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PubMed2001

A role for fluorescence in situ hybridization detection of chromosome 22q dosage in distinguishing atypical teratoid/rhabdoid tumors from medulloblastoma/central primitive neuroectodermal tumors.

It has been postulated that infants with medulloblastomas/central primitive neuroectodermal tumors (MB/PNET) may fare worse than older patients because some of them harbor unrecognized atypical teratoid/rhabdoid tumors (AT/RT), rare intracranial neoplasms that are typically unresponsive to therapy and rapidly fatal. Although small primitive cells are common to both entities, chromosome 22q11.2 deletions are common only in AT/RTs. Using fluorescence in situ hybridization (FISH) on archival, paraffin-embedded biopsy tissue with commercially available probes to 22q11.2, the region associated with RTs, we studied 8 cases of AT/RT, 12 cases of MB/PNET, and 4 cases of primitive central nervous system (CNS) neoplasms, which were difficult to classify. 22q Deletions were identified in 6 of 8 (75%) conventional AT/RTs and 0 of 12 (0%) children with classic MB/PNET. Of the 4 originally "difficult to classify" cases, 3 had deletions of 22q. In light of the FISH results, review of the morphology and immunophenotype resulted in 3 tumors being reclassified as AT/RTs and 1 as a large cell MB. These 4 cases highlight the potential diagnostic use of FISH for selected cases of primitive CNS malignancies in children and substantiate the notion that misdiagnosed AT/RTs may, in part account for the worse prognosis associated with "MB/PNET" in children younger than 2 years of age.

Adolescent↗
PubMed1994

Rhabdoid tumor of the kidney with primitive neuroectodermal tumor of the central nervous system: associated tumors with different histologic, cytogenetic, and molecular findings.

Rhabdoid tumor of the kidney (RTK) is associated with tumors of the central nervous system (CNS) in approximately 15% of cases. We describe the clinical features, histologic and cytogenetic findings, and molecular analysis of renal and CNS tumors from the same patient. The histology of the renal tumor was consistent with rhabdoid tumor. The CNS tumor was a primitive neuroectodermal tumor (PNET). The karyotype of the RTK was normal male. The PNET of the brain demonstrated monosomy 22 as the only cytogenetic abnormality, similar to reported cases of malignant rhabdoid tumor of the brain, but dissimilar to nonrandom cytogenetic findings in other CNS PNETs. Molecular cytogenetic and DNA marker studies confirmed loss of chromosome 22 in this patient's brain tumor. DNA allelotyping showed retention of both parental chromosome 22 alleles in the RTK and loss of the maternal allele in the PNET. Evaluation of additional RTKs and brain tumors occurring in the same patient may provide insight into the origins and relationships of these enigmatic tumors.

Brain Neoplasms↗
PubMed1999

Comparative genomic hybridization in patients with supratentorial and infratentorial primitive neuroectodermal tumors.

BACKGROUND: Intracranial primitive neuroectodermal tumors (PNETs) occur in the supratentorial and infratentorial regions of the brain. Although histologically similar, the natural history of the tumor at each site differs. The study goal was to determine whether there was evidence of a genetic difference between supratentorial and infratentorial PNETs. METHODS: Using comparative genomic hybridization (CGH), 53 PNETs were analyzed to determine copy number aberrations. Forty-three tumors were located in the cerebellum (IPNETs), and ten were supratentorial PNETs (SPNETs). All samples were reviewed to confirm the diagnosis. Each specimen had at least 50% tumor. RESULTS: Six of the 43 cases of IPNET had no copy number aberrations. In contrast, each case of SPNET had copy number aberrations detected by CGH. Statistically significant differences in copy number aberrations of chromosomes 14, 17, and 19 were detected in the two groups. The most common copy number aberration in the IPNETs was gain of chromosome 17q, which was observed in 16 of 43 cases (37%). However, no case of SPNET had gain of 17q. Loss of 14q was detected in four of ten SPNETs but was not detected in any of the IPNET cases. Loss of 19q was detected in 4 of 10 SPNETs and in only 1 of 43 IPNETs. CONCLUSIONS: These results indicate that the genetic aberrations of IPNETs differ from the genetic aberrations of SPNETs. Although they are similar histologically, SPNETs and IPNETs appear to be biologically distinct entities.

