Clinicopathological study of pleomorphic xanthoastrocytoma: correlation between histological features and prognosis

Pediatric Low-Grade Gliomas

Brain tumors constitute the largest source of oncologic mortality in children and low-grade gliomas are among most common pediatric central nervous system tumors. Pediatric low-grade gliomas differ from their counterparts in the adult population in their histopathology, genetics, and standard of care. Over the past decade, an increasingly detailed understanding of the molecular and genetic characteristics of pediatric brain tumors led to tailored therapy directed by integrated phenotypic and genotypic parameters and the availability of an increasing array of molecular-directed therapies. Advances in neuroimaging, conformal radiation therapy, and conventional chemotherapy further improved treatment outcomes. This article reviews the current classification of pediatric low-grade gliomas, their histopathologic and radiographic features, state-of-the-art surgical and adjuvant therapies, and emerging therapies currently under study in clinical trials.

Rare clinical presentations of pleomorphic xanthoastrocytoma with a high proliferative index: Two case reports

INTRODUCTION

Pleomorphic xanthoastrocytomas (PXA) are rare, typically benign, slow-growing tumors that commonly occur in the cerebral hemispheres. We describe two cases of clinically aggressive PXA with uncommon locations; one was in the tectal plate, and the other had simultaneous multicentric lesions.

PATIENT CONCERNS

The both cases presented with severe headache with no significant past medical history.

DIAGNOSIS

PXA World Health Organization grade II were histopathologically diagnosed from surgically resected specimens, and immunohistochemical and sequence analysis revealed a high Ki-67 proliferative index and BRAF V600E mutation in both the cases.

INTERVENTIONS

The first case presented with multicentric lesions and underwent partial resection, whereas the second case presented with a tectal plate tumor that was managed by gross total surgical resection. Strong 5-aminolevulinic acid (5-ALA)-induced fluorescence was observed in both the lesions. Postoperative radiotherapy plus concomitant and adjuvant temozolomide was administered to both the patients.

OUTCOMES

Despite completing adjuvant chemo-radiotherapy, both the patients had local tumor recurrence at 2 and 5 months after the operation, respectively.

CONCLUSION

The progressive clinical courses in our cases suggest that additional postoperative therapy should be considered during the treatment of PXA with a high Ki67 index, and that temozolomide with radiotherapy, followed by temozolomide maintenance therapy, may not prevent recurrence in such tumors. Importantly, our experience implies that unlike other subtypes of low grade gliomas, 5-ALA fluorescence is useful for intraoperative visualization of PXA.

Demography, Pattern of Care, and Survival in Patients with Xanthoastrocytoma: A Systematic Review and Individual Patient Data Analysis of 325 Cases

Objectives Xanthoastrocytoma (XA) is a low-grade glial tumor seen in young adults and there is lack of robust data on treatment of this rare tumor. In this systematic review and individual patient's data analysis, we aimed to look into the demography, pattern of care, survival outcomes, and prognostic factors in patients with both Grade II and III XA. Methods A comprehensive search was conducted with the Medical Subject Heading terms: "Xanthoastrocytoma; Pleomorphic Xanthoastrocytoma; Anaplastic Xanthoastrocytoma; Xanthoastrocytoma AND treatment; and Anaplastic Xanthoastrocytoma AND survival" to find all possible publications. Results A total of 325 individual patients from a total of 138 publications pertaining to XA were retrieved. Median age of the entire cohort was 19 years. About 56.1% of the patients underwent a gross total resection (GTR) and 31.4% underwent a subtotal resection. Nearly, 76.6% of the patients had a Grade II tumor and adjuvant radiation was delivered in 27.4% of the patients. Estimated 2- and 5-year progression-free survival (PFS) were 68.5 and 51.2%, respectively. Age, grade, and extent of surgery were significant factors affecting PFS. Estimated 2- and 5-year overall survival (OS) was 88.8 and 78%, respectively. The median OS for Grade II and Grade III tumors were 209 and 49 months, respectively. Age and extent of surgery were significant factors affecting OS. Conclusion XA is a disease of young adults with favorable prognosis. Younger patients (<20 years), patients who undergo a GTR, and patients with a lower grade tumor have a better treatment outcome.

