Search

The BRAF-V600E mutation defines genetically hairy cell leukemia among B-cell leukemias and lymphomas. In solid tumors, BRAF-V600E is known to aberrantly activate the oncogenic MEK-ERK pathway, and targeted BRAF and/or MEK inhibitors have shown remarkable efficacy in clinical trials in melanoma patients. However, the MEK-ERK pathway status in hairy cell leukemia has not been thoroughly investigated. We assessed phospho-ERK expression in 37 patients with hairy cell leukemia and 44 patients with neoplasms mimicking hairy cell leukemia (40 splenic marginal zone lymphoma, 2 hairy cell leukemia-variant and 2 splenic lymphoma/leukemia unclassifiable) using immunohistochemistry on routine biopsies and/or Western blotting on purified leukemic cells, and correlated the phospho-ERK status with the BRAF-V600E mutation status. Besides confirming the constant presence of BRAF-V600E in all patients with hairy cell leukemia, we observed ubiquitous phospho-ERK expression in this malignancy. Conversely, all 44 cases with neoplasms mimicking hairy cell leukemia were devoid of BRAF-V600E and none expressed phospho-ERK. Furthermore, the two exceptionally rare cases of non-hairy cell leukemia unclassifiable chronic B-cell neoplasms previously reported to be BRAF-V600E(+) on allele-specific polymerase chain reaction lacked phospho-ERK expression as well, suggesting the presence of the mutation in only a small part of the leukemic clone in these cases. In conclusion, our findings support the use of phospho-ERK immunohistochemistry in the differential diagnosis between hairy cell leukemia and its mimics, and establish the MEK-ERK pathway as a rational therapeutic target in this malignancy.

Within a cohort of 1,915 consecutive patients with myeloproliferative neoplasm followed for a median time of 5.2 years (range 0-33.3), we investigated the occurrence of lymphoid neoplasm with the aim of defining this risk and to investigate the role of genetic predisposing factors. We identified 22 patients with myeloproliferative neoplasm who developed lymphoid neoplasm over their lifetime. We found that the risk of developing lymphoid neoplasm was 2.79-fold higher (95% CI, 1.80-4.33; P<0.001) than that of the general Italian population. A tag SNP surrogate for JAK2 GGCC haplotype was used to clarify a potential correlation between lymphoid-myeloid neoplasm occurrence and this genetic predisposing factor. As we did not find any difference in GGCC haplotype frequency between patients with both myeloid and lymphoid neoplasm and patients with myeloid neoplasm, JAK2 GGCC haplotype should not be considered a genetic predisposing factor. No difference in familial clustering was observed between the two groups.

Risk stratification in primary myelofibrosis is currently based on two international prognostic scoring systems, neither of which takes into consideration red blood cell transfusion-dependency. In 288 consecutive patients with primary myelofibrosis, red blood cell transfusion-dependency at diagnosis affects survival independently of the International Prognostic Scoring System (P < 0.001). To evaluate the dynamic impact on survival of red blood cell transfusion-dependency, we performed a Cox's regression analysis with transfusion status as time-dependent covariate in 220 regularly followed patients with primary myelofibrosis. Patients who begin red blood cell transfusions anytime (n = 80, 36%) have a significantly worse survival compared to those who continue follow up without transfusions (HR: 7.8, 95%CI: 5.1-11.9; P < 0.001). Adjusting for Dynamic International Prognostic Scoring System in a multivariate analysis, red blood cell transfusion-dependency retained an independent prognostic impact on survival. This study suggests that red blood cell transfusion-dependency should be considered to improve risk stratification of primary myelofibrosis during follow up.