Adolescent↗
PubMed2001

Differentiation, proliferation and apoptosis in primary and recurrent primitive neuroectodermal tumors of childhood.

Primitive neuroectodermal tumors (PNETs) of the CNS are a group of embryonal tumors composed of small undifferentiated or poorly differentiated cells. Infratentorially located PNETs are a synonym for medulloblastomas. In this study 31 PNETs, including 5 recurrent tumors, were examined. All children underwent neurosurgery and chemotherapy according to the HIT and HIT-SKK protocols. The specimens were investigated both for their expression of nine immunohistochemical markers for neuronal, astrocytic, mesenchymal and epithelial differentiation and for their proliferation. Results regarding cellular differentiation were confirmed ultrastructurally. Apoptosis was detected by labeling the 3'OH ends generated by DNA fragmentation and by electron microscopy. Glial differentiation was shown to have a prognostic relevance, with an elevated (twofold) risk of recurrence. Neuronal differentiation also indicated a tendency to poor prognosis. Those tumors that recurred later showed an increased proliferation rate (69%) compared with nonrecurrent tumors (58%). Apoptosis was identified in all tumors examined. The proportion of apoptotic cells could not be related to the effect of therapy. These results indicate that cellular differentiation may be a useful predicative factor for the prognosis of cerebral PNETs.

Adolescent↗
PubMedDate not supplied

[Spinal primitive neuroectodermal tumor].

The term primitive neuroectodermal tumor (PNET) names a group of malignant neoplasms of presumed neural crest origin; they are composed of round small cells, and may be centrally located or outside. The former are currently seen in childhood, mostly in reference to the posterior fossa, and include medulloblastoma and neuroblastoma. Outside of the central nervous system includes peripheral neuroectodermal tumor of the bone (PNET-B, Tefft's tumor), Askin's tumor, and even Ewing's sarcoma. We describe a case in a young adult, with extremely unusual spinal localization, in which histopathological and immunohistochemical analysis were done; also, a review of some features is presented clinical-histopathological issues concerning related.

Adult↗
PubMed2000

[A rare primitive neuroectodermal tumor: the medulloepithelioma].

Primitive neuroectodermal tumors (PNET) is a name used to describe rare and highly malignant tumors composed of undifferentiated cells resembling germinal or matrix cells of the embryonic neural tube. These tumors occur most commonly in the first decade of life, and have a particular radiological, histological and evolution features. We report a case of a PNET in an 8-year-old boy who presented intracranial hypertension studied with computed tomography scan, which demonstrated a sharply circumscribed expansive mass in the frontoparietal deep white matter, with a large cystic component, which was considered at first as a glial tumor. It was treated by total excision, and the histologic study demonstrated a medulloepithelioma. We studied the concept of PNET and their pathological, radiological and prognostic features.

Brain↗
PubMed1994

[A case of primitive neuroectodermal tumor from rib].

Primitive Neuroectodermal Tumor (PNET) is a small round cell malignancy arising in bone and soft tissue. With the progress of immunohisto-chemical and ultrastructural studies, the tumor has getting attention. We report a rare case of PNET arising from rib. A 19-year-old man was admitted to our hospital complaining of chest and back pain. The tumor arised from 5th rib and en bloc resection was performed. Pathological diagnosis was PNET. After the operation, he is doing well, except being treated with chemotherapy (T9-protocol).

Adult↗
PubMed1995

Animal models of medulloblastomas and related primitive neuroectodermal tumors. A review.

