C. Bouvier

Tubular lesions determine prognosis of IgA nephropathy

To assess the prognostic value of histological classification for renal outcome, we did a multivariate analysis of 194 patients with immunoglobulin A (IgA) nephropathy between 1985 and 1995. We also evaluated semiquantitative scales of tubular lesions and vessel lesions. At the time of the biopsy, 65 patients (33.5%) had chronic renal failure. At the end of the follow-up, 33 patients (17%) required hemodialysis. The mean age of the patients was 37.8 +/-18.9 years with predominance of men (sex-ratio: 3.12). Patients were followed-up for a mean of 43.2 +/- 37.2 months. Univariate analysis showed that hypertension (P < 10(-4)), nephrotic syndrome (P = 0.01), and crescents (P = 0.02) were significant in predicting renal failure, unlike subendothelial topography of IgA deposits (P = 0.05) and proteinuria (P = 0.05). Hematuria was a protective factor (P = 0.03). Multivariate analysis showed that tubular grade 2 (relative risk [RR], 5.5) and tubular grade 3 (RR = 28.8) were the best factors to predict chronic renal failure. The histological classification of Haas was significant in the univariate analysis, but not in the multivariate analysis. Tubular grading predicted renal outcome better than did the other histological parameters.

Solitary Fibrous Tumors and Hemangiopericytomas of the Meninges: Overlapping Pathological Features and Common Prognostic Factors Suggest the Same Spectrum of Tumors

Meningeal solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs) are distinct entities in the World Health Organization (WHO) classification of central nervous system (CNS) tumors while they belong to the same spectrum of tumors in other locations. Well‐defined histological prognostic factors are also lacking for these tumors. In order to clarify the relationship between SFT and HPC and to find histological and immunohistochemical prognostic factors, we carried out a retrospective study in 89 patients. The following histological parameters were recorded: hypercellularity, collagenic areas, cytonuclear atypias, necrosis, mitotic count per 10 high‐power fields, vasculo‐nervous adherences defined by engulfment of vessel or nerve by the tumor, brain infiltration. We found overlapping histological and immunohistochemical features between SFT and HPC. The most relevant histological prognostic factors in the whole cohort for both progression‐free survival (PFS) and overall survival (OS) in univariate analysis were hypercellularity, high mitotic count (>5 per 10 high‐power fields) and necrosis. On the basis of these results, we propose a new grading scheme for these tumors which was of pronostic value for both PFS and OS in uni‐ and multivariate analysis. As extent of surgery was also a prognostic factor for both PFS and OS in univariate analysis, we propose that management of SFT/HPC might be based both on quality of removal and histological grade.

In vitro identification and functional characterization of glial precursor cells in human gliomas

Human gliomas including astrocytomas and oligodendrogliomas are defined as being composed of neoplastic astrocytes and oligodendrocytes respectively. Here, on the basis of in vitro functional assays, we show that gliomas contain a mixture of glial progenitor cells and their progeny. We have set up explant cultures from pilocytic astrocytomas, glioblastomas and oligodendrogliomas and studied antigens that characterize glial lineage, from the precursor cells (glial restricted precursors and oligodendrocyte‐type2‐astrocyte/oligodendrocyte precursor cells expressing the A2B5 ganglioside) to the differentiated cells (oligodendrocyte and type‐1 and type‐2 astrocytes). All tumoral explants contain A2B5+ cells and can generate migrating cells with distinctive functional properties according to glioma subtypes. In pilocytic astrocytomas, very few migrating cells are dividing and can differentiate in type‐2 astrocytes or towards the oligodendrocyte lineage. In glioblastomas, most migrating cells are dividing, express A2B5 or glial fibrillary acid protein (GFAP) and can generate oligodendrocytes and type‐1 and type‐2 astrocytes in appropriate medium. Oligodendroglioma explants are made by actively dividing glial precursor cells expressing A2B5 or PSA‐NCAM. Only few cells can migrate and differentiation towards oligodendrocyte lineage does not occur. Isolated A2B5+ cells from both glioblastomas and oligodendrogliomas showed similar genetic alterations as the whole tumour. Therefore, pilocytic astrocytomas contain slowly dividing oligodendrocyte‐type2‐astrocyte/oligodendrocyte precursor cells in keeping with their benign behaviour whereas both glioblastomas and oligodendrogliomas contain neoplastic glial restricted precursor cells. In oligodendrogliomas, these cells are trapped in undifferentiated and proliferating state. The precursor cells properties present in gliomas give new insight into their histogenesis and open up new avenues for research in the field of gliomagenesis.

