Molecular abnormalities in pediatric embryonal brain tumors--analysis of loss of heterozygosity on chromosomes 1, 5, 9, 10, 11, 16, 17 and 22.

Embryonal tumors, the most common group of malignant brain tumors in childhood, are heterogeneous and have been associated with a large number of genetic abnormalities. The aim of this study was to comprehensively analyze loss of heterozygosity (LOH) on regions harboring suppressor genes (PTCH2, PTCH1, APC, PTEN, DMBT1, SUFU, AXIN1, hSNF5/INI1) and to study chromosomal regions in which deletions have been described most frequently (1p, 1q, 11p, 16p, 17p). Twenty-nine children (17 male and 12 female), aged from 1 year 13 years were included in this study. There were 24 medulloblastomas (MB) and 5 supratentorial primitive neuroectodermal tumors (sPNET). Tissue samples from 29 primary and 11 recurrent tumors were analyzed according to the LOH standard procedures, which were extended to include fluorescence in situ hybridization for detection of isochromosome 17q (i(17q)) and direct sequencing ofTP53 exon 4. LOH on 17p was found in 15 out of 29 tumors. FISH analysis identified the presence of i(17q) in 16 tumors. Comparison of LOH analysis and the FISH data indicated that alterations of 17p were related to be the introduction of an i(17q) formation. LOH on 10q and 9q was observed in 4 and 2 cases, respectively, and was associated with alterations of chromosome 17. These results indicated a connection between alterations of PTCH/SHH genes and abnormalities of chromosome 17. A deleted region on 22q, covering the hSNF5/INI1 locus, was observed in 3 tumors. Progression of the molecular changes occurred in 1 case of recurrent medulloblastoma. LOH on 10q and 17p was found in both primary and recurrent tumor, while losses on 11p, 16p, and 16q occurred only in the recurrent tumor. No evidence of alteration in TP53 exon 4 was identified.

Microsatellite instability and expression of DNA mismatch repair genes in malignant astrocytic tumors from adult and pediatric patients.

Microsatellite instability (MSI) is used as a molecular marker for defective DNA mismatch repair (MMR) genes. We report here alterations of MSI in 15 malignant astrocytomas (WHO grade III) and glioblastomas (GBM; WHO grade IV) of pediatric patients (2 - 21 years) and 12 GBM from adults (44 - 68 years) by comparative analysis of BAT25/BAT26 loci and 10 other microsatellite markers. High-level microsatellite instability (MSI-H) occurred in 4 of the 15 pediatric cases (26.7%) and in 1 of the 12 adult GBM cases (8.3%). Low-level microsatellite instability (MSI-L) was observed in 6 pediatric cases (40%) and 8 adult GBM (66.7%). Unstable BAT-25 locus was found in 1 of the MSI-H pediatric cases. Thus, 2 unstable cases showed no instability of this marker. For BAT-26, such a discordance was even more profound: in 1 of MSI-H cases, we obtained no PCR product and the remaining 3 showed no alterations of this marker. MSH2 (Human MutS, Homologue2) protein was detected in all but 3 pediatric cases (1 highly unstable and 2 low-level unstable) and in all adult cases. MLH1 (Human MutL, Homologue 1) protein was detected in all but 2 pediatric cases (1 highly unstable and 1 low-level unstable). Thus, 2 highly unstable pediatric cases showed no detectable MLH1/MSH2 proteins. Our data support earlier observations that MSI occurs predominantly in malignant astrocytic tumors of young patients, which lends support to the hypothesis of different molecular mechanisms of pediatric brain tumors. Surprisingly, we found no significant correlation between the status of 10 microsatellite markers and that of either BAT25 or BAT26 loci or with the expression of MMR genes.

Clinico-pathological analysis of pilocytic astrocytomas and gangliogliomas.

A pathological analysis of 58 pilocytic astrocytomas (PA) and 11 gangliogliomas (GG) was performed using immunohistochemistry. Antibodies against neuronal and glial markers (GFAP, SYN, NFP) were used. An analysis of survivors using the Kaplan Meier curve was also performed and compared with the literature reports. During the retrospective review of 58 cases recognized primarily as PA, 11 verified neoplasms demonstrated strong, immunopositive reaction for SYN or NFP or both antibodies. These cases were reclassified as gangliogliomas (GG). None of the 11 tumors recognized as GG was reclassified as PA. The overall 5-year survival was 88.89% in the PA and 70% in GG groups.

