Myelodysplastic syndrome (MDS)

Myelodysplastic syndrome (MDS) is the umbrella term for a group of disorders in which the body does not produce enough myeloid cells in the bone marrow, and those myeloid cells produced often do not function correctly.  Myeloid cells are certain types of white blood cells, like eosinophils, basophils, neutrophils and mast cells.  MDS patients develop low blood cell counts due to failure of the bone marrow to produce enough cells.

Not all patients with MDS have symptoms.  Those who do are often tired and short of breath.  They may have chest pain and are more likely to develop frequent infections.  They often bruise and bleed easily.  When investigated, patients are often found to have low white and red blood cell counts, as well as low platelets.  The spleen is often swollen.  When blood is looked at with a microscope, the blood cells are often shaped wrong.

In order to determine if MDS is the cause of the low cell counts, blood tests are performed to rule out other causes, like hemolytic anemia.  A bone marrow biopsy is the deciding factor in diagnosis.  Once it is diagnosed, further testing is done to determine the reason for MDS, including chromosome studies.  Exposure to some chemicals can cause MDS, including some types of chemotherapy.  Radiation can also cause MDS.  People exposed to Agent Orange are at risk.

Blood transfusions are a mainstay of MDS treatment and can lead to iron overload, which causes liver, heart and endocrine dysfunction.  5-azacytidine, decitabine and lenalidomide are medications used in the treatment of MDS.  Decitabine and lenalidomide treatment result in fewer blood transfusions and decreases the risk of developing AML leukemia. 

In very severe patients, stem cell transplant may be considered.  Stem cell transplant has about a 50% survival rate 3 years after transplant.  However, for those who survive, it can be curative.  Stem cell transplant is more likely to be successful in patients under 40.

The majority of MDS patients progress to AML leukemia that is hard to treat.  Younger age, normal or moderately reduced neutrophil count, normal or moderately reduced platelet count, less than 20% blasts in bone marrow and no blasts in the blood generally indicate a better prognosis.  Severely low neutrophil or platelet count, more than 20% blasts in bone marrow or blasts in the blood, abnormal or immature granulocyte precursor cells in the bone marrow and severe chromosome abnormalities indicate a poorer prognosis.

MDS sometimes occurs in patients who have SM.  SM-MDS accounts for 23% of cases of SM-AHNMD.  I do not know the frequency with which MDS occurs in MCAS patients, but I would not surprised to find that some people have both.