Abstract
Triple-negative essential thrombocythemia (ET) is a condition in which mutations in JAK2, CALR and MPL are all negative. Transformation to acute myeloid leukemia may occur during the course of ET, while B-acute lymphoblastic leukemia B-(ALL) is rare. We experienced a case diagnosed as B-ALL during the course of triple-negative ET. Notably, cytoreduction was required for the excessive increase in blood cells during the bone marrow recovery period after chemotherapies. Whole exome sequencing identified 17 somatic mutations: 9 were identified in both ET and B-ALL samples, while 8 were specific to B-ALL, suggesting that these 8 might have caused the transformation.