Fifty-five essential thrombocythemia patients follow-up study in single institution of Japan

Background: Report on the changes of diagnostic criteria since 1970 and correspondence due to the development of new therapeutic drugs during long term clinical period.Patients and method: The subjects were Fifty-five ET patients who were 21-95years old who newly diagnosed Sendai Blood Disease Center (renaming Sendai Tomita Hospital from March 2013) between 1991 year and 2010 year.As a substitute for bone biopsy for convenient diagnostic tool, we diagnosed essential thrombocythemia (ET) by the smear sample of bone marrow aspiration focusing on platelet production of megakaryocyte cytoplasm.Result: We classified megakaryocytes into 7 types (0 to 5 and U) with platelet counts in the cytoplasm.We named Type U which was filled and spilling out platelets from megakaryocyte.Type U was not observed in our experienced 25 chronic myeloid leukemia cases, 10 polycythemia vera cases and another hematologic malignancies.The proportion of seven types was Type 0 was 35.9%, type I 4.7%, type II 6.0%, type III 3.0%, type IV 0.8%, type NK 4.4% and type U was 45.2% respectively.30 males and 25 females, the age at the time of diagnosis was the median 64 years and range 21 to 95 with 61.8% above the age 60 years.The observation periods was from 17 months to 303 months and the median was 94 months.The main goal in ET is to prevent thrombohemorrhagic complications and the same for older patients.The frailty of elderly people, 15 of the 19 patients who stopped receiving medical examination was brought about by falls and aspiration pneumonia which caused the physical condition to decrease, not accompanied by ET treatment.The cause of frailty in older ET patients was irrespective ET treatment, and so on based on risk-adapted therapy was necessary for older ET patients.Conclusion: Megakaryocytes of ET patients showed platelet-free production and overproduction of platelets in cytoplasm.Based on risk-adapted therapy was necessary for frail older ET patients.