Association of pleomorphic xanthoastrocytoma with cortical dysplasia and neuronal tumors: A report of three cases

Noninvasive prediction of BRAF V600E mutation status of pleomorphic xanthoastrocytomas with MRI morphologic features and diffusion-weighted imaging

OBJECTIVES

Seeking a noninvasive predictor for BRAF V600E mutation status of pleomorphic xanthoastrocytomas (PXAs) is essential for their prognoses and therapeutic use of BRAF inhibitors. We aimed to noninvasively diagnose BRAF V600E-mutated PXAs using MRI morphologic, DWI and clinical parameters.

METHODS

The clinical findings, anatomical MRI characteristics, and diffusion parameters of 36 pathologically confirmed PXAs were retrospectively analyzed, and BRAF V600E-mutated (n = 16) and wild-type (n = 20) groups were compared. A binary logistic-regression analysis was performed, and a ROC curve was calculated to determine the independent predictors of BRAF V600E mutation status, diagnostic accuracy, and optimal cut-off value.

RESULTS

A comparison of findings between groups showed that BRAF V600E-mutated PXAs were more frequent in children and young adults (≤ 35 years; P = 0.042) who often had histories of seizures (P = 0.004). Furthermore, BRAF V600E-mutated PXAs generally presented as solitary masses (P = 0.024), superficial locations with meningeal attachment (P < 0.001), predominantly cystic with mural nodules (P = 0.005), and had greater minimal ADC ratio (ADCratio) values of the tumor and peritumoral edema (P < 0.001). Binary logistic regression showed that age ≤ 35 years, solitary mass, superficial locations with meningeal attachment, and a greater minimal ADCratio of the tumor were independent predictors of BRAF V600E-mutated PXAs. The combination of all four independent predictors resulted in the highest sensitivity (100%) and specificity (90%), with AUC = 0.984.

CONCLUSION

The BRAF V600E mutation status of PXAs could be noninvasively predicted using clinical and MRI characteristics.

CRITICAL RELEVANCE STATEMENT

The noninvasive diagnostic criteria for BRAF V600E-mutated PXAs could offer guidance for the administration of BRAF V600E mutation inhibitors in the future.

The Frequency of Focal Cortical Dysplasia-Like Histologic Features Near Adult-Type Diffuse Gliomas

While the coexistence of focal cortical dysplasia (FCD) and grade 1 noninfiltrative gliomas has been described, to date, only rare case reports have described FCD adjacent to infiltrating gliomas. We therefore sought to determine how often FCD-like findings occur near adult-type diffuse gliomas. This was a retrospective survey of 186 consecutive, newly diagnosed, en bloc glioma resections. Fifty-nine (31.7%) had sufficient adjacent cortex to evaluate for FCD-like features. Among IDH mutant (“IDHmut”) gliomas, 40/77 (52%) had adjacent evaluable cortex, whereas only 19/109 (17%) of IDH wild-type (“IDHwt”) gliomas did (p &lt; 0.0001). Among cases with evaluable cortex, 15 (25.4%) contained features suggestive of FCD, including radial/tangential dyslamination and/or maloriented neurons. In a multivariable analysis, increasing glioma grade (OR = 4.0, 95% CI = 1.2–13.5, p = 0.027) and IDHmut (OR = 6.5, 95% CI = 1.3–32.2, p = 0.022) emerged as independently positive correlates with the appearance of FCD-like findings. However, FCD-like features were also found in 13/32 (40.6%) cortical samples from adult brains without any neoplastic disease or seizure histories (p = 0.16). Together, these data suggest that, while FCD-like histologic features can be incidentally found in at least a subset of diffusely infiltrative gliomas, the frequencies are not significantly different from that seen in otherwise non-neoplastic brains, and are therefore most likely nonpathologic.

Ultrastructural evidence for presenсe of gap junctions in rare case of pleomorphic xanthoastrocytoma

The phenomenon of unstable expression of gap junction's proteins connexins remains a "visiting card" of astrocytic tumors with various degrees of malignancy. At the same time, it stays unclear what is detected by the positive expression of connexins in astrocytic tumors: gap junctions, hemi-channels, or connexin proteins in cytosol. In the present work, for the first time, we demonstrate an ultrastructural evidence of gap junctions in pleomorphic xanthoastrocytoma, a rare primary brain tumor, the intercellular characteristics of which are poorly studied and remain very discursive and controversial. The primary tumor mass was resected during craniotomy from a 57-old patient diagnosed with pleomorphic xanthoastrocytoma Grade II based on the histopathological analysis. The immunohistochemical study was conducted with primary antibodies: Neurofilament, Myelin basic protein, Glial fibrillary acidic protein, and Synaptophysin. For electron microscopic examination fragments of tumor tissue were fixed in a glutaraldehyde, postfixed in a 1% OsO₄, dehydrated and embedded into resin. After the detailed clinical, histological, and immunohistochemical study we revealed some ultrastructural characteristics of the tumor, as well as the first evidence of direct intercellular connection between the tumor cells via gap junctions. Regularly arranged gap junctions connected the somas of xanthastrocytes with dark cytoplasm containing lipid drops. Besides the localization between the cell bodies, from one to several gap junctions were found between the branches of xanthoastrocytoma in tumor intercellular space in close proximity to tumor cell. Our results may indicate gap junctions as a possible structure for intercellular communication between pleomorphic xanthoastrocytoma cells.

