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PubMed1997

Chromosome arm 17p deletion analysis reveals molecular genetic heterogeneity in supratentorial and infratentorial primitive neuroectodermal tumors of the central nervous system.

The current World Health Organization (WHO) classification groups together both infratentorial neoplasms (medulloblastomas) and their supratentorial counterparts as primitive neuroectodermal tumors (PNETs), implying a common origin. Previous analyses of medulloblastoma have shown loss of chromosome arm 17p as the most frequent genetic abnormality: the molecular genetic constitution of supratentorial PNETS has not been systematically studied. We therefore examined 8 hemispheric PNETs and 35 medulloblastomas with 17p restriction fragment length polymorphism (RFLP) and microsatellite markers. We also examined the TP53 tumor suppressor gene by a combined polymerase chain reaction-denaturing gradient gel (PCR-DGGE) technique. Our results showed that all of the 17p markers tested were preserved in all of the supratentorial PNET specimens. In contrast, loss of distal chromosome arm 17p was detected in 37% of the medulloblastomas. Analysis of the TP53 gene showed 2 mutations in the medulloblastomas and no mutations in the supratentorial tumors. These results show that the most common molecular genetic abnormality in infratentorial PNETS is absent in their supratentorial counterparts and suggests that alternative pathways and genetic events may be involved in their etiology.

Adolescent↗
PubMedDate not supplied

Primitive neuroectodermal tumors of the cerebrum: a histological and immunohistochemical study of 10 cases.

Four males and 6 females, 5-66 (mean 27) years, with supratentorial primitive neuroectodermal tumors (PNETs) have been treated in one center in a 5-year period. Symptoms and signs had been present from 4 days to 8 years and were highly variable. The frontal hemisphere was involved in 6 cases. Seven patients have died but with a combination of surgery and radiotherapy 3 patients have survived 20 months or longer. All tumors were composed of rounded, hyperchromatic undifferentiated cells but there were focal areas of astrocytic (5 cases), mesenchymal (4 cases) or neuronal differentiation (1 case). In 9 of the 10 cases a proportion of the undifferentiated round cells stained with antibodies to GFAP. Seven of these also showed nuclear staining for S100 protein and 6 of these, plus the tumor that did not stain for GFAP, had cytoplasmic staining for neuron specific enolase. Six tumors stained with antibodies to vimentin but there was no staining for common leukocyte antibody, cytokeratin or myoglobin. These results, in particular those with GFAP, indicate that PNETs undergo differentiation even in areas of apparent morphological uniformity. Furthermore, immunohistochemistry is useful in distinguishing PNETs from other "small blue cell tumors" such as malignant lymphoma and undifferentiated secondary carcinoma.

Adolescent↗
PubMed1989

Primitive neuroectodermal tumor of the brain associated with malignant rhabdoid tumor of the liver: a histologic, immunohistochemical, and electron microscopic study.

A 14-day-old white male, born with a large primitive neuroectodermal tumor of the left cerebral hemisphere, was found to have a solitary rhabdoid tumor in the liver incidentally at autopsy. Cells resembling the liver rhabdoid cells were also found by histology, immunohistochemistry, and electron microscopy in the brain tumor. The concurrence of rhabdoid cells in the tumors of the brain and liver suggests a common histogenesis and further supports the previous suggestion that the rhabdoid tumor is of neuroectodermal origin. The rhabdoid tumor in the liver in this case is likely to be a metastatic tumor from the brain rather than a second primary tumor.

Brain Neoplasms↗
PubMed1979

Electron microscopic findings in primitive neuroectodermal tumors of the cerebrum.

The fine structure of 3 primitive neuroectodermal neoplasms of the cerebral hemispheres was studied. The predominant tumor cells were undifferentiated cells with prominent nuclei and scanty cytoplasm containing few organelles. Ultrastructural evidence suggesting differentiation into ependymal, neuronal and possibly astrocytic elements was also present. This study suggests that the cell of origin of this tumor is a primitive multipotential cell of the cerebrum.

