Gray zones in brain tumor classification: evolving concepts

Association between Ki-67 Labeling index and Histopathological Grading of Glioma in Indonesian Population

Background:

Gliomas are the most frequent primary brain tumors. According to World Health Organization guidelines, gliomas are graded into four groups (Group I-IV). This histological grading will determine prognosis and treatment of the patient. Morphological criteria are not always accurate. Tumor proliferation index is a potent quantitative marker for tumor behavior and prognosis, also it’s the basis of gliomagenesis. Ki-67 immunohistochemistry examination for determining proliferation index has been suggested as an ancillary marker in deciding the definitive grading of glioma.

Objective:

To analyze the correlation between Ki-67 labeling index and histopathological grading of glioma in Indonesian population.

Methods:

One hundred and six formalin fixed-paraffin embedded tissue of glioma patients were collected from 4 different hospitals. Expression of Ki-67 was detected using immunohistochemistry staining and the labeling index was counted. The association between Ki-67 labeling index and histopathological grading was analyzed.

Results:

Age range of patient were 1-73-years old, with male predominance (55.70%). Glioblastoma was the most common diagnosis accounting for 41.51% of all samples. Ki-67 labeling index cut point of 6.35% was obtained and significantly sensitive and specific for determining low- or high-grade glioma (p<0.001).

Conclusion:

A significant association between Ki-67 labeling index and histopathological grading in Indonesian glioma patients has been revealed. The result of this study may be used to improve diagnostic and grading accuracy of glioma cases in Indonesia, especially in small biopsy specimens.

Multi-faceted computational assessment of risk and progression in oligodendroglioma implicates NOTCH and PI3K pathways

Oligodendrogliomas are diffusely infiltrative gliomas defined by IDH-mutation and co-deletion of 1p/19q. They have highly variable clinical courses, with survivals ranging from 6 months to over 20 years, but little is known regarding the pathways involved with their progression or optimal markers for stratifying risk. We utilized machine-learning approaches with genomic data from The Cancer Genome Atlas to objectively identify molecular factors associated with clinical outcomes of oligodendroglioma and extended these findings to study signaling pathways implicated in oncogenesis and clinical endpoints associated with glioma progression. Our multi-faceted computational approach uncovered key genetic alterations associated with disease progression and shorter survival in oligodendroglioma and specifically identified Notch pathway inactivation and PI3K pathway activation as the most strongly associated with MRI and pathology findings of advanced disease and poor clinical outcome. Our findings that Notch pathway inactivation and PI3K pathway activation are associated with advanced disease and survival risk will pave the way for clinically relevant markers of disease progression and therapeutic targets to improve clinical outcomes. Furthermore, our approach demonstrates the strength of machine learning and computational methods for identifying genetic events critical to disease progression in the era of big data and precision medicine.

Invasive benign meningioma: Clinical characteristics, surgical strategies and outcomes from a single neurosurgical institute

The aim of the present study was to improve the prognosis for patients with invasive benign meningioma by increasing the precision of pre-operative evaluation and refining the surgical resection strategy. A retrospective review of all the cases of invasive benign meningioma admitted to a single institute from 2005 to 2010 was conducted. The clinical characteristics, magnetic resonance imaging (MRI) findings, refined surgical strategies and outcomes were summarized and analyzed. There were 19 cases of invasive benign meningioma among 254 cases of meningioma. Of the earliest 4 cases, a traditional extra-capsular surgical removal approach was applied, which resulted in permanent neurological deficits for all cases. A modified surgical strategy combining intra- and extra-capsular resection techniques was employed for the subsequent 15 cases, which lead to mild neurological impairment in only 1 case. Pre-operative recognition of this unique sub-type of meningioma maybe facilitated by its typical MRI study findings, and the combination of intra- and extra-capsular resection techniques may be of critical importance in achieving complete tumor removal while maintaining intact neurological functions.

Benign meningiomas (WHO Grade I) with atypical histological features: correlation of histopathological features with clinical outcomes

OBJECT

World Health Organization (WHO) Grade I (benign) meningiomas with atypical features may behave more aggressively than similarly graded tumors without atypical features. Here, the prognostic significance of atypical features in benign meningiomas was determined.

