Lê–Greuel type formula for the Euler obstruction and applications

The Euler obstruction of a function f can be viewed as a generalization of the Milnor number for functions defined on singular spaces. In this work, using the Euler obstruction of a function, we establish several Lê–Greuel type formulas for germs f:(X,0)→(C,0) and g:(X,0)→(C,0). We give applications when g is a generic linear form and when f and g have isolated singularities.

Deriving Deligne-Mumford stacks with perfect obstruction theories

Intersection theory on moduli spaces has lead to immense progress in certain areas of enumerative geometry. For some important areas, most notably counting stable maps and counting stable sheaves, it is important to work with a virtual fundamental class instead of the usual fundamental class of the moduli space. The crucial prerequisite for the existence of such a class is a two-term complex controlling deformations of the moduli space. Kontsevich conjectured in 1994 that there should exist derived version of spaces with this specific property. Another hint at the existence of these spaces comes from derived algebraic geometry. It is expected that for every pair of a space and a complex controlling deformations of the space their exists, under some additional hypothesis, a derived version of the space having the chosen complex as cotangent complex. In this thesis one version of these additional hypothesis is identified. We then show that every space admitting a two-term complex controlling deformations satisfies these hypothesis, and we finally construct the derived spaces.

Rapid spontaneous malignant progression of supratentorial tanycytic ependymoma with sarcomatous features - "Ependymosarcoma"

By analogy to gliosarcoma, the term "ependymosarcoma" has recently been coined to thematize the rare phenomenon of a malignant mesenchymal component arising within an ependymoma. We report on an example of this paradigm, involving tanycytic ependymoma as the host tumor in a 40-year-old female who underwent two tumor extirpation procedures at one-year interval. She first presented with severe headaches, and was seen by imaging to harbor a moderately enhancing mass 2.5cm in diameter at the rostral septum pellucidum accompanied by occlusive hydrocephalus. Microscopically, the tumor consisted of solid, wavy fascicles of elongated cells that were occasionally interrupted by vague perivascular pseudorosettes. Mitotic activity was absent, and less than 1% of nuclei immunoreacted for MIB-1. A histological diagnosis of tanycytic ependymoma (WHO grade II) was rendered, and no adjuvant therapy given. At recurrence, the lesion was 3.5cm in diameter, intensely enhancing, and had already seeded into the subarachnoid space. Histology showed a biphasic glial-sarcomatous architecture with remnants of the original ependymoma now displaying hypercellularity and atypical - yet not frankly anaplastic - features. The sarcomatous moiety consisted of spindle and epithelioid cells densely interwoven with reticulin fibers. While the ependymal component was GFAP and S100 protein positive, and featured punctate staining for EMA, none of these markers was expressed in the adjacent sarcoma. Instead, the latter reacted for vimentin and smooth muscle actin. To the best of our knowledge, this is the first documentation of tanycytic ependymoma undergoing malignant transformation, one driven by a highly anaplastic mesenchymal component, corresponding to "ependymosarcoma".

[The thoracoscopic talc pleurodesis with intraoperative pleural biopsy - a retrospective analysis in patients with malignant pleural effusion]

The thoracoscopic pleurodesis with talc is an established therapy in case of malignant pleural effusion. With the instillation of talc a -localised inflammation is induced. However, some-times it turns into a severe systemic reaction. In this study of the postoperative course, the -question is examined whether a pleural biopsy is an additional risk factor for morbidity and mortality after talc pleurodesis.

Putative cancer stem cells in malignant pleural mesothelioma show resistance to cisplatin and pemetrexed

Malignant pleural mesothelioma (MPM) is a lethal cancer of the mesothelium with high chemotherapeutic resistance via unknown mechanisms. A prevailing hypothesis states that cancer stem cells (CSCs) persist in tumors causing relapse after chemotherapy, thus, rendering these cells as critical targets responsible for tumor resistance and recurrence. We selected candidate CSC markers based on expansion under hypoxic conditions, a hallmark for the selection of chemoresistant cells; and investigated the expression of CSC markers: CD133, Bmi-1, uPAR and ABCG2 in three MPM cell lines and normal mesothelial cells by quantitative RT-PCR. Furthermore, we evaluated the chemotherapeutic resistance associated with each CSC marker by determining the change in CSC marker-mRNA levels as an index of drug-resistance following treatment with either cisplatin or pemetrexed. We demonstrate the expression of CSC markers: CD133, Bmi-1, uPAR and ABCG2 in both normal and MPM cell lines. Bmi-1+, uPAR+ and ABCG2+ cells show a distinct role in conferring chemoresistance to cisplatin and pemetrexed in the malignant setting. By contrast, these markers have no apparent participation in chemoresistance to drug treatments in normal mesothelial cells. Intriguingly, CD133 revealed chemoresistant properties in both normal mesothelial and malignant pleural mesothelioma cells. This study provides evidence of putative CSCs conferring drug-resistance to cisplatin and pemetrexed in MPM cell lines. Specific targeting of these drug-resistant cells, while considering the functional heterogeneity of the MPM subtypes, may contribute to more focused and effective chemotherapeutic regimens for malignant pleural mesothelioma.