CD146(+) bone marrow stromal cells have been recently recognized as clonogenic osteoprogenitors able to organize a complete hematopoietic microenvironment. In this study we used immunohistochemical analysis to investigate the contribution of CD146(+) bone marrow osteoprogenitors to the stromal remodeling occurring in the different stages of primary myelofibrosis. We found that CD146(+) cells sited at the abluminal side of the bone marrow vessels and branching among hematopoietic cells significantly increased in the advanced stages of primary myelofibrosis (p<0.001), paralleling the extent of fibrosis (rho=0.916, p<0.0001) and the microvascular density (r=0.883, p<0.0001). Coherently with a mural cell function, such cells also displayed smooth-muscle actin expression. Our data providing evidence of CD146(+) cell involvement in bone marrow stromal changes occurring in primary myelofibrosis are consistent with the capability of these cells to participate in fiber deposition, angiogenesis, and bone formation. They could also represent rationale for new therapies targeting the bone marrow stroma in primary myelofibrosis.

Background: Essential thrombocythemia is a chronic myeloproliferative disorder; patients with this disorder have a propensity to develop thrombosis, myelofibrosis, and leukemia., Design and Methods: We studied 605 patients with essential thrombocythemia (follow-up 4596 person-years) with the aim of defining prognostic factors for thrombosis, myelofibrosis, and leukemia during follow-up., Results: Sixty-six patients (11%) developed thrombosis with a 10-year risk of 14%. Age >60 years (p<0.001) and a history of thrombosis (p=0.03) were independent risk factors for thrombosis. Progression to myelofibrosis occurred in 17 patients (2.8%) with a 10-year risk of 3.9%. Anemia at diagnosis of essential thrombocythemia was significantly correlated (p<0.001) with progression to myelofibrosis. Leukemia occurred in 14 patients (2.3%) at a median time of 11 years after the diagnosis of essential thrombocythemia; the risk was 2.6% at 10 years. Age >60 years (p=0.02) was significantly correlated with the development of leukemia. Cytotoxic treatment did not imply a higher risk of leukemia. At the time of the analysis, 64 of the 605 patients (10.6%) had died. The 10-year probability of survival was 88%, with a median survival of 22.3 years. Age >60 years (p<0.001) and history of thrombosis (p=0.001) were independent risk factors for survival., Conclusions: The findings from this study on a large series of patients treated according to current clinical practice provide reassurance that essential thrombocythemia is an indolent disorder and affected patients have a long survival. The main risk is thrombosis, while myelofibrosis and leukemia are rare and late complications.

Background: The marginal zone is an anatomically distinct B-cell compartment of lymphoid tissue with an abundant antigenic influx. Among marginal zone-derived lymphomas the WHO classification listed, in addition to extranodal marginal zone B-cell lymphoma of MALT type, two other marginal zone B-cell neoplasms: splenic marginal zone B-cell lymphoma (+/- villous lymphocytes) and nodal marginal zone B-cell lymphoma (+/- monocytoid B cells). These two entities are well characterized histologically, but specific biological markers are lacking. Treatment options are heterogeneous, including a watch-and-wait policy, surgery with or without chemotherapy, purine analogs, and interferon. No prospective studies have been conducted so far., Information Sources: Clinical and pathologic data were reviewed by searches of the published medical literature, including searches in PubMed , important printed publications, and abstracts presented at recent hematology and pathology meetings., State of the Art: Splenic and nodal marginal zone lymphomas are typical low-grade lymphomas with an indolent course. A subset of patients, however, presents with more aggressive disease and have a shorter survival. Clinical and biological prognostic factors identified in reported series are heterogeneous. The role played by hepatitis C virus (HCV) in marginal zone lymphomas is not fully elucidated, but there is demonstration that eradication of HCV infection in splenic lymphoma with villous lymphocytes causes regression of the lymphoma. The optimal treatment has not yet been identified. Retrospective series, however, show that splenectomy is a good option if symptoms from the presence of spleen enlargement or cytopenias need to be treated. The utility of purine analogs and of anti-CD20 immunotherapy needs to be clarified in prospective trials., Perspectives: Clinicians and pathologists should co-operate to define stringent diagnostic criteria for these indolent disorders. The optimal therapeutic approach and the role of new treatments need to be assessed in prospective clinical trials.