Adolescent↗
PubMed2000

Lovastatin induces apoptosis in a primitive neuroectodermal tumor cell line in association with RB down-regulation and loss of the G1 checkpoint.

To develop a new approach to the treatment of primitive neuroectodermal tumors we evaluated the effect of the HMG-CoA reductase inhibitor lovastatin on the Ewing's sarcoma cell line CHP-100. Lovastatin induced neural morphology and markers including neuron-specific enolase and neurofilament protein. The acquisition of neural morphology required new mRNA synthesis, and cDNA microarray analysis confirmed that lovastatin altered the program of gene expression. After morphologic differentiation the cells underwent rapidly progressive apoptosis. In normal development of neuronal progenitors, differentiation signals trigger p21WAF1 accumulation, RB hypophosphorylation, enhanced RB-E2F-1 association, and G1 arrest, and these events have been shown to protect from apoptosis. In contrast, in the Ewing's sarcoma cells lovastatin triggered differentiation without causing cell cycle arrest: p21WAF1 was not induced, RB remained hyperphosphorylated, and RB protein expression and RB-E2F-1 association were markedly downregulated, suggesting that loss of an RB-regulated G1 checkpoint promoted apoptosis. Consistent with this hypothesis, adenoviral p21WAF1 decreased DNA synthesis and partially protected from lovastatin-induced cytotoxicity. The data demonstrate a new model for examining the genetic regulation of cell fate in a neural progenitor tumor and suggest a new approach to the treatment of this neoplasm.

Apoptosis↗
PubMed1998

Diffuse cerebral vasospasm with ischemia after resection of a cerebellopontine angle primitive neuroectodermal tumor in a child.

This case report describes a 15-month-old female who developed diffuse cerebral vasospasm after resection of a cerebellopontine angle primitive neuroectodermal tumor. The patient developed an acute dense left hemiparesis 16 days postoperatively with partial right ptosis. Initial magnetic resonance imaging and diffusion study were unremarkable, though a magnetic resonance angiography 1 day later demonstrated severe intracranial vasospasm of both carotid and vertebral arteries. The vasospasm was confirmed with cerebral angiography. The patient progressed to bihemispheric infarcts with laminar necrosis despite combination therapy with anticoagulation, pharmacological hypertension, hypervolemia, and nimodipine. The clinical course, radiographic, and pathological findings are presented.

Brain Ischemia↗
PubMed1990

Primitive neuroectodermal tumors of the central nervous system. Patterns of expression of neuroendocrine markers, and all classes of intermediate filament proteins.

Snap-frozen samples from 22 primitive neuroectodermal tumors (PNETs) primary in the central nervous system were studied with antibodies to synaptophysin, bombesin, somatostatin, substance P, vasoactive intestinal polypeptide, all classes of intermediate filaments, and desmoplakins I and II. Frozen sections were immunostained by the avidin-biotin peroxidase complex and indirect immunofluorescence microscopy methods. Selected cases were also studied by double and triple label immunofluorescence microscopy, and by two-dimensional gel electrophoresis and immunoblot analysis. We found that all 22 PNETs expressed synaptophysin extensively. Focal expression of 2 or more neuropeptides was noted in 10 samples studied. All PNETs expressed vimentin, 21 of 22 expressed glial filament protein (GFP), 16 of 22 expressed neurofilament proteins (NFP), 4 of 22 expressed desmin, and 3 of 22 expressed cytokeratins. In only one case were focal and questionable reactions with desmoplakin antibodies seen. Immunoblots confirmed the presence of desmin. Double and triple immunofluorescence revealed a number of antigenic coexpressions in individual cells including: synaptophysin with vimentin, GFP, NFP and desmin, vimentin-GFP, vimentin-NFP, vimentin-cytokeratin, vimentin-desmin and desmin-NFP; similarly, combinations of vimentin-GFP-NFP, vimentin-GFP-desmin, and vimentin-GFP-cytokeratin were found. The consistent expression of synaptophysin and 2 or more neuropeptides indicates that central nervous system PNETs have significant phenotypic features in common with neuroendocrine tumors. Their complex and variable intermediate filament complement patterns combined with their consistent expression of specific neuroendocrine differentiation markers, suggest that central nervous system PNETs comprise a distinct, albeit heterogeneous group of neoplasms.