Grade II Pleomorphic Xanthoastrocytoma; a meta-analysis of data from previously reported 167 cases

Pleomorphic Xanthoastrocytoma [PXA] is a rare low grade glial tumor commonly affecting young adults. We did this systematic review and meta-analysis to identify prognostic factors and optimal treatment in these patients. A thorough search of the PubMed, Google scholar was made to find all possible publications related to grade II PXA. A total of 167 patients from 89 articles were included in the analysis. Median age of the entire cohort was 20 years. Headache was the most common presentation in 49.1% of the patients followed by seizure in 27.9%. Temporal lobe was the most common location of the tumor. 63% patents underwent a gross total resection [GTR] and 26.7% underwent a sub total excision [STR]. Adjuvant radiation was given to 17.6% of patients. Median follow-up for the entire cohort was 33 months. Estimated median overall survival [OS] for the entire cohort was 209.0 months [96% CI: 149.7-268.3]. Estimated median progression free survival [PFS] was 48 months [95% CI: 31.9-64.0]. In univariate and multivariate analysis younger patients and patients who underwent a GTR had a significantly better survival outcome. Use of adjuvant therapy was not found to be a significant factor affecting PFS or OS. Radiotherapy was used in salvage treatment in 76.1% of the patients. Younger patients and patients who undergo a GTR, have better survival outcomes. There is inadequate evidence to recommend routine adjuvant radiation or chemotherapy in all patients with grade II PXA.

Pleomorphic Xanthoastrocytoma: Natural History and Long-Term Follow-Up

Prognostic significance of histological anaplasia and BRAF V600E mutation were retrospectively evaluated in 74 patients with pleomorphic xanthoastrocytoma (PXA). Median age at diagnosis was 21.5 years (31 pediatric, 43 adult) and median follow-up 7.6 years. Anaplasia (PXA-AF), defined as mitotic index ≥ 5/10 HPF and/or presence of necrosis, was present in 33 cases. BRAF V600E mutation was detected in 39 (of 60) cases by immunohistochemical and/or molecular analysis, all negative for IDH1 (R132H). Mitotic index ≥ 5/10 HPF and necrosis were associated with decreased overall survival (OS; P = 0.0005 and P = 0.0002, respectively). In all cases except two, necrosis was associated with mitotic index ≥ 5/10 HPF. Patients with BRAF V600E mutant tumors had significantly longer OS compared with those without BRAF V600E mutation (P = 0.02). PXA-AF patients, regardless of age, had significantly shorter OS compared with those without (P = 0.0003). Recurrence-free survival was significantly shorter for adult PXA-AF patients (P = 0.047) only. Patients who either recurred or died ≤ 3 years from diagnosis were more likely to have had either PXA-AF at first diagnosis (P = 0.008) or undergone a non-gross total resection procedure (P = 0.004) as compared with patients who did not. This study provides further evidence that PXA-AF behaves more aggressively than PXA and may qualify for WHO grade III "anaplastic" designation.

Treatment of low-grade gliomas in children: an update

Pediatric low-grade gliomas are a heterogeneous group of tumors that require integration of the pathology and radiographic appearance with the biologic heterogeneity associated with these tumors. Balancing surgery, radiation and chemotherapy to optimize disease control while limiting treatment-related morbidity is of critical importance in this susceptible population and is the focus of this review.

