Jose Gonzalez-Darder

Multimodal navigation in the functional microsurgical resection of intrinsic brain tumors located in eloquent motor areas: role of tractography

OBJECTnNowadays the role of microsurgical management of intrinsic brain tumors is to maximize the volumetric resection of the tumoral tissue, minimizing the postoperative morbidity. The purpose of this paper was to study the benefits of an original protocol developed for the microsurgical treatment of tumors located in eloquent motor areas where the navigation and electrical stimulation of motor subcortical pathways have been implemented.nnnMETHODSnA total of 17 patients who underwent resection of cortical or subcortical tumors in motor areas have been included in the series. The preoperative planning for multimodal navigation was done by integrating anatomical studies, motor functional MR (fMR) imaging, and subcortical pathway volumes generated by diffusion tensor (DT) imaging. Intraoperative neuromonitoring included motor mapping by direct cortical stimulation (CS) and subcortical stimulation (sCS), and localization of the central sulcus by using cortical multipolar electrodes and the N20 wave inversion technique. The location of all cortically and subcortically stimulated points with positive motor response was stored in the navigator and correlated with the cortical and subcortical motor functional structures defined preoperatively.nnnRESULTSnThe mean tumoral volumetric resection was 89.1 +/- 14.2% of the preoperative volume, with a total resection (> or = 100%) in 8 patients. Preoperatively a total of 58.8% of the patients had some kind of motor neurological deficit, increasing 24 hours after surgery to 70.6% and decreasing to 47.1% at 1 month later. There was a great correlation between anatomical and functional data, both cortically and subcortically. A total of 52 cortical points submitted to CS had positive motor response, with a positive correlation of 83.7%. Also, a total of 55 subcortical points had positive motor response; in these cases the mean distance from the stimulated point to the subcortical tract was 7.3 +/- 3.1 mm.nnnCONCLUSIONSnThe integration of anatomical and functional studies allows a safe functional resection of the brain tumors located in eloquent areas. Multimodal navigation allows integration and correlation among preoperative and intraoperative anatomical and functional data. Cortical motor functional areas are anatomically and functionally located preoperatively thanks to MR and fMR imaging and subcortical motor pathways with DT imaging and tractography. Intraoperative confirmation is done with CS and N20 inversion wave for cortical structures and with sCS for subcortical pathways. With this protocol the authors achieved a good volumetric resection in cortical and subcortical tumors located in eloquent motor areas, with an increase in the incidence of neurological deficits in the immediate postoperative period that significantly decreased 1 month later. Ongoing studies must define the safe limits for functional resection, taking into account the intraoperative brain shift. Finally, it must be demonstrated whether this protocol has any long-term benefit for patients by prolonging the disease-free interval, the time to recurrence, or the survival time.

New pattern of EGFR amplification in glioblastoma and the relationship of gene copy number with gene expression profile.

Gene amplification is a process that is characterized by an increase in the copy number of a restricted region in a chromosome arm, and is frequently associated with an overexpression of the corresponding amplified gene. Amplified DNA can be organized either as extrachromosomal elements, repeated units at a single locus or scattered throughout the genome. The amplification of the gene for epidermal growth factor receptor (EGFR) is a common finding in glioblastomas and the amplified gene copies appears as double minutes. The aim of this study was to investigate the different patterns of EGFR amplification in 40 cases of glioblastoma using FISH analysis in metaphases and paraffin sections, and to investigate the relationship of gene copy number with gene expression profile. The analysis of copy number alterations of EGFR was validated by quantitative PCR and SNP microarrays. We observed that in 42% of the cases, the type of amplification of EGFR was as double minute chromosomes. In addition, we detected another type of amplification, with extra copies of EGFR inserted in different loci of chromosome 7, present in 28% of cases. In this form of amplification, the number of copies is small, and the percentage of cells with EGFR amplification is rarely more than 15%. This model of amplification could correspond to a variant of the insertion mechanism, or a consequence of a process of duplication. Our results suggest that this mechanism could represent an early stage of amplification in glioblastomas. Overall, we found a close correlation between EGFR gene copy-number alterations and the level of EGFR protein expression. However, all cases with a high level of mRNA exhibited strong expression for the EGFR protein, and most cases with a low level of mRNA showed no overexpression of EGFR protein.

Benign and Atypical Meningioma Metabolic Signatures by High-Resolution Magic-Angle Spinning Molecular Profiling

Meningiomas are neoplasms that arise from the leptomeningeal covering of the brain and spinal cord, accounting for 15%-20% of CNS tumors. The WHO classifies meningiomas into three histological grades: benign, atypical, and anaplasic in accordance with the clinical prognosis. Atypical and anaplasic meningiomas tend to recur. Sometimes, meningiomas with histological diagnosis of benign meningioma show clinical characteristics of atypical meningioma. In this context, high-resolution magic-angle spinning (HR-MAS) spectroscopy of intact tissue from brain tumor biopsies has shown great potential as a support diagnostic tool. In this work, we show differences between benign and atypical meningiomas in HR-MAS molecular profiles of meningioma biopsies. Metabolic differences between meningioma grades include changes in the levels of glutathione. Glutathione role in cancer is still unclear, as it may act both as protective and pathogenic factor. Glutamine and glutamate, which are related to glutathione metabolism and have been associated with tumor recurrence, are also increased in atypical meningiomas. Other metabolites associated with tumor malignancy that show statistically significant differences between benign and atypical meningiomas include phosphocholine and phosphoethanolamine. Overall, this work suggests that the additional information obtained by NMR metabolomics applied to biopsies of human meningiomas may be useful for assessing tumor grade and determining optimum treatment strategies.