Drug Refractory Epilepsy - A Series of Lesions with Triple Pathology

The associations between gangliogliomas, dysembryoplastic neuroepithelial tumors (DNETs), and cortical dysplasias remain debatable. We report five cases of drug refractory epilepsy with temporal lobe lesions. On resection, histopathological examination showed distinctive areas of gangliogliomas and DNETs with cortical dysplasia. The coexistence of the above three lesions as distinct entities in a single lesion is virtually unknown. This points to the presence of a possible etiological relationship among them. Finally, we also delve into a plausible hypothesis for such a pathogenesis.

Ganglioglioma Progression to Combined Anaplastic Ganglioglioma and Anaplastic Pleomorphic Xanthoastrocytoma. Case Report and Literature Review

BACKGROUND

Composite ganglioma and pleomorphic xanthoastrocytoma with anaplastic features in both components is an extremely rare glioneuronal tumor. Five cases of anaplastic progression in the glioma component have been reported. These tumors generally affect young patients who have brain tumor-related epilepsy, which are usually located in the temporal lobe or in the cerebellum and may have associated leptomeningeal spreading. Its current optimal treatment consists of maximal safe surgical resection and adjuvant chemoradiotherapy. Overall survival at 5 years is 33% in anaplastic pleomorphic xanthoastrocytoma and 53% in anaplastic ganglioglioma.

CASE DESCRIPTION

We describe a progression from ganglioglioma to this composite anaplastic entity after 32 months of follow-up, with apparently nontumoral parenchyma separating the 2 components. Polymerase chain reaction showed a wild-type BRAF gene. Seven months after concomitant chemoradiotherapy, radiologic progression led to a second line of chemotherapy, and a third line of chemotherapy was initiated after a subsequent progression at 11 months.

CONCLUSIONS

This case may add some evidence in favor of the glioneuronal maldevelopment hypothesis to explain the oncogenesis of these neuroepithelial tumors.

Melanosomal melanin pigment in pleomorphic xanthoastrocytoma, evidence for neuronal-glial origin: A case report with review of the literature

We describe a unique case of pleomorphic xanthoastrocytoma (PXA) in a 19-year-old male presenting with the chief complaint of seizures. On radiology, the tumor was located in the temporal lobe. It was cortically based and solid cystic in nature. Light microscopy showed pleomorphic large polygonal cells with inclusions, nuclear clustering, lipidization, and foamy cytoplasm intermingled with spindle cells arranged in sweeping pattern and focally containing cytoplasmic brownish black pigment. The pigment stained black with Fontana-Masson stain and bleached with potassium permanganate. Gomori silver stain showed reticulin fibers surrounding individual tumor cells as well as groups of cells. On immunohistochemistry, tumor cells were positive for GFAP, S-100 and focally for synaptophysin and CD34 but negative for HMB-45. CD34 revealed a specific membranous pattern around individual cells as well as groups of cells along the fibers replicating a reticulin pattern. The ultrastructural examination showed supporting melanosomes, thus confirming the melanin pigment. Sequencing for BRAF V600E showed a heterozygous mutation. To our knowledge only five cases of PXA with melanin pigment have been reported and none of which described BRAF V600E mutation analysis. This case provides further insight into the origin and pathogenesis of pigmented astrocytic tumor, additionally highlighting the characteristic CD34 staining pattern.

Combined pleomorphic xanthoastrocytoma-ganglioglioma with BRAF V600E mutation: case report

Combined pleomorphic xanthoastrocytoma (PXA) and ganglioglioma (GG) is an extremely rare tumor, with fewer than 20 cases reported. The authors report a case of combined PXA-GG in an 18-year-old man with a history of seizures. The tumor showed necrosis and the BRAF V600E mutation on histological examination, with no evidence of tumor recurrence 1 year after gross-total resection. The BRAF V600E mutation was present, which suggests that both cell lineages may share a common cellular origin.

