The proposed revised World Health Organization criteria for the diagnosis of essential thrombocythemia requires the following criteria.
Sustained platelet count of at least 450 × 109 /L.
Bone marrow biopsy showing predominant proliferation of enlarged mature megakaryocytes; no significant increase of granulocytic or erythroid precursors. This finding distinguishes essential thrombocythemia from another entity with thrombocytosis, namely prefibrotic...
About 12,000 Americans develop different types of myelodysplastic syndrome each year. The risks of MDS increase with age. Factors that raise your risk of these problems include:
Cancer therapy. The use of certain chemotherapy drugs for cancer plays a role in many cases of later myelodysplastic syndrome. MDS may be more likely to occur after treatment for acute lymphocytic leukemia in childhood, Hodgkin's disease, or non-Hodgkin's lymphoma.
Cancer drugs linked to myelodysplastic syndrome include:
Some inherited conditions raise people's risk of having myelodysplastic syndrome. These include:
Fanconi anemia. In this condition, the bone marrow fails to make sufficient amounts of all three types of blood cells.
Shwachman-Diamond syndrome. This keeps the bone marrow from making enough white blood cells.
Severe congenital neutropenia. This condition is marked by insufficient neutrophils, which are a type of white blood cell.
Exposure to chemicals. You may be more likely to develop myelodysplastic syndrome if you're exposed to certain industrial chemicals over a long period of time. Smoking also raises people's risk of MDS.