Definition and diagnostic implications of gemistocytic astrocytomas: a pathological perspective

Prognosis prediction via histological evaluation of cellular heterogeneity in glioblastoma

Glioblastomas (GBMs) are the most aggressive types of central nervous system tumors. Although certain genomic alterations have been identified as prognostic biomarkers of GBMs, the histomorphological features that predict their prognosis remain elusive. In this study, following an integrative diagnosis of 227 GBMs based on the 2021 World Health Organization classification system, the cases were histologically fractionated by cellular variations and abundance to evaluate the relationship between cellular heterogeneity and prognosis in combination with O-6-methylguanine-DNA methyltransferase gene promoter methylation (mMGMTp) status. GBMs comprised four major cell types: astrocytic, pleomorphic, gemistocytic, and rhabdoid cells. t-distributed stochastic neighbor embedding analysis using the histological abundance of heterogeneous cell types identified two distinct groups with significantly different prognoses. In individual cell component analysis, the abundance of gemistocytes showed a significantly favorable prognosis but confounding to mMGMTp status. Conversely, the abundance of epithelioid cells was correlated with the unfavorable prognosis. Linear model analysis showed the favorable prognostic utility of quantifying gemistocytic and epithelioid cells, independent of mMGMTp. The evaluation of GBM cell histomorphological heterogeneity is more effective for prognosis prediction in combination with mMGMTp analysis, indicating that histomorphological analysis is a practical and useful prognostication tool in an integrative diagnosis of GBMs.

Early High-Grade Transformation of IDH-Mutant Central Nervous System WHO Grade 2 Astrocytoma: A Case Report

High-grade transformation of low-grade gliomas has long been a poor prognostic factor during therapy. In 2016, the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) adopted isocitrate dehydrogenase (IDH) mutation status in the classification of diffuse astrocytomas. The 2021 classification denoted glioblastomas as IDH-wildtype and graded IDH-mutant astrocytomas as 2, 3, or 4. Gemistocytic morphology, a large proportion of residual tumor, the patient's age, and recurrence after radiotherapy were previously mentioned as risk factors for high-grade transformation of low-grade gliomas. We report a 34-year-old male patient initially diagnosed with IDH-mutant grade 2 astrocytoma according to the 2021 WHO classification of CNS tumors. As the first surgical resection achieved gross total resection on postoperative MRI, no adjuvant therapy was given and regular follow-up was planned. On 1-year follow-up MRI, two new enhancing nodular lesions appeared at the ipsilateral brain parenchyma abutting the surgical resection cavity. Salvage craniotomy achieved gross total resection, and the pathologic diagnosis was IDH-mutant WHO grade 4 astrocytoma. We describe this tumor in terms of the previous WHO classification to evaluate the risk of high-grade transformation and discuss possible risk factors leading to high-grade transformation of low-grade astrocytoma.

Gemistocytic Differentiation in Isocitrate Dehydrogenase Mutant Astrocytomas: A Histopathological and Survival Analysis

Gemistocytic differentiation is a rare histological feature seen in IDH mutant Astrocytomas. The 2021 World Health Organization (WHO) retains the diagnosis of IDH mutant Astrocytoma with its classical histology and tumors with the rare histological pattern of gemistocytic differentiation. Gemistocytic differentiation has historically been associated with a worse prognosis and shorter survival, and this prognostic difference has not been investigated in detail in our population. A population-based retrospective study included 56 patients with IDH mutant Astrocytoma with Gemistocytic differentiation and IDH mutant Astrocytoma diagnosed between 2010 and 2018 in our hospital. Demographic, histopathological, and clinical parameters were compared between the two groups. Gemistocyte percentage, perivascular lymphoid infiltrates, and Ki-67 proliferation index were also analyzed. A Kaplan-Meier analysis was done to analyze any prognostic difference in the overall survival time between the two groups. Patients with an IDH mutant Astrocytoma having gemistocytic differentiation had an average survival period of 2 years, while patients diagnosed with an IDH mutant Astrocytoma had an average survival time of approximately 6 years. There was a statistically significant decrease in survival time (p = 0.005) for patients with tumors with gemistocytic differentiation. The percentage of gemistocytes and the presence of perivascular lymphoid aggregates did not correlate with survival time (p = 0.303 and 0.602, respectively). Tumors with gemistocytic morphology had a higher mean Ki-67 proliferation index (4.4%) than IDH mutant Astrocytoma (2.0%, p = 0.005). Our data suggest that IDH mutant Astrocytoma with Gemistocytic differentiation is an aggressive variant of IDH mutant Astrocytoma associated with a shorter survival time and an overall worse prognosis. This data might be helpful to clinicians in the future management of IDH mutant Astrocytoma with Gesmistocytic differentiation as an aggressive tumor.

