Development of JAK2 positive myelofibrosis on a background of chronic myeloid leukaemia

[摘要] A 50-year-old male patient was admitted with a history of constitutional symptoms and weight loss with a marked leucocytosis(WBC 270 × 109/L) and blood film appearances suggestive of chronicmyeloid leukaemia (CML). Platelet count was normal at presentation(298 × 109/L).BCR-ABL1 was detected (b2a2) confirming CML. Bone marrowtrephine sections revealed a markedly expanded myeloid series but noexcess of blasts (Figure 1). Megakaryocytes were noted to be reducedin size with some bare nuclei seen. Cytogenetics confirmed 46,XY,t(9;22)(q34;q11) with no additional anomalies. He was commencedon imatinib but developed progressive full blood count abnormalities (WBC 9.6 × 109/L, Neutrophils 6.7 × 109/L, Hb 99 g/L, Platelets650 × 109/L) with an increase in his BCR-ABL1 ratio 3 months followingthis.