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Primary cerebral neuroectodermal tumors: neuroblastoma, differentiated neuroblastoma, and composite neuroectodermal tumor.

Seven cases of primary cerebral neuroectodermal tumors with predominant neuroblastic features were studied ultrastructurally and five were evaluated immunohistochemically. The fine structural features were indicative of neuroblastic differentiation by the presence of elongated cytoplasmic processes, electron-dense neurosecretory granules, and neurotubules. Five of the seven cases had the morphologic findings of classic cerebral neuroblastoma, and the sixth case, originally diagnosed as an oligodendroglioma, had the features of a differentiated neuroblastoma. Desmoplastic and/or stromal foci were intermingled with neuronal-ganglionic cells and neuroblasts in the seventh case. In addition to strong immunoreactivity for S-100 protein and glial fibrillary acidic protein in the desmoplastic areas, the spindle cells had fibroblastic and Schwannian features by electron microscopy in the latter case. The neuroblastic cells and fibrillary network were immunoreactive for neuron-specific enolase and neurofilament in the five study cases. It is concluded that cerebral neuroectodermal tumors may express an range of phenotypic features from the exclusive neuroblastic stage to a neuronal and stromogenic phase analogous to the classic neuroblastoma of the sympathetic nervous system.

Adult

Multiple primitive neuroectodermal tumors.

Primitive neuroectodermal tumors are rare, highly aggressive neoplasms that affect both sexes and occur in all age groups. They are a large group of neoplasms with neuroepithelial differentiation, including cutaneous neuroblastomas. Histopathologically they are characterized by a rather uniform population of small, dark cells, with or without Homer Wright rosettes. Immunohistochemically they stain for one or more of the reputed neural markers. Ultrastructurally they show interdigitating processes containing neurosecretory granules, intermediate filaments, and microtubules. We describe a patient with unusual multiple peripheral neuroectodermal tumors localized to the skin, with benign biologic behavior. The patient related the appearance of new lesions for several years without evidence of visceral dissemination or systemic complications. The histopathologic, immunohistochemical, and ultrastructural findings support the diagnosis of a peripheral neuroectodermal tumor.

Diagnosis, Differential

In vivo metabolism of childhood posterior fossa tumors and primitive neuroectodermal tumors before and after treatment.

BACKGROUND: Despite an increasing interest in the clinical application of positron emission tomography (PET) in tumors of the adult patient as a diagnostic and prognostic tool, only a few studies have been concerned with the usefulness of PET with [18F]2-deoxy-2-fluoro-D-glucose (FDG) in childhood tumors. METHODS: Fifteen children and young adults (0.5-26.0 years of age) with histologically confirmed brain tumors were studied with PET and FDG. Seven children with medulloblastoma (n = 5) or primitive neuroectodermal tumor (PNET) (n = 2) underwent repeated PET studies during their therapy. The other eight children with medulloblastoma (n = 5) or astrocytoma (n = 3) were studied only once before initiation of treatment. A close clinical follow-up was performed in every case. RESULTS: Comparison of local glucose metabolic rates obtained in the various tumor lesions revealed that the mean rates found in medulloblastomas (mean glucose metabolic rate, 42.8 +/- 14.03 mumol/100 g/min) were twice as high as the rates measured in either PNET (17.3 +/- 4.5 mumol/100g/min) or infratentorial gliomas (21.8 +/- 4.2 mumol/100g/min). The high metabolism of medulloblastomas enabled the observer to identify the tumor more easily and to clearly separate it from the surrounding unaffected brain tissue. In the seven patients with follow-up PET studies during therapy, decreasing or increasing ratios of tumor-to-white matter metabolic rate were not only commensurate with neuroradiologically defined tumor reduction or growth, but also corresponded to the duration of initial clinical improvement. CONCLUSIONS: These preliminary results suggest that PET with FDG may be a useful tool to evaluate metabolic activity of pediatric brain tumors over time and to assess response to treatment.

Adolescent

Expression of N-myc, c-myc and c-erbB-1 proto-oncogenes in cerebral primitive neuroectodermal tumors (PNET).

Neuroectodermal tumors demonstrate a relatively high incidence of proto-oncogenes amplification. This study attempted to determine the frequency of overexpression of three genes: N-myc, c-myc and c-erbB-1, in human PNET. Immunohistochemical studies revealed 5 to 74% neoplastic cells with positive immunoreactivity to anti-c-myc antibody in all investigated samples. In 3 cases the reactivity was particularly strong and present in more than 50% of tumor cells. Northern blot analysis revealed normal (2.3-kb in size) but significantly higher level of c-myc transcripts in these cases. By using anti-EGFR antibody 3 tumors disclosed 10 to 65% neoplastic cells with positive immunoreactivity. There was no rearrangement detected of their c-erbB-1 or N-myc genes by means of applied methods. Our results suggest that overexpression of c-myc gene is present in 10% of PNET but it is not the consequence of gene amplification. Amplification of N-myc and c-erbB-1 are rare events during PNET development.