Significant Systemic Insulin Resistance is Associated With Unique Glioblastoma Multiforme Phenotype

Background

Some glioblastoma multiforme (GBM) are characterized by the presence of gemistocytes (GCs), a unique phenotype of reactive astrocytes. Certain GCs can be identified as neoplastic cells but these cells were also found to be associated with diabetes in non-neoplastic lesions of the central nervous system. Our aim was to find a correlation between insulin - resistance metabolic features and the presence of GCs in patients with newly diagnosed GBM.

Methods

Medical records from histologically confirmed GBM patients were retrospectively extracted for different systemic metabolic variables. A statistic-based comparison was made between GBM, diabetic patients with and without GC. Patients with poorly controlled diabetes (ie, hemoglobin A1C ⩾ 8.0) were also compared between the 2 groups.

Results

A total of 220 newly diagnosed GBM patients were included in our study. 58 (26.3%) patients had a history of diabetes mellitus type 2 (DM2) at the time of admission. The rate of poorly-controlled DM2 was nearly as twice in the GC-GBM group than in the non-GC GBM group (18.75% vs 9.5%; P = .130). In the DM2 cohort, the subgroup of GC-GBM was significantly associated with demographic and metabolic features related to insulin resistance such as male gender predominance (89% vs 50%, P = .073) and morbid obesity (weight ⩾85 kg: OR 6.16; P = .0019 and mean BMI: 34.1 ± 11.42 vs 28.7 ± 5.44; P = .034 for group with and without GCs, respectively). In the poorly-controlled DM2 group, none of the GC-GBM patients were using insulin prior to diagnosis, compared to 61.1% in the non-GC GBM patients (OR = 0.04, P = .045).

Conclusion

Systemic metabolic factors related to marked insulin resistance (DM2, morbid obesity, male gender) are associated with a unique histologic phenotype of GBM, characterized by the presence of GCs. This feature is prominent in poorly-controlled DM2 GBM patients who are not using synthetic insulin. This novel finding may add to the growing data on the relevance of glucose metabolism in astrocytes and in astrocytes associated with high-grade gliomas. In GBM patients, a correlation between patients' metabolic status, tumor's histologic phenotype, tumor's molecular changes, use of anti-diabetic drugs and the respective impact of these factor on survival warrants further investigation.

Differential Glial Chitotriosidase 1 and Chitinase 3-like Protein 1 Expression in the Human Primary Visual Cortex and Cerebellum after Global Hypoxia-Ischemia