[The treatment of cerebral abscesses in children--the clinical experiences of neurosurgical clinic of PMMH in Lodz]. / Postepowanie kliniczne w leczeniu ropni u dzieci--doswiadczenia Kliniki Neurochirurgii ICZMP w Lodzi.

In our study we made attempt to assess which clinical criteria are essential for choosing optimal treatment for children suffering from cerebral abscesses. We observed the clinical results obtained at our Department from treatment of infections of the central nervous system (CNS) in children and analysed them with respect to applied therapy and clinical conditions. Between 1990 to 2000, 45 children aged 3 days to 15 years (mean 1.34 years, standard deviation 3.23 years) with infections of the CNS were treated at our Department. Within this group, 26 patients were diagnosed with cerebral abscesses, 1 with epidural empyema, 3 with subdural empyema and 15 with pyocephalus. 42 patients were operated. In 3 patients a conservative treatment was introduced at the moment when the abscesses were in the initial stage of organisation; in each case after a complete cycle of antibiotic therapy a regression of lesion was noted. The most frequently performed--in 19 patients--surgical procedure was the radical excision of the abscess by craniotomy. In 2 cases a re-operation was necessary. The highest rate of re-operations was noted in the group of children treated by external drainage; within this group of 18 patients only one 3-month-old girl did not require an additional surgical intervention. Neuroendoscopic techniques were used in 7 patients with compound hydrocephalus. Out of 45 treated children, 3 died from encephalitis, the primary reason being the infection of the ventriculo-peritoneal shunt. All children were assessed according to the Glasgow Outcome Scale and the results were significantly worse in those under 3 years in age. We suggest that in children above 3 years of age with mature abscesses of the central nervous system an operative evacuation of the abscesses by craniotomy should be performed.

[Clinical application of proton magnetic resonance spectroscopy for differential diagnosis of pediatric posterior fossa tumors]. / Zastosowanie Spektroskopii Protonowej Rezonansu Magnetycznego w diagnostyce róznicowej nowotworów tylnego dolu czaszki u dzieci.

We report here on a correlation between proton magnetic resonance spectroscopy (MRS) spectra obtained in children with posterior fossa tumors and tumor histology and grading. Twenty-six children (age 1-16) were investigated before surgery by using single-voxel proton MRS. All examination were performed on a 1.5 T MR scanner by using single-voxel (8 cm3) with PRESS sequence (TR 1600 ms, TE 270 ms, NEX 256). Spectra of N-acetylaspartate (NAA), choline containing compounds (Cho), creatine and phosphocreatine (Cr) and lactate (Lac) were evaluated. Absolute concentrations of the metabolites were measured and their ratios were calculated. Correlation between these and tumor histology and grading were then determined. Concentration of Cho and Lac, and Cho/NAA ratio were the major statistically significant parameters for discrimination between benign (WHO grade I and II) and malignant tumors (WHO grade III and IV), in particular between pilocytic astrocytomas and medulloblastomas. Discrimination between individual histological types within malignant and benign tumor groups was not possible. Proton MRS of pediatric posterior fossa tumors seems to be helpful in prediction of tumor grading and histology. Specific character of the examination requires establishing of the individual standards for every MR scanner.

Dysembryoplastic neuroectodermal tumor: an ultrastructural study of six cases.

Dysembryoplastic neuroectodermal tumor (DNT) is a rare brain neoplasm. Although the tumor pathology is relatively well charactererized, its full clinicopathological spectrum is still discussed, and ultrastructural data on it are very limited. Here, the authors describe detailed ultrastructural pathology of 7 cases of DNT. Each tumor consisted of 3 major elements: neoplastic cells (oligodendroglial-like cells, OLC), elongated processes forming neuropil-like structure, and expanded "mucoid" extracellular space, the latter giving an impression of cellular elements floating within it. Neoplastic cells had round, oval, or elongated nuclei, no discernible nucleoli, and a relatively narrow rim of cytoplasm. Some nuclei were irregular and invaginated, and pseudoinclusions (invaginations of cytoplasm penetrated into toroid-like nuclear formations) were observed. Part of the cytoplasm sequestrated within pseudoinclusions often appeared degenerated with large blebs and electron-lucent vesicles, and some of these contained, in turn, semicircular profiles of unknown significance. Chromatin was clustered below the nuclear membrane. The cytoplasm contained a few mitochondria, round rather than elongated, a few stacks of rough endoplasmic reticulum, and scanty microtubules and clear vesicles. The second element consisted of innumerable cellular processes. Some of these were elongated and formed stacks connected by symmetric or asymetric adhesive plaque junctions. Others had shorter "neck" containing microtubules extending into bulbous extensions. Dense-cored vesicles were occasionally observed, both in the cytoplasm of neoplastic cells and within processes. In one cell, cross-sectioned annulate lamellae were found. In the cytoplasm of a few cells, unusual inclusions reminiscent of ribosome-lamellae resembled "laboratory tubes" with cone-like endings. At higher power, walls of the "tubes" resolved into layered structures composed of several laminae; between these, ribosome-like structures were visible. The authors conclude that OLC exhibit clear-cut characteristics of neuronal cells and not true oligodendocytes.

