Prognostic Factors in Adult Medulloblastoma. A Clinico-Pathologic Study

Aims and background.

Medulloblastoma in adults is a rare tumor. The small number of cases in the reported series has not permitted a definite assessment of the prognostic role of clinical, pathologic and cell kinetics factors. The largest series of medulloblastoma in adults treated in a single institution is herein reported.

Methods.

The clinical, therapeutic, pathologic and proliferation features of medulloblastoma in 44 adult patients (> 18 years) were analyzed retrospectively with regard to postoperative survival. The proliferation potential of each tumor was evaluated by the immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA) and Ki-67, clone MIB-1, in paraffin sections.

Results.

The overall 5- and 10-year survival rates were 40% and 35.6%, respectively. Significant factors in predicting a longer postoperative survival were: age < 37 years, decade of management (1977-1990), radiotherapy (50-55 Gy on the posterior fossa and 30-35 Gy on the spinal cord) and nuclear isomorphism. When corrected for adequacy of radiotreatment, desmoplastic type and differentiation were significantly correlated with a shorter survival. The PCNA-labelling index (LI) ranged from 34.5 to 82.2%, the MIB-1-LI ranged from 9.6 to 64.7%. No association was found between PCNA- or MIB-1-LI values and microscopic features, or between LI values and prognosis.

Conclusions.

Contrary to a general assumption, desmoplastic medulloblastoma and differentiated medulloblastoma are negative prognostic factors in adequately radiotreated adult patients. This may possibly be referred to lower radiosensitivity of these tumor variants. The LI with PCNA or Ki-67 is of no help in identifying aggressive tumors.

A case of multifocal medulloblastoma in an adult patient

Only five cases of multifocal medulloblastoma in the adult have been reported to date. We present a case in a male patient in his 50th decade of life who presented with three extra-axial lesions associated with a parenchymatous lesion of the right middle cerebellar peduncle. Sputum sample examination revealed larvae compatible with strongyloides stercoralis, which was our main differential diagnosis. Histological and immunohistochemical studies revealed the existence of a desmoplastic medulloblastoma.

Biomarker-driven stratification of disease-risk in non-metastatic medulloblastoma: Results from the multi-center HIT-SIOP-PNET4 clinical trial

PURPOSE

To improve stratification of risk-adapted treatment for non-metastatic (M0), standard-risk medulloblastoma patients by prospective evaluation of biomarkers of reported biological or prognostic significance, alongside clinico-pathological variables, within the multi-center HIT-SIOP-PNET4 trial.

METHODS

Formalin-fixed paraffin-embedded tumor tissues were collected from 338 M0 patients (>4.0 years at diagnosis) for pathology review and assessment of the WNT subgroup (MBWNT) and genomic copy-number defects (chromosome 17, MYC/MYCN, 9q22 (PTCH1) and DNA ploidy). Clinical characteristics were reviewed centrally.

RESULTS

The favorable prognosis of MBWNT was confirmed, however better outcomes were observed for non-MBWNT tumors in this clinical risk-defined cohort compared to previous disease-wide clinical trials. Chromosome 17p/q defects were heterogeneous when assessed at the cellular copy-number level, and predicted poor prognosis when they occurred against a diploid (ch17(im)/diploid(cen)), but not polyploid, genetic background. These factors, together with post-surgical tumor residuum (R+) and radiotherapy delay, were supported as independent prognostic markers in multivariate testing. Notably, MYC and MYCN amplification were not associated with adverse outcome. In cross-validated survival models derived for the clinical standard-risk (M0/R0) disease group, (ch17(im)/diploid(cen); 14% of patients) predicted high disease-risk, while the outcomes of patients without (ch17(im)/diploid(cen)) did not differ significantly from MBWNT, allowing re-classification of 86% as favorable-risk.

CONCLUSIONS

Biomarkers, established previously in disease-wide studies, behave differently in clinically-defined standard-risk disease. Distinct biomarkers are required to assess disease-risk in this group, and define improved risk-stratification models. Routine testing for specific patterns of chromosome 17 imbalance at the cellular level, and MBWNT, provides a strong basis for incorporation into future trials.

Cerebellar pleomorphic xanthoastrocytoma in a patient with neurofibromatosis type 1: a case report and literature review

Pleomorphic xanthoastrocytoma (PXA) is an uncommon tumor of young adults that typically occurs supratentorially. It is generally considered to be a low-grade, circumscribed tumor that when treated by surgical resection has a relatively favorable outcome. Cases of cerebellar PXA are rare, and those associated with neurofibromatosis type 1 (NF1) are even less common, with only 2 cases reported to date. We present herein a third case of PXA-NF1 with unusual features. A 33-year-old woman presented with a history of headache. Her medical and family history was significant for NF1. Brain MRI revealed a 3.4 cm ill-defined lesion with a gyriform enhancing pattern in the left cerebellum, superficially mimicking Lhermitte-Duclos disease. The patient underwent a gross total resection of the lesion and had an unremarkable postoperative course. While the lesion had histological features typical of "pure" PXA (WHO grade II) it had an unusual growth pattern with thickening of the superficial cerebellar folia and predominant leptomeningeal involvement. No BRAF, IDH-1, or IDH-2 mutation was identified. Three months after surgery, local recurrence was detected, and the patient was treated with radiation therapy. One year after the first surgery, she underwent surgical resection of the recurrent/residual tumor. Histologically, the recurrent tumor showed very similar features to the initially resected tumor, with no anaplastic features. Most cerebellar PXAs have an indolent clinical behavior as do most cerebral PXAs. Whether co-existence of NF1 was a factor in altering the clinical course and biologic behavior of this patient's tumor is currently unknown.

Cerebellar glioblastoma multiforme in an adult woman

AIMS AND BACKGROUND

Glioblastoma multiforme (GBM) is the most frequent primary central nervous system malignancy in adults, accounting for 50% of all primary intracranial malignancies. GBM mostly arises within the cerebral hemispheres and frequently affects patients in the fifth and sixth decades of life. Conversely, primary cerebellar GBM is a rather infrequent occurrence in the adult population, accounting for 1%-2.2% of all GBMs. Here we report a case of cerebellar GBM in an adult woman and provide an extensive review of the literature.

METHODS

A 42-year-old woman was referred to our hospital for occipital constrictive headache, dizziness and gait disturbance. Multimodality imaging including computed tomography and magnetic resonance imaging (MRI) showed a right cerebellar mass. Gross total resection was performed. Histological examination showed grade IV GBM according to the World Health Organization classification, with a synchronous component of low-grade glioma. Immunohistochemistry showed positivity for p53 and negativity for epidermal growth factor receptor (EGFR). After surgical tumor excision, the patient underwent adjuvant radiation to the posterior fossa with an intensity-modulated approach for a total dose of 60 Gy in 30 fractions. In addition, she received concurrent and adjuvant chemotherapy with temozolomide.

RESULTS

Treatment was well tolerated, with mild acute toxicity. There was no evidence of recurrence on brain and spinal gadolinium-enhanced MRI scans 4, 8 and 12 months after primary surgery. No late side effects were recorded.