Adolescent↗
PubMed1993

Primitive neuroectodermal tumor and Ewing's sarcoma.

Many of the major solid, malignant tumors of childhood have histologic similarities that reflect their dysembryonic and primitive features. One subset of these neoplasms, Ewing's sarcoma (ES) and primitive neuroectodermal tumor (PNET), presents primarily in the bone and soft tissues. Both tumor types were reported at a time and date well before the advent of electron microscopy and immunohistochemistry. Opposition to ES and PNET as distinctive entities developed and persisted because these tumors were considered incompletely documented examples of metastatic neuroblastoma or malignant lymphoma. General acceptance of ES as a unique tumor type occurred well before the PNET had been fully defined and characterized. Once these neoplasms had joined the other round cell neoplasms, the quest for the histogenesis was pursued, but the results were frustratingly inconclusive, especially for ES. Because of the resemblance of the PNET to classic neuroblastoma, the neural crest was regarded as the most likely progenitor. With the recognition of osseous PNET, extraosseous ES, and a shared cytogenetic abnormality between ES and PNET, more recent speculation has focused on the possibility that these presumably separate neoplasms are closely related histogenetically without directly answering the question of histogenesis. Despite the likely common progenitorship of ES and PNET, the latter neoplasm is seemingly the more aggressive. Although melanotic neuroectodermal tumor of infancy, intra-abdominal desmoplastic small cell tumor, and polyphenotypic small cell tumors have some overlapping microscopic and immunohistochemical features with PNET, their relationship to ES-PNET has otherwise not been resolved.

Bone Neoplasms↗
PubMedDate not supplied

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.

Adolescent↗
PubMed2002

Histopathological and immuno-histochemical characteristics of primary renal primitive neuroectodermal tumor.

We report a 32-year-old male who presented with huge (17 x 10.5 x 5 cm) right kidney with metastasis in the liver and retroperitoneal lymph nodes. Histological, detailed immunohistochemical studies and electron microscopic examinations were performed. Microscopy revealed small to intermediate sized cells with hyperchromatic nuclei, scanty cytoplasm, abundant mitosis with no pseudorossete formation. Immunohistochemical study revealed positive staining of the tumor cells for S100, neurofilaments, neuron specific enolase, vimentin and myoglobin. Primitive neuroectodermal tumors are rare malignant round cell tumors of the kidney. A correct diagnosis can be made on light microscopic features, and by immunohistochemically positive staining for more than one neural marker. This neoplasm should be differentiated from other renal neoplasms composed of small round cells.

Adult↗
PubMed1995

Survival and prognostic factors following radiation and/or chemotherapy for primitive neuroectodermal tumors of the pineal region in infants and children: a report of the Childrens Cancer Group.

PURPOSE: To describe the biologic and clinical features of children with primitive neuroectodermal tumors (PNETs) arising in the pineal region (pineoblastomas) and evaluate prospectively the efficacy of radiation therapy (RT) and/or chemotherapy. PATIENTS AND METHODS: Between 1986 and 1992, 25 children with PNETs of the pineal region were treated as part of a Childrens Cancer Group study. Eight infants less than 18 months of age were nonrandomly treated with eight-drugs-in-1-day chemotherapy without RT. The remaining 17 patients were treated with craniospinal RT and randomized to receive either vincristine, lomustine (CCNU), and prednisone or the eight-drugs-in-1-day regimen. RESULTS: Of 24 completely staged patients, 20 (83%) had localized disease at diagnosis. All infants developed progressive disease a median of 4 months from the start of treatment. Of the 17 older patients treated with RT and chemotherapy, the Kaplan-Meier estimate of progression-free survival (PFS) at 3 years is 61% +/- 13%. This is superior to the PFS of children with other supratentorial PNETs (P = .026). Following RT, 12 of 17 patients (70.6%) had a residual pineal region mass, which persisted for as long as 5 years before resolving; only four subsequently developed progressive disease. CONCLUSION: (1) Eight-in-1 chemotherapy without RT appears to be ineffective therapy for young children with PNETs of the pineal region. (2) For children more than 18 months of age at diagnosis treated with craniospinal RT and chemotherapy, the PFS is superior to that of children with other supratentorial PNETs. (3) A residual enhancing mass following RT is not predictive of treatment failure.