METHODS

Data from patients diagnosed with WHO Grade I benign meningiomas per the 2007 WHO criteria and who underwent surgery between 2002 and 2012 were retrospectively reviewed. Patients were stratified by the absence or presence of 1 to 2 atypical features with review of the clinical and histological factors.

RESULTS

A total of 148 patients met the inclusion criteria (n = 77 with atypia; n = 71 without atypia). The median follow-up duration after pathological diagnosis was 37.5 months. Thirty patients had progression/recurrence (P/R) after initial treatment, and 22 (73%) of 30 patients with P/R had 1–2 atypical features. The presence of atypical features was significantly associated with P/R (p = 0.03) and independent of the MIB-1 labeling index. The 1-year and 5-year actuarial rates of P/R were 9.6% versus 1.4% and 30.8% versus 13.8% fortumors with and without atypical features, respectively. Higher Simpson grade resection (II–IV vs I) was associated with the increased risk of P/R (p < 0.001). Stratification of patients into low-risk (Simpson Grade I), intermediate-risk (Simpson Grade II–IV with no atypical features), and high-risk groups (Simpson Grade II–IV with atypical features) was significantly correlated with increased risk of P/R (p < 0.001).

CONCLUSIONS

Patients with benign meningiomas with atypical features and those undergoing Simpson Grade II–IV resection are at significantly increased risk of P/R. Patients with these features may benefit from the consideration of additional surgery and/or radiation therapy.

Combined ATRX/IDH1 immunohistochemistry predicts genotype of oligoastrocytomas

AIMS

To assess whether in oligoastrocytomas ATRX deficiency, as a surrogate of the alternative lengthening of telomeres (ALT) pathway, has a role in predicting the presence or absence of loss of heterozygosity (LOH) of 1p and 19q, the genetic signature of oligodendroglial differentiation and a favourable prognostic marker.

METHODS AND RESULTS

A series of 54 oligoastrocytomas were investigated by immunohistochemistry as well as microsatellite analysis for LOH 1p19q. Genetic findings were correlated with morphological assessment.

CONCLUSIONS

ATRX deficiency was mutually exclusive with LOH. Conversely, ATRX-proficient tumours immunoreactive for R132H-mutant isocitrate dehydrogenase 1 (IDH1) showed a high rate (85%) of LOH. A more oligodendroglioma-like morphology was associated with a higher rate of LOH even in the morphologically ambiguous group of oligoastrocytomas. Our findings support the concept that oligoastrocytomas represent a morphological grey zone, rather than a group of truly 'mixed' or 'intermediate' tumours. More precise classification of diffuse gliomas may also improve grading of borderline cases. We propose an immunohistochemical algorithm for classification of morphologically ambiguous diffuse gliomas.

[Molecular methods in diagnosis of poorly differentiated malignant brain tumors in children]

The histological diagnosis of malignant brain tumors in children is a complex process. In some cases, glioblastoma, primitive neuroectodermal tumor of the central nervous system, and atypical teratoid/rhabdoid tumor have a histological type similar to that of small blue round cell malignant tumor. Despite the similar histology, biological properties and approaches to treatment, these neoplasms are completely different and require their own treatment protocols. We retrospectively reviewed the most malignant types of childhood tumors and analyzed our own experience to propose a diagnostic algorithm for intracerebral small blue round cell malignant tumors in children based on the use of immunohistochemistry and fluorescence in situ hybridization.