CONCLUSION

Our patient had several immunohistochemical characteristics of secondary glioblastoma such as p53 positivity, EGFR negativity and the presence of a low-grade glioma component. Intensity-modulated radiation therapy allowed us to safely deliver full-dose radiation with sparing of critical structures.

MRS water resonance frequency in childhood brain tumours: a novel potential biomarker of temperature and tumour environment

(1)H MRS thermometry has been investigated for brain trauma and hypothermia monitoring applications but has not been explored in brain tumours. The proton resonance frequency (PRF) of water is dependent on temperature but is also influenced by microenvironment factors, such as fast proton exchange with macromolecules, ionic concentration and magnetic susceptibility. (1)H MRS has been utilized for brain tumour diagnostic and prognostic purposes in children; however, the water PRF measure may provide complementary information to further improve characterization. Water PRF values were investigated from a repository of MRS data acquired from childhood brain tumours and children with apparently normal brains. The cohort consisted of histologically proven glioma (22), medulloblastoma (19) and control groups (28, MRS in both the basal ganglia and parietal white matter regions). All data were acquired at 1.5 T using a short TE (30 ms) single voxel spectroscopy (PRESS) protocol. Water PRF values were calculated using methyl creatine and total choline. Spectral peak amplitude weighted averaging was used to improve the accuracy of the measurements. Mean PRF values were significantly larger for medulloblastoma compared with glioma, with a difference in the means of 0.0147 ppm (p < 0.05), while the mean PRF for glioma was significantly lower than for the healthy cohort, with a difference in the means of 0.0061 ppm (p < 0.05). This would suggest the apparent temperature of the glioma group was ~1.5 °C higher than the medulloblastomas and ~0.7 °C higher than a healthy brain. However, the PRF shift may not reflect a change in temperature, given that alterations in protein content, microstructure and ionic concentration contribute to PRF shifts. Measurement of these effects could also be used as a supplementary biomarker, and further investigation is required. This study has shown that the water PRF value has the potential to be used for characterizing childhood brain tumours, which has not been reported previously.

[Corpus callosum tumor as the presenting symptom of neurofibromatosis type 1 in a patient and literature review]

INTRODUCTION

Neurofibromatosis type 1 (NF1) is one of the most frequent neurocutaneous syndromes. NF1 can be associated with intracranial tumors in any location, but only rarely in the corpus callosum.

AIMS

To describe a case of NF1 presenting as a tumor of the corpus callosum and to carry out a review of the incidence of the tumors of corpus callosum in our series and in the literature.

CASE REPORT

We present a child who was studied since 3 years of age because of complete NF1 clinical diagnostic criteria (without genetic study). He was studied by MR and magnetic resonance spectroscopy (MRS). MR study showed neurofibromatosis bright objects distributed over several regions of the cerebral hemispheres and cerebellum, a possible brain stem tumor (bulbar zone) and the splenium of the corpus callosum. The MRS of the brain stem tumor showed changes consistent with a low grade glial tumor. The patient was followed until 19-years of age without demonstrating any changes in the clinical features or the tumor size in both locations Only six cases of corpus callosum tumor in patients with NF1 have been published to date.

CONCLUSIONS

We present a new case with tumor of the corpus callosum and NF1. The imaging characteristics and the clinical course were in favour of the benign nature of this type of tumor.

Growth hormone receptor expression in brain tumors

Growth hormone (GH) is essential for quality of life in both children and adults, but it is also believed to enhance the growth of various neoplasms. However, the role of GH in the brain, particularly in brain tumors, has yet to be established. To clarify these problems from the perspective of receptor expression, we examined GH receptor (GHR) expression in brain tumors using immunohistochemistry and the correlation between GHR expression and clinical features. Surgical specimens obtained from patients with brain tumors (106 pituitary adenomas, 12 craniopharyngiomas, 13 germ cell tumors, 6 medulloblastomas, and 12 malignant gliomas) were examined immunohistochemically for GHR expression. The GHR positive rate was lower in malignant tumors than in benign tumors (59% in pituitary adenomas, 73% in craniopharyngiomas, 23% in germ cell tumors, and 0% in medulloblastomas and gliomas). GHR staining in pituitary adenomas was weaker than that in normal pituitary gland. Among the GH-producing pituitary adenomas, there was no difference in size between GHR-positive and -negative tumors. However, among the non-GH-producing adenomas, GHR-positive tumors were significantly smaller. Thus, immunohistochemical GHR expression may have, at least in part, a negative impact on tumor growth potential in brain tumors.

[Medullomyoblastoma: a medulloblastoma with rhabdomyoblastic differentiation]

A 26 years old patient was operated for a tumor of cerebellar vermix, and then reoperated for a relapse at the age of 35 years, with a similar histological pattern in both cases. At pathologic examination, the tumor was composed of hypercellular sheets typical of medulloblastoma, containing also sparse large cells with eosinophilic cytoplasm and round nuclei containing voluminous nucleoli. Neuroblastic cells showed expression of neurofilament protein and synaptophysin. The large cells expressed desmin, myogenin, and neurofilament. These morphological and immunohistochemical features are characteristic of medullomyoblastoma. The patient deceased 11 years after the initial surgery. Medullomyoblastoma is a rare variant of medulloblastoma with a rhabdomyoblastic differentiation. The two tumoral populations share the same genetic alterations. The main differential diagnoses are atypical teratoid/rhabdoid tumor, immature teratoma, medulloepithelioma, primitive intracranial rhabdomyosarcoma and myoneurocytoma.

Clear-cell Ependymoma of the Cerebellum: A Case Report

A case of clear-cell ependymoma occurring in the cerebellum of a 3-year-old girl is reported. Light-microscopically, the tumor consisted mainly of clear cells with a perinuclear halo and showed some vague perivascular pseudorosettes, not true rosettes. In addition, the histological features of anaplasia, characterized by increased mitosis and focal pseudopalisading necrosis, were also observed. Immunohistochemically, the tumor cells were focally positive for glial fibrillary acidic protein and weakly positive for epithelial membrane antigen. Ultrastructurally, the intermediate junctions and rudimentary cilia confirmed the ependymal differentiation. Fifteen cases of infratentorial clear-cell ependymoma have been reported to date, and this case is the second childhood tumor among them, to the best of the authors' knowledge.

Protein chemical identification and characterization of the human variants of far upstream element binding protein in medulloblastoma DAOY cell line

The assembly of trans-acting proteins on sequence-specific DNA cis-elements is crucial in the regulation of eukaryotic gene expression. Far upstream element binding proteins (FAB) are proteins that regulate the expression of the c-myc oncogene by binding to the far upstream element of the c-myc gene. The present study unambiguously identified the two human variants of FAB (FAB1, FAB2) in the medulloblastoma DAOY cell line and characterized their structure for the first time by tandem mass spectrometry independent of antibody availability and specificity. The study also tentatively assigned the third variant (FAB3) at the level of mass spectrometry, although tandem mass spectrometric analysis failed to corroborate the result. These findings open up an exciting possibility for discerning the cellular roles of FAB in tumor biology.