Here, we studied the neuroinflammation- and ischemia-related glial markers chitotriosidase 1 (CHIT1) and chitinase-3-like protein 1 (CHI3L1, alias YKL-40) in the human striate cortex and cerebellum at different time points after global hypoxic-ischemic brain injury (HIBI). Both regions differ considerably in their glial cell population but are supplied by the posterior circulation. CHIT1 and CHI3L1 expression was compared to changes in microglial (IBA1, CD68), astrocytic (GFAP, S100β), and neuronal markers (H&E, neurofilament heavy chain, NfH; calretinin, CALR) using immunohistochemistry and multiple-label immunofluorescence. Initial striatal cortical and cerebellar Purkinje cell damage, detectable already 1/2 d after HIBI, led to delayed neuronal death, whereas loss of cerebellar NfH-positive stellate and CALR-positive granule cells was variable. During the first week post-HIBI, a transient reduction of IBA1-positive microglia was observed in both regions, and fragmented/clasmatodendritic cerebellar Bergmann glia appeared. In long-term survivors, both brain regions displayed high densities of activated IBA1-positive cells and CD68-positive macrophages, which showed CHIT1 co-localization in the striate cortex. Furthermore, enlarged GFAP- and S100β-positive astroglia emerged in both regions around 9-10 d post-HIBI, i.e., along with clearance of dead neurons from the neuropil, although GFAP-/S100β-positive gemistocytic astrocytes that co-expressed CHI3L1 were found only in the striate cortex. Thus, only GFAP-/S100β-positive astrocytes in the striate cortex, but not cerebellar Bergmann glia, differentiated into CHI3L1-positive gemistocytes. CHIT1 was co-expressed almost entirely in macrophages in the striate cortex and not cerebellum of long-term survivors, thereby indicating that CHIT1 and CHI3L1 could be valuable biomarkers for monitoring the outcome of global HIBI.

An Updated Comparison Between World Health Organization Grade II Gemistocytic and Diffuse Astrocytoma Survival and Treatment Patterns

BACKGROUND

In 2016, the World Health Organization revised its guidelines to retain only gemistocytic astrocytoma (GemA) as a distinct variant of diffuse astrocytoma (DA). In the past, grade II GemAs were linked with a worse prognosis than DA. However, it is unclear how consistently the tumor subtype has been diagnosed over time. We used more recent data to compare outcomes between grade II GemA and DA.

METHODS

Patients with grade II DA and GemA were extracted from the Surveillance, Epidemiology, and End Results database between 1973 and 2016. Kaplan-Meier curves estimated survival differences across different eras, with a focus on patients diagnosed between 2000 and 2016, and propensity score matching was used to balance baseline characteristics between DA and GemA cohorts.

RESULTS

Of 2467 patients with grade II astrocytoma diagnosed between 2000 and 2016, 132 (5.35%) had GemA, and 2335 (94.65%) had DA. At baseline, marked demographic and treatment differences were noted between tumor subtypes, including age at diagnosis and female sex. GemA patients did not have worse survival compared with DA patients at baseline (P = 0.349) or after propensity score matching (P = 0.497). Multivariate Cox models found that surgical extent of resection was associated with a survival benefit for DA patients, and both DA and GemA patients >65 years old had dramatically inferior survival.

CONCLUSIONS

Our data suggest that the impact of GemA versus DA histopathology depends more on the decade of queried data rather than patient-specific demographics. Using more recent longitudinal data, we found that grade II GemA and DA tumors did not have significant differences in survival. These data may prove useful for clinicians counseling patients with grade II GemA.

Gemistocytes in newly diagnosed glioblastoma multiforme: Clinical significance and practical implications in the modern era

BACKGROUND

Gemistocytes (GCs) in low grade gliomas are associated with rapid growth and worse prognosis. However, their clinical significance in glioblastomas (GBM) is a matter of debate.

AIM OF STUDY

To investigate the clinical significance of the presence of GCs in newly-diagnosed GBM patients in the modern era.

METHODS

Computerized medical records from newly diagnosed GBM patients were retrospectively reviewed and extracted for demographic, clinical, radiological and pathological variables. Patients with at least 5% GCs of neoplastic cells were considered GC-GBM (group 1). All other cases were considered non-GC GBM (group 2). Group 1 was further divided into two subgroups: Low percentage GCs (group 1a, ≤ 20% GCs) and high percentage GC (group 1b, >20% GCs).

RESULTS

A total of 220 patients with newly diagnosed GBM were included. 14.5% were defined as GC-GBM (group I, n = 32) and 85.5% were defined as non-GC GBM (group 2, n = 188). 8.5% had ≤ 20% GCs (group 1a, n = 19) and 5.9% had > 20% GCs (group 1b, n = 13). Groups were similar for most epidemiological and clinical variables. There was a trend toward worse prognosis in group 1b. Several distinguished radiological and molecular features were observed in group 1.