Microvascular MRI and unsupervised clustering yields histology-resembling images in two rat models of glioma

Imaging heterogeneous cancer lesions is a real challenge. For diagnosis, histology often remains the reference, but it is widely acknowledged that biopsies are not reliable. There is thus a strong interest in establishing a link between clinical in vivo imaging and the biologic properties of tissues. In this study, we propose to construct histology-resembling images based on tissue microvascularization, a magnetic resonance imaging (MRI) accessible source of contrast. To integrate the large amount of information collected with microvascular MRI, we combined a manual delineation of a spatial region of interest with an unsupervised, model-based cluster analysis (Mclust). This approach was applied to two rat models of glioma (C6 and F98). Six MRI parameters were mapped: apparent diffusion coefficient, vessel wall permeability, cerebral blood volume fraction, cerebral blood flow, tissular oxygen saturation, and cerebral metabolic rate of oxygen. Five clusters, defined by their MRI features, were found to correspond to specific histologic features, and revealed intratumoral spatial structures. These results suggest that the presence of a cluster within a tumor can be used to assess the presence of a tissue type. In addition, the cluster composition, i.e., a signature of the intratumoral structure, could be used to characterize tumor models as histology does.

Polymorphous oligodendroglioma of Zülch revisited: a genetically heterogeneous group of anaplastic gliomas including tumors of bona fide oligodendroglial differentiation

A polymorphous variant of oligodendroglioma was described by K.J. Zülch half a century ago, and is only very sporadically referred to in the subsequent literature. In particular, no comprehensive analysis with respect to clinical or genetic features of these tumors is available. From a current perspective, the term polymorphous oligodendroglioma (pO) may appear as contradictory in terms, as nuclear monotony is a histomorphological hallmark of oligodendrogliomas. For the purpose of this study, we defined pO as diffusely infiltrating gliomas felt to be of oligodendroglial rather than astrocytic differentiation and characterized by the presence of multinucleate tumor giant cells and/or nuclear pleomorphism. In a total of nine patients, we identified tumors consistent with this working definition. All tumors were high-grade. We characterized these with respect to clinical, histomorphological and genetic features. Despite clinical and genetic heterogeneity, we identified a subset of tumors of bona fide oligodendroglial differentiation as characterized by combined loss of heterozygosity of chromosome arms 1p and 19q (LOH 1p19q). Those tumors that lacked LOH 1p19q showed a high frequency of IDH1 mutations and loss of alpha thalassemia/mental retardation syndrome X-linked gene (ATRX) immunoreactivity, indicating a possible phenotypic convergence of true oligodendrogliomas and gliomas of the alternative lengthening of telomeres (ALT) pathway. p53 alterations were common irrespective of the 1p19q status. Histomorphologically, the tumors featured interspersed bizarre multinucleate giant tumor cells, while the background population varied from monotonous to significantly pleomorphic. Our findings indicate, that a rare polymorphous - or "giant cell" - variant of oligodendroglioma does indeed exist.

A new der(1;7)(q10;p10) leading to a singular 1p loss in a case of glioblastoma with oligodendroglioma component

The combined 1p-/19q- deletions in oligodendrogliomas originate from translocation between both chromosomes. In the few cases of oligoastrocytomas and glioblastomas with an oligodendroglioma component (GBMO) where only 1p deletion was described, the origin remains unknown. We report the first case of GBMO, in which a single 1p deletion was detected and was linked to a translocation between chromosomes 1 and 7. Fresh surgical specimens were collected during surgery and the samples were used for cell culture, touch preparation smear slides (TP slides) and DNA extraction. Peripheral venous blood was also collected from the patient. G-banding using Trypsin and stained with Giemsa (GTG) banding and karyotyping were performed and 1p-/19q-, TP53, PTEN and c-MYC were analyzed by fluorescent in situ hybridization (FISH). Multicolor FISH (mFISH) and microsatellites analyses were also performed to complete the investigation. Three-dimensional quantitative FISH (3D-QFISH) of telomeres was performed on nuclei from TP slides and analyzed using TeloView(TM) to determine whether the 3D telomere profile as an assessment of telomere dysfunction and a characterization of genomic instability could predict the disease aggressiveness. An unbalanced chromosomal translocation was found in all metaphases and confirmed by mFISH. The karyotype of the case is: 50∼99,XXX, +der(1;7)(q10;p10),inc[47] The derivative chromosome was found in all 47 analyzed cells, but the number of derivatives varied from one to four. There was neither imbalance in copy number for genes TP53 and PTEN, nor amplification of c-MYC gene. We did not find loss of heterozygosity with analysis of microsatellite markers for chromosomes 1p and 19q in tumor cells. The 3D-telomere profile predicted a very poor prognostic and short-term survival of the patient and highlights the potential clinical power of telomere signatures as a solid biomarker of GBMO. Furthermore, this translocation between chromosomes 1 and 7 led to a singular 1p deletion in this GBMO and may generate the 1p and 7q deletions.