Loss of cyclin D1 impairs cerebellar development and suppresses medulloblastoma formation

Medulloblastoma, the most common malignant brain tumor of childhood, is believed to derive from immature granule neuron precursors (GNPs) that normally proliferate in the external granule layer before exiting the cell cycle and migrating to their mature location in the inner granule layer. In this study, we examined the expression of D type cyclins in GNPs during cerebellar development and showed that GNPs in early development expressed only cyclin D1, whereas later GNPs expressed both cyclins D1 and D2. Coinciding with the period of cyclin D1-only expression, Ccnd1(-/-) mice showed reduced proliferation of GNPs and impaired growth of the cerebellum. Interestingly, removal of cyclin D1 was sufficient to drastically reduce the incidence of medulloblastoma in Ptch1(+/-) mice, despite the fact that these tumors showed upregulation of both cyclins D1 and D2. We showed that cyclin D1 has an earlier role in tumorigenesis: in the absence of cyclin D1, the incidence and overall volume of ;preneoplastic' lesions were significantly decreased. We propose a model that links a role of cyclin D1 in normal GNP proliferation with its early role in tumorigenesis.

Intracerebellar granulocytic sarcoma. A case report

Granulocytic sarcoma is a form of extramedullary leukaemia. The intraparenchymal localisation is extremely rare. We report a case of cerebellar granulocytic sarcoma occuring in a 43 years old woman without any precedent medical history. The diagnosis of granulocytic sarcoma was established by neoplastic cells findings through morphological and immunohistochemical studies. The patient died few days after surgery. There are still no conclusive treatment strategies for this entity; however, early antileukemic chemotherapy seems to lower the probability of developing systemic disease and thus prolong survival.

Immunocytochemical detection of members of the caspase cascade of apoptosis in childhood medulloblastomas

During the process of programmed cell death (PCD), the cell disintegrates into small, membrane-bound apoptotic bodies. Caspase-3 is ubiquitously expressed in normal and neoplastically-transformed human cells and serves as an executioner in the apoptotic or PCD pathway. During our immunocytochemical study, a sensitive, four-step, alkaline phosphatase-conjugated antigen detection technique was employed. The results demonstrated the presence of apoptotic activity within the cellular microenvironment of childhood medulloblastoma/primitive neuroectodermal tumor. The observations identified the cytoplasmic presence of caspase-3 in more than 20% of neoplastic cells. The immunocytochemical expression pattern demonstrated a translocation tendency from the cytoplasm to the cell nuclei in the apoptotic cells in about 5% of the tumor cells. Caspase-3 presence was also detected in the tumor infiltrating lymphocytes (TILs), representing the host's immune, mostly CD8+, cytotoxic, tumor-associated antigen (TAA)-directed effector cells. This phenomenon may play an important role in these tumors' maintenance of immune privilege and evasion of immune attacks. We suggest that the grade and intensity of apoptosis may not only have diagnostic and prognostic significance, but could also play a leading role in the biological (fourth modality) antineoplastic treatment of these highly malignant, neuroectodermal brain tumors.

[BCL-2 in primary central nervous system lymphomas. Immunohistochemistry and molecular biology]

BCL-2 is a membrane protein known to be an apoptosis inhibitor. It is the product of the bcl-2 gene located on chromosome 18. Several different tumors show BCL-2 over-expression as result of a translocation or independently from it. More than 85% of follicular lymphomas and a smaller number of diffuse large cell B lymphomas contain t(14;18) (q32;q21). The aim of this study was to investigate the immunohistochemical expression of the BCL-2 protein and to ascertain, by means of traditional PCR (Polimerase Chain Reaction), its possible dependence from t(14;18) (q32;q21) in 9 primary central nervous system lymphomas. Six cases (67%) shoved immunohistochemical BCL-2 over-expression and 3 cases (33%) had t(14;18). Precisely: 2 cases (22%) had immunohistochemical BCL-2 over-expression and t(14;18) (q32;q21); 4 cases (44%) had BCL-2 over-expression without translocation; 1 case (11%) did not show diffuse BCL-2 over-expression in presence of the traslocation; the remaining 2 cases (22%) did not demonstrate BCL-2 over-expression or t(14;18) (q32;q21). In conclusion, our results indicate primary central nervous system lymphomas frequently show BCL-2 over-expression that in some case may be related to t(14;18) (q32;q21). Nevertheless, t(14;18) (q32;q21), as evaluated by traditional PCR, may not correspond to diffuse immunohistochemical BCL-2 positivity.

[Cerebellar hemangioblastomas--a study of the immunoprofile of neoplastic stromal component]

BACKGROUND

Central nervous system hemangioblastomas (HBs) are uncommon, highly vascularized tumors that are predominantly found in the cerebellum. They occur sporadically or in association with von Hippel-Lindau (VHL) disease. HBs are of unknown histogenesis, and the origin of stromal cells is still a subject of debate. The aim of this study was to investigate the immunoprofile of neoplastic stromal component, and to determine whether the profile of the expression of immunomarkers used can contribute to the elucidation of the histogenesis of HBs.

METHODS

A series of eight cerebellar HBs were histochemically examined for the detection of mast cells and immunohistochemically for the expression of factor VIII-related antigen (FVIII-RAg), CD34, vimentin, factor XIIIa (FXIIIa), S-100 protein, glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE), neurofilaments (NF), synaptophysin, chromogranin, and somatostatin.

RESULTS

Mast cells were present in all hemangioblastomas, and were particularly abundant in one tumor. Immunohistochemically, intense reactivity for vimentin and NSE in the stromal cells was constantly seen. Immunoreactivity with S-100 protein and FXIIIa was variable, but generally many HBs stromal cells were negative for these markers. However, stromal cells were uniformly negative for FVIII-RAg in all HBs investigated. They were negative for CD34, GFAP, NF, synaptophysin, chromogranin, as well as somatostatin. GFAP-positivity of the occasional stromal type cells, located only peripherally, was interpreted as "pseudopositivity".

CONCLUSION

The immunoprofile of neoplastic stromal component in this study suggested a possible origin from undifferentiated multipotential mesenchymal cells. High expression of NSE (glycolytic and hypoxia-inducible enzyme) in the HBs stromal cells might be related to the loss of the VHL protein function.

Cerebellar liponeurocytoma: a case report and review of the literature

Cerebellar liponeurocytoma has recently been recognised by the 2000 World Health Organisation classification of tumours of the central nervous system as a distinct clinicopathologic entity. To our knowledge, 18 cases have been reported so far, under different names, such as "lipomatous medulloblastoma, lipidized medulloblastoma, neurolipocytoma, medullocytoma and lipomatous glioneurocytoma". The new classification included cerebellar liponeurocytoma in the category of glioneuronal tumours grade I or II because of its favourable clinical behaviour. The origin and nature of the lipomatous component have been matter of debate and make this tumour entity puzzling. We describe a new case of liponeurocytoma removed from the left cerebellar hemisphere of a 38-year-old-woman. The patient showed unspecific signs of intracranial hypertension and symptoms suggesting a posterior fossa lesion.