CONCLUSION

GCs are found in minority of naïve, newly diagnosed, GBM cases in adults. They seem to carry minimal implications on daily clinical practice. Higher percentage of GCs is associated with distinct radiological features such as multifocality that might be correlated with decreased OS. High-percentage GC-GBMs are also associated with increased prevalence of isocitrate dehydrogenase (IDH) mutations.

Prognostic relevance of adding MRI data to WHO 2016 and cIMPACT-NOW updates for diffuse astrocytic tumors in adults. Working toward the extended use of MRI data in integrated glioma diagnosis

Assess the contribution of preoperative MRI data in improving grading of adult astrocytomas reclassified according to the WHO 2016 and cIMPACT-NOW update 3. Retrospective unicentric cohort study of 679 adult patients treated for newly diagnosed diffuse astrocytic and oligodendroglial tumors (January 2006-December 2016). We first systematically compared radiological (contrast enhancement present [CE+] vs. absent [CE-]) and histopathological findings (microvascular proliferation present [MPV+] vs. absent [MPV-]) to validate whether this comparing step of neoangiogenesis represents an efficient method to appreciate the representativity of the tumoral sampling. We focused on 629 cases of astrocytomas for radio-histological integrated analyses. In 598 cases (95.1%), neoangiogenesis evaluated by MRI or histology (CE+/MPV+ or CE-/MPV-) was identical. For the CE+/MPV- and CE-/MPV+ groups (23 cases), the radio-histological face-to-face evaluation allowed us to assess that for 13 cases (56.5%) the reason for this discrepancy was an undersampled tumor. We analyzed the group of CE+/MPV- (n = 8) and CE-/MPV+ (n = 2) in verified image-guided tumoral samples. Finally, we identified three new prognostic subgroups for molecular glioblastomas: (1) "non-representative sampling" (n = 9), (2) "Non neoangiogenic glioblastoma at the time of diagnosis, without contrast enhancement and microvascular proliferation" (n = 8), and (3) "contrast enhancing glioblastoma but without microvascular proliferation in a representative sample" (n = 4). Neoangiogenesis processes should be assessed to improve the prognosis accuracy of the current integrated diagnosis. We suggest adding imaging analyses during the neuropathological analysis of astrocytomas in adults.

[Gemistocytic astrocytomas]

Gemistocytic astrocytomas (GA) are a variant of diffuse astrocytomas GII (WHO, 2016). Like all diffuse astrocytomas, GA recur with time, which is often accompanied by malignant degeneretion into the anaplastic astrocytoma GIII or to the secondary glioblastoma GIV. However, the progression-free survival and overall survival in patients with GA is less than in patients with diffuse astrocytomas. Given that this group of patients, according to the WHO classification (2016), is classified as GII, patients with GA usually do not receive comprehensive treatment. We have conducted a thorough analysis of research on this problem for the period from 1956 to 2017. Differences in the histological pattern, immunohistochemical and molecular-genetic profiles, survival of patients with GA and diffuse astrocytomas GII are shown there. A clinical case of a patient with transformation of a diffuse astrocytoma in GA (GIII) and then into a secondary glioblastoma is presented.

Low-grade astrocytomas: the prognostic value of fibrillary, gemistocytic, and protoplasmic tumor histology

OBJECT

Low-grade astrocytomas are slow-growing, infiltrative gliomas that over time may progress into more malignant tumors. Various factors have been shown to affect the time to progression and overall survival including age, performance status, tumor size, and the extent of resection. However, more recently it has been suggested that histological subtypes (fibrillary, protoplasmic, and gemistocytic) may impact patient outcome. In this study the authors have performed a large comparative population-based analysis to examine the characteristics and survival of patients with the various subtypes of WHO Grade II astrocytomas.

METHODS

Patients diagnosed with fibrillary, protoplasmic, and gemistocytic astrocytomas were identified through the Surveillance, Epidemiology, and End Results (SEER) database. The chi-square test and Student t-test were used to evaluate differences in patient and treatment characteristics between astrocytoma subtypes. Kaplan-Meier analysis was used to assess overall survival, and the log-rank test was used to evaluate the differences between survival curves. Univariate and multivariate analyses were also performed to determine the effect of various patient, tumor, and treatment variables on overall survival.