Aggressive behavior and anaplasia in pleomorphic xanthoastrocytoma: a plea for a revision of the current WHO classification

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic neoplasm that commonly affects children and young adults, and presents with seizures. PXA is typically supratentorial with a predilection to the temporal lobe, and often involves the cortex and the meninges. PXAs have a favorable prognosis with a 10-year survival probability of >70%, and are WHO grade II neoplasms. Recent observations and studies demonstrate that PXAs are clinically, histologically and genetically distinct. Some PXAs recur and exhibit aggressive clinical behavior. In such cases, certain histological and clinical factors could account for the aggressive behavior. However, the histological features that predict adverse outcome are poorly defined. In the current WHO classification of CNS tumors, there is no option for a high-grade PXA, even if the tumor had numerous recurrences and poor outcome. In this review, we focus on aggressive clinical behavior and anaplasia in PXA, and discuss how our current experience suggests modifications in the current WHO classification. We also review recent discoveries on the molecular characteristics of PXA that could help us better understand their biological behavior.

Classification and pathological characteristics of the cortical dysplasias

BACKGROUND

Focal cortical dysplasias (FCD) are a well-recognized cause of medically intractable epilepsy. They are defined as malformations of cortical development and are marked by abnormalities of cortical layering and neuronal differentiation and maturation. A number of classification approaches have been devised over the last four decades, indicating controversies surrounding issues of recognition, definition, and philosophical approach. More recent attempts have attempted to correlate morphologic phenotype with clinical or developmental parameters in order to provide a clinical relevance.

DISCUSSION

This short review provides an overview of the issues which account for the varied historical approaches to FCD classification and descriptions of gross pathologic findings associated with FCD and an overview of two more recently developed and widely used schema, the Palmini et al. (Neurology 62: S2-8, 2004) and the International League Against Epilepsy (ILAE) classifications Blumcke et al. Epilepsia 52: 158-174, 2011. The pathologic features of these two approaches will be reviewed and compared, including discussion of their limitations.

Prognostic factors and therapeutic outcomes in 22 patients with pleomorphic xanthoastrocytoma

OBJECTIVE

Pleomorphic xanthoastrocytoma (PXA) is a rare primary low-grade astrocytic tumor classified as WHO II. It is generally benign, but disease progression and malignant transformation have been reported. Prognostic factors for PXA and optimal therapies are not well known.

METHODS

The study period was January 2000 to March 2012. Data on MR findings, histology, surgical extents and adjuvant therapies were reviewed in twenty-two patients diagnosed with PXA.

RESULTS

The frequent symptoms of PXA included seizures, headaches and neurologic deficits. Tumors were most common in the temporal lobe followed by frontal, parietal and occipital lobes. One patient who died from immediate post-operative complications was excluded from the statistical analysis. Of the remaining 21 patients, 3 (14%) died and 7 (33%) showed disease progression. Atypical tumor location (p<0.001), peritumoral edema (p=0.022) and large tumor size (p=0.048) were correlated with disease progression, however, Ki-67 index and necrosis were not statistically significant. Disease progression occurred in three (21%) of 14 patients who underwent GTR, compared with 4 (57%) of 7 patients who did not undergo GTR, however, it was not statistically significant. Ten patients received adjuvant radiotherapy and the tumors were controlled in 5 of these patients.

CONCLUSION

The prognosis for PXA is good; in our patients overall survival was 84%, and event-free survival was 59% at 3 years. Atypical tumor location, peritumoral edema and large tumor size are significantly correlated with disease progression. GTR may provide prolonged disease control, and adjuvant radiotherapy may be beneficial, but further study is needed.

Pleomorphic xanthoastrocytoma: magnetic resonance imaging findings in a series of cases with histopathological confirmation

Pleomorphic xanthoastrocytoma (PXA) is a rare glioma. This paper aimed to analyze magnetic resonance imaging (MRI) characteristics in a series of patients diagnosed with PXA. We analyzed MRI findings in 9 patients with histopathologic diagnosis of PXA in our department over the last 12 years. The mean age of patients was 27.3 years. Cortical location was observed in all cases. The lesion imaging was solid-cystic in six cases. In eight cases, the solid component presented hypo or isointense on T1 and iso or hyperintense on T2. Contrast enhancement in the solid component was observed in eight cases. The observed imaging pattern of PXA was superficial location with leptomeningeal involvement, solid-cystic pattern and contrast enhancement in the solid component. We should consider that the association between PXA and other cortical tumors may occur, particularly, with gangliogliomas, which tend to be the main differential diagnosis in MRI.