Epithelial differentiation in medulloblastoma: Comparison with other embryonal tumors of neuroectodermal origin

Three cases of medulloblastoma characterized by epithelial differentiation are described in patients 6-months-, 1-month- and 8-years-old. Histologically, tumors from the two infant patients showed a perivascular arrangement without apparent radiated cytoplasmic processes from the vessels. Tumor cells displayed round and/or pleomorphic vesicular nuclei and a more abundant eosinophilic cytoplasm than that found in classic medulloblastoma. Neither Homer-Wright rosettes nor ependymal or ependymoblastic rosettes were noted in these tumors. The tumor in the 8-year-old patient exhibited a classic medulloblastoma component intermingled with abundant eosinophilic cytoplasm forming a tubular structure. Immunohistochemically, tumor cells in all cases were positive for cytokeratin, synaptophysin, and vimentin. In the third case involving the 8-year-old patient, epithelial tumor cells were positive for cytokeratin, whereas classic medulloblastoma components were negative for cytokeratin. Positive staining for melanoma-specific antigen was seen only in the third case, where strong reactivity of tumor cells formed a tubulus. However, the classic medulloblastoma component was negative for melanoma-specific antigen. Ultrastructurally, basal laminae were observed around tumor cells in the 6-month-old patient. These morphological and immunohistochemical features suggest that medulloblastoma with epithelial differentiation is a rare but distinct variant of medulloblastoma, and that some of these tumors should show differentiation in ocular pigment epithelium.

Protein profiles of medulloblastoma cell lines DAOY and D283: identification of tumor-related proteins and principles

Medulloblastoma is the most frequent malignant brain tumor in children and is considered to be of neuroectodermal origin. Two main representative cell lines, DAOY and D283, are widely used in studies of medulloblastoma. The former shows expression of neuronal and glial elements whereas the latter is assigned to neuronal lineages. We decided to systematically study the proteome of these cell lines in order to find novel and known proteins that could serve as candidate markers or could be of interest as specific antigens for future vaccines. We studied DAOY and D283 by two-dimensional gel electrophoresis with subsequent matrix-assisted laser desorption/ionization identification. A series of identified medulloblastoma proteins were already described in many other malignancies of different origin. An antiapoptotic principle, Ded protein, was observed in both cell lines. Several hypothetical proteins, that were never described at the protein level but only predicted from nucleic acid sequences, could be identified. We conclude that medulloblastoma proteins SYT interacting protein, similar to glucose related protein 58 kDa, hypothetical 37.5 kDa protein, serologically defined colon cancer antigen 10, hepatocellular carcinoma-associated antigen 59, X-ray repair complementing defective repair in CHO 5, hypothetical protein Q96ir7, nit protein 2 and hypothetical protein Q96e67, have been described in a series of other malignancies possibly indicating a role for those in tumor biology and pathomechanisms. The antiapoptotic principle, Ded protein, found in both cell lineages may stand for immortalization but could also determine malignancy per se in medulloblastoma.

Pigmented ependymoma with lipofuscin and neuromelanin production

We report an unusual case of ependymoma with pigmentation, a phenomenon that has only been described in a few cases, to our knowledge. This tumor occurred in the fourth ventricle of a 45-year-old man. It showed the typical histologic appearance of ependymoma with perivascular pseudorosettes and rare ependymal rosettes. Some tumor cells contained brown cytoplasmic pigment, which was shown histochemically to represent a mixture of lipofuscin and neuromelanin. The pigment was positive for acid-fast and periodic acid-Schiff stains and was also focally positive for Masson-Fontana and Schmorl stains (bleached by pretreatment with potassium permanganate). In addition, some other tumor cells showed a signet ring morphology as a result of prominent intracytoplasmic vacuolation. Immunohistochemically, all the tumor cells expressed glial fibrillary acidic protein, and rare pigmented tumor cells also expressed HMB-45. Ultrastructural examination showed irregularly shaped heterogeneous electron-dense bodies corresponding to the pigment, and the cytoplasmic vacuoles were formed by dilatation of intracytoplasmic lumens lined by microvilli. Since lipofuscin production can occur in normal ependymal cells and neuromelanin has been suggested to be a melanized form of lipofuscin, it is not surprising that these 2 pigments can be found in ependymoma. In all the previously reported cases, the pigment was shown to represent melanin only. In our case, the HMB-45 positivity in rare tumor cells indicated that there might also be a minor melanin component in the pigment in addition to lipofuscin and neuromelanin.

A comparative study of classical vs. desmoplastic medulloblastomas

Classical and desmoplastic medulloblastomas (MBs) have been suspected to be biologically different, though comparative studies on markers of biological aggressiveness in these two variants are sparse in the literature. 87 classical and 43 desmoplastic variants of MB were studied with respect to clinical and histological characteristics, MIB-1 labeling index (MIB-1 LI), apoptotic index (AI), ratio of AI to MIB-1 LI, expression of p53 and Bcl-2 protein and 3-year progression-free survival. The only differences documented between the variants were with regard to age distribution and location. Thus, classical histology cases occurred predominantly in children and 80% were midline in location. In contrast, lateral location was seen more frequently with tumors of desmoplastic histology, which occurred in an almost equal distribution between children (56%) and adults (44%). No difference was noted between the variants with regard to proliferation index, apoptotic index, their ratio on or their molecular controls (p53 and Bcl-2). This was reflected in the clinical outcome wherein no significant difference was observed in the 3-year progression-free survival between the variants. It is concluded that the two histological variants of medulloblastoma are not different with regard to biological parameters of aggressiveness. The growth rate and clinical outcome in medulloblastomas have no correlation with the histological variant.

Calbindin-d(28k): a marker of recurrence for medulloblastomas

BACKGROUND

The expression of the Ca(2+)-binding protein calbindin-D(28k) was analyzed in medulloblastomas in relation to clinical features and other biologic markers related to cell proliferation, differentiation, p53, and cerebellar developmental regulated gene expression.

METHODS

Immunohistochemistry was carried out on histologic slides from a first retrospective series of 29 nonmetastatic and 10 metastatic medulloblastoma formalin-fixed, paraffin-embedded tissues, using specific antibodies against calbindin-D(28k), calretinin, alpha-parvalbumin and beta-parvalbumin, and S100 proteins. Informed consent was obtained from the subjects and/or guardians. Other biologic markers for differentiation, cell proliferation, the expression of the p53 tumor suppressor gene protein, and cerebellar developmental regulated genes were similarly investigated. A second series of 16 medulloblastomas from young patients (younger than 15 years) was added in order to validate the results obtained in the first series.

RESULTS

Of all the markers investigated, only calbindin-D(28k) was significantly associated with prognosis. Survival and remission (i.e. recurrence free) time analysis performed on all the cases (n = 55) confirmed a high risk of death (P = 0.004) and recurrence (P = 0.003) associated with calbindin-positivity. As calbindin-positivity was predominantly observed in tumors from young patients, the authors confirmed its prognostic value in the subgroup of patients younger than 15 years (n = 37). Cox regression analysis showed a significant and independent prognostic value for calbindin expression and, to a lesser extent, the type of surgery (total or subtotal). Three risk groups were thus identified, distinguishing among the cases characterized by a total resection and calbindin-negativity (good prognosis), by a subtotal resection and calbindin-negativity (intermediary), and by calbindin-positivity (bad prognosis).

