Stephen B. Hunter

Pseudopalisades in Glioblastoma Are Hypoxic, Express Extracellular Matrix Proteases, and Are Formed by an Actively Migrating Cell Population

Necrosis and vascular proliferation are the pathologic features that distinguish the most malignant infiltrative astrocytoma, glioblastoma (GBM), from those of lower grades. In GBM, hypercellular zones called pseudopalisades typically surround necrotic foci. Although these cells are known to secrete high levels of proangiogenic factors that promote tumor growth, their origins are ill defined. We propose that pseudopalisades represent differing stages and histologic samplings of astrocytoma cells migrating away from a hypoxic/anoxic focus, often triggered by a central vaso-occlusive event. This proposition is based on our findings that pseudopalisading cells are 5–50% less proliferative and 6–20 times more apoptotic than adjacent astrocytoma, indicating that cell accumulation does not result from increased proliferation or resistance to apoptosis. Coexisting inflammatory cells account for <2% of pseudopalisading cells and cannot account for hypercellularity. Pseudopalisading cells show nuclear expression of hypoxia-inducible factor 1α, consistent with their hypoxic nature, and hypoxia induces a 20–60% increase in glioma cell migration in vitro. Hypoxic cells in vitro and pseudopalisades in GBM specimens show enhanced gelatinase activity, typical of an invasive phenotype. These results suggest that pseudopalisading cells are migrating at the periphery of a hypoxic center. To uncover a potential source of hypoxia and sequence of structural events leading to pseudopalisade formation, we performed a morphometric analysis of 234 pseudopalisades from 85 pretreatment GBMs. We found distorted, degenerating, or thrombosed blood vessels within the center of more than half the pseudopalisades, suggesting that at least a subset of pseudopalisades are two-dimensional histologic representations of tumor cells migrating away from a vaso-occlusive event.

Tumor angiogenesis as a prognostic factor in oral cavity tumors

BACKGROUND Lymph-node metastasis is the single greatest predictor of survival in patients with oral cavity cancers. Tumor angiogenesis has been correlated with metastasis in breast cancer and may have prognostic value in other tumors. PATIENTS AND METHODS Sixty-six patients with clinically node-negative oral cavity squamous cell cancers were reviewed. Samples were cut and stained for factor VIII. The percentage of area of tissue stained for factor VIII was quantitated by a computerized image analyzer. Tumor depth was measured with an ocular micrometer to the nearest 0.1 mm. Variables were statistically examined against regional recurrence. RESULTS The probability of metastasis (%) was 2 for tumor staining of < or = 10% and 93 for tumor staining > 10% (P < 0.0001). The tumor depth was < or = 4 mm in 10 and > 4 mm in 83 (P < 0.0001). Patients with < or = 4 mm and < or = 10% staining had a 2% rate of recurrence, and patients with > 4 mm and > 10% staining had a 100% rate of recurrence (P < 0.0001). CONCLUSION Although tumor thickness was suggestive of predictability, only angiogenesis was a statistically significant predictor of recurrence in a multivariate analysis (P < 0.0001). Angiogenesis showed a strong correlation with regional recurrence and may be used as an independent prognostic indicator.

Genetic markers in glioblastoma: prognostic significance and future therapeutic implications.

Glioblastoma multiforme (GBM) is the highest-grade infiltrative astrocytoma and also the most common. It is generally associated with a dismal prognosis (mean survival 11 months), yet individual patient survivals vary. Histologic parameters have had limited value in predicting survival among patients with GBM. The current view of GBM as a histopathologic entity consisting of several genetic subtypes raises the possibility that molecular alterations could be predictive of survival. Common genetic alterations in GBM include gene amplification of epidermal growth factor receptor (EGFR), mutations in the tumor suppressors TP53 and PTEN, and genetic losses on chromosome 10. Less common in GBMs is the combined loss of chromosomes 1p and 19q—a combination that has proven prognostically favorable in oligodendrogliomas. A recent article on prognostic factors in a series of 97 GBMs by Schmidt et al. finds that both TP53 mutations and young patient age at presentation are independent factors associated with a long survival. Loss of heterozygosity (LOH) of chromosome 10q was predictive of a poor outcome. Perhaps most intriguing, the finding of combined LOH of 1p and 19q, which was noted in only five GBMs, was associated with a significantly longer survival. Thus, combined losses of 1p and 19 may be associated with a favorable prognosis in a wider range of infiltrative gliomas that includes GBM. While these findings will be debated and need to be confirmed, it is clear that genotyping of infiltrative gliomas will be an important component of neuro-oncology in the future. Not only will genetic alterations offer prognostication, but they will also serve as targets for directed therapies. Treatments directed against tumors with EGFR amplification, TP53, mutations and PTEN mutations are being developed and tested in clinical trials. It remains to be seen if GBMs with 1p and 19q losses are chemosensitive in the same manner as oligodendrogliomas.