Long-term epilepsy-associated tumors

The term long-term epilepsy associated tumor (LEAT) encompasses lesions identified in patients investigated for long histories (often 2 years or more) of drug-resistant epilepsy. They are generally slowly growing, low grade, cortically based tumors, more often arising in younger age groups and in many cases exhibit neuronal in addition to glial differentiation. Gangliogliomas and dysembryoplastic neuroepithelial tumors predominate in this group. LEATs are further united by cyto-architectural changes that may be present in the adjacent cortex which have some similarities to developmental focal cortical dysplasias (FCD); these are now grouped as FCD type IIIb in the updated International League Against Epilepsy (ILAE) classification. In the majority of cases, surgical treatments are beneficial from both perspectives of managing the seizures and the tumor. However, in a minority, seizures may recur, tumors may show regrowth or recurrence, and rarely undergo anaplastic progression. Predicting and identifying tumors likely to behave less favorably are key objectives of the neuropathologist. With immunohistochemistry and modern molecular pathology, it is becoming increasingly possible to refine diagnostic groups. Despite this, some LEATs remain difficult to classify, particularly tumors with "non-specific" or diffuse growth patterns. Modification of LEAT classification is inevitable with the goal of unifying terminological criteria applied between centers for accurate clinico-pathological-molecular correlative data to emerge. Finally, establishing the epileptogenic components of LEAT, either within the lesion or perilesional cortex, will elucidate the cellular mechanisms of epileptogenesis, which in turn will guide optimal surgical management of these lesions.

Magnetic resonance imaging in epilepsy

With a major role in revealing epileptogenic lesions, magnetic resonance imaging (MRI) has also been very helpful in surgical planning and postoperative follow-up of drug-resistant focal epilepsies. In this article, in addition to discussing the most common epileptogenic lesions, advanced quantitative and functional MRI techniques in detecting abnormalities and revealing hemodynamic and microstructural changes are emphasized.

Coexistent pathology in chronic epilepsy patients with neoplasms

Neoplasms are a well-established cause of medically intractable or chronic epilepsy. Certain tumors, including gangliogliomas and dysembryoplastic neuroepithelial tumors, are well known to be associated with cortical dysplasia. This study retrospectively examines the incidence of coexistent pathology in patients with tumors and chronic epilepsy. This study is a retrospective review of 270 tumors arising in patients with medically intractable epilepsy encountered during a 20-year period (1989-2009). Coexistent pathology was noted in 50 of 270 (17.8%) patients, including 27 males (54%) with a mean age at surgery of 18 years (range 1-52 years). The vast majority of lesions (n=40) (80%) were located in the temporal lobe and less commonly in the parietal lobe (n=4) and the occipital lobe (n=3). Tumor diagnoses included ganglioglioma (n=29), dysembryoplastic neuroepithelial tumor (n=10), low-grade glial/glioneuronal neoplasm (n=5), low-grade astrocytoma (n=2), angiocentric glioma (n=1), low-grade mixed glioma (n=1), dysembryoplastic neuroepithelial tumor/ganglioglioma mixed tumor (n=1), and meningioangiomatosis (n=1). Forty-one (82%) tumors represented WHO grade-I neoplasms. Concomitant pathology included malformation of cortical development (cortical dysplasia) in 40 patients (80%) (Palmini et al type-I: n=37; Palmini et al type-II: n=3). Hamartias were identified in 10 patients (20%), hippocampal sclerosis in four patients (8%), and nodular heterotopia in one patient (2%). The true incidence of coexistent pathology (17.8% in this study) was likely underrepresented, given the limited extent of adjacent non-tumoral tissue sampling in cases of resected tumor. Coexistent pathology may account for the incidence of recurrent or residual epilepsy in patients who undergo tumor resection.

Cerebellar pleomorphic xanthoastrocytoma: case report and literature review

BACKGROUND

PXA generally has histologic features characteristic of benign biological behavior, although malignant forms have been reported. This neoplasm has also been observed in atypical locations.

METHODS

The authors report a case of cerebellar PXA with rapid malignant transformation in a 58-year-old woman and review the rare presentations and atypical features of this tumor.

RESULTS

Among the "unusual" locations, the most frequent is the cerebellum with 15 cases having been described, 9 in adults, with an average age of 33 years. In contrast, supratentorial forms had a younger age profile (26 years). The time from onset of symptoms to diagnosis was approximately 5.3 months. PXA in the posterior fossa had a higher rate of solid enhancing tumor (9/14). Regarding histologic appearance, two thirds were composite lesions.

CONCLUSIONS

The clinicopathologic features of cerebellar PXA show some differences from PXA located in the cerebral hemispheres. Recognizing the potential for PXA to present with unusual manifestations, regardless of location, has an obvious impact on the accuracy of diagnosis.

