crowded.
Definition of myelodysplastic syndromes
Myelodysplastic syndromes are a group of blood cancers in which faulty stem cells in the bone marrow produce misshapen blood cells that work poorly and often die before reaching the circulation. The result is a shortage of red cells, white cells, platelets or any combination of them, despite a marrow that is usually crowded rather than empty.
Why are they counted as cancers?
Because each case begins in a single stem cell that acquires a genetic fault and then outcompetes its neighbors, so the bone marrow gradually fills with the descendants of one abnormal cell. That is the defining feature of a cancer, and it is why the older labels preleukemia and smoldering leukemia are misleading. They suggest a waiting room before the real disease, when the disease is already present and already causing harm through low blood counts. Most cases appear without an identifiable trigger and become more common with age. A minority follow earlier chemotherapy or radiation given for another cancer, or heavy exposure to solvents such as benzene, and that group tends to behave more aggressively.
What do the low counts cause?
| Cell in short supply | What follows |
|---|---|
| Red cells | Anemia, with tiredness, pallor and breathlessness on exertion |
| Neutrophils | Repeated or stubborn infections |
| Platelets | Easy bruising, nosebleeds and bleeding gums |
Anemia is usually the first thing noticed, and it is often the reason a blood count is ordered in the first place. The severity of the syndromes ranges widely, from a mild abnormality found on routine testing to disease that requires regular transfusion, and this range is why they are described as a group of syndromes rather than one condition.
How is the outlook judged?
Diagnosis rests on examining both blood and marrow, so a bone marrow aspiration and biopsy are central. A pathologist looks at the shape of the cells, counts the proportion of immature cells known as blasts, and sends samples for chromosome and gene testing. Those findings are combined with the depth of the low counts into a risk score, which estimates how likely the disease is to worsen and to turn into acute myeloid leukemia. The score matters because it separates people whose disease may be watched or supported with transfusion from those whose disease calls for treatment aimed at changing its course. Progression is not inevitable, and many people live with the condition for a long time without it ever developing.
Also known as
Used in a sentence
Bone marrow biopsy findings were consistent with a myelodysplastic syndrome.
Good to know
Some cases of myelodysplastic syndromes progress into acute myeloid leukemia, though the pace and likelihood of that progression vary widely between individuals. The older names preleukemia and smoldering leukemia are misleading, since the condition is itself a cancer of the marrow rather than a stage before one.
Word origin
Where “myelodysplastic syndromes” comes from
Formed from myelo-, Greek for marrow, dys-, meaning abnormal or difficult, and -plastic, from plassein, meaning to form, describing bone marrow that forms blood cells abnormally.