Brain Neoplasms

Ewing's sarcoma and primitive neuroectodermal tumor in adults: are they different from Ewing's sarcoma and primitive neuroectodermal tumor in children?

PURPOSE: To determine whether age at diagnosis influences the behavior of Ewing's sarcoma and primitive neuroectodermal tumor (PNET). PATIENTS AND METHODS: We reviewed the clinical features, treatment, and outcome of 59 consecutive patients with Ewing's sarcoma and PNET treated on the Adult Sarcoma Unit at our institution from 1980 to 1995. RESULTS: The 37 male and 22 female patients had a median age of 24 years. Lower limb was the most common primary tumor site. Fifteen patients had nonmetastatic tumor less than 100-mL volume, 27 had nonmetastatic disease greater than 100-mL volume, and 17 had evidence of metastatic disease at presentation. The origin of the primary tumor was soft tissue in 28 cases, bone in 30, and uncertain in one. The Kaplan-Meier estimate of 5-year overall survival (OS) in all patients was 38% and of progression-free survival (PFS), 27%. When patients with metastatic disease at presentation were excluded, these figures increased to 52% and 34%, respectively. Bulk of disease at presentation and response to primary treatment were statistically highly significant predictors of both PFS and OS. Age and tissue of origin of the tumor did not influence outcome. CONCLUSION: The behavior of Ewing's sarcoma and PNET in adults is no different from its behavior in children. We feel the way forward in the treatment of adults with Ewing's sarcoma and PNET is for them to be included in the current multicenter trials of multidisciplinary treatment directed at children.

Adolescent

MR findings on primitive neuroectodermal tumors.

Primitive neuroectodermal tumors (PNETs) are highly cellular primitive CNS neoplasms that resemble microscopically the undifferentiated cells of the germinal matrix of the primitive neural tube. These tumors exhibit a highly malignant behavior with a tendency to disseminate along the CSF pathways. Previous descriptions of the neuroradiological findings in patients with PNET were published prior to the clinical application of magnetic resonance (MR) imaging. We describe our experience with the MR evaluation of four patients with pathologically proven PNET.

Brain

Absence of p53 mutations in childhood central nervous system primitive neuroectodermal tumors.

The primitive neuroectodermal tumor of the central nervous system is one of a number of tumors in which deletions on chromosome 17p have been identified. The tumor suppressor gene, p53, is located in the region of the deletion. To determine if the p53 gene is involved in the development of primitive neuroectodermal tumors, deoxyribonucleic acid (DNA) blot analysis, ribonucleic acid blot analysis, and p53 complementary DNA sequencing were performed on 34 primitive neuroectodermal tumors removed from children. No rearrangement in the gene was detected in 21 tumors. The p53 messenger ribonucleic acid was of the expected size in all 18 tumors for which ribonucleic acid was available. Sequencing of p53 Exons 5 through 9 revealed a mutation in the cell line DAOY and in only 1 of 14 tumors examined. A DNA rearrangement was detected in the DNA from one tumor with a probe mapping to the distal portion of 17p. Taken together, these data suggest that the p53 gene is not involved in the development of most primitive neuroectodermal tumors. In addition, a gene of interest may be present on distal 17p.

Adolescent

Parental occupation and childhood brain tumors: astroglial and primitive neuroectodermal tumors.

Data from a population-based case-control study in 19 counties in California and Washington State were used to investigate the association between parental employment and childhood brain tumors. Parents of 540 cases (including 308 astroglial and 109 primitive neuroectodermal tumors) and 801 controls diagnosed from 1984 to 1991 were interviewed. Analysis was completed for parents' self-reported industry of employment and job tasks during the five years preceding the birth of the child. Parents who worked in the chemical industry were at increased risk of having had children with astroglial tumors (fathers' odds ratio [OR] = 2.1; 95% confidence interval [CI], 1.1-3.9); mothers' OR = 3.3; 95% CI, 1.4-7.7), but no trend by duration of employment was seen for mothers. Children of fathers employed as electrical workers were at increased risk of developing brain tumors of any histologic type (OR = 2.3; 95% CI, 1.3-4.0).

Astrocytoma

Primitive neuroectodermal tumors of bone and soft tissue: histological subclassification and clinicopathologic correlations.

