Essential thrombocytosis with the Philadelphia chromosome (Ph').

Essential thrombocytosis is a myeloproliferative disease not known to have consistent cytogenetic abnormalities. A 46-year-old black woman with essential thrombocytosis and a Philadelphia chromosome is reported. Iron deficiency and tuberculosis were present but when effectively treated did not result in resolution of thrombocytosis. Megakaryocytic hyperplasia of bone marrow, abnormal platelet function studies and a compatible clinical state suggested the diagnosis of essential thrombocytosis. The diagnostic criteria for other myeloproliferative diseases were not met. The Philadelphia chromosome was consistently obtained from bone marrow preparations. We conclude that the Philadelphia chromosome may be found in essential thrombocytosis as well as other, previously reported, myeloproliferative diseases.