Adolescent↗
PubMed2000

The primitive neuroectodermal tumor of the heart.

A young man was admitted to hospital with dyspnea, malaise, chest pain and night sweating. Investigative studies revealed a cystic mass lesion originating from the heart. Surgical exploration of the tumor showed that it was unresectable and pathology of the biopsy material was primitive neuroectodermal tumor. Medical literature concerning this unusual type of tumor is reviewed.

Adult↗
PubMed1999

Hyperfractionated craniospinal radiation therapy for primitive neuroectodermal tumors: results of a Phase II study.

PURPOSE: To report the results of a Phase II study of hyperfractionated craniospinal radiation therapy, with and without adjuvant chemotherapy for primitive neuroectodermal brain tumors (PNETs) and malignant ependymomas. METHODS AND MATERIALS: Newly diagnosed PNET or malignant ependymomas were treated with hyperfractionated craniospinal radiation therapy. The primary tumor site was treated to a dose of 72 Gy, with 30 Gy given to the rest of the craniospinal axis. The fraction size was 1.0 Gy, given twice a day. Patients with poor risk factors also received adjuvant chemotherapy with CCNU, cisplatin, and vincristine. Patients had follow-up for survival, time to tumor progression, and patterns of relapse. RESULTS: A total of 39 patients (21 males/18 females) were treated between March 12, 1990 and October 29, 1992. The median age was 16 years (range 3-59 years). Tumor types included 25 medulloblastomas, 5 pineoblastomas, 5 cerebral PNETs, 1 spinal cord PNET, and 3 malignant ependymomas. Twenty cases were staged as poor-risk and received adjuvant chemotherapy following radiation. Three-year progression-free survival (PFS) was 60% and 63% for poor-risk and good-risk patients, respectively. Overall 3-year survival for these groups was 70% and 79%, respectively. For the 25 patients with medulloblastoma, there were 16 good-risk and 9 poor-risk patients. Three-year PFSs were 63% and 56%, respectively. The 5-year survival for good-risk medulloblastoma was 69% with 43.7% of these patients having failures outside the primary site. CONCLUSIONS: Survival in patients with good-risk medulloblastoma was no better than that seen in previous studies with single-fraction radiation, and the rate of failure outside the primary site is excessive. Those with poor-risk features had comparable survival to that seen in patients with good risk factors, but these patients were treated with chemotherapy, and the role that hyperfractionated radiation played in their outcome is uncertain.

Adolescent↗
PubMed1988

In vitro cytolysis of primitive neuroectodermal tumors of the posterior fossa (medulloblastoma) by lymphokine-activated killer cells.

Short-term stimulation of nonantigen-primed peripheral blood mononuclear leukocytes with interleukin-2 generates a population of oncolytic effectors designated "lymphokine-activated killer" (LAK) cells. These LAK cells express potent lytic activity against a wide spectrum of fresh or cultured autochthonous (patient's own) and allogeneic (unrelated) tumors, yet specifically spare normal tissues. In this study, cells derived from primitive neuroectodermal tumors of the posterior fossa (PNET-PF) were examined for their sensitivity to LAK cytolysis utilizing an in vitro 4-hour chromium-51-release assay. Five early-passage cell lines, derived from primary PNET-PF, demonstrated significant sensitivity to LAK cell cytolysis. Lysis was equally effective in culture medium and cerebrospinal fluid. Three freshly excised PNET-PF exhibited similar susceptibility to lysis by autochthonous LAK cells. Greatly increased expansion of LAK cell cultures could be achieved by short-term stimulation with monoclonal anti-CD3 antibodies in addition to interleukin-2 activation. These findings constitute the preliminary in vitro foundations for potential intrathecal adoptive immunotherapy of PNET-PF with LAK cells.