Recent reports of Ewing's sarcoma (EW) and extraskeletal Ewing's sarcoma (EEW) support the hypothesis that these tumors are neuroectodermal in origin. Primitive neuroectodermal tumors (PNET) of bone (32 cases) and soft tissue (25 cases) including those previously categorized as EW in 27 cases and EEW in 15 cases were carefully studied histologically, immunocytochemically and morphometrically, focusing on tumor cell differentiation. This study attempts to subclassify these tumors on the basis of the size of tumor cells and nuclei, their variations (uniformity or diversity), arrangement of tumor cells (rosette or non-rosette), focal differentiation to larger ganglion-like cells, and staining intensity for neural markers. All tumors were histologically subclassified as small, medium or large cell types, three basic subtypes (rosette type, abortive rosette type, non-rosette type) and four complementary subtypes (fibrillary type, non-fibrillary type, angiomatoid type, ganglion cell type). Classic EW or EEW is consistent with small or medium, non-rosette, non-fibrillary type tumors, previously described large cell EW with large, non-rosette, fibrillary or non-fibrillary type tumors, and classic neuroectodermal tumor with small or medium, rosette, fibrillary type tumors, according to the present subclassification. Clinicopathologic correlations with the different subtypes are discussed. Long-term survival, more than 5 years, was seen in patients with small cell type, and those younger than 14 years of age.

Adolescent

MIC2 is a specific marker for Ewing's sarcoma and peripheral primitive neuroectodermal tumors. Evidence for a common histogenesis of Ewing's sarcoma and peripheral primitive neuroectodermal tumors from MIC2 expression and specific chromosome aberration.

This study reports on the specific expression of the MIC2 gene, a pseudoautosomal gene located on the short arms of the X and Y chromosomes, on Ewing's sarcoma (ES) and peripheral primitive neuroectodermal tumor (pPNET) cells. The gene product, a cell membrane protein, is recognized by the newly established monoclonal antibody (MoAb) HBA-71 and the previously described MoAb 12E7 and RFB-1. Furthermore, the reaction pattern of the MIC2 antibodies, especially HBA-71, with normal tissues and a great number of benign and malignant tumors (70 different tumors, 199 tumor samples), as well as the correlation between the specific chromosomal aberrations, i.e., the t(11;22) and the del(22) and the expression of this antigen, are demonstrated. Both ES and pPNET cells express the MIC2 gene in very high amounts, which represents a highly selective and almost unique feature of these cells, making an assignment of these tumors in one entity even more likely. The MIC2 antibodies are of great value for clinical and research purposes.

12E7 Antigen

Evidence for a 17p tumor related locus distinct from p53 in pediatric primitive neuroectodermal tumors.

Primitive neuroectodermal tumors of the central nervous system are the most common malignant brain tumors in children. Cytogenetic analysis of these tumors has demonstrated alterations of chromosome 17, in particular isochromosome 17q, as the most frequent chromosomal abnormality detected. Since the consistent loss of a specific chromosomal region in a given tumor type most likely indicates the presence of a tumor related gene in that region, we undertook a combined molecular and cytogenetic approach to examine alterations of chromosome 17 in primitive neuroectodermal tumors. Seven of 14 tumors analyzed demonstrated loss of alleles for loci on 17p. In three of the seven tumors tested, a loss in copy number was observed for only the most telomeric locus on 17p13.3, D17S34. Limited sequence analysis of the same seven tumors did not reveal mutations in four highly conserved coding regions of the p53 gene. These data suggest a new tumor associated locus on 17p distinct from and distal to TP53, which is involved in the initiation or progression of at least a subset of primitive neuroectodermal tumors.

Amino Acid Sequence

The Ewing tumor family of peripheral primitive neuroectodermal tumors expresses human gastrin-releasing peptide.

The Ewing tumor family of peripheral primitive neuroectodermal tumors (pPNETs) are characterized by chromosomal translocations leading to EWS-ETS gene fusions. These hybrid genes express chimeric proteins that are thought to act as aberrant transcription factors. We therefore used differential display-PCR to compare gene expression patterns in pPNET cell lines with those of other small round cell tumors (SRCTs) of childhood. This technique detected differential expression of sequences corresponding to human gastrin-releasing peptide (GRP) in pPNET cell lines but not in other SRCT cell lines. Subsequent Northern and reverse transcription-PCR analysis of SRCT cell lines confirmed GRP positivity in all pPNET lines tested. Of primary tumors tested by reverse transcription-PCR, GRP expression was found in 7 (44%) of 16 pPNETs but in no other primary SRCTs examined. Expression of the GRP receptor gene was demonstrable in 55% of pPNET cell lines and 25% of primary pPNET tumors but also in several other SRCTs. Radioimmunoassays and immunohistochemistry confirmed expression of bioactive GRP peptide in pPNET cell lines and primary tumors, respectively. Moreover, in vitro growth of a pPNET cell line was slowed by treatment with a GRP receptor antagonist and accelerated by a GRP receptor agonist. GRP is a known autocrine growth factor in small cell lung cancer and other neuroendocrine tumors. Its expression in pPNETs provides further evidence for a neuroectodermal histogenesis of these tumors and suggests that autocrine growth of this family of tumors may be at least partially regulated by GRP.