Epithelioid GBMs show a high percentage of BRAF V600E mutation

BRAF V600E mutation has been identified in up to 2/3 of pleomorphic xanthoastrocytomas (PXAs), World Health Organization grade II, as well as in varying percentages of PXAs with anaplastic features (PXA-A), gangliogliomas, extracerebellar pilocytic astrocytomas, and, rarely, giant cell glioblastoma multiforme (GC-GBMs). GC-GBMs and epithelioid GBMs (E-GBMs) can be histologically challenging to distinguish from PXA-A. We undertook this study specifically to address whether these 2 tumor types also showed the mutation. We tested our originally reported cohort of 8 E-GBMs and 2 rhabdoid GBMs (R-GBM) as well as 5 new E-GBMs (1 pediatric, 4 adult) and 9 GC-GBMs (2 pediatric, 7 adult) (n=24) for BRAF V600E mutational status. Twenty-one of 24 had sufficient material for IDH-1 immunostaining, which is usually absent in PXAs, PXA-As, and primary GBMs but present in secondary GBMs. Patients ranged in age from 4 to 67 years. BRAF V600E mutation was identified in 7/13 of E-GBMs, including 3 of our original cases; patients with mutation were aged 10 to 50 years. None of the 9 GC-GBMs or 2 R-GBMs manifested this mutation, including pediatric patients. The sole secondary E-GBM was the single case manifesting positive IDH-1 immunoreactivity. A high percentage of E-GBMs manifest BRAF V600E mutation, paralleling PXAs. All R-GBMs and GC-GBMs were negative, although larger multi-institutional cohorts will have to be tested to extend this result. BRAF V600E mutational analyses should be performed on E-GBMs, particularly in all pediatric and young-aged adults, given the potential for BRAF inhibitor therapy in this subset of GBM patients.

Anaplastic PXA in adults: case series with clinicopathologic and molecular features

Pleomorphic xanthoastrocytomas with anaplastic features (PXA-As) are rare tumors about which little is known regarding clinicopathologic and molecular features. Several studies have identified BRAF V600E mutations in PXA-As, but the percentage with mutation may differ between adult and pediatric examples, and limited information exists about immunohistochemistry for isocitrate dehydrogenase 1 (IDH1). Ten cases of adult PXA-As seen at our institution since 2000 were assessed for BRAF V600E mutation by polymerase chain reaction testing (PCR) and IDH1 by immunohistochemistry. Patients ranged in age from 18-68 years; four PXA-As affected temporal lobe and two were cystic. Four patients underwent gross total resection and 9 of 10 patients received cranial irradiation and/or adjuvant chemotherapy. Five survived less than 5 years, although 2 of 5 patients died from non-tumor causes. Four long-term survivors are alive at 7.5, 9.8, 11.4, and 11.9 years post-diagnosis. Two of four long term survivors had BRAF V600E mutation: patients were ages 18 and 28 years. A 48-year-old male without BRAF mutation survives at 9.8 years, even with thalamic location; conversely a 68-year-old female with temporal lobe tumor and BRAF mutation survived 1.9 years after diagnosis. All tumors were IDH1 immunonegative. This case series details clinicopathologic features of a subset of rare PXA-As in adults. BRAF V600E mutation was identified in 50 % of these cases.

[Pleomorphic xanthoastrocytoma with intraventricular extension and anaplastic transformation in an adult patient: Case report]

Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumour that usually occurs in the superficial cerebral hemispheres of children and young adults. Although it has a relatively favourable prognosis, malignant progression of these tumours has been described. Therefore, we present an unusual case of a 54-year-old male with a right, multicystic, parietooccipital tumour extending through the ipsilateral ventricle. After surgical resection, histological examination revealed a lesion with pleomorphic cells, cytoplasmic lipidisation, intensely eosinophilic granular bodies, well-delimitated unique nuclei and focal, positive immunoreactivity for synaptophysin, glial fibrillary acidic protein (GFAP), S-100 protein, vimentin and CD56. Once other tumours, such as giant cell metastatic carcinoma or primary lesion like subependymal giant cell astrocytoma, were ruled out, a final diagnosis of XAP was established. After a follow-up period of 9 months, the patient suffered an extensive and local tumour relapse considered inoperable, with progressive neurological deterioration and radiological findings of malignant progression. The brain biopsy procedure revealed anaplastic changes, including necrosis foci, higher mitotic activity (5×10 high-power fields) and a 10% proliferation index measured by Ki67 labelling. The present case showed intraventricular extension and a more aggressive behaviour, both uncommon in these tumours (similar to anaplastic astrocytoma or glioblastoma multiforme), thus demanding an initial, optimal surgical treatment with close clinical and radiological follow-up, due to the high potential for malignant transformation of XAPs.