Malignant progression in pleomorphic xanthoastrocytoma: Personal experience and review of the literature

Pleomorphic xanthoastrocytoma (PXA) is a rare primary low-grade astrocytic tumor, recently classified as a neuroglial tumor. It generally occurs in children and young adults and shows benign behaviour (WHO II), although an anaplastic variant and malignant potential have been described. Pleomorphic xanthoastrocytomas with malignant transformation have been reported in three out of eight patients operated on for this type of tumor in our department in the last 15 years. The three patients were two adult women and a child, the primary tumors were located in the cortex of the right temporal lobe, and treatment consisted of complete surgical resection. Histological examination revealed simple PXA in two patients and a PXA with anaplastic foci in the other. Mean recurrence time was 5.7 years, with the original xanthoastrocytoma evolving to glioblastoma in two cases and anaplastic astrocytoma in the third. All three patients underwent a second operation, followed by adjuvant therapies. Two died from tumor progression and one from brain edema after intracerebral haemorrhage. A review of the available PXA literature dating back to 1979 revealed 16 cases of primary anaplastic astrocytoma and 21 cases of PXA with malignant transformation. Our experience adds three more cases of malignant transformations, outlining once again the potential malignancy of pleomorphic xanthoastrocytomas and the fact that prognosis in these cases is the same as for primary anaplastic astrocytoma and glioblastoma. Analysis of glioneuronal markers, Ki67 and p53 in all pleomorphic xanthoastrocytomas did not prove to be a discriminating factor to identify a subgroup of xanthoastrocytomas prone to malignancy. Accordingly, these tumors demand close long-term clinical and radiological follow-up.

Desmoplastic noninfantile ganglioglioma: report of a case

Desmoplastic infantile ganglioglioma is a rare superficial supratentorial tumor that occurs within the first two years of life. Despite the worrisome radiological and histological appearance, the tumors are often curable following gross total resection. Tumors with similar characteristics are exceedingly rare in the noninfantile population. We present a six-year-old boy with seizures, weakness, and unsteady gait. Radiographic imaging confirmed a very large, solid and cystic mass in the right temporal-parietal region. Pathological examination demonstrated a tumor with severe desmoplasia identical to those reported as "desmoplastic infantile ganglioglioma." This case adds to the limited data available for desmoplastic gangliogliomas in the noninfantile population. It is not clear, yet likely, that the noninfantile form of this neoplasm is biologically similar to the infantile form. It is also unclear whether the desmoplastic noninfantile ganglioglioma has characteristics similar to classical ganglioglioma. This rare case highlights the remarkable versatility of glioneuronal tumors in children.

Imaging surgical epilepsy in children

INTRODUCTION

Epilepsy surgery rests heavily upon magnetic resonance imaging (MRI). Technical developments have brought significantly improved efficacy of MR imaging in detecting and assessing surgical epileptogenic lesions, while more clinical experience has brought better definition of the pathological groups.

DISCUSSION

MRI is fairly efficient in identifying developmental, epilepsy-associated tumors such as ganglioglioma (with its variants gangliocytoma and desmoplastic infantile ganglioglioma), the complex, simple and nonspecific forms of dysembryoplastic neuroepithelial tumor, and the rare pleomorphic xanthoastrocytoma. The efficacy of MR imaging is not as good for the diagnosis of focal cortical dysplasia (FCD), as it does not necessarily correlate with histopathological FCD subtypes and does not show the real extent of the dysplasia which may even be missed in a high percentage of cases. Further developments with better, multichannel coils, higher magnetic fields, specific sequences, and different approaches (such as diffusion tensor imaging) for depicting the structural abnormalities may hopefully improve this efficacy. A general review of the MR features of the diverse pathologies concerned with epilepsy surgery in the pediatric context is provided with illustrative images.

Interictal electroencephalographic findings in children and adults with temporal lobe tumors

OBJECTIVE

To characterize clinical and interictal electroencephalographic aspects of children and adults with temporal lobe epilepsy (TLE) due to tumoral lesions.

METHOD

We performed a retrospective analysis of the clinical and interictal electroencephalographic aspects of 16 children (64 exams) and 12 adults (78 exams) with lesions in the temporal lobe.

RESULTS

The most frequent etiologies were gangliogliomas, DNETs, followed by astrocytomas. Auras occurred in both groups, the most common being epigastric sensation. Other findings such as myoclonias, behavioral arrest and vomiting were more frequent in children. Temporal epileptiform and nonepileptiform activities, mostly unilateral, were found in both groups. Extratemporal epileptiform activities (frontal, parietal, central, occipital and generalized) were also found equally in both groups.

CONCLUSION

Our data show that children and adults with TLE due to expansive lesions present with similar EEG findings.

New variants of malignant glioneuronal tumors: a clinicopathological study of 40 cases

OBJECTIVE

To demonstrate that malignant glioneuronal tumors comprise a large spectrum of neoplasms, without mature ganglion-like cells, that may histologically resemble any malignant glioma (World Health Organization Grade III or IV) but have a distinct biological behavior.