Primary glioblastomas with and without EGFR amplification: Relationship to genetic alterations and clinicopathological features

Glioblastomas express a notable heterogeneity in both the histological and cell patterns with glial astrocytic differentiation. Primary glioblastoma, which is the most frequent presentation (90–95%), occurs mainly in older patients and arises de novo, without any clinical or histological evidence of a less malignant precursor lesion. EGFR amplification has been identified as a genetic hallmark of primary glioblastomas and occurs in 40–60% of cases. However, there exist primary glioblastomas without EGFR amplification/overexpression. The purpose of this study was to stabilize the association between cases with and without EGFR gene amplification with clinical and genetic parameters in 45 cases of primary glioblastomas. EGFR amplification was observed in 24 cases (53%), while in the remaining 21 cases (47%) this alteration was not displayed. And whereas EGFR was overexpressed in 79% of cases with EGFR amplification, only 33% of the cases without EGFR amplification showed overexpression. The amplification of EGFR was associated with amplifications in MDM2 and CDK4 and a higher percentage of cases with promoter methylation of INK4a. Only one case of glioblastoma with EGFR amplification presented TP53 mutation simultaneously. Seven remaining cases with TP53 mutations were glioblastomas without EGFR amplification. The INK4a, INK4b and ARF deletions were similar in the two groups. Primary glioblastomas with and without EGFR amplification did not show any significant differences in average survival. The genetic studies suggest the existence of molecular subtypes within primary glioblastoma that may, when fully defined, contribute toward the development of drugs that specifically target tumors with divergent genetic profiles.

The activation of ERK1/2 MAP kinases in glioblastoma pathobiology and its relationship with EGFR amplification.

The ERK1/2 activated protein kinase (MAPK) pathway is a critical signaling system that mediates ligand‐stimulated signals for the induction of cell proliferation, differentiation and survival, involved in malignant transformation. The purpose of this study was to determine the activation of ERK1/2 in this tumor, and to determine the relationship of ERK1/2 activation with the amplification/overexpression of EGFR as well as with 9p21 locus gene alterations, both of which are genetic factors frequently associated with glioblastoma. We used immunohistochemistry and Western blot analysis to analyze the activation of ERK1/2 in 22 patients with glioblastoma, and we studied the amplification/overexpression of EGFR; as well as the molecular alterations in 9p21 locus genes. Positive immunostaining ERK1/2 was observed in 86.4% of the tumors, displaying mainly nuclear immunolocalization; and by immunoblotting, ERK1/2 was activated in 68% of the cases. The 70% of cases with EGFR amplification presented activated ERK1/2. The joint presence of amplified EGFR and alterations in the 9p21 genes was observed in 50% of the cases, whereas the simultaneous occurrence of these two phenomena with the activation of ERK1/2 was observed in 40% of the cases. Our results suggest that the activation of ERK1/2 is implicated in the pathobiology of glioblastoma. This activation of ERK1/2 is probably related in part to the amplification of EGFR as well as to alterations in 9p21 locus genes (homozygous deletion and promoter methylation). However, the activation of ERK1/2 also involves pathways that are independent of the EGFR.

Metabolic Aggressiveness in Benign Meningiomas with Chromosomal Instabilities

Meningiomas are often considered benign tumors curable by surgery, but most recurrent meningiomas correspond to histologic benign tumors. Because alterations in chromosome 14 among others have suggested clinical aggressiveness and recurrence, determining both the molecular phenotype and the genetic profile may help distinguish tumors with aggressive metabolism. The aim of this study was to achieve higher specificity in the detection of meningioma subgroups by measuring chromosomal instabilities by fluorescence in situ hybridization and cytogenetics and metabolic phenotypes by high-resolution magic angle spinning spectroscopy. We studied 46 meningioma biopsies with these methodologies. Of these, 34 were of WHO grade 1 and 12 were of WHO grade 2. Genetic analysis showed a subgroup of histologic benign meningioma with chromosomal instabilities. The metabolic phenotype of this subgroup indicated an aggressive metabolism resembling that observed for atypical meningioma. According to the metabolic profiles, these tumors had increased energy demand, higher hypoxic conditions, increased membrane turnover and cell proliferation, and possibly increased resistance to apoptosis. Taken together, our results identify distinct metabolic phenotypes for otherwise benign meningiomas based on cytogenetic studies and global metabolic profiles of intact tumors. Measuring the metabolic phenotype of meningioma intact biopsies at the same time as histopathologic analysis may allow the early detection of clinically aggressive tumors.