Relevance of combinatorial profiles of intermediate filaments and transcription factors for glioma histogenesis

In order to define specific markers for histogenesis of three well‐characterized subgroups of human gliomas (pilocytic astrocytomas, glioblastoma multiforme and oligodendrogliomas), we studied the expression of relevant markers that characterize gliomagenesis, by immunohistochemistry and in situ hybridization. They include the intermediate filament proteins glial fibrillary acidic protein (GFAP), vimentin and nestin, the transcription factors Olig2, Nkx2.2 and Sox10, and the proteolipid protein transcripts plp/dm20. We show that the three major categories of human gliomas express a combinatorial profile of markers that gives new insights to their histogenesis and may help diagnosis. Pilocytic astrocytomas strongly express GFAP, vimentin, Olig2, Nkx2.2 and Sox10 but not nestin. In contrast, glioblastomas strongly express GFAP, vimentin and nestin but these tumours are heterogeneous regarding the expression of the transcription factors studied. Finally, in oligodendrogliomas, intermediate filament proteins are generally not observed whereas Olig2 was found in almost all tumour cells nuclei while only a subpopulation of tumour cells expressed Nkx2.2 and Sox10.

Outcome analysis of childhood pilocytic astrocytomas: a retrospective study of 148 cases at a single institution.

Pilocytic astrocytomas (PAs) are characterized by an excellent prognosis although several factors of adverse outcome have been reported. The mitogen‐activated protein kinase pathway plays a major role in their tumorigenesis.

Histomolecular classification of adult diffuse gliomas: the diagnostic value of immunohistochemical markers.

Adult gliomas are most often infiltrative. The World Health Organization (WHO) has classed them into three major groups according to the presomptive cell of origin: astrocytoma, oligodendroglioma and mixed oligoastrocytoma. Depending on the presence or absence of a small number of signs of anaplasia (mitosis, nuclear atypia, cell density, microvascular proliferation and necrosis) the WHO distinguishes grade II (LGG), III (anaplastic), and IV (glioblastomas, GBM). Mutation in the isocitrate deshydrogenase I and II (IDH1 and 2) genes distinguishes grade II, III and secondary GBM from primary GBM. Moreover two additional genetic alterations are recorded in grade II and III gliomas: TP53 mutations that characterize astrocytomas and 1p19q codeletion (as the result of t(1;19)(q10;p10) translocation) recorded in oligodendrogliomas. Mixed gliomas, the most non-reproducible category, share with astrocytomas and oligodendrogliomas the same genetic alterations. Interestingly TP53 mutation (p53+) and 1p19q codeletion (1p19q+) are mutually exclusive and involve IDH mutated (IDH+) glial precursor cells. According to IDH, TP53, and 1p19q status, four major subtypes of LGG are recorded: IDH+/p53-/1p19q-, IDH+/p53+/1p19q-, IDH+/p53-/1p19q+ and triple negative, this last subgroup having the worst prognosis. Interestingly, p53 expression and internexin alpha (INA) expression can replace to some extent TP53 mutation and 1p19 codeletion, respectively. Moreover the antibody directed against the IDH1R132H isoform is highly specific. Because this mutation is the most frequent it is sufficient to assess IDH status in more than 80% of grade II and III gliomas. Taken together these three immunohistochemical markers are contribute greatly to the classification of gliomas and should be tested routinely as diagnostic markers. Finally, although GBM are genetically heterogeneous, the vast majority display EGFR amplification, often associated with EGFR expression, which can be helpful for diagnosis in certain cases.

Correlation between ERK1 and STAT3 expression and chemoresistance in patients with conventional osteosarcoma

BackgroundThe standard therapy regimen of conventional osteosarcoma includes neoadjuvant chemotherapy followed by surgical resection and postoperative chemotherapy. The percentage of necrotic tissue following induction chemotherapy is assessed by using the Huvos grading system, which classifies patients as “poor responders” (PR) and “good responders” (GR). The aim of this study was to identify molecular markers expressed differentially between good and poor responders to neoadjuvant chemotherapy in order to predict the response to chemotherapy in conventional osteosarcomas before beginning treatment.MethodsSuppression Substractive Hybridization (SSH) was performed by using cDNA from frozen biopsy specimens. Expression of selected relevant genes identified by SSH was validated by using QRT-PCR. Immunohistochemistry (IHC) on tissue microarray (TMA) sections of 52 biopsies was performed to investigate protein expression in an independent cohort.ResultsERK1 and STAT3 mRNA level were significantly different between PR and GR in an independent cohort. Phosphorylated STAT3 and ERK1 expressions by IHC on TMA were correlated with poor response to chemotherapy.ConclusionsOur results suggest that ERK1 and STAT3 expression are good predictive markers for chemotherapy response and that inhibitors might be used in combination with common chemotherapeutic drugs in conventional osteosarcomas.