RESULTS

A total of 500 cases were included in the analysis, consisting of 326 fibrillary (65.2%), 29 protoplasmic (5.8%), and 145 gemistocytic (29%) variants. Gemistocytic astrocytomas presented at a significantly older age than the fibrillary variant (46.8 vs 37.7 years, p < 0.0001), with protoplasmic and fibrillary subtypes having a similar age. Although protoplasmic and fibrillary variants underwent radiotherapy at similar rates, gemistocytic tumors more frequently received radiotherapy (p = 0.0001). Univariate analysis revealed older age, larger tumor size, and the use of radiotherapy to be poor prognostic factors, with resection being associated with improved survival. The gemistocytic subtype (hazard ratio [HR] 1.62 [95% CI 1.27-2.07], p = 0.0001) also resulted in significantly worse survival than fibrillary tumors. Bivariate analyses demonstrated that older age, the use of radiotherapy, and resection significantly influenced median survival. Tumor subtype also affected median survival; patients who harbored gemistocytic tumors experienced less than half the median survival of fibrillary and protoplasmic tumors (38 vs 82 months, p = 0.0003). Multivariate analysis revealed increasing age (HR 1.05 [95% CI 1.04-1.05], p < 0.0001), larger tumor size (HR 1.02 [95% CI 1.01-1.03], p = 0.0002), and the use of resection (HR 0.70 [95% CI 0.52-0.94], p = 0.018) to be independent predictors of survival. Examination of tumor subtype revealed that the gemistocytic variant (HR 1.30 [95% CI 0.98-1.74], p = 0.074) was associated with worse patient survival than fibrillary tumors, although this only approached significance. The protoplasmic subtype did not affect overall survival (p = 0.33).

CONCLUSIONS

Gemistocytic tumor histology was associated with worse survival than fibrillary and protoplasmic astrocytomas. As protoplasmic astrocytomas have a survival similar to fibrillary tumors, there may be limited utility to the identification of this rare variant. However, increased attention should be paid to the presence of gemistocytes in low-grade gliomas as this is associated with shorter time to progression, increased malignant transformation, and reduced overall survival.

The assessment of prognostic factors in surgical treatment of low-grade gliomas: a prospective study

OBJECTIVE

A prospective volumetric analysis of extent of resection (EOR) was carried out to assess surgical outcomes in adults diagnosed with hemispheric low grade gliomas (LGGs).

MATERIALS AND METHODS

68 consecutive patients diagnosed with LGGs were enrolled in the study. Pre- and post-operative tumor volumes and EOR were measured based on FLAIR MRI. Dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC MRI) was used for the assessment of relative cerebral blood volume (rCBV). Three outcome measures were assessed: overall survival (OS), progression-free survival (PFS), and malignant degeneration-free survival (MFS).

RESULTS

In 6 (9%) patients permanent neurologic deficits were observed. No statistically significant dependence between the EOR and the occurrence of permanent deficits was found. The eloquent or close to the eloquent location was statistically connected with lower EOR (p=0.023). The preoperative volume of tumors treated with gross total resection was significantly smaller than the volume of tumors in subtotal or partial resection groups (p=0.020, p<0.001, respectively). OS was predicted by age at diagnosis (p=0.032), and rCBV (p=0.002). Progression and malignant transformation occurred in 22 (32%) and 11 (16%) out of 68 patients. PFS was predicted by preoperative tumor volume (p=0.005), postoperative tumor volume (p=0.008), the EOR (p=0.001), and by the rCBV (p=0.033). MFS was predicted by preoperative tumor volume (p=0.034), the EOR (pp=0.020), and by rCBV (p=0.022). Postoperative tumor volume was associated with a trend of improved MFS (p=0.072). The univariate analysis shows the statistical trend for the relationship between histological subtype and PFS and MFS (p=0.079, p=0.078, respectively). Multivariate analysis selected preoperative tumor volume and rCBV as independently associated with PFS (p=0.009, p=0.019, respectively) and MFS (p=0.023, p=0.035, respectively). EOR was associated with a trend of improved PFS, and MFS (p=0.069, p=0.094, respectively).

