JAK2 V617F detected in two B-cell chronic lymphocytic leukemia patients without coexisting Philadelphia chromosome-negative myeloproliferative neoplasms: A report of two cases

Primary Immune Thrombocytopenia and Essential Thrombocythemia: So Different and yet Somehow Similar-Cases Series and a Review of the Literature

This article collects several published cases in which immune thrombocytopenic purpura (ITP) is followed by essential thrombocythemia (ET) and vice versa. This surprising clinical condition is possible, but very rare and difficult to diagnose and manage. We have made an attempt to analyse the possible causes of the sequential appearance of ITP and ET taking into consideration the following: alteration of the thrombopoietin (TPO) receptor, the role of autoimmunity and inflammation, and cytokine modulation. A better understanding of these interactions may provide opportunities to determine predisposing factors and aid in finding new treatment modalities both for ITP and ET patients.

Coexistence of chronic lymphocytic leukemia and polycythemia vera: a case report and review of the literature

Polycythemia vera is a Philadelphia chromosome-negative myeloproliferative neoplasm. Chronic lymphocytic leukemia is a monoclonal expansion of a CD5+ CD19+ B lymphocytes. Chronic myeloproliferative neoplasms may coexist with indolent B-cell malignant lymphomas of various types. The association of chronic lymphocytic leukemia with polycythemia vera is a rare event with only a few cases of coexistence ever reported. We report a 56-year-old man in whom these two disorders were diagnosed concomitantly. Possible etiopathogenic relationships between both disorders are discussed in this case report.

SIMILAR CASES PUBLISHED

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JAK2 tyrosine kinase mediates integrin activation induced by CXCL12 in B-cell chronic lymphocytic leukemia

Chemokines participate to B-cell chronic lymphocytic leukemia (B-CLL) pathogenesis by promoting cell adhesion and survival in bone marrow stromal niches and mediating cell dissemination to secondary lymphoid organs. In this study we investigated the role of JAK protein tyrosine kinases (PTK) in adhesion triggering by the CXC chemokine CXCL12 in normal versus CLL B-lymphocytes. We demonstrate that CXCL12 activates JAK2 in normal as well as CLL B-lymphocytes, with kinetics consistent with rapid adhesion triggering. By using complementary methodologies of signal transduction interference, we found that JAK2 mediates CXCL12-triggered activation of lymphocyte function-associated antigen-1 (LFA-1) and very late antigen-4 (VLA-4) integrins. We also show that JAK2 mediates the activation of the small GTP-binding protein RhoA, in turn controlling LFA-1 affinity triggering by CXCL12. Importantly, comparative analysis of 41 B-CLL patients did not evidence JAK2 functional variability between subjects, thus suggesting that JAK2, differently from other signaling events involved in adhesion regulation in B-CLL, is a signaling molecule downstream to CXCR4 characterized by a conserved regulatory role. Our results reveal JAK2 as critical component of chemokine signaling in CLL B-lymphocytes and indicate JAK inhibition as a potentially useful new pharmacological approach to B-CLL treatment.

Acute Lymphoblastic Leukemia in the Course of Polycythemia Vera: A Case Report and Review of Literature

INTRODUCTION

Polycythemia vera (PV) is one of the most common forms of myeloproliferative neoplasms. Acute myeloid leukemia secondary to PV is well reported, and the mechanism has been clarified to some extent. Only a limited number of cases have been reported about the development of acute lymphoblastic leukemia (ALL) in the course of PV, and the possible underlying mechanism has not been explored well.

CASE PRESENTATION

A 75-year-old patient who developed ALL 3 years after he was diagnosed with PV. The presence of remarkable splenomegaly, typical immunophenotyping of the peripheral blood and increased expression of serum fibrosis markers indicated the existence of extramedullary hematopoiesis which may ascribe to myelofibrosis. After the treatment of dosage-modulated chemotherapy, the patient got complete remission.

CONCLUSION

The JAK2 mutation may the underlying factor that contributes to the development of ALL, and the existence of MF may indicate the progression to post- polycythemic MF, which may be a risk factor for the accelerated transformation.