Atypical teratoid/rhabdoid tumour: 7-year event-free survival with gross total resection and radiotherapy in a 7-year-old boy

Case studyWe report the case of a 7-year-old boy who presented in 1998 a tumour of the left frontal lobe. Initially diagnosed as anaplastic ependymoma, the boy was treated by gross total resection followed by radiotherapy at the operated site. In July 2005, an orbital tumour was discovered and resected. The tumour was composed of sheets of rhabdoid cells which diffusely expressed vimentin and focally epithelial membrane antigen (EMA) and α-smooth actin by immunohistochemistry. The first tumour was re-examined. Small foci of rhabdoid cells were found. Immunohistochemistry anti-INI1 performed on both tumours was negative. Molecular techniques performed on frozen specimen of the orbital tumour confirmed the diagnosis of atypical teratoid/rhabdoid tumour (ATRT).DiscussionWe discuss the pathological criteria for diagnosis of ATRT and the usefulness of early radiotherapy in the light of the recent literature.

Classification morphologique des glioblastomes

BACKGROUND AND PURPOSE In the 2007 WHO classification, glioblastomas are classified among the group of astrocytic tumors. They are highly malignant (grade IV). This group of tumors is morphologically heterogeneous. The WHO distinguishes between clinico-pathological entities, variants of entities and histological pattern. Variants are defined as being reliably indentified histologically and having some relevance for clinical outcome but as still being part of a previously defined overarching entity. Patterns of differentiation are identifiable by histological appearances but without clinical or pathological significance. METHODS The description of the histological and immunohistochemical features is based on the 2007 WHO classification. RESULTS In addition to the classic form of glioblastoma, two variants exist: the giant cell GBM and the gliosarcoma. The first but not the second would have a better outcome than the classic glioblastoma. The WHO classification also distinguishes several patterns of differentiation: small cells glioblastoma; glioblastoma with lipidized cells; glioblastoma with oligodendroglioma component; glioblastoma with heterologous differentiation. These patterns have to be recognized because they represent sometimes a diagnostic challenge. GFAP, Olig2 and Mib1/Ki67 are the most relevant immunohistochemical markers. Diagnostic value of neuronal markers is still controversial. EGFR or p53 expression can be detected and their prognosis value is discussed in this chapter. A systematic analysis of some markers in routine, for example IDH1 or internexin-a, could help to define more homogeneous groups of patients.

Les tumeurs gliales et glioneuronales de l'adulte et de l'enfant : principales altérations génétiques et classification histomoléculaire

Glial and glioneuronal tumors in children and adult demonstrate distinctive clinical, neuroradiological and molecular features depending on the pathological subtype and within a same subgroup according to the age. In children, gliomas are mainly located in the infratentorial part of the brain. They are most often benign and circumscribed but infiltrative tumors with dismal prognosis are recorded within the pons (DIGP) or the thalamus. Glioblastomas are very rare in children. In contrast, gliomas in adult mainly occur in the cerebral hemispheres and the most frequent subtype is glioblastoma. Glioneuronal tumors mainly occurred in children and young adults. In addition, although pilocytic astrocytomas, pleomorphic xanthoastrocytomas and gangliogliomas are classified into different subgroups according to the WHO 2007 classification, these tumors demonstrate similar neuroradiological findings: they are cystic with contrast enhancement of a mural nodule. Major advances have been made these last five years in the discovery of some master genes that are involved in gliomagenesis and point out differences between children and adults. In adults, infiltrative gliomas can be classified into two major subgroups depending on the existence or not of IDH mutations. IDH-dependent gliomagenesis encompasses diffuse grade II and grade III (they can also show additional molecular alterations such as TP53 mutation or 1p19q codeletion) and secondary glioblastomas. IDH-independent gliomagenesis include triple negative grade II gliomas, gliomatosis cerebri (grade III) and de novo glioblastomas. Pilocytic astrocytomas, pleomorphic xanthoastrocytomas and gangliogliomas share in common BRAF alterations. However, KIAA1549-BRAF fusion characterizes pilocytic astrocytomas whereas V600E BRAF mutation is mainly recorded in pleomorphic xanthoastrocytomas and gangliogliomas.