Long-term tumor-free survival case of congenital embryonal tumor with various pathological components

PURPOSE

Treatment strategy of malignant congenital brain tumor is controversial. We report a congenital embryonal tumor case with various pathological components.

METHODS

A normally delivered male infant had an enlarged head circumference at 1 month after birth. The abnormality of the right side of the head was also noted during the routine 4-month health check. The head circumference was 45.1 cm (+2.25, SD); neurological status, however, was normal, with a pediatric GCS of 9 and body weight of 6,370 g (-0.85, SD). Magnetic resonance imaging (MRI) revealed right brain tumor whose size was 99 × 91 × 86 mm. The tumor was enhanced homogeneously with central necrosis, and the margin of the tumor was well circumscribed.

RESULTS

We performed a subtotal removal of the tumor. The pathological diagnosis was meningioma (MIB-1 index was 2 %). The residual tumor gradually shrank, and we performed monthly MRI follow-up. The tumor abruptly recurred 7 months after the operation. The level of patient consciousness deteriorated, and emergency removal surgery was performed. The histological examination showed various types of embryonal components without meningioma-like parts. The pathological diagnosis was an embryonal tumor. The MIB-1 index was 48 %. One month after the second operation, dissemination of the tumor occurred at the right temporal lobe, cerebellum, and in subcutaneous tissue. Chemotherapy (vincristine, cisplatin, cyclophosphamide, and etoposide) was initiated following radiation therapy (3 Gy/day, 8×). Adjuvant therapies were effective, and no tumor recurrence was detected during 34 months follow-up.

CONCLUSION

Treatment strategies for malignant indefinite diagnosed tumor need to be discussed.

Strategies for annotation and curation of translational databases: the eTUMOUR project

The eTUMOUR (eT) multi-centre project gathered in vivo and ex vivo magnetic resonance (MR) data, as well as transcriptomic and clinical information from brain tumour patients, with the purpose of improving the diagnostic and prognostic evaluation of future patients. In order to carry this out, among other work, a database—the eTDB—was developed. In addition to complex permission rules and software and management quality control (QC), it was necessary to develop anonymization, processing and data visualization tools for the data uploaded. It was also necessary to develop sophisticated curation strategies that involved on one hand, dedicated fields for QC-generated meta-data and specialized queries and global permissions for senior curators and on the other, to establish a set of metrics to quantify its contents. The indispensable dataset (ID), completeness and pairedness indices were set. The database contains 1317 cases created as a result of the eT project and 304 from a previous project, INTERPRET. The number of cases fulfilling the ID was 656. Completeness and pairedness were heterogeneous, depending on the data type involved.

Low-grade gliomas: when and how to treat

Low-grade gliomas are uncommon tumors whose optimal management remains to be determined. Although well-designed clinical trials have been mounted to address certain aspects of postoperative radiotherapeutic management, additional studies are required to refine management based on tumor-specific and patient-specific variables. There is mounting evidence that the relative completeness of surgical resection can improve survival, and the molecular and histopathologic characterization of the glioma requires adequate samples for analysis. Current imaging and operative techniques can direct surgical resection, and the same imaging techniques can help monitor patients postoperatively and predict prognosis.