An uncommon cause of coronary artery ostial obstruction: papillary fibroelastoma

Cardiac papillary fibroelastoma is a benign tumor that mainly affects cardiac valves. The tumor has the potential to cause angina and myocardial infarction due to embolization of tumor fragments. We describe a rare case of right coronary artery ostial obstruction by a 12 x 19 mm sized papillary fibroelastoma located in the sinus of Valsalva. The report underlies the importance of echocardiography in diagnosis and intraoperative treatment of this type of cardiac mass.

[Pathology of malignant lymphomas--clarity instead of confusion]

After decades of confusion in lymphoma classification clearness was achieved with the publication of the REAL classification 1994 and of the WHO classification 2001. The revised 4th edition 2008 features some additional new categories. The WHO classification comprises B- and T-lymphoblastic neoplasms, mature B-cell lymphomas, mature T-cell and NK-cell lymphomas and Hodgkin lymphomas. A modern diagnostic work-up of lymphomas is based on morphology, immunohistochemistry and increasingly on molecular studies. Last but not least the evaluation of all these findings by an expert haematopathologist, who collaborates closely with the treating clinicians, is essential. The aim is to give an overview of the most frequent mature B-cell lymphomas and the most important classical Hodgkin lymphomas with focus on morphology and immunohistochemistry.

Peptide receptor radioligand therapy is an effective treatment for the long-term stabilization of malignant gastrinomas

Gastrinomas, a rare group of neuroendocrine tumors, are responsible for severe peptic disease and diarrhea. Although symptomatic control may be achieved with proton-pump inhibitors (PPIs) and somatostatin analogues (SSAs), data are limited regarding the possible antitumor effect of the peptide receptor radioligand therapy (PRRT) with radiolabeled SSAs in gastrinoma patients. The goal of this study was to assess the effect of PRRT on symptoms, gastrin secretion, and tumor load in patients with progressive malignant gastrinomas.

[Molecular biology of malignant lymphomas for non-specialists]

Lymphomas comprise a variety of entities with remarkable clinical heterogeneity. This review summarizes the current knowledge on the pathogenesis of major mature B-cell lymphoma subtypes for clinicians working outside the field of hemato-oncology. The understanding of the pathogenesis of lymphomas is linked to the knowledge on normal B-cell differentiation. The clinical diversity is manifested in the different mechanisms involved in lymphomagenesis that include characteristic chromosomal translocations deregulating proto-oncogenes, and inactivation of tumor suppressor genes through deletions and mutations. Gene-expression profiling has dissected certain lymphomas into morphologically indistinguishable, but clinically important subgroups and uncovered pathways suitable for specific therapeutic interventions.

Glucagon-like peptide-1 versus somatostatin receptor targeting reveals 2 distinct forms of malignant insulinomas

Glucagon-like peptide-1 (GLP-1) receptor imaging is superior to somatostatin receptor subtype 2 (sst(2)) imaging in localizing benign insulinomas. Here, the role of GLP-1 and sst(2) receptor imaging in the management of malignant insulinoma patients was investigated.

Malignant pheochromocytomas and paragangliomas: a diagnostic challenge

Malignant pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare disorders arising from the adrenal gland, from the glomera along parasympathetic nerves or from paraganglia along the sympathetic trunk. According to the WHO classification, malignancy of PCCs and PGLs is defined by the presence of metastases at non-chromaffin sites distant from that of the primary tumor and not by local invasion. The overall prognosis of metastasized PCCs/PGLs is poor. Surgery offers currently the only change of cure. Preferably, the discrimination between malignant and benign PCCs/PGLs should be made preoperatively.

Chiasmatic Infiltration Secondary to Late Malignant Transformation of Retinoma

To report the lethal course of malignant transformation of retinoma in an adult.

Xenotransplantation of cryopreserved ovarian tissue from patients with ovarian tumors into SCID mice--no evidence of malignant cell contamination

This study examined the possible presence of malignant cells in ovarian cortex from patients with ovarian tumors after xenografting of the ovarian tissue into severe combined immunodeficiency mice. None of the mice presented symptoms of reintroduced malignancy nor did microscopic and immunohistochemical evaluation of the grafts raise any suspicion of residual malignant disease.