Essential thrombocytosis is primarily a diagnosis of exclusion. Other causes to be ruled out are a reactive thrombocytosis, and thrombocytosis seen in other myeloproliferative diseases.
The patient usually presents with bruising, bleeding and cerebrovascular symptoms. The spleen may be enlarged early in the disease but then is reduced, and may possibly atrophy, as a result of recurrent thromboses.
Very small or giant platelets are often present. The bone marrow is hypercellular with an increased number of megakaryocytes, many of which are often abnormally shaped and clustered. The white cell count may be normal or elevated.
Last reviewed 01/2018