Cancer susceptibility variants and the risk of adult glioma in a US case-control study

Malignant gliomas are the most common and deadly brain tumors. Although their etiology remains elusive, recent studies have narrowed the search for genetic loci that influence risk. We examined variants implicated in recent cancer genome-wide association studies (GWAS) for associations with glioma risk in a US case-control study. Cases were identified from neurosurgical and neuro-oncology clinics at major academic centers in the Southeastern US. Controls were identified from the community or were friends or other associates of cases. We examined a total of 191 susceptibility variants in genes identified in published cancer GWAS including glioma. A total of 639 glioma cases and 649 controls, all Caucasian, were included in analysis. Cases were enrolled a median of 1 month following diagnosis. Among glioma GWAS-identified variants, we detected associations in CDKN2B, RTEL1, TERT and PHLDB1, whereas we did not find overall associations for CCDC26. Results showed clear heterogeneity according to histologic subtypes of glioma, with TERT and RTEL variants a feature of astrocytic tumors and glioblastoma (GBM), CCDC26 and PHLDB1 variants a feature of astrocytic and oligodendroglial tumors, and CDKN2B variants most prominent in GBM. No examined variant in other cancer GWAS was found to be related to risk after adjustment for multiple comparisons. These results suggest that GWAS-identified SNPs in glioma mark different molecular etiologies in glioma. Stratification by broad histological subgroups may shed light on molecular mechanisms and assist in the discovery of novel loci in future studies of genetic susceptibility variants in glioma.

Pituicytoma: Report of two cases

This report describes two cases of pituicytoma. The two patients were female and presented with visual complaints, diabetes insipidus, headaches and menstrual disorders. The imaging characteristic was an intrasellar or suprasellar mass, and one mass originated in the pituitary stalk. The mass showed homogeneous enhancement with contrast administration. A hematoxylin and eosin stain showed a compact structure consisting of elongated, bipolar spindle cells arranged in interlacing fascicles or assuming a storiform pattern. Immunohistochemically, the tumor showed diffuse strong expression of S-100 protein, vimentin and epithelial membrane antigen, and glial fibrillary acidic protein was focally positive. The pituicytoma may have originated in the pituitary stalk and presented with diabetes insipidus, and the differential diagnosis should be compared with the pituitary stalk mass. Bleeding during resection was moderate, and surgery was regarded as the first choice of treatment for pituicytomas.

Reinventing diagnostics for personalized therapy in oncology

Human cancers are still diagnosed and classified using the light microscope. The criteria are based upon morphologic observations by pathologists and tend to be subject to interobserver variation. In preoperative biopsies of non-small cell lung cancers, the diagnostic concordance, even amongst experienced pulmonary pathologists, is no better than a coin-toss. Only 25% of cancer patients, on average, benefit from therapy as most therapies do not account for individual factors that influence response or outcome. Unsuccessful first line therapy costs Canada CAN$1.2 billion for the top 14 cancer types, and this extrapolates to $90 billion globally. The availability of accurate drug selection for personalized therapy could better allocate these precious resources to the right therapies. This wasteful situation is beginning to change with the completion of the human genome sequencing project and with the increasing availability of targeted therapies. Both factors are giving rise to attempts to correlate tumor characteristics and response to specific adjuvant and neoadjuvant therapies. Static cancer classification and grading systems need to be replaced by functional classification systems that not only account for intra- and inter- tumor heterogeneity, but which also allow for the selection of the correct chemotherapeutic compounds for the individual patient. In this review, the examples of lung and breast cancer are used to illustrate the issues to be addressed in the coming years, as well as the emerging technologies that have great promise in enabling personalized therapy.

Classification and controversies in pathology of ependymomas

PURPOSE

Bailey and Cushing established ependymoma as a brain tumour entity in the first brain tumour classification (1926). Diagnosis of ependymomas is not subject to controversy as long as other tumours presenting ependymoma-like features have been ruled out. Grading conversely is a source of debate. Description of histological features establishing diagnosis and grading of ependymomas may help to better understand this controversy.

METHODS

Literature has been reviewed using PubMed with the following key words: ependymoma, +/- prognosis, +/- biomaker, +/- grading, +/- immunohistochemistry, +/- proliferative index.

RESULTS

Grading controversy arises from elusive WHO features and individual characteristics of ependymomas including tumour location, tumour pattern/variant and variable expression of biomarkers.

CONCLUSION

There is a need for a grading scheme with a proven general ability to dissociate grades, and to predict individual clinical evolution. Only then will stratified and targeted therapeutics for ependymal tumours be possible.