The objective of this study was to evaluate the clinical features, prognostic factors, and efficacy of treatments in patients with blastic plasmacytoid dendritic cell neoplasm with a leukemic presentation at onset of the disease. In order to do this, a retrospective multicenter study was performed from 2005-2011 in 28 Italian hematology divisions in which 43 cases were collected. Forty-one patients received an induction therapy, consisting of an acute myeloid leukemia-type regimen in 26 patients (60%) and acute lymphoid leukemia/lymphoma-type regimen in 15 patients (35%). Six patients (14%) underwent allogeneic hematopoietic stem cell transplantation. Seventeen patients (41%) achieved a complete remission: seven after acute myeloid leukemia-type treatment and 10 after an acute lymphoid leukemia/lymphoma-type regimen, with a significant advantage for acute lymphoid leukemia/lymphoma-type chemotherapy (P=0.02). Relapse occurred in six of the 17 patients (35%) who achieved complete remission, more frequently after acute lymphoid leukemia/lymphoma-type chemotherapy. The median overall survival was 8.7 months (range, 0.2-32.9). The patients treated with an acute myeloid leukemia-type regimen had an overall survival of 7.1 months (range, 0.2-19.5), whereas that of the patients receiving acute lymphoid leukemia/lymphoma-type chemotherapy was 12.3 months (range, 1-32.9) (P=0.02). The median overall survival of the allogeneic hematopoietic stem cell transplant recipients was 22.7 months (range, 12-32.9), and these patients had a significant survival advantage compared to the non-transplanted patients (median 7.1 months, 0.2-21.3; P=0.03). In conclusion, blastic plasmacytoid dendritic cell neoplasm with bone-marrow involvement is an aggressive subtype of high-risk acute leukemia. The rarity of this disease does not enable prospective clinical trials to identify the better therapeutic strategy, which, at present, is based on clinicians' experience. Blastic plasmacytoid dendritic cell neoplasm with leukemic presentation: an Italian multicenter study

The distinction between malignant mesothelioma and reactive mesothelial proliferation can be challenging both on histology and cytology. Recently, variants of the BRCA1-associated protein 1 (BAP1) gene resulting in nuclear protein loss were reported in hereditary and sporadic mesothelioma. Using immunohistochemistry, we evaluated the utility of BAP1 expression in the differential diagnosis between mesothelioma and other mesothelial proliferations on a large series of biopsies that included 212 mesotheliomas, 12 benign mesothelial tumors, and 42 reactive mesothelial proliferations. BAP1 stain was also performed in 70 cytological samples (45 mesotheliomas and 25 reactive mesothelial proliferations). BAP1 was expressed in all benign mesothelial tumors, whereas 139/212 (66%) mesotheliomas were BAP1 negative, especially in epithelioid/biphasic compared with sarcomatoid/desmoplastic subtypes (69% vs 15%). BAP1 loss was homogeneous in neoplastic cells except for two epithelioid mesotheliomas showing tumor heterogeneity. By fluorescence in situ hybridization, BAP1 protein loss was paralleled by homozygous deletion of the BAP1 locus in the vast majority of BAP1-negative tumors (31/41, 76%), whereas 9/10 BAP1-positive mesotheliomas were normal. In biopsies interpreted as reactive mesothelial proliferation BAP1 loss was 100% predictive of malignancy, as all 6 cases subsequently developed BAP1-negative mesothelioma, whereas only 3/36 (8%) BAP1-positive cases progressed to mesothelioma. On cytology/cell blocks, benign mesothelial cells were invariably positive for BAP1, whereas 64% of mesotheliomas showed loss of protein; all 6 cases showing BAP1 negativity were associated with histological diagnosis of BAP1-negative mesothelioma. BAP1 stain also showed utility in the differential of mesothelioma from most common pleural and peritoneal mimickers, such as lung and ovary carcinomas, with specificity and sensitivity of 99/70% and 100/70%, respectively. Our results show that BAP1 protein is frequently lost in mesothelioma, especially of epithelioid/biphasic subtype and is commonly associated with homozygous BAP1 deletion. BAP1 immunostain represents an excellent biomarker with an unprecedented specificity (100%) in the distinction between benign and malignant mesothelial proliferations. Finding BAP1 loss in mesothelial cells should prompt to immediately reevaluate the patient; moreover, it might be useful in mapping tumor extent and planning surgical resection.

Various studies have described abnormalities of the enteric nervous system (ENS) in tissue samples from patients with chronic idiopathic inflammatory bowel diseases (IBD). The distribution of density of the different cell types of the ENS was however not studied in a systematic way. The aim of this study was to examine the density of neurons, enteroglial cells and interstitial cells of Cajal (ICC) in the different plexuses of the ENS in samples from patients with Crohn's disease (CD), ulcerative colitis (UC) and controls. Tissue samples from 16 patients with CD (ileum) and 16 patients with UC obtained in involved and non-involved areas were studied using immunohistochemistry with antibodies directed against neuron-specific enolase, S100, C-Kit and CD3. Sections were analysed blindly by two pathologists and the number of positive cells was counted for each type. Overall, an increase was noted for neuronal cell bodies, enteroglia and ICC in the deep muscular plexus in CD. In uninvolved areas of CD patients, the number of enteroglial cells was decreased. In UC, an increase of ICC in the muscularis propria and enteroglial cells was observed in diseased tissue. The study confirms the presence of abnormalities of the different cells of the ENS in IBD. The presence of lesions in samples from uninvolved areas, such as a reduction of enteroglia, supports a pathogenetic role of the ENS.