Proton magnetic resonance spectroscopy of primary pediatric brain tumors: neuropathological correlation.

Forty-five children with primary brain tumors were evaluated by in vivo proton magnetic resonance spectroscopy (MRS) with the aim of detecting correlations between the obtained spectra and tumor malignancy and histology. All investigations were performed using a 1.5 T MR scanner (Picker) with point-resolved spectroscopic (PRESS) sequence (TR 1600 ms, TE 270 ms, NEX 256). Spectra were analyzed for N-acetylaspartate (NAA), choline containing-compounds (Cho), creatine and phosphocreatine (Cr) and lactate (Lac). The Cho/NAA ratio was the most useful parameter for differentiating between normal brain, benign and malignant tumors as well as discriminating the three main groups of pediatric brain tumors namely pilocytic astrocytoma, ependymoma and medulloblastoma. Proton MRS appears to be an important noninvasive technique in the differential diagnosis of pediatric brain tumors.

Clinicopathological analysis of pilocytic astrocytomas and gangliogliomas in children.

We present here a clinico-pathological analysis of 58 pilocytic astrocytomas (PA) and 11 gangliogliomas (GG) based on an analysis of neuronal markers (GFAP, SYN, NFP) in these two groups of neoplasms. During the retrospective review of 58 cases recognized primarily as PA, 11 verified neoplasms demonstrated strong reaction for SYN or NFP or for both antibodies. These cases were reclassified as gangliogliomas. None of 11 tumors recognized as GG were further reclassified as PA. The overall 5-year survival was 88.89% in PA and 70.00% in GG group.

Dysembryoplastic neuroepithelial tumor (DNT): an ultrastructural study of six cases.

We report six cases od DNT with a detailed ultrastructural characteristics. The patient age ranged from 7 to 16 years (mean 12), the location was temporal in three cases and frontal, temporooccipital and parietooccipital in each of one remaining cases. The predominant clinical feature in each case was history of episodes of intractable seizures. Histopathologically, the neoplasms were multinodular, each nodule was well-circumscribed and was composed of glioneuronal elements embedded in the variable amount of myxoid matrix. The oligodendroglial-like cells (OLC) predominated in the nodules with some accompanying mature neurons. The nodules were frequently surrounded by small calcifications which could be found also within the tumors. OLCs were immunoreactive for S-100 protein and neurons had the expression of synaptophysin and neurofilament proteins. Ultrastructurally, each tumor consisted of three major elements: neoplastic cells (OLC), elongated processes forming neuropil-like structure and expanded "mucoid" extracellular space: the latter gave an impression of cellular elements floating within it. Neoplastic cells had round, oval or elongated nuclei, no discernible nucleoli and a relatively narrow rim of the cytoplasm. Some nuclei were irregular and invaginated and pseudoinclusions were observed; a part of cytoplasm sequestered within pseudoinclusions often appeared degenerated with large blabs and electron-lucent vesicles, some of these contained in turn semicircular profiles of unknown significance. The second element consisted of innumerable cellular processes. Some of these were elongated and formed stacks connected by symmetrical symmetric or asymmetric adhesive plaque junctions. The others had shorter "neck" containing microtubules, these extended into bullous extensions. Dense-cored vesicles were occasionally observed, in both cytoplasm of neoplastic cells and within processes. In one cell, cross-sectioned annulate lamellae were found. In cytoplasm of a few cells, unusual inclusions reminiscent ribosome-lamellae complexes were observed. These were cylindrical resembling "laboratory tubes" with a cone-like endings. At higher power, walls of the "tubes" resolved into layered structures composed of several laminae; between laminae, ribosome-like structures were visible.

