A case of transformation of polycythemia vera to chronic myelogenous leukemia

초록

Polycythemia vera (PV) is one of the Philadelphia chromosome-netative chronic myeloproliferative neoplasms characterized by increased red blood cell production and a clonal disorder arising in a hematopoietic cell. The most common pattern of the disease progression is port-polycythhemic myelofibrosis accompanied by myeloid metaplasia, myelodysplasi, or AML. The development of CML in the course of PV is extremely rare. We report a case PV transformed to CML. A 55-yr-old woman had been treated with hydroxyurea and phlebotomies for 5 years under PV diagnosis. At initial worl up, CBC analysis revealed HB 20.5 g/dL, WBC 21.4 x 10(9)/L and platelet count 545 s 10(9)/L; bone marrow aspiratio and biopsy revealed panmyelosis with a decreased myeloid to erythroid ratio (1:1) and 100% cellularity. There was no evidence of myelofibrosis. Erythropoietin was 3.5 mIU/mL (10.2 - 25.2) and 90 - 100% JAK2 V617F mutation was detected. Bone marrow cell cytogenetic study showed a 46,XX,del(13)(q12Q14) karyotype in the majority of examined cells (12/20). After 49 months, leukocytosis and thrombodcytosis were found on CBC. Although hydroxyurea was continuously administrated, WBC and platelet countwere gradually increased. The second bone marrow examination was performed 60 months after initial diagnosis: Hb 12.5 g/dL, WBC 29.0 x 10(9)/L. Bone marrow aspiration and biopsy showed 90% cellularity with a 2:1 myeloid to erythroid ration and markedly increased egalaryocytes. An analysis of allele-specific real-time quantitative PCR revealed no JAK2 V617F mutaion, and FISH fo BCR-ABL1 gene rearrangement revealed a fusion aignal in 8.8% of interphase cells. Cytogenetic study on bone marrow cells showed 46,XX,t(9;ss)(q34;q11.2)[3/32].