CONCLUSIONS

The current study suggests that calbindin-positive medulloblastomas represent a subclass of aggressive tumors more frequently seen in younger patients.

Expression of survivin, an inhibitor of apoptosis protein, in tumors of the nervous system

Survivin is an inhibitor of apoptosis protein that blocks apoptosis by binding to caspases-3 and -7. It is highly expressed in less-differentiated embryonic cells and rapidly dividing tumors, but not in terminally differentiated adult tissues. Elevated survivin levels are found in malignant systemic tumors, and are associated with chemo-resistance, radiation resistance, and poor prognosis. However, expression of survivin in primary nervous system tumors has not been previously characterized. Immunohistochemistry using anti-human survivin antibody (SURV11-A) was performed on formalin-fixed, paraffin-embedded archival tissue from 112 primary central nervous system tumors. Survivin immunoreactivity was seen in most diffuse astrocytomas [WHO II (2/4), III (3/3), IV (9/10), giant-cell glioblastoma (1), and gliosarcoma (1)]. The intensity and degree of survivin expression showed trends with tumor grade, with glioblastomas having the highest positivity. Pilocytic astrocytomas (5) and pleomorphic xanthoastrocytoma (1) were positive to a lesser degree. In oligodendrogliomas (6) and mixed oligo-astrocytomas [grade II (5), II-III (3), and III (7)], oligodendroglial elements appear to be negative compared to positive mini-gemistocytic oligodendrocytes. Ependymomas [grade II (6) and grade III (1)] were positive. Medulloblastomas (5) and retinoblastoma (1/4) showed focal positivity. All meningiomas [grade I (12), II (9), III (4), and grade I (3) and II (5) with frank brain invasion] were intensely positive. All schwannomas (11) and neurofibromas (6) were intensely positive. Thus, survivin is expressed in the majority of the primary nervous system tumors, particularly in glioblastomas, meningiomas, schwannomas and neurofibromas. Overexpression of survivin in meningiomas and benign peripheral nerve sheath tumors contrasts with previous reports relating it to rapid division and poor prognosis.

Central liponeurocytoma

The 2000 World Health Organization has included cerebellar liponeurocytoma in the category of glioneuronal tumors of the central nervous system. Once termed medullocytoma and considered an embryonal tumor, a variant of medulloblastoma, its indolent behavior and morphologic features prompted this nosologic change. Biphasic in appearance, the tumor consists of well-differentiated neurons with the cytology of neurocytes in addition to a population of lipidized cells resembling mature adipose tissue. Such tumors occur in older adults and have a relatively good prognosis. Linking the concept of liponeurocytoma to its occurrence in the cerebellum unnecessarily obscures the existence of similar neoplasms at other sites, such as among classic central neurocytomas of the lateral and third ventricles. Indeed, two such cases have briefly been reported. To these, we add a third example, the first to be ultrastructurally examined. Our case provides evidence that the lipid vacuoles progressively accumulate and coalesce within cells retaining neurocytic features. Thus, these distinctive lesions are the result of tumoral lipidization, rather than true adipose metaplasia.

Primary Ki-1 lymphoma in the central nervous system

Large cell anaplastic malignant lymphoma with Ki-1 (CD30) antigen is a new entity among human non-Hodgkin's malignant lymphomas according Updated Kiel Classification and is also a very rare subtype in primary central nervous system (CNS) malignant lymphomas. The precise clinical characteristics and the significance of Ki-1 antigen have yet to be clarified. The authors herein report a case of Ki-1 positive primary T-cell CNS malignant lymphoma. A 49-year-old man presented with multiple mass lesions in the brain on MRI. Immunohistochemical investigations of biopsy specimens from the superior medullary velum revealed a large cell anaplastic T-cell lymphoma positive for Ki-1 antigen. After administering extensive chemo-radiotherapy, the patient has survived for more than 42 months after the onset of symptoms.

Histological and genetic diagnosis of gliomatosis cerebri: case report

Gliomatosis cerebri is considered grade III astrocytoma because of the short survival period of patients with this tumor, while the tumor histologically consists of widespread low grade astrocytoma cells. The authors tried to clarify this discrepancy by applying genetic analysis of the tumor. A 29-year-old man originally presented with mild headache and showed diffuse high intensity areas in both hemispheres and in the cerebellum by T2-weighted magnetic resonance imaging (MRI) without gadolinium-dimeglumine (Gd)-enhancement in T1-weighted imaging. Histological diagnosis was gliomatosis cerebri with diffuse grade II astrocytoma. Seven months after temporary improvement following irradiation and chemotherapy, he developed progressive mental deterioration, and died in one year after the surgery. At this time T1-weighted imaging showed Gd-enhanced lesions with enlargement only of the cerebellar tumor. Genetic analysis demonstrated positive FGFR 1 and less FGFR 2 mRNA in the tumor tissue, and FGFR 1 mRNA was beta type dominant. These results indicated that the genetic features of this tumor are similar to those of glioblastoma multiforme concerning FGFR expression. The authors conclude that genetic investigation of the tumor tissue is required to predict the prognosis of gliomatosis cerebri patients, in addition to imaging and histological examinations.

Cerebellar liponeurocytoma: immunohistochemical and ultrastructural study of a case

The clinical, histopathological, and ultrastructural features of a cerebellar liponeurocytoma are reported. The tumor, a 3-cm mass localized in the right cerebellar hemisphere, was resected from a 61-year-old man clinically presenting with symptoms of intracranial hypertension. The lesion was composed of small, in some areas closely packed, medulloblastoma-like cells with prominent areas of lipidization phenomena. Moreover, mitoses, cellular atypia, and numerous vascular structures were focally observed. Glial and neuronal differentiation was immunohistochemically noted (glial fibrillary acidic protein, synaptophysin, neurofilaments, and neuron-specific enolase positivity). The p53 oncoprotein was detected in the majority of neoplastic cells and a moderate proliferation activity, evaluated by Mib-1 antibody, was focally appreciated. Ultrastructural study did not show evident neuritic processes, synapses, or dense core neuroendocrine granules. This cerebellar tumor previously called lipidized medulloblastoma and recently renamed cerebellar liponeurocytoma is considered an adult neoplasm with excellent prognosis histologically presenting prominent lipidized areas and, at the immunohistochemical and ultrastructural level, both glial and neuronal differentiation. The present study provides the first description of a less differentiated and histologically more aggressive form of this unusual tumor.

MR diffusion imaging and 1H spectroscopy in a child with medulloblastoma. A case report

We report on a child with a metastasising medulloblastoma which was assessed by MR diffusion imaging and 1H MR spectroscopy (MRS). Reduced mean apparent diffusion coefficients and a high amount of taurine could be demonstrated. This is the first reported case of high taurine in medulloblastoma in vivo and confirms earlier in vitro findings. It is suggested that the changes on diffusion imaging, possibly reflecting the small-cell histology of the tumour and high taurine in MRS, are indicative of medulloblastoma.

