[Clinical Analysis of 66 Patients with Essential Thrombocytopenia]

To investigate the clinical characteristics of essential thrombocytopenia (ET) patients with positive mutations including JAK2, CALR, MPL, or negative mutations.

A total of 66 newly diagnosed ET cases from January 2016 to December 2018 in Department of Hematology, Huaian No.1 People's Hospital affiliated to Nanjing Medical University were analyzed. Statistical analysis data included the patient's sex, age, symptoms, thrombosis and embolism events, spleen omegaly, platelet count (Plt), leukocyte (WBC) count, hemoglobin (Hb), fibrinogen (FIB), thrombus elastic diagram (TEG), serum potassium, blood glucose (GLU), lactate dehydrogenase (LDH), JAK2, CALR and MPL mutations, treatment options, and efficacy.

All the patients were not MPL-positive, and divided in three groups: JAK2 mutation (46 cases, 69.7%), CALR mutation (9 cases, 13.6%) and gene negative mutation (11 cases, 16.7%) group. The average age of patients in the JAK2 mutation group was 63.2 years old, and significantly higher than that in the CALR mutation group (51.8 year) and gene negative group (50.2 year) (P＜0.05). Compared with the JAK2 mutation group and gene negative group, the CALR mutation group had lower WBC count (6.3×10⁹/L vs 13.79×10⁹/L) (P=0.003) (6.3×10⁹/L vs 9.70×10⁹/L) (P=0.009). Also the Hb level of patients in CALR mutation group was lower than the JAK2 mutation group (121.22 g/L vs 136.2 g/L) (P=0.036). However, there was higher tumor burden in the CALR mutation group, compared with the gene negative mutation group (300.11 U/L vs 227.4 U/L) (P=0. 033). There was no significant difference among the three groups, such as the Plt counts, serum potassium level, GLU level and FIB level (P＞0.05). In addition, thrombus and embolism appeared in 30.3% (20/66) cases. 18.2% (12/66) cases were complicated with hyperkalemia, which significantly correlated with Plt counts (r=0.518). TEG was performed in 34 patients, of which 41.2% (14/34) had abnormal TEG and 55.9% (19/34) were accompanied by Plt count ＞ 1 000 ×10⁹/L, but there was no significant correlation between them (r=0.134). After routine clinical treatment, all the 66 cases achieved partial or complete hematological remission, but the disease usually repeated. Until now 4.5% (3/66) cases had been converted to myelofibrosis (MF) all with JAK2 mutation, but without advancing to acute myeloid leukemia.

ET patients with JAK2 mutation have higher incidence, moreover were in older age. However, the patients with CALR mutations display lower WBC count and Hb level, but higher tumor burden. In short, the multiple gene mutations of ET showed different clinical features closely relates with the prognosis, thus providing guidance for the clinical diagnosis and treatment.