CONCLUSIONS

Tumor resection of LGG with the use of intraoperative monitoring and neuronavigation is associated with a low risk of new permanent deficits, but EOR significantly decreases with the size of the tumor and/or its location in/close to the eloquent areas. Smaller preoperative tumor volume and greater EOR are significantly associated with longer OS, PFS and MFS. Preoperative rCBV is one of the important prognostic factors significantly connected with survival. Prognosis in LGGs is still under discussion. Other factors such as age, histopathological subtype and KPS should not be underestimated.

Anti-tumor immune response correlates with neurological symptoms in a dog with spontaneous astrocytoma treated by gene and vaccine therapy

Gene therapy and vaccination have been tested in malignant glioma patients with modest, albeit encouraging results. The combination of these therapies has demonstrated synergistic efficacy in murine models but has not been reported in large animals. Gemistocytic astrocytoma (GemA) is a low-grade glioma that typically progresses to lethal malignancy despite conventional therapies. Until now there has been no useful animal model of GemA. Here we report the treatment of a dog with spontaneous GemA using the combination of surgery, intracavitary adenoviral interferon gamma (IFNgamma) gene transfer, and vaccination with glioma cell lysates mixed with CpG oligodeoxynucleotides. Surgical tumor debulking and delivery of Ad-IFNgamma into the resection cavity were performed. Autologous tumor cells grew slowly in culture, necessitating vaccination with allogeneic tumor lysate in four of the five vaccinations. Transient left-sided blindness and hemiparesis occurred following the fourth and fifth vaccinations. These neurological symptoms correlated with a peak in the levels of tumor-reactive IgG and CD8(+) T cells measured in the blood. All symptoms resolved and this dog remains tumor-free over 450 days following surgery. This case report preliminarily demonstrates the feasibility of treating dogs with spontaneous glioma using immune-based therapy and warrants further study using this therapeutic approach.

Expression of the Polycomb-Group protein BMI1 and correlation with p16 in astrocytomas an immunohistochemical study on 80 cases

A number of studies on the putative relation between Polycomb-Group (PcG) proteins overexpression and carcinogenesis have been published recently. BMI1, the prototype PcG gene, is critically involved in cell cycle control and differentiation, and despite the regulatory role demonstrated in central nervous system (CNS) development, its implication in brain tumorigenesis is scarcely known. Moreover, to the best of our knowledge, large studies on human brain tumors tissue are lacking. To gain a new insight, we tested 80 primary brain astrocytomas for BMI1 expression using immunohistochemistry and established a correlation with the expression of p16, a negatively regulated target of BMI1 function. Fifty-four cases (72.5%) were BMI1 + /p16-, and 22 cases (27.5%) were BMI1 + /p16+. Slight non-significant differences were noted in the expression profile between grades II, III, and IV astrocytomas. However, when the 22 BMI1 + /p16+ tumors were examined cytologically, a substantial proportion contained a significant gemistocytic component, which is thought to be an adverse prognostic factor or to display a high degree of anaplasia, suggesting a common molecular mechanism of BMI1/p16 pathway disruption, which may have prognostic implications.

Role of Extent of Resection in the Long-Term Outcome of Low-Grade Hemispheric Gliomas

Purpose

The prognostic role of extent of resection (EOR) of low-grade gliomas (LGGs) is a major controversy. We designed a retrospective study to assess the influence of EOR on long-term outcomes of LGGs.

Patients and Methods

The study population (N = 216) included adults undergoing initial resection of hemispheric LGG. Region-of-interest analysis was performed to measure tumor volumes based on fluid-attenuated inversion-recovery (FLAIR) imaging.