METHODS

This series includes all tumors diagnosed as malignant glioneuronal tumors (MGNTs) in our routine practice during a 2-year period during which neurofilament protein (NFP) immunostaining was performed in any case of suspected malignant glioma with unusual clinical, radiographic, and/or histological features. Immunostaining using neuronal markers (NFP, NeuN, synaptophysin, and chromogranin) and glial fibrillary acidic protein was done on paraffin sections after antigen retrieval. The presence of NFP-positive tumor cells, including those in mitosis, was used as a hallmark diagnostic criterion of MGNT.

RESULTS

All tumors coexpressed glial fibrillary acidic protein and NFP. Other neuronal markers tested were inconstantly expressed. No recurrence was observed at the primary site in 36.4% of patients who underwent gross total resection. Twelve patients (33.3%) developed intra-axial and/or systemic metastases, and 4 were free of disease at 39 to 184 months. Univariate analysis revealed that gross total surgical resection was the most important prognostic factor predicting survival (44 versus 15 mo; P < 0.0001), followed by a long duration of symptoms (>1 yr; P = 0.005), young age at symptom onset (children versus adults; P = 0.045), and absence of necrosis (P = 0.02). Gross total surgical resection (P = 0.001) and a long duration of symptoms (symptoms > 1 yr; P = 0.013) proved to be independent and statistically significant prognostic factors in the multivariate analysis.

CONCLUSION

NFP immunostaining is required to identify MGNTs accurately. Their distinction from malignant gliomas is of paramount clinical importance, particularly for neurosurgeons, because gross total surgical resection may be curative in some cases. Finally, MGNTs may account for the long-term survival and/or occurrence of metastases demonstrated in a subset of malignant gliomas.

Multicentric pleomorphic xanthoastrocytoma in a patient with neurofibromatosis Type 1

✓ The authors report an unusual case of multicentric pleomorphic xanthoastrocytoma (PXA) in a 36-year-old woman with neurofibromatosis Type 1 (NF1). Both lesions were diagnosed as PXA but demonstrated different neuroimaging features and very different outcomes. Although the occipital lesion was cured surgically, the cerebellar tumor recurred three times and underwent malignant transformation into an anaplastic oligodendroglioma.

The authors discuss the causes of PXA and suggest that it could originate from common bipotential precursor cells with two phenotypes.

Composite pleomorphic xanthoastrocytoma-ganglioglioma presenting as a suprasellar mass: case report

OBJECTIVE AND IMPORTANCE

Composite pleomorphic xanthoastrocytoma (PXA)-ganglioglioma (GG) is a recently recognized, rare type of neoplasm that most commonly presents as a temporal seizure focus among male patients less than 30 years of age. This case represents the only reported suprasellar presentation, with the youngest reported age at diagnosis.

CLINICAL PRESENTATION

We present the case of a 12-year-old boy with new-onset diplopia who was diagnosed as having a large suprasellar mass, which was presumptively designated a craniopharyngioma on the basis of its clinical and radiological appearance.

INTERVENTION

Gross total resection of a well-encapsulated tumor with adjacent cysts was achieved, without postoperative neurological deficits. Frozen-section studies suggested pilocytic astrocytoma; however, the final histological diagnosis was composite PXA-GG.

CONCLUSION

Composite PXA-GG, although extremely rare, may present as a pediatric suprasellar mass. The histopathological diagnosis is contingent on the demonstration of distinct coincident PXA and GG components. The prognosis after gross subtotal resection is likely favorable; however, long-term follow-up monitoring is indicated for these rare neoplasms.

Expression of the CD34 antigen in pleomorphic xanthoastrocytomas

Pleomorphic xanthoastrocytoma (PXA) is a rare, superficially located astrocytic glioma of children and young adults, which is associated with a relatively favorable prognosis. Here we report on the expression of the hematopoietic progenitor cell and vascular endothelial cell associated antigen CD34 in PXAs. We found CD34 immunoreactivity in various fractions of tumor cells in 44 of 60 PXAs investigated (73%). CD34 expression was more common in PXAs of WHO grade II (37 of 44 tumors, 84%) than in PXAs with anaplastic features (7 of 16 tumors, 44%). Immunoreactivity for CD34 was also commonly detected in single or clustered dysplastic neural cells within the cerebral cortex adjacent to the PXAs. Reverse transcription-PCR revealed that PXAs express the full-length CD34 transcript and a known splice variant encoding a truncated form of CD34. Both transcripts were detectable at higher levels in PXAs as compared to diffuse astrocytomas and non-neoplastic brain tissue. Taken together, our findings demonstrate that PXAs frequently express CD34 not only in vascular endothelial cells but also in tumor cells and in dysplastic cells of the adjacent cortex. Therefore, immunostaining for CD34 may be a helpful tool for the histological differential diagnosis of PXAs.