Cdk5-mediated regulation of the PIKE-A-Akt pathway and glioblastoma cell invasion

Isoform A of phosphatidylinositol 3-kinase enhancer (PIKE-A) is a newly identified prooncogenic factor that has been implicated in cancer cell growth. How PIKE-A activity is regulated in response to growth signal is poorly understood. Here, we demonstrate that cyclin dependent kinase 5 (Cdk5), a protein known to function mainly in postmitotic neurons, directly phosphorylates PIKE-A at Ser-279 in its GTPase domain in glioblastoma cells. This phosphorylation event stimulates PIKE-A GTPase activity and the activity of its downstream effector Akt. Growth signal activates Cdk5 and results in a Cdk5-dependent accumulation of phosphorylated PIKE-A and activation of Akt in the nucleus. Furthermore, PIKE-A phosphorylation and Cdk5 are increased in human glioblastoma specimens. Phosphorylation of PIKE-A by Cdk5 mediates growth factor-induced migration and invasion of human glioblastoma cells. Together, these findings identify PIKE as the first Cdk5 target in cancer cells, revealing a previously undescribed regulatory mechanism that mediates growth signal-induced activation of PIKE-A/Akt and tumor invasion.

Reliability of Differential PCR for the Detection of EGFR and MDM2 Gene Amplification in DNA Extracted from FFPE Glioma Tissue

A series of 43 human gliomas, consisting of 30 glioblastomas, 7 anaplastic astrocytomas, 3 low grade astrocytomas, 2 epcndymomas, and I oligodendroglioma, was studied for amplification of the epidermal growth factor receptor (EGFR) and mouse double minute 2 (MDM2) genes. DNA extracted from formalin-fixed, paraffin-embedded tissue sections was analyzed by differential PCR and the results were compared with slot blot examination of DNA extracted from frozen tissue from the same neoplasms. Twelve glioblastomas (40%) showed amplification of the EGFR gene, and overexpression of EGFR was evident in each of these tumors as indicated by the immunoperoxidase technique. Two of the tumors with EGFR gene amplification also revealed amplification of the MDM2 gene, while one additional glioblastoma revealed MDM2 amplification only. A 100% concordance in the detection of amplification was observed between differential PCR and slot blot analysis; consequently, these results indicate that differential PCR using DNA extracted from archival tissue sections is a reliable method of demonstrating gene amplifications in glial tumors.

Intrasellar pituicytoma in a patient with other endocrine neoplasms.

Considered a neoplasm of pituicytes, pituicytoma is a rare and distinct type of glioma that arises in the suprasellar space and within the sella turcica. Only 12 previously reported cases of pituicytoma are documented in the literature. We report an intrasellar pituicytoma in a 66-year-old man presenting with symptoms and radiologic appearance indistinguishable from a nonfunctional pituitary adenoma. The patient also had a medical history significant for parathyroid adenomas and follicular carcinoma of the thyroid. The intrasellar tumor had morphologic features of a pituicytoma, with interlacing fascicles and a storiform pattern much like a benign fibrous histiocytoma. Immunoreactivity for S100 was strong, but the tumor lacked intercellular collagen type IV. The differential diagnosis of a low-grade spindle cell lesion of the sellar space is discussed, and the literature is reviewed. A summary of the clinical and pathologic features of this case, as well as the 12 previously reported cases, is presented.