Primitive neuroectodermal tumors (PNET) belong to a family of pediatric neoplasms of the central nervous system (CNS) that are composed predominantly of primitive neuroepithelial cells. Among the different CNS PNET, those arising in the posterior fossa (i.e. medulloblastomas) are prototypical of this group of brain tumors. The basic cell biology of PNET is incompletely understood, but recent studies of human PNET biopsies and cell lines derived therefrom demonstrate that neoplastic cells in human PNET recapitulate many of the phenotypic properties of immature CNS neurons or their progenitors. Based on these findings, it has been possible to develop several animal models of human PNET that will enhance efforts to gain fundamental insights into the induction and progression of PNET. In addition, these model systems will enable emerging gene therapies to be targeted specifically for human PNET. Accordingly, this review summarizes current understanding of the cell biology of human PNET, particularly medulloblastomas, and it highlights the most salient features of representative in vivo model systems of human PNET that are relevant to future studies of these tumors.

Animals↗
PubMed1998

Poorly differentiated synovial sarcoma: immunohistochemical distinction from primitive neuroectodermal tumors and high-grade malignant peripheral nerve sheath tumors.

Synovial sarcoma is a relatively common sarcoma in adults, which in its classic bimorphic form infrequently poses a diagnostic problem. Monomorphic spindled variants, as well as the less common poorly differentiated variants, may be confused with other soft-tissue sarcomas; the poorly differentiated variant (PDSS), in particular, may be histologically indistinguishable from other small, blue, round cell tumors, including primitive neuroectodermal tumors (PNETs). Detection of the synovial sarcoma-associated t(X;18) by either cytogenetic or molecular genetic approaches may be necessary to confirm the diagnosis of synovial sarcoma in difficult cases. We evaluated 10 cases of PDSS from eight patients using a panel of antibodies (including those to intermediate filament proteins, nerve-sheath associated markers, and neuronal and neuroectodermal associated markers) in order to better establish the immunophenotype of this tumor and to help distinguish it from the tumors with which it may be confused, particularly PNETs and high-grade malignant peripheral nerve sheath tumors (MPNSTs). Our results showed PDSS to have significant immunophenotypic overlap with both PNETs and MPNSTs. In most instances these three entities may be differentiated by a panel of antibodies that should include those to both low and high molecular weight cytokeratins, epithelial membrane antigen, type IV collagen, CD99, CD56, and S-100 protein. Our results also suggest that synovial sarcoma may be a tumor showing combined neuroectodermal and nerve sheath differentiation--perhaps because of translocation-associated expression of specific proteins--rather than a carcinosarcoma of soft tissues or a tumor of specialized arthrogenous mesenchyme.

12E7 Antigen↗
PubMed1998

Peripheral primitive neuroectodermal tumors in adults: documentation by molecular analysis.

PURPOSE: The Ewing tumor (ET) family of peripheral primitive neuroectodermal tumors (pPNETs) are primitive small round-cell tumors (SRCTs) of the bone and soft tissue that occur predominantly in children and adolescents. However, pPNETs only rarely enter the differential diagnosis of bone and soft tissue SRCTs in adults. Recently, gene fusions between the EWS gene and different members of the ETS transcription factor family have been shown to occur in virtually all pPNETs and thus constitute a pathognomonic marker for this tumor subclass. The aim of the present study was to document EWS/ETS fusion gene expression in suspected pPNETs of adults as objective evidence for the existence of this tumor family in older patients. PATIENTS AND METHODS: The three contributing molecular diagnostic laboratories retrospectively compiled a cohort of all SRCT cases in which EWS/ETS gene fusions had been shown by molecular analysis. This cohort was surveyed for cases that occurred in patients aged 40 years or older, which were then analyzed for their clinical and pathologic features. RESULTS: Nine patients between 40 and 65 years of age were found to have tumors positive for EWS/ETS gene fusions. Standard histopathologic and clinical features of these cases, other than age, were similar to those of childhood pPNETs. Patients were initiated on appropriate therapy after molecular analysis confirmed the diagnosis of pPNET. CONCLUSION: Identification of an EWS/ETS gene fusion is useful in providing objective evidence of the diagnosis of pPNET in patients over the age of 40 years. This diagnosis should be considered in adults who present with bone and soft tissue SRCTs and appropriate biopsy specimens should be collected for molecular analysis at the time of diagnosis.