Tumoral presentation of primary central nervous system lymphomatoid granulomatosis

PurposeLymphomatoid granulomatosis (LYG) is an angiocentric Epstein-Barr virus (EBV) related B-cell proliferation associated with a reactive T-cell component with an uncertain malignant potential. LYG present at diagnosis as a mass lesion in the central nervous system (CNS) is rare, and only a few cases have been reported. In this article we present four cases of tumoral CNS-LYG and propose some guidelines for its management.MethodsClinical, pathological, imaging and laboratory information of four immunocompetent patients, all of them treated surgically, with a final diagnosis of LYG and presenting with an isolated intracranial tumoral mass is reviewed.ResultsTwo parenchymal lesions were located in the cerebellum and temporal lobe, and the other two involved the cavernous sinus. At surgery they were avascular, hard, lard-like, necrotic and plastic well-defined lesions, with invasion of the leptomeninges and thrombosis of the small leptomeningeal arteries and veins. Intraoperative pathology excluded any tumor. Pathological studies showed a polymorphic and polyclonal infiltration around, in the wall and into the lumen of medium-sized cortical and leptomeningeal vessels causing their obstruction and tissular necrosis. EBV-infected cells were present.ConclusionsMaking a preoperative diagnosis of CNS-LYG appearing initially as a tumoral mass is difficult because of the lack of pathognomonic clinical symptoms or imaging signs. Surgical management with radical resection of the mass is almost always followed by the long-term local control of the lesion, although the disease may have a disseminated, systemic or malignant evolution.

Klippel–Feil syndrome associated with posterior fossa dermoid cyst. Case report

Abstract A patient with association of Klippel-Feil syndrome and posterior fossa dermoid cyst is presented. The patient, a 36-year-old man, presented with an acute obstructive hydrocephalus due to the cyst and exhibited the typical triad of the Klippel-Feil abnormality with short neck, low hairline implantation and limited neck motion along with a complex cervical vertebrae fusion. The anatomical and clinical features as well as the pathophysiology of this rare association are discussed after a review of the literature. [Neurol Res 2002; 24: 501-504]

BRAF V600E Mutation in Two Distinct Meningeal Melanocytomas Associated With a Nevus of Ota

Introduction Meningeal melanocytomas are rare tumors of the CNS that develop from melanocytes that are present in leptomeninges, with differing pigmented appearance. They generally occur in the posterior fossa and the spinal cord. This lesion may manifest at any age, but most patients are in the fifth decade of life. Occasionally, these tumors appear in a complex neurocutaneous grouping with other melanocytic lesions. The nevus of Ota (oculodermal melanocytosis) is a blue hyperpigmented dermal lesion that affects the trigeminal dermatome. The association of a meningeal melanocytoma with an ipsilateral nevus of Ota is extremely rare; to our knowledge, only eight cases have been reported in the literature to date. In these cases, the melanocytomas were located in the supratentorial area. We present a patient with neurocutaneous melanosis showing a highly pigmented meningeal melanocytoma and a less pigmented meningeal melanocytoma in association with a meningeal melanocytosis and a congenital nevus of Ota. We have analyzed the histopathologic and molecular characteristics of these lesions. To our knowledge, this is the first report of melanocytomas with mutations in BRAF, PTEN, and NF2, genes that are involved in the melanomagenesis process.

Magnetic Resonance Microscopy at 14 Tesla and Correlative Histopathology of Human Brain Tumor Tissue

Magnetic Resonance Microscopy (MRM) can provide high microstructural detail in excised human lesions. Previous MRM images on some experimental models and a few human samples suggest the large potential of the technique. The aim of this study was the characterization of specific morphological features of human brain tumor samples by MRM and correlative histopathology. We performed MRM imaging and correlative histopathology in 19 meningioma and 11 glioma human brain tumor samples obtained at surgery. To our knowledge, this is the first MRM direct structural characterization of human brain tumor samples. MRM of brain tumor tissue provided images with 35 to 40 µm spatial resolution. The use of MRM to study human brain tumor samples provides new microstructural information on brain tumors for better classification and characterization. The correlation between MRM and histopathology images allowed the determination of image parameters for critical microstructures of the tumor, like collagen patterns, necrotic foci, calcifications and/or psammoma bodies, vascular distribution and hemorrhage among others. Therefore, MRM may help in interpreting the Clinical Magnetic Resonance images in terms of cell biology processes and tissue patterns. Finally, and most importantly for clinical diagnosis purposes, it provides three-dimensional information in intact samples which may help in selecting a preferential orientation for the histopathology slicing which contains most of the informative elements of the biopsy. Overall, the findings reported here provide a new and unique microstructural view of intact human brain tumor tissue. At this point, our approach and results allow the identification of specific tissue types and pathological features in unprocessed tumor samples.