Solitary intracerebral juvenile xanthogranuloma : Case report and review of the literature

A case of an intracerebral juvenile xanthogranuloma (JXG) producing complex-partial seizures in a 13-year-old boy is presented. Although the child had no history of JXGs or a systemic histiocytic proliferative disorder, the histopathological and immunocytochemical studies of this lesion were identical to that of a cutaneous JXG. This represents the first description of an isolated intracerebral JXG. On extensive review of the literature, this case comprises only the second reported intracranial lesion and the fourth CNS lesion in a child without cutaneous manifestations of JXG. In contrast to cerebral xanthogranulomas of adulthood, all reported cases of isolated CNS JXG presented with focal symptoms referable to the neuroanatomic localization of the lesion. In this limited series, the magnetic resonance imaging appearance was predictable and consistent, although spinal and intracranial lesions differ with respect to their enhancement with paramagnetic contrast media. While complete surgical excision, if feasible, has been the most utilized form of therapy for symptomatic or progressive lesions, external beam irradiation and cytotoxic chemotherapy have been utilized for unresectable or recurrent disease. Given their rare occurrence and uncertain natural history, it remains unclear whether these solitary CNS lesions represent a distinct clinical entity with a potentially more aggressive clinical course or merely a variant of the systemic non-Langerhans cell histiocytoses.

Lipomatous glioneurocytoma of the posterior fossa with divergent differentiation: case report.

OBJECTIVE AND IMPORTANCE We report a case of a posterior fossa neuroepithelial tumor with unusual clinical presentation, magnetic resonance imaging appearance, and morphological features. CLINICAL PRESENTATION This 66-year-old man presented with a history of gait ataxia, dizziness, and tinnitus and was found to have a large tumor in the posterior fossa and cerebellopontine angle. INTERVENTION Gross total excision of the tumor was accomplished. Histologically, the most unique features were macrovesicular accumulations of lipid, giving the tumor (at least focally) an appearance virtually identical to that of mature adipose tissue. Evidence of biphasic neuronal and glial differentiation was noted by immunohistochemistry and electron microscopy. CONCLUSION A literature review is presented. Diagnostically, this neoplasm seems to fit in a unique group of rarely described, lipomatous neuroectodermal tumors that show divergent neuronal and glial differentiation.OBJECTIVE AND IMPORTANCE: We report a case of a posterior fossa neuroepithelial tumor with unusual clinical presentation, magnetic resonance imaging appearance, and morphological features. CLINICAL PRESENTATION: This 66-year-old man presented with a history of gait ataxia, dizziness, and tinnitus and was found to have a large tumor in the posterior fossa and cerebellopontine angle. INTERVENTION: Gross total excision of the tumor was accomplished. Histologically, the most unique features were macrovesicular accumulations of lipid, giving the tumor (at least focally) an appearance virtually identical to that of mature adipose tissue. Evidence of biphasic neuronal and glial differentiation was noted by immunohistochemistry and electron microscopy. CONCLUSION: A literature review is presented. Diagnostically, this neoplasm seems to fit in a unique group of rarely described, lipomatous neuroectodermal tumors that show divergent neuronal and glial differentiation.

Glioblastoma with Oligodendroglioma Component (GBM‐O): Molecular Genetic and Clinical Characteristics

Glioblastoma (GBM) is an aggressive primary brain tumor with an average survival of approximately 1 year. A recently recognized subtype, glioblastoma with oligodendroglioma component (GBM‐O), was designated by the World Health Organization (WHO) in 2007. We investigated GBM‐Os for their clinical and molecular characteristics as compared to other forms of GBM. Tissue samples were used to determine EGFR, PTEN, and 1p and 19q status by fluorescence in situ hybridization (FISH); p53 and mutant IDH1 protein expression by immunohistochemistry (IHC); and MGMT promoter status by methylation‐specific polymerase chain reaction (PCR). GBM‐Os accounted for 11.9% of all GBMs. GBM‐Os arose in younger patients compared to other forms of GBMs (50.7 years vs. 58.7 years, respectively), were more frequently secondary neoplasms, had a higher frequency of IDH1 mutations and had a lower frequency of PTEN deletions. Survival was longer in patients with GBM‐Os compared to those with other GBMs, with median survivals of 16.2 and 8.1 months, respectively. Most of the survival advantage for GBM‐O appeared to be associated with a younger age at presentation. Among patients with GBM‐O, younger age at presentation and 1p deletion were most significant in conferring prolonged survival. Thus, GBM‐O represents a subset of GBMs with distinctive morphologic, clinical and molecular characteristics.

Low-grade astrocytomas arising from the pineal gland

Two cases of low-grade astrocytoma arising from the pineal gland are described in this report. These rare lesions have only been reported on two previous occasions to arise distinctly from the pineal gland. Histologically, one tumor was consistent with a juvenile pilocytic astrocytoma, while the other was consistent with a fibrillary astrocytoma. The pathological features, clinical implications, and treatment of low-grade astrocytomas in the pineal region are discussed.