Intraventricular pleomorphic xanthoastrocytoma with anaplastic features

Pleomorphic xanthoastrocytoma (PXA) is a rare astrocytic tumor that usually occurs in the superficial cerebral hemispheres of children and young adults and has a relatively favorable prognosis. We report an unusual case of supratentorial, intraventricular tumor in a 52-year-old man. The tumor was composed of pleomorphic cells, including giant cells, most of which were multinucleated, and small cells. In addition, frequent xanthic changes in the cytoplasm of the tumor cells, and widespread reticulin deposits and lymphocytic infiltrates in the stroma were characteristic features. Large areas of necrosis were also evident. However, mitotic figures were rare (1-2 mitoses per 10 high-power fields). Many tumor cells were positive for GFAP, and a number were positive for neurofilament protein and synaptophysin, indicating their neuronal differentiation. In addition, occasional tumor cells were positive for CD34. p53 protein was entirely negative in the tumor cells. In diagnosing this tumor histopathologically, differentiation between PXA and giant cell glioblastoma (GCG), a rare variant of glioblastoma, was problematic. However, considering the overall histopathological picture, a final diagnosis of PXA with anaplastic features was made. The present case indicates that PXA can occur as an intraventricular tumor, and suggests that in some instances, it would be very difficult to differentiate PXA and GCG histopathologically.

A 28-year-old man with headache, visual and aphasic speech disturbances

A 28-year-old man presented with a short history of headache, visual and aphasic speech disturbances. MR scans revealed a large, partly cystic, contrast-enhancing lesion of the left temporal lobe that upon microscopic examination was diagnosed as pleomorphic xanthoastrocytoma (PXA) with anaplastic features (WHO grade III). Remarkably, this tumor featured an unusual gliovascular, rosette-like histoarchitecture, which had previously been hypothesized to possibly indicate a greater likelihood of PXA recurrence. Indeed, only 14 months later, the patient presented with a recurrent lesion, which contained the previous histology, but now also featured a distinct fibrosarcoma-like component replete with numerous osteoclast-type giant cells. In addition, whereas eosinophilic granular bodies were plentiful at the lesion's periphery, numerous CD34 - positive satellite cells were found in the adjacent non-infiltrated cortex. Regarding the origin of this recurrent tumor and in reflection of its composition of distinct PXA as well as sarcomatous components, the diagnosis of a pleomorphic xanthoastrosarcoma, to be conceptually considered as a gliosarcoma subtype, was made.To our knowledge, this is an unprecedented case of sarcomatous transformation of a PXA. Particular attention should be given to gliovascular pseudopapillary structures in PXAs, the presence of which may potentially herald a more aggressive clinical behavior.

Pleomorphic xanthoastrocytoma: a comparative pathological study between conventional and anaplastic types

AIMS

To facilitate the understanding and correct diagnosis of the anaplastic variant of pleomorphic xanthoastrocytoma (PXA).

METHODS AND RESULTS

Twelve cases of PXA were divided into six conventional and six anaplastic types. Three anaplastic PXAs developed in recurrent tumours and three occurred as the primary tumour. Anaplastic PXAs were microscopically characterized by monotonous proliferation of atypical cells, increased mitotic activity, necrosis and microvascular proliferation. Characteristic features of conventional PXA are also variously included in all anaplastic PXAs. No remarkable differences were detected in the immunohistochemical profiles including the neuronal phenotype between the conventional and anaplastic types. Ki67 labelling indices of the anaplastic type were significantly higher than those of the conventional type, whereas p53 showed no difference. Immunohistochemical and fluorescence in situ hybridization analyses on epidermal growth factor receptor did not demonstrate overexpression or gene amplification.

CONCLUSIONS

The anaplastic PXA, which occurs de novo or through recurrence, should be distinguished from glioblastoma by identifying the salient microscopic features of conventional PXA even in the anaplastic areas; and by demonstrating the expression of neuronal markers, in that the former is expected to have longer survival.