The ultrastructural study of primary intracranial germ tumors.

We describe here ultrastructural and clinicopathological features of five primary intracranial germinomas. By electron microscopy, two major tumor components were defined as large, well differentiated tumor cells and non-neoplastic cells such as macrophages, astrocytes and lymphocytes. Nuclei of tumor cells were round to oval, often presented irregularly contoured nuclear membranes with oval indentations and, occasionally, cytoplasmic invagination. Some of them constituted unusual conformational changes of nuclear membranes rarely described as intranuclear pockets. Desmosome-like intercellular junctions were observed in several neoplastic cells. The nucleoli were composed of a loose, fragmented nucleolonema, whereas elongated, anastomosing and rope-like nucleolonemas, described previously as characteristic for germinomas were not seen. Most tumor cells had villous cytoplasmic projections sometimes intermingled with similar projections of macrophages. Cytoplasm contained a moderate number of mitochondria, a few lysosomes, annulate lamellae, centrioles and glycogen particles. The other distinct components of tumor were lymphocytes, macrophages and astrocytes. Scattered astrocytes typically contained abundant glial filaments adjacent to primary tumor cell. A filopodia-like processes of macrophages often interspersed between other cells, were very prominent features of germinomas. Small lymphocytes were found scattered between the tumor cells, single or in clusters.

The ultrastructural study of primary intracranial germ cell tumours.

We describe here ultrastructural and clinicopathological features of five primary intracranial germinomas. By electron microscopy, two major tumour components were defined as large, well differentiated tumour cells and non-neoplastic cells such as macrophages, astrocytes and lymphocytes. Nuclei of the tumour cells often presented irregularly contoured nuclear membranes with oval indentations and, occasionally, cytoplasmic invagination. Some of them constituted unusual conformational changes of nuclear membranes rarely described as intranuclear pockets. Desmosome-like intercellular junctions were observed in several neoplastic cells. Nucleoli were composed of a loose, fragmented nucleolonema whereas elongated, anastomosing and rope-like nucleolonemas, described previously as characteristic for germinomas were not seen. Typically, the cytoplasm contained glycogen particles. Most tumour cells had villous cytoplasmic projections sometimes intermingled with similar projections of macrophages. Scattered astrocytes typically containing abundant glial filaments were adjacent to primary tumour cells.

Desmoplastic cerebral astrocytoma of infancy: a case report.

We report a case of desmoplastic cerebral astrocytoma of infancy (DCAI), in a 7-month-old boy. DCAI belongs to a group of recently described central nervous system (CNS) tumors, which also includes desmoplastic infantile ganglioglioma (DIG), pleomorphic xanthoastrocytoma (PXA) and dysembryoplastic neuroepithelial tumor (DNT), all characterized by relatively favorable prognosis and occurring mostly in children and young adults. DCAI is a rare neoplasm arising in the cerebral hemispheres within the first two years of life, and histologically is characterized by dense fibrous desmoplasia. In our case, CT scan presents a massive partially cystic tumor of the left cerebral hemisphere with an enlargement of the ventricular system. Histologically, the tumor was composed of cells arranged in fascicles and whorls forming storiform pattern. Immunohistochemical stainings for glial fibrillary acidic protein proved glial histogenesis of this tumor, while no cells were unequivocally immunopositive for neuron specific enolase, neurofilament proteins and synaptophysin what excludes a diagnosis of DIG--a similar entity but containing also a neuronal elements. Our studies, comprising a complete clinical, radiological, histopathological and immunohistochemical data, correspond to a cases of DCAI published before and it is the first one described in Poland.

Ultrastructural study of subependymal giant cell astrocytoma: unusual paracrystalloid inclusions in tumour cells.

Subependymal giant cell astrocytoma (SEGA) is a tumour with a broad range of morphological, immunohistochemical and ultrastructural neoplastic cellular features. We report here the presence of this tumor in two 7-year-old-boys presented with a lateral intraventricular mass. Further clinical investigation confirmed the diagnosis of tuberous sclerosis. Ultrastructural and immunohistochemical investigation revealed that glial differentiation was more pronounced in these cases. Interestingly, tumour cells containing unusual paracrystalline inclusions, infrequently described in SEGA, were identified ultrastructurally. These inclusions are probably not related to other cellular organelles.

Analysis of 200 consecutive neuropathologically verified brain tumors of childhood.