Adult↗
PubMed1999

Successful removal of a primitive neuroectodermal tumor in the lung with gross extension into the left atrium.

We report here the successful multi-model treatment of a 31-year-old female demonstrating a primitive neuroectodermal tumor originating in the lower lobe of the right lung with gross extension into the left atrium via the inferior pulmonary vein. The tumor was markedly reduced by combination chemotherapy consisting of vincristine, doxorubicin, cyclophosphamide, and ifosfamide. The residual tumor was completely removed through a combined left atrial resection and right middle and lower lobectomy, using a percutaneous cardiopulmonary support system.

Adult↗
PubMed1987

Pigmented primitive neuroectodermal tumor with multipotential differentiation in cerebellum (pigmented medullomyoblastoma). A case with light- and electron-microscopic, and immunohistochemical analysis.

A 5-year-old girl had a midline cerebellar primitive neuroectodermal tumor (PNET) with neuronal, astrocytic, rhabdomyoblastic and melanocytic differentiation (a variant of pigmented medullomyoblastoma). The tumor recurred following surgery and radiation therapy and the child died within 6 months. Autopsy revealed spread into cerebellar hemispheres, subarachnoidal space and brain stem. Neuronal differentiation was verified by electron microscopy and antiserum against neurofilament protein. Neoplastic astrocytes were identified by use of antisera to glial fibrillary acidic and S-100 proteins. Rhabdomyoblasts were identified by the use of antisera against skeletal muscle type 2 myosin and myoglobin, as well as by electron microscopy. This tumor is compared with 20 previously reported cases of cerebellar PNETs containing muscle, 2 of which showed a similar pattern of multipotential differentiation. The oncogenesis of these tumors is in dispute although origin of both the neuroectodermal and mesenchymal components from the neural crest (mesectodermal differentiation) is most widely accepted.

Cerebellar Neoplasms↗
PubMed1997

High-resolution deletion mapping of chromosome arm 17p in childhood primitive neuroectodermal tumors reveals a common chromosomal disruption within the Smith-Magenis region, an unstable region in chromosome band 17p11.2.

Loss of heterozygosity (LOH) on chromosome arm 17p is the most common genetic aberration in childhood primitive neuroectodermal tumors (PNETs). To determine the frequency and extent of 17p deletions, 29 loci on 17p were investigated in 24 tumors by using restriction fragment length polymorphism (RFLP) and microsatellite analysis. LOH on 17p was found in 9 of 24 tumors. In all tumors with LOH, a continuous stretch from the telomere to chromosome band 17p11.2 was completely deleted, and no interstitial or terminal small-scale deletions were detected in the remaining 15 tumors. In four tumors with LOH on 17p, the chromosomal breakpoint was located between D17S953 and D17S805. To identify this deletion breakpoint on the cytogenetic map of chromosome 17 and to exclude uniparental disomy, we verified our data by using fluorescence in situ hybridization (FISH) analyses. By using two yeast artificial chromosome (YAC) clones that were positive for D17S689 and D17S953, the same breakpoint was confirmed in two specimens of cerebrospinal fluid (CSF) metastases by using FISH on interphase preparations. We demonstrate that, in most childhood PNETs with LOH on 17p, the breakpoint is close to, but not within, the centromere. It varies, and it occurs predominantly between the two markers D17S689 and D17S953, which is an unstable chromosomal region that is deleted or duplicated in the Smith-Magenis syndrome. Because LOH of 17p is associated with the formation of isochromosome 17q in the majority of PNETs, this study provides entry points to determine the molecular nature of this phenomenon.

Adolescent↗