Pleomorphic xanthoastrocytoma in elderly patients may portend a poor prognosis

Pleomorphic xanthoastrocytoma (PXA) is a rare primary astrocytic tumour of the nervous system usually involving the superficial temporal cortex of children and young adults. Although the tumour may exhibit histological features of pleomorphism or cellular atypia, the overall prognosis is good compared with other glial tumours, with only 30% of PXA recurring and 20% undergoing anaplastic transformation. Increased mitotic activity, high MIB-1 and proliferating cell nuclear antigen labelling indices and necrosis are poor prognostic factors, whereas abundant lymphocytic infiltration is associated with more benign biological behaviour. Rarely, in older patients, PXA may have a poor prognosis as these patients tend to have intracranial hypertension and focal deficits, as well as histological features of mitosis, increased cellularity and necrosis. We report the case of a 76-year-old woman who presented with dysphasia and right hemiparesis. A left fronto-temporal lobe PXA was misdiagnosed as glioblastoma multiforme. Although a rare and benign tumour type, PXA in the elderly tend to be more malignant, may have the radiological appearance of a malignant tumour and have poor prognosis.

Pleomorphic xanthoastrocytoma with anaplastic features presenting without GFAP immunoreactivity: Implications for differential diagnosis

Pleomorphic xanthoastrocytoma (PXA) is an uncommon, usually low-grade, astrocytic tumor. Characteristic histological features include tumor cell pleomorphism and lipidization of tumor cells. Albeit prognosis in PXA is generally good, cases with histological signs of anaplasia have been observed. In these cases, the differential diagnosis needs to exclude other malignancies, for example, glioblastoma or malignant fibrous histiocytoma. Immunocytochemical detection of GFAP may support exclusion of non-glial neoplasms resembling PXA. However, GFAP expression in PXA may be faint or focal, although complete lack of GFAP has not been described. A 43-year-old woman was operated on for a left occipital parasagital tumor attached to the dura. Histopathology showed a pleomorphic tumor with moderate mitotic activity and necrosis, lack of GFAP immunoreactivity and ultrastructural detection of premelanosome-like structures. These features led to the tentative diagnosis of amelanotic melanoma, and the patient was irradiated. Three years later she had local tumor recurrence and underwent another operation. The recurrent tumor showed similar plain histology as the first specimen. In contrast, anti-GFAP immunoreactivity was now detectable in pleomorphic tumor cells. Anti-GFAP staining of the first biopsy was repeated using monoclonal and polyclonal antibodies in combination with prolonged tissue pretreatment. Focal GFAP staining of tumor cells was now achieved. We conclude that non-standard GFAP staining protocols may enhance sensitivity and thus lead to detection of a low level of GFAP expression in tumor specimens, in which PXA is considered in the differential diagnosis. This may avoid misleading diagnostic considerations that impact on postoperative patient management.

Coexistence of pleomorphic xanthoastrocytoma with Sturge-Weber syndrome: MRI features

Pleomorphic xanthoastrocytoma is a rare, cortically based, partially cystic astroglial tumour with a strongly enhancing solid mural nodule. We report an 11-year-old boy with a pleomorphic xanthoastrocytoma in the contralateral hemisphere to that affected by Sturge-Weber syndrome. This unique case supports the association between Sturge-Weber syndrome and astrocytomas. Patients with Sturge-Weber syndrome who experience unexpected neurological symptoms should be evaluated with MRI.

Prognosis-related histomorphological and immunohistochemical markers in central nervous system tumors of childhood and adolescence

Brain tumors account for approximately 20% of all childhood cancers, and are the leading cause of cancer morbidity and mortality among children. Although numerous demographic, clinical and therapeutic parameters have been identified over the past few years that have significant prognostic bearing for some pediatric brain tumors, predicting the clinical course and outcome among children with central nervous system tumors is still difficult. A survey of publications on prognosis-related histopathological and immunohistochemical features among pediatric brain tumors revealed 172 series, of which 91 presented statistically significant outcome-associated parameters as defined by a P value of less than 0.05. Most investigations revealing significant prognosis-related markers were performed on medulloblastomas (30 publications), ependymomas (25) and astrocytic tumors (18). In total, 16 cohorts consisted of more than 100 cases (5 on ependymomas, 3 each on medulloblastomas and astrocytic tumors). On the other hand, there were also 13 series with fewer than 20 cases (5 on medulloblastomas). Potentially prognostic histopathological markers vary among different entities and consist of assessment of necroses, mitoses, differentiation, vascular proliferation, and growth pattern, whereas immunohistochemical features include proliferation markers (Ki-67, MIB-1), expression of oncogenes/tumor suppressor genes and their proteins (TP53, c-erbB2), growth factor and hormonal receptors (VEGF, EGFR, HER2, HER4, ErbB-2), cell cycle genes (p27, p14ARF) and cell adhesion molecules, as well as factors potentially related to therapeutic resistance (DNA topoisomerase IIalpha, metallothionein, P-glycoprotein, tenascin). This review discusses the prognostic potential of histopathological and immunohistochemical markers that can be investigated by the practicing neuropathologist as part of the routine diagnostic workload, and scrutinizes their benefit for predicting therapy response and patient outcome among children with brain tumors.