Atypical teratoid/rhabdoid tumor of the central nervous system: a comparative study with primitive neuroectodermal tumor/medulloblastoma

Eleven atypical teratoid/rhabdoid tumors (AT/RT) and 121 primitive neuroectodermal tumors/medulloblastomas (PNET/MB) were included in this study for evaluation of the histopathological features of AT/RT and comparison between AT/RT and PNET/MB. Histopathological studies of AT/RT showed that in addition to the commonly recognized components, i.e., rhabdoid cells, small (PNET/MB) cells, spindle cells and epithelial components, there was a previously unrecognized component, sickle-shaped embracing cells, which were present in all cases and could be useful as a histological marker of this tumor. Immunohistochemical studies showed divergent differentiation of the tumor cells and among the 16 antibodies studied, vimentin, neuron-specific enolase, epithelial membrane antigen and glial fibrillary acidic protein were most commonly reactive. The frequency of AT/RT expressed as a ratio of AT/RT to PNET/MB was 1:11 in general and increased to 1:3.8 among patients younger than 3 years old. The AT/RT patients were younger than those with PNET/MB and had a female predominance. The MIB-1 labeling index of AT/RT was significantly higher than that of PNET/MB (mean 63.9 vs 40.1), which correlated with a shorter survival in patients with AT/RT than those with PNET/MB (median survival time 15.4 months vs 156.4 months).

Expression of the neurotrophin receptor p75NTR in medulloblastomas is correlated with distinct histological and clinical features: evidence for a medulloblastoma subtype derived from the external granule cell layer

Medulloblastomas (MBs) are primitive neuroectodermal tumors (PNET) of the cerebellum. They represent the most frequent malignant pediatric brain tumors, but their origin still remains unresolved and controversial. MB cells correspond to different stages of neural development and differentiation as illustrated by their expression of neuronal and glial markers. In the present study, we examined the expression pattern of the common low-affinity neurotrophin receptor p75NTR in a series of 167 MBs by immunohistochemistry. While p75NTR was present in only 17% of classic MBs (CMB), we found expression of p75NTR in all desmoplastic (nodular) MBs (DMB) examined, and in 71% of those MBs with a significant desmoplastic component. Furthermore, both desmoplastic histology and p75NTR expression were present preferentially in those tumors of adolescents and adults that are frequently located laterally in the cerebellar hemispheres. In DMBs, p75NTR was expressed predominantly in the proliferative, reticulin-rich areas, which may show coexpression of GFAP. In the pale islands of DMB, p75NTR was expressed only weakly or was absent. The expression pattern showed an inverse relation to that of the synaptic vesicle protein synaptophysin that was predominant in p75NTR negative classic MBs. Since the neurotrophin receptor p75NTR is expressed in cells of the external granule cell layer (EGL) of the fetal cerebellum, our findings suggest that progenitor cells of the EGL are the cellular origin of a distinct subset of MB, namely the desmoplastic variant and MBs with a significant desmoplastic component.

Cerebellar pleomorphic xanthoastrocytoma in an infant

Pleomorphic xanthoastrocytoma (PXA) is a rare brain tumor and typically occurs in the superficial cerebral hemispheres of young subjects. We report a case of PXA in the cerebellum of a 3-month-old infant in view of its unusual location and age. The patient presented with a 1-month history of upward eyeball gazing difficulty. To the authors' knowledge, this is the first report of occurrence of this neoplasm in the cerebellum of an infant. We report the morphologic and immunophenotypical features, and literature review with regard to the clinicopathologic aspects of a case of unusual PXA.

Angiogenic histogenesis of stromal cells in hemangioblastoma: ultrastructural and immunohistochemical study

Controversy regarding the origin of characteristic stromal cells (SC) is responsible for the placement of hemangioblastoma as a single entity in the category of "tumors of uncertain histogenesis" in the current WHO classification of brain tumors. This subclassification of hemangioblastoma is, to a large extent, a consequence of a remarkable antigenic heterogeneity of SC demonstrated in many, often contradictory immunohistochemical studies. In contrast, most of the electron microscopic studies demonstrated a number of features indicating angiogenic nature of SC and, therefore, hemangioblastoma. This study reevaluated the histogenesis of SC, applying immunohistochemistry as well as electron microscopy and immunoelectron microscopy. Immunohistochemical studies confirmed most of the previous results indicating a very frequent expression of vimentin, S-100 protein, neuron-specific enolase, and cytokeratins. SC were less commonly immunoreactive for desmin, factor XIIIa, and Ricinus communis lectin receptors, and only occasionally for factor VIII and Ulex europeus lectin. They were negative for other markers of endothelial, neuronal, glial, neuroendocrine, and smooth muscle differentiation. Approximately 1% of SC showed Ki67 immunoreactivity, indicating their slight proliferative activity, consistent with the benign nature of the tumor. In contrast to the inconclusive results of the immunohistochemistry, electron microscopy demonstrated a clear relationship of SC to endothelial cells, smooth muscle cells, and pericytes. Occasional SC were found within the vascular lumina. SC often showed intracellular caveolae consistent with the formation of early capillary lumina. Moreover, occasional SC contained small Weibel-Palade bodies positive for factor VIII in immunoelectron microscopy. SC represent a heterogeneous population of abnormally differentiating mesenchymal cells of angiogenic lineage, with some morphological features of endothelium, pericytes, and smooth muscle cells. Occurrence of SC in hemangioblastoma could be related to a limited ability of angioformative stromal cells to develop an architecture of capillary lumina integrated with the vascular network of the tumor. Hemangioblastoma should be reclassified and included together with other vascular tumors of the central nervous system.

Expression of leukemia-inhibitory factor as an autocrinal growth factor in human medulloblastomas

Medulloblastoma is the most frequent pediatric brain tumor, with the capacities of rapid proliferation and intracranial dissemination. However, the factor(s) regulating medulloblastoma growth has not yet been well characterized. Leukemia-inhibitory factor (LIF) and interleukin-6 (IL-6) play different roles in the formation/progression of various embryonic and pediatric tumors, but their biological effects on medulloblastoma cells are less well known. Therefore, in vivo and in vitro expression of LIF, IL-6 and their signal transducer genes encoding LIF receptor (LIFR), IL-6 receptor (IL-6R) and gp130 in human medulloblastoma cells were investigated by multiple cellular and molecular biology approaches. The results revealed that LIF expression could be found in 26 out of 28 tumors/cell line and over 90% of the samples expressed LIFR, IL-6R and gp130. In contrast, none of the samples showed IL-6 expression. An established medulloblastoma cell line, Med-3, was used to evaluate the potential effects of LIF and IL-6 on the proliferation of medulloblastoma cells. The growth of Med-3 cells was efficiently inhibited either by anti-LIF antibody or by antisense LIF oligonucleotide. Addition of exogenous human recombinant IL-6 could dramatically enhance Med-3 cell outgrowth. Our data thus for the first time demonstrated the important role of LIF as an autocrinal and IL-6 as a paracrinal growth factor in the proliferation of medulloblastoma cells.