Artificial Gene Fusion

Melanotic neuroectodermal tumor of infancy: a molecular genetic study.

Melanotic neuroectodermal tumor of infancy is a rare but well-recognized entity in pediatric pathology. However, the relationship of this tumor to other pediatric small cell tumors with neuroectodermal features (such as neuroblastoma, Ewing sarcoma/peripheral primitive neuroectodermal tumor, and desmoplastic small round cell tumor) is undetermined. Molecular genetic studies of melanotic neuroectodermal tumor of infancy have not been reported. We studied three typical cases of melanotic neuroectodermal tumor of infancy in an attempt to link this tumor to other small cell tumors with well-characterized molecular genetic changes. Tests performed included: detection of MYCN gene amplification and deletion of 1p (all 3 cases), and presence of the t(11;22)(q24;q12) and the t(11;22)(p13;q12) translocations (2 of 3 cases). None of these tests yielded positive results. Thus, there is no genetic basis at present to link melanotic neuroectodermal tumor of infancy to neuroblastoma, Ewing sarcoma/peripheral primitive neuroectodermal tumor, or desmoplastic small round cell tumor.

Female

Molecular markers of primitive neuroectodermal tumors and other pediatric central nervous system tumors. Monoclonal antibodies to neuronal and glial antigens distinguish subsets of primitive neuroectodermal tumors.

Seventy-one tumors of the central nervous system in children were studied immunohistologically. Thirty-seven were classified histologically as PNETs, of which 35 were located in the cerebellum (medulloblastomas), one in the cerebrum, and one in the spinal cord. The 34 non-PNETs included five ependymomas, seven gangliogliomas, 15 astrocytomas, and seven tumors of other histology. We used monoclonal antibodies specific for neurofilament (NF) triplet proteins, for microtubule associated protein 2 and tau protein and for glial fibrillary acidic protein (GFAP) and myelin basic protein. In addition, a monoclonal antibody to epithelial membrane antigen was applied. The presence or absence of these antigens defined four major groups of PNETs: 1) PNETs not otherwise specified (10 cases), 2) PNETs with neuronal differentiation (eight cases), 3) PNETs with astrocytic differentiation (six cases), and 4) PNETs with both neuronal and astrocytic differentiation (12 cases). One case showed ependymal differentiation. The pattern of expression of NF isoforms in PNETs was reminiscent of that seen during normal mammalian development, such that phosphorylated NF-H was only present in combination with NF-M and NF-L. Among the other central nervous system tumors, all astrocytomas and gangliogliomas were positive for GFAP, and the gangliogliomas also expressed all NF isoforms. Three atypical teratoid tumors and two rhabdoid tumors showed strong positivity for epithelial membrane antigen and also for GFAP. We conclude that the differentiation antigens described here serve to distinguish PNETs from other pediatric central nervous system tumors and to identify subsets of PNETs. Accordingly, PNETs represent a heterogeneous group of pediatric brain tumors capable of neuronal and glial differentiation.

Adolescent

[A case of primitive neuroectodermal tumor in the chest wall ("Askin's tumor")].

We report a case of Askin's tumor, primitive neuroectodermal tumor (PNET) in the chest wall, with review of reported cases of PNET. Our case was the ninth of Askin's tumor and the 36th of PNET in Japan. A 12-year-old girl was hospitalized because of a large right intrathoracic mass. The serum neuron-specific enolase (NSE) was 11.4 ng/ml, slightly increased, and the urinary excretion of catecholamine metabolites was normal. The needle biopsy specimens were diagnosed as small round cell sarcoma. At surgery we found an encapsulated multilobular mass in the region. The chest wall was resected partially to extirpate it completely. Its macroscopic and microscopic features were almost similar to the description of Askin et al. The immunohistochemical staining of the cells was positive for NSE, strongly suggesting the neurogenic origin. After surgery, intensive chemotherapy with autologous bone marrow transplant was performed, and she has been living without sign of recurrence for two years.

Child