Pathologic characteristics of the cortical dysplasias

The gross and microscopic features of cortical dysplasia (malformations caused by abnormalities of cortical development) are reviewed and illustrated in this article. The pathologic associations of neurocutaneous disorders, neoplasms, and hippocampal sclerosis with cortical dysplasia also are discussed.

Genetic imbalances in pleomorphic xanthoastrocytoma detected by comparative genomic hybridization and literature review

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumor found in the central nervous system. Histologically, the tumor is characterized by markedly pleomorphic and lipidized cells. Although most of the patients have a favorable prognosis, a small number of cases undergoing recurrence or progression to anaplastic astrocytoma were reported. Very few genetic studies have been performed on PXA because of its rarity and the pathogenesis of this neoplasm is largely unknown. In order to provide an overview of genetic alterations in PXA, we performed comparative genomic hybridization to identify chromosomal imbalances (DNA gains and losses) in three cases of PXA. Genetic imbalance was detected on at least one chromosome for each case. One case, which revealed multiple genetic alterations, showed a poor prognosis. DNA gain on chromosome 7 and loss on 8p were demonstrated in two of three cases, suggesting that the candidate gene(s) located on these regions may play a role in the development of PXA. Further studies are needed to identify the residing candidate genes that are involved in the tumorigenesis of PXA. In addition, the histopathological features and previous genetic studies on PXA are reviewed.

Combined pleomorphic xanthoastrocytoma-ganglioglioma of the cerebellum

Combined pleomorphic xanthoastrocytoma-ganglioma is a rare neoplasm, occurring in patients younger than 30 years. The clinical course of these tumors is difficult to predict because of their rarity. We report a case of combined pleomorphic xanthoastrocytoma-ganglioma that, in addition to the patient's age, is unusual in several respects. The lesion was located in the cerebellar vermis of a 60-year-old man and was radiographically solid. Histologically, there was an admixture of markedly pleomorphic astrocytic cells and neoplastic ganglion cells, with permeation of the overlying leptomeninges and surrounding cerebellum. In addition, there was focal capillary endothelial proliferation. There was no necrosis, and mitotic activity was rare at 1 mitotic figure per 40 high-power fields. The patient underwent a near gross total resection and postoperative radiotherapy and remains well through 16 months of follow-up.

Surgical pathologic findings of extratemporal-based intractable epilepsy: a study of 133 consecutive resections

BACKGROUND

Surgical management of intractable epilepsy continues to be important in select cases to achieve seizure control.

DESIGN

This study retrospectively reviews the pathologic findings in 133 consecutive cases of extratemporal lobe epilepsy experienced during a 17-year period.

RESULTS

The study group consists of 133 patients (78 males) who underwent extratemporal lobe resection for epilepsy at a mean age of 21.1 years (range, 3 months to 57 years). In 50 patients (37.6%), cortical dysplasia (neuronal migration abnormalities) was identified. The most common patterns of dysplasia observed included diffuse architectural disorganization in 46 cases, neuronal cytomegaly in 30 cases, increased numbers of molecular layer neurons in 30 cases, and balloon cells in 18 cases. Tumors were identified in 37 cases (27.8%) and included 13 astrocytomas, 7 gangliogliomas, 6 dysembryoplastic neuroepithelial tumors, 6 glioneuronal hamartomas, 4 oligodendrogliomas, and 1 oligoastrocytoma (mixed glioma). Twenty-four resections (18%) showed evidence of remote ischemic damage or infarct. Neuronal heterotopia was identified in 59 resection specimens (44.4%). Other less common findings included vascular malformations in 4 patients (3.0%), Sturge-Weber malformations in 3 patients (2.3%), and Rasmussen encephalitis in 2 patients (1.5%). Two patients were known to have tuberous sclerosis. In 23 resection specimens (17.3%), no significant pathologic finding was identified. Coexistent cortical dysplasia and tumor were seen in 10 cases and coexistent dysplasia and infarct or remote ischemic damage in 11 cases.

CONCLUSION

This series demonstrates that most patients with extratemporal lobe epilepsy have significant histopathologic findings, which most frequently include cortical dysplasia, tumor, or evidence of remote ischemic damage or infarct. Coexistent pathologic findings were present in a significant minority of cases (16.5%).