Posterior fossa surgery in the sitting position in a pregnant patient with cerebellopontine angle meningioma

Primary brain tumours and pregnancy rarely occur together; meningioma and pregnancy is rarer still. We describe a 30-yr-old woman in the 25th week of pregnancy who underwent surgery in the sitting position for a large cerebellopontine angle meningioma that was compressing and displacing the pons and medulla. The surgical procedure and postoperative period were uneventful. This case demonstrates that when absolutely necessary, anaesthesia and neurosurgery for posterior fossa lesions can be successful during the second trimester of pregnancy. Furthermore, if indicated and if the operating team is experienced, the operation can be performed safely with the patient in the classical sitting position. It is emphasized that continuous and attentive monitoring of the mother and fetus are essential.

Clinicopathological correlation of cell proliferation, apoptosis and p53 in cerebellar pilocytic astrocytomas

We have analysed 78 cerebellar pilocytic astrocytomas to assess whether histopathology, cell proliferation, apoptosis rate, p53 immunoreactivity, or flow cytometry could predict their long-term behaviour. Classic pilocytic/microcystic pattern was seen in 62 patients and 16 patients had mixed pattern with an additional non-pilocytic glial component. The overall 5-year survival was 93%, complete resection providing 100% survival. The four patients who died during the follow-up were more than 14 years of age, their primary operation had been incomplete and three of them were mixed variants. In 15 cases the tumour recurred giving a recurrence-free 5-year survival of 77%. The proliferation indices were low: Ki-67MIB-1 (median 2.0%), PCNA (1.2%) and S-phase fraction (4.4%). The Ki-67MIB-1-labelling index was significantly higher in young patients, but did not differ between the classic and mixed variants. Twenty-two per cent of the tumours were aneuploid with a significantly higher S-phase fraction than in diploid tumours. p53 seems to act as ardian of the genome' in pilocytic astrocytomas, because aberrant/increased expression of p53 and aneuploidy associated with enhanced apoptosis. Only patient age (P = 0.01), radicality of the primary operation (P = 0.0001) and histology (classic vs mixed, P=0.008) significantly correlated with survival. The poorer prognosis of the mixed variant suggests that this may represent a distinct entity. Although none of the novel parameters significantly predicted recurrence or survival, they indicate substantial biological variation among cerebellar pilocytic astrocytomas.

Gangliosides and neutral glycolipids in ependymal, neuronal and primitive neuroectodermal tumors

Neutral glycolipid and ganglioside compositions were determined on 11 ependymal tumors, 12 medulloblastomas, 6 other neuronal tumors of the brain, 4 peripheral neuroblastomas, 1 cerebral primitive neuroectodermal tumor (PNET), and 1 PNET of the thoracic wall. Within the group of tumors that can demonstrate neuronal phenotypes, there was an association between the degree of neuronal differentiation usually demonstrated by these tumors and the proportions of both GD1a and 1b-pathway gangliosides. The amount of globoside also correlated with the amount of 1b pathway gangliosides. Patients with medulloblastomas whose 1b gangliosides made up over 15% of the total gangliosides survived longer that those with lower proportions of 1b gangliosides. The only gangliosides in the choroid plexus papilloma were GM3 and GD1a, but other ependymal tumors had significant amounts of GD1b and its metabolic precursors. Ependymoma and anaplastic ependymoma had similar neutral glycolipid compositions, which were different from subependymoma, which lacked ceramide monohexoside and ceramide dihexoside. These differences in glycolipid compositions suggest that there may be fundamental biological differences between these types of ependymal tumors.

Cerebellar medulloblastoma with multiple differentiation in a dog

A 4-year-old female, spayed Border Collie Dog was brought to the Veterinary Medical Teaching Hospital for evaluation of a progressive head tilt and ataxia that were unresponsive to therapy. Neurologic examination localized a right-sided lesion. The owner refused additional diagnostic tests, and necropsy was performed after euthanasia. Gross findings included atrophy of the temporal muscles and a moderately well delineated, 2.5- x 1.5- x 1.0-cm, gray soft-tissue mass compressing the right cerebellar hemisphere and dorsal hindbrain, resulting in massive dilatation of the lateral, third, and fourth ventricles and hydrocephalus. Histologic examination revealed two distinct features: undifferentiated, primitive, polygonal to fusiform cells with typical morphologic characteristics of medulloblastoma and interspersed areas containing myelinated axons and cells with glial and neuronal differentiation. Immunohistochemical examination confirmed the presence of primitive neuroepithelium and cells with glial and neuronal differentiation.

Profiles of the fatty acids in the plasma membrane of human brain tumors

Several studies demonstrated that certain fatty acids have specific effects on tumor cells. n-3 series fatty acids (alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid) may suppress the carcinogenesis, whereas n-6 series fatty acids (arachidonic acid, linoleic acid) may exert tumor promoting effects. In this study, 19 patients with various brain tumors and 12 control brain tissues were studied. n-3, n-6, n-9 unsaturated fatty acids and certain saturated fatty acids levels were measured in the plasma membrane of tumor or control brain tissues by capillary gas chromatography. We found that the level of docosahexaenoic acid from n-3 series fatty acids was significantly lower in gliomas and meningiomas than controls (p = 0.000). Total n-3 fatty acids level was also significantly lower in tumors than controls (p = 0.000). The levels of linoleic acid, arachidonic acid and dihomogamma linolenic acid from n-6 series were significantly higher in gliomas and meningiomas compared with controls (p = 0.000). Total n-6 fatty acids level was also significantly higher in tumors than controls (p = 0.000). Furthermore, in total n-9 fatty acids, total unsaturated fatty acids and total saturated fatty acids levels, there were no significant differences in gliomas and meningiomas compared with controls (p = 0.6840, p = 0.4388 and p = 0.4343, respectively). This findings suggest that n-6 fatty acids can act as a tumor-promoting agent in human brain tumors.

[A clinicopathological analysis of primitive neuroectodermal tumors of the CNS]

OBJECTIVE

To investigate the difference between cerebellar medulloblastoma (MB) and primary cerebral small cell tumor in histogenesis, morphologic features and biological behavior.

METHODS

210 cases of MB and 9 cases of small cell tumor of cerebrum were observed with histologic and immunohistochemical techniques.

RESULTS

Both tumors were composed of primitive cells with focal evidence of glial and/or neuronal differentiation. In 63.2% of MB and five-eighths of small cell tumor of cerebrum coexpressed GFAP and Syn. Both types of tumors were highly malignant. The overall 1 year survival rates were 34.63% and 25.65% respectively. The survival rate was lower for patients with high proliferative index, with necrosis or without receiving radiation therapy.

CONCLUSION

MB is similar to other small cell tumors of CNS in morphological features, specific marker expression and biological behavior. These tumors can be classified as primitive neuro-ectodermal tumors (PNET).

[A clinical and pathological study of cerebellar medulloblastoma in adult patients]

OBJECTIVE

In order to study the clinicopathological characteristics, histogenesis and prognosis of medulloblastoma in the adult patients.

METHODS

Altogether 27 patients of medulloblastoma admitted form 1974-1995 were reviewed.