Anaplastic pleomorphic xanthoastrocytomas. Review of the literature with reference to malignancy potential

Malignancy potential of pleomorphic xanthoastrocytomas (PXAs) has rather been an underestimated reality. We report the case of a 13-year-old boy who presented with signs of increased intracranial pressure. The child had been epileptic since the age of 2. Computed tomography and magnetic resonance scans revealed a huge left frontal mass. At surgery, a subtotal excision was accomplished. Histopathological diagnosis was anaplastic PXA (grade III; WHO, 2000). The tumor showed an increased mitotic index and minimal endothelial proliferation. The patient died 3.5 months later due to a fatal intracranial hemorrhage. A review of the entire PXA literature revealed 15 well-documented cases of PXA with subsequent malignant transformation and 11 cases of primary anaplastic PXA. The prognosis was grim for both subsets of patients. Anaplastic PXAs clearly represent the transition between the original PXA concept and lipidized giant-cell glioblastoma.

Pleomorphic xanthoastrocytoma: report of two cases and review of the prognostic factors

Pleomorphic xanthoastrocytoma (PXA) is a superficially located, rare glial tumour first described in 1979. It affects young patients, who often present with seizures. The tumour has a relatively favourable prognosis, but 15-20% progress to malignancy. We describe two cases of PXA, both with benign features at presentation, one of which underwent anaplastic transformation. Surgery remains the mainstay of treatment. Factors influencing clinical outcome include extent of resection, and histological features such as mitotic index, necrosis and lymphocytic infiltration. The roles of radiotherapy and chemotherapy remain undefined. We advocate lifelong follow-up and establishment of a central registry in order to further the understanding of this infrequently encountered tumour.

Pleomorphic xanthoastrocytomas: immunohistochemistry, grading and clinico-pathologic correlations. An analysis of 34 cases from a single Institute

Pleomorphic xanthoastrocytomas (PXAs) are characterized as a well-delineated tumor entity with clear peculiarities in clinico-radiological picture, pathological appearance and biological behavior. Usually the PXAs are associated with relatively good prognosis. Nevertheless, up to 35% of patients die following one and more recurrence with or without tumor malignant transformation. Till now, there is no agreement on what histopathological features constitute to objective and reliable signs of PXAs malignancy and clinical outcome. Thirty-four PXAs were subdivided on three subsets: typical (Grade I) - tumors without mitoses per 20 high power fields, proliferating (Grade II) tumors with mitoses but without necroses, and malignant (Grade III) - tumors with elevated mitotic index and necrotic foci. Also, immunohistochemical investigation with various tumor-associated antigens was performed. All PXAs subtypes showed differences in clinical outcomes. There were no recurrences and death among the tumors Grade I. Five out of 14 (36%) Grade II PXAs have recurred and one of them died. All 5 patients with PXAs Grade III have rapidly recurred and four of them died. Immunohistochemical variables, such as Ki-S1, p27/Kip1, vascular endothelial growth factor expression, p53 immunoreactivity and apoptotic index also exhibited significant differences among the three PXAs grades. The progression-free survival was significantly reduced for PXAs grade and presence of mitoses, whereas overall survival was reduced for mitotic index >or= 3 and presence of necroses. No one from immunohistochemical variables reached significant value. In summary, the three-tiered PXAs subdivision proposed by us is carrying some element of rationality but, undoubtedly, requires further prospective studies.