Brain tumors are the most frequent solid neoplasms of childhood. We present here a series of 200 consecutive cases of neuropathologically verified brain tumors in children under 18, operated on between 1990-1996 at the Polish Mother Memorial Hospital in Lódz. The respective diagnoses were established on the basis of light microscopy, ultrastructure and immunohistochemistry. The criteria of the World Health Organization (WHO) classification of central nervous system (CNS) tumors were used in all but one (superficial desmoplastic cerebral astrocytoma of infancy) case. The location of tumors, age and sex of children and tumors' histology in our material were compared with those of previously published series of pediatric brain tumors.

Clinical, radiological and histological presentations of dysembryoplastic neuroepithelial tumors (DNT). Report of two cases.

Dysembryoplastic neuroepithelial tumor (DNT) is a recently described rare brain neoplasm with characteristic clinical and morphological features and favorable prognosis. We report here two cases of DNT. The first concerned a 12 years old girl who presented complex seizures preceded by acoustic aura (melodies). Computed tomography revealed a hypodense tumor measuring 2 x 2.5 cm in diameter, located paracortically in the left temporal lobe. The second tumor was removed from a 21-year-old man with partial complex seizures. Nine years earlier patient underwent neurosurgery with partial removal of the tumor The tumor's histopathologic diagnosis is unfortunately lacking. Computed and magnetic resonance imaging showed a mass occupying the cortex and paracortical areas of the anterior pole of the temporal lobe. Histologically, both tumors consisted of small, S-100 protein immunopositive oligodendrocyte-like cells (OLCs) arranged between synaptophysin- and, to a lesser degree, NFP-immunopositive axons (glioneuronal element). In the second case, an area of pilocytic astrocytoma-like appearance was also found, these cells were immunopositive for GFAP. The present study provides clinical, radiological and histological data, which may be helpful in differential diagnosis of this newly recognised brain tumor.

Primitive neuroectodermal tumors: ultrastructural and immunohistochemical studies.

We report here ultrastructural and immunohistochemical studies of neuroblastic differentiation in the retrospective (n = 17) and prospective (n = 26) series of primitive neuroectodermal tumors (PNETs). By electron microscopy, neuritelike structures containing parallel-oriented microtubules, adhesive plaque junctions, and pleomorphic dense-core vesicles were found in the majority of tumor specimens while synaptic specializations were very rare. By immunohistochemistry, synaptophysin appeared to be the most reliable marker for neuroblastic differentiation present in the most reliable marker for neuroblastic differentiation present in the majority of tumors, while 200 kDa neurofilament protein was immunovisualized in a lower proportion of tumors. Glial fibrillary acidic protein (GFAP) was expressed in both reactive astrocytes and in a small proportion of otherwise typical neoplastic cells. We conclude that the majority of PNETs revealed diverse differentiation and that electron microscopy is still the most reliable tool for its detection followed by immunohistochemistry for synaptophysin.

Expression of synaptophysin and neurofilament protein confirms predominantly neuroblastic differentiation of primitive neuroectodermal tumors (PNET).

We report here that neuronal and glial differentiation is easily detected using synaptophysin (SF) and neurofilament protein (NFP) immunohistochemistry in primitive neuroectodermal tumors (PNET). Thus, for all practical reasons, every PNET should be regarded as PNET with "hidden" multipotential or bipotential differentiation.

[Operative treatment of deep arteriovenous malformations]. / Leczenie operacyjne glebokich znieksztalcen tetniczo-zylnych mózgu.

The authors present 12 patients operated upon for arteriovenous malformations located in deep structures of brain. In terms of the location, clinical course and neurological status there were three distinct groups of patients. The results of the operative treatment lead to the conclusion that the operative treatment risk is no greater than in cases of superficial AVMs, in which it is generally accepted.

Ultrastructure of the primitive neuroectodermal tumors (PNET).

We report a prospective series of consecutive cases of primitive neuroectodermal tumor (PNET) studied by electron microscopy. Virtually all specimens showed a differentiation along neuroblastic lines as evidenced by the presence of neurites, dense-cored vesicles, microtubules and adhesive plaque junctions. We observed also numerous intracytoplasmic cilia and autophagic vacuoles. Synaptic specializations were only rarely seen. We conclude that PNET is a tumor category which is not undifferentiated ("primitive") and clearly exhibits features of neuroblastic differentiation.