RESULTS

In all of the cases, age ranged from 16 to 55, (average 25.8 years) with 21 tumors localized in the cerebellar vermis, and 6 tumors in the cerebellum. Among them, 12 cases were completely while 14 cases were subtotally removed and biopsy was done in only one case. In the 21 patients to be followed up, 7 survived for 2.5-17 years after the operation, and 14 died. The average survival period was 41.6 months. One year survival rate was 71.4%, five years and ten years survival rates were 14.3% respectively. Regarding to the histological types, 14 cases were considered to be classic and 13 cases were desmoplastic by histological classification.

CONCLUSION

Medulloblastoma keeps still the ability of differentiation to neurons and astrocytes confirmed by electronmicroscopy and immunohistochemical staining for Syn, NSE and GFAP. Factors considered responsible to the prognosis included age, tumor location, various therapeutic measurements and the histological classification.

Neurocytoma/rhabdomyoma (myoneurocytoma) of the cerebellum

An unusual case of cerebellar neurocytoma with rhabdomyomatous differentiation in a 6-year-old boy is reported. Immunocytochemical and ultrastructural features of the tumour were studied. Abortive synapse formation, the presence of clear vesicles and synaptophysin immunoreactivity of the tumour cells indicated its intermediate neuronal differentiation, while the presence of myoblasts and myotubes and immunolabelling by desmin confirmed the rhabdomyomatous differentiation. In addition, the mesenchymal cells variably expressed neurofilament protein and glial fibrillary acidic protein, suggesting inductive interaction between the neuroectodermal and ectomesenchymal elements and persistence of the pleuripotential nature of the cells along the rhombic area of the brain stem.

Rosenthal fibers and eosinophilic granular bodies in a classic acoustic schwannoma

We describe unique features seen in a case of classic acoustic schwannoma. In the central portion of the tumor, abundant Rosenthal fibers and occasional eosinophilic granular bodies were present. Rosenthal fibers are homogeneous eosinophilic structures commonly seen in central nervous system lesions, such as pilocytic astrocytoma, or in the gliotic tissues adjacent to slowly growing neoplasms and some congenital malformations. Eosinophilic granular bodies are also structural markers of slow-growing, well-differentiated neuroglial neoplasms, such as pleomorphic xanthoastrocytoma, ganglion cell tumors, and pilocytic astrocytoma. To the best of our knowledge, however, these two structures have never before been described in schwannomas.

Congenital oligodendroglioma: a case report of a 34th-gestational week fetus with immunohistochemical study and review of the literature

A case of congenital oligodendroglioma occurring in a 34th-gestational week fetus is reported. The tumor was necrotic, hemorrhagic, and gelatinous. It covered the basal part of the brain, and almost the entire cerebellum was replaced by the tumor. The tumor cells had small, round, hyperchromatic nuclei and watery clear cytoplasm, and were arranged in a paved or alveolar pattern. Immunohistochemically, S100 protein, myelin-basic protein, neuron-specific enolase and Leu 7 were weakly positive for the cytoplasm, but glial fibrilliary acidic protein, synaptophysin, neurofilament, desmin, and vimentin were negative. Many tumor cell nuclei were positive for mutant p53 protein, and the labeling index was 85%. But there was no genetic alteration in exons 4 to 9 of p53 gene from the peripheral blood. The apoptosis index was 1.5%. Considering the p53 labeling index and the apoptosis index together, this congenital oligodendroglioma may be regarded as potentially malignant despite the benign morphological features.

Human medulloblastoma gangliosides

To establish a model system for the study of ganglioside metabolism of the human brain tumor, medulloblastoma, we have chemically characterized the gangliosides of the Daoy cell line. These cells contain a high concentration of gangliosides (143 +/- 13 nmol LBSA/10(8) cells). The major species have been structurally confirmed to be GM2 (65.9%), GM3 (13.0%), and GD1a (10.3%). Isolation of individual gangliosides homogeneous in both carbohydrate and ceramide moieties by reversed-phase HPLC and analysis by negative-ion fast atom bombardment collisionally activated dissociation tandem mass spectrometry have allowed us to unequivocally characterize ceramide structures. In the case of GM2, 10 major ceramide subspecies were identified: d18:1-hC16:0, d18:1-C16:0, d18:0-C16:0, d18:1-C18:0, d18:1-C20:0, d18:1-C22:0, d18:2-C24:1, d18:1-C23:1, d18:1-C24:1, and d18:1-C24:0. Taken together with previous studies, these findings in buman medulloblastoma cells support the view that high expression and marked heterogeneity of ceramide structure are general characteristics of tumor gangliosides, molecules which are shed by the tumor cells and which are biologically active in vivo.

Mitotic percentage index: a new prognostic factor for childhood medulloblastoma

We investigated the prognostic significance of a new method of mitotic figure quantitation, 'mitotic percentage index' (MPI), tumour S phase fraction (SPF) and DNA ploidy measured by flow cytometry, and various clinical prognostic factors including age, sex, tumour stage, degree of surgical resection, radiotherapy dose and adjuvant chemotherapy in 70 cases of childhood medulloblastoma diagnosed between 1968 and 1996. In univariate analysis, MPI (P < 0.0001), posterior fossa radiotherapy dose (P = 0.003), tumour stage (P = 0.014), craniospinal radiotherapy dose (P = 0.019), year of diagnosis (P = 0.024) and SPF (P = 0.048) were significantly related to survival. In multivariate analysis, including tumour c-erbB-2 oncogene product expression, only MPI (P < 0.0001), craniospinal radiotherapy dose (P = 0.003) and tumour stage (P = 0.035) retained independent prognostic significance, while age achieved significance (P = 0.039). A close relationship was observed between MPI and SPF (coeff = 0.8, P < 0.0001) and MPI and the percentage of tumour cells expressing the c-erbB-2 oncogene product (coeff = 0.416, P < 0.0001). This study has identified MPI as a new independent prognostic factor for childhood medulloblastoma. Its close relationship with tumour SPF confirms it as an accurate measure of tumour proliferation and its close relationship to expression of the c-erbB-2 oncogene supports a role for this growth factor receptor in the deregulation of normal mitogenic signal transduction in this malignancy.

Lipomatous medulloblastoma in adults. A distinct clinicopathological entity

We report on three patients who presented with a cerebellar medulloblastoma at age 48, 53, and 59 years. Histopathology showed typical features of medulloblastoma, in one case with marked neuronal differentiation. In addition, all neoplasms contained focal accumulations of mature fat cells. Immunoreactivity of adipocytes for S-100 protein, neuron-specific enolase, synaptophysin, microtubule-associated protein-2, and glial fibrillary acidic protein and the lack of immunoreactivity to type IV collagen suggest lipomatous differentiation of neoplastic primitive neuroectodermal cells rather than an admixture of mesenchymal elements. Mitotic activity was low and the growth faction, as determined by the MIB-1 labeling index, was less than 5%. All patients are alive with a recurrence-free interval ranging from 3.5 to 12 years. These three patients and five similar previously reported cases all fit into the concept of the lipomatous medulloblastoma as a new clinicopathological entity characterized by (a) typical features of a cerebellar medulloblastoma with advanced neuronal differentiation, (b) areas of lipomatous differentiation, (c) low proliferative potential, (d) manifestation in adults (mean age, 50 years), and (e) apparent favorable clinical prognosis.