Bcl-2 and Bcl-X expression in gangliogliomas

Bcl-2 and bcl-xL are proteins known to inhibit cell death (apoptosis). Expression of these proteins in gangliogliomas has not been extensively examined. This study retrospectively evaluates bcl-2 and bcl-x immunostaining in paraffin-embedded materials in gangliogliomas. Twenty-nine gangliogliomas in 17 males and 12 females, age 2.5 to 47 years (mean, 20.7 years), were studied. Nineteen tumors were situated primarily in the temporal lobe. All but three patients presented with seizures ranging from 3 months to 28 years' duration (mean, 11.1 years) before surgery. All tumors histologically were comprised of an atypical neuronal component and a glioma component, which most frequently resembled a low-grade astrocytoma. Cortical dysplasia was observed adjacent to eight tumors. MIB-1 (marker of cell proliferation) labeling indices (percentage of positively staining tumor cell nuclei) ranged from 0 to 7.7 (mean, 0.8). bcl-2 staining was observed in 25 tumors (86%); neuronal staining was present in 24 cases (83%), and glial cell staining in 21 tumors (72%). Bcl-xL staining was only observed in eight gangliogliomas (28%); in all eight tumors (28%), neuronal staining was seen, and focal glial cell staining was present in two cases (7%). Four tumors (14%) did not stain with either bcl-2 or bcl-xL. There appeared to be no relationship between MIB-1 immunostaining and staining with bcl-2 or bcl-xL. bcl-2 expression by immunohistochemistry was observed more frequently than bcl-xL in gangliogliomas. Expression of these proteins may reflect abnormalities of apoptosis, which could play a role in the survival of cells that may be involved in the development of gangliogliomas.

Linear epidermal nevus and nevus sebaceus syndromes: a clinicopathologic study of 3 patients

BACKGROUND

Linear epidermal nevus syndrome and linear sebaceus nevus syndrome are rare neurocutaneous syndromes characterized by epidermal nevi, epilepsy, and mental retardation. Pathologic descriptions of the central nervous system findings in such patients are rare.

DESIGN

We examined the clinicopathologic features of 2 patients with linear epidermal nevus syndrome and 1 with nevus sebaceus syndrome who underwent surgical resections for chronic epilepsy in a tertiary referral center with a high volume of epilepsy surgery.

RESULTS

Patients included 3 females, aged 11 months (patient 1), 8 years (patient 2), and 2 1/2 years (patient 3) at the time of surgery. The duration of seizures prior to surgery was 11 months, 6 years, and 28 months, respectively. Two patients had epidermal nevi involving the head region (patients 1 and 3), and 1 had a nevus sebaceus of Jadassohn (patient 2); patient 2 had a choristoma, and patient 3 had a dermoid cyst in the eye region. Patient 1 demonstrated hemimegalencephaly radiographically. Histologic examination of resected cortical tissue in patients 1 and 2 demonstrated severe diffuse cortical dysplasia characterized by a disorganized cortical architectural pattern, a haphazard orientation of cortical neurons, and increased molecular layer neurons. Gyral fusion was seen in patient 1. Pial glioneuronal hamartomas were observed in patient 1. Prominent cortical astrocytosis was seen in patients 1 and 2, and foci of microcalcification were evident in patient 1. Cortical dysplasia was milder in patient 3 and consisted of an increased number of molecular layer neurons. Neuronal heterotopia was observed in all 3 patients.

CONCLUSION

The spectrum of neuronal migration abnormalities in the setting of these syndromes may be variable in terms of its histologic phenotypic manifestations.

Composite ganglioglioma and dysembryoplastic neuroepithelial tumor

Both ganglioglioma and dysembryoplastic neuroepithelial tumors are well-recognized glial-neuronal neoplasms associated with chronic epilepsy and cortical dysplasia (neuronal migration abnormalities). The exact relationship between these 2 glial-neuronal tumors continues to be debated. This article reports a case of a composite ganglioglioma and dysembryoplastic neuroepithelial tumor occurring in a 36-year-old woman in the left temporal lobe region. The resection histologically demonstrated distinct areas of ganglioglioma and dysembryoplastic neuroepithelial tumor. A focal area of cortical dysplasia is also identified. The MIB-1 labeling indexes in both components were low (<1% of tumor cell nuclei). The coexistence of these 2 lesions and cortical dysplasia suggest a possible etiologic relationship between these 2 tumors.

Pleomorphic xanthoastrocytoma with gangliogliomatous component

We describe a composite glio-neuronal tumor comprising pleomorphic xanthoastrocytoma (PXA) and ganglioglioma identified in a left temporal biopsy. The 32-year-old male patient underwent surgery following a clinical history of persistent headaches of 6 years' duration. Immunohistochemical double labeling with antibodies to synaptophysin, beta-tubulin isotype III, GFAP and CD44H demonstrated neoplastic neurons and astrocytes in the ganglioglioma, while coexpression of glial and neuronal markers was found in a subset of PXA tumor cells variously showing giant cell or spindle cell morphology. There were gradual transitions between the two neoplastic populations. These findings raise the possibility of ganglioglioma having evolved by differentiation of bipotential PXA tumor cells along astrocytic and neuronal lineages. The PXA may, therefore, be closely related to desmoplastic neuroepithelial tumors of infancy, a group of neoplasms of presumed embryonal origin.