Results

Median preoperative and postoperative tumor volumes and EOR were 36.6 cm3 (range, 0.7 to 246.1 cm3), 3.7 cm3 (range, 0 to 197.8 cm3) and 88.0% (range, 5% to 100%), respectively. There was no operative mortality. New postoperative deficits were noted in 36 patients (17%); however, all but four had complete recovery. There were 34 deaths (16%; median follow-up, 4.4 years). Progression and malignant progression were identified in 95 (44%) and 44 (20%) cases, respectively. Patients with at least 90% EOR had 5- and 8-year overall survival (OS) rates of 97% and 91%, respectively, whereas patients with less than 90% EOR had 5- and 8-year OS rates of 76% and 60%, respectively. After adjusting each measure of tumor burden for age, Karnofsky performance score (KPS), tumor location, and tumor subtype, OS was predicted by EOR (hazard ratio [HR] = 0.972; 95% CI, 0.960 to 0.983; P < .001), log preoperative tumor volume (HR = 4.442; 95% CI, 1.601 to 12.320; P = .004), and postoperative tumor volume (HR = 1.010; 95% CI, 1.001 to 1.019; P = .03), progression-free survival was predicted by log preoperative tumor volume (HR = 2.711; 95% CI, 1.590 to 4.623; P ≤ .001) and postoperative tumor volume (HR = 1.007; 95% CI, 1.001 to 1.014; P = .035), and malignant progression-free survival was predicted by EOR (HR = 0.983; 95% CI, 0.972 to 0.995; P = .005) and log preoperative tumor volume (HR = 3.826; 95% CI, 1.632 to 8.969; P = .002).

Conclusion

Improved outcome among adult patients with hemispheric LGG is predicted by greater EOR.

Glioblastoma

CONTEXT

Glioblastoma (GBM), the most common primary intracranial malignancy, is a morphologically diverse neoplasm with dismal prognosis despite multimodality therapy. Only 3 distinct morphologic variants of GBM are currently recognized by the current World Health Organization classification scheme, including GBM, giant cell GBM, and gliosarcoma. Additional variants, some of which have significant morphologic overlap with tumors that have more favorable prognosis and treatment response rates, particularly anaplastic oligodendroglioma, have been described since its publication in 2000 and may be included in the next classification.

OBJECTIVE

To summarize the morphologic and molecular genetic diversity of both well-established and novel GBM variants and outline our approach to these heterogeneous neoplasms and their distinction from other diffuse, high-grade gliomas.

DATA SOURCES

Published literature and our own experience in an active academic diagnostic surgical neuropathology practice were reviewed.

CONCLUSIONS

Precise subclassification of GBM is required for accurate prognostication and appropriate treatment planning.

Gemistocytes in astrocytomas: Are they a significant prognostic factor?

Our aim was to retrospectively evaluate the influence of gemistocytic astrocytes, cellular proliferation indices, immunoexpression of proteins p53 and bcl-2 in the clinical outcome of 39 patients with WHO grade II and III astrocytomas with the presence of gemistocytes. The mean proportion of gemistocytes was 18.7% and the mean proliferative index was 3.3%. Immunoexpression of p53 was detected in 29 cases (74.4%) and all cases (100%) were positive for bcl-2. The median overall survival was 97.2 months and the progression-free survival was 43.1 months. Estimated 1-, 5- and 10-year overall survival rates were 94.3%, 69.5% and 46.4%; 1-, 5- and 10-year progression-free survival rates were 91.1%, 26.1% and 13.1%. Out of 24 who presented clinical and neuroimaging worsening, characterized as tumor progression or recurrence, 16 had histological confirmation and were also analyzed. We could not detect significant differences when comparing all the indices between WHO grade II and III and also between the first and second biopsies. We also could not detect significant differences in progression-free and overall survival when analyzing the gemistocyte index and the immunohistochemical labeling indices p53, bcl-2 and MIB-1, as well as patientsa9 age (median value, up to 34 vs. over 34 years) and histological grade (II or III). Our finding confirms recent reports that question the role of gemistocytes as a prognostic factor in diffuse astrocytomas. The significance and role of gemistocytes in astrocytomas has yet to be defined and warrants further study.