Adult↗
PubMed2001

Primitive neuroectodermal tumor of the lung.

Primitive neuroectodermal tumors occur most frequently in bone and soft tissue but have been reported in other locations. Primary lung primitive neuroectodermal tumors without pleural or chest wall involvement are extremely rare. We present a case with immunohistochemical and ultrastructural studies and follow-up of the patient. An 18-year-old man presented with hemoptysis. Chest radiographs revealed a right middle lobe mass, and bronchoscopy showed an endobronchial tumor. The lesion was resected by middle lobectomy. After 2 years, a local recurrence was treated by pneumonectomy. The patient died after surgery. Histologically, the tumor was composed of uniform cells with round nuclei and scanty cytoplasm arranged in cohesive lobules with occasional rosette formation. Immunohistochemically, the tumor was positive for vimentin, CD99, neuron-specific enolase, and neurofilaments. Ultrastructural study revealed neurosecretory granules and cytoplasmic processes. Our case shows the value of immunohistochemistry and electron microscopy in the diagnosis of primitive neuroectodermal tumors in unusual locations.

Adolescent↗
PubMed2001

Cytogenetic and histopathologic studies of congenital supratentorial primitive neuroectodermal tumors: a case report.

Primitive neuroectodermal tumors (PNET) represent about 25% of primary central nervous system tumors in childhood, but congenital PNETs are rare. Cytogenetic studies and studies on molecular pathology have identified several genetic alterations in medulloblastoma, but molecular investigations on supratentorial PNETs are infrequent. We present a male newborn with a large congenital PNET of the right cerebral hemisphere and the molecular analysis of the tumor. Tumor tissue was investigated by routine histology and immunohistochemistry. Fluorescence in-situ hybridization was carried out on native tumor tissue to investigate deletions on chromosome 17p and to analyze c-Myc or N-Myc amplifications. Histologic examination revealed a primitive neuroectodermal tumor with massive extension covering almost the entire right hemisphere. Genetic analysis of the native tumor tissue of our patient excluded a deletion of chromosome 17p. An amplification of the c-Myc or N-Myc oncogene was absent using fluorescence in-situ hybridization. Despite unremarkable genetic analysis in our case prognosis was poor, suggesting that there are additional, yet unknown constitutional genetic aberrations in the pathogenesis of congenital supratentorial PNET.

Biomarkers, Tumor↗
PubMed1997

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↗
PubMed1984

CNS primitive neuroectodermal tumors of childhood.

Primitive neuroectodermal tumors ( PNET ) of the central nervous system in children are rare, highly malignant, cystic, and sometimes calcific, and hemorrhagic tumors sharply demarcated from adjacent brain. Microscopically they consist of small predominantly undifferentiated dark cells with neuronal, glial, and mesenchymal elements. We have recently diagnosed and treated five children with PNET . We will review their case histories as well as summarize the previous 133 reported cases with reference to presenting complaints, tumor location, neurodiagnostic studies, and the retrospective results of four treatment programs: 1) surgery alone; 2) surgery and radiation therapy; 3) surgery, radiation therapy, and chemotherapy at time of recurrence; and 4) surgery, radiation therapy, and chemotherapy at onset.

Brain Neoplasms↗
PubMed1996

Glial differentiation predicts poor clinical outcome in primitive neuroectodermal brain tumors.

Primitive neuroectodermal tumors (PNETs) of the central nervous system, including medulloblastomas (PNET/MB), are the most common malignant brain tumor of childhood. These tumors often express proteins characteristic of glial differentiation (glial fibrillary acidic protein, GFAP), neuronal differentiation (neurofilament proteins, NFPs), and/or photoreceptor differentiation (retinal-S antigen). To identify biological factors of prognostic significance in PNETs, the expression of glial, neuronal, or photoreceptor antigens was evaluated in the tumor specimens of 86 patients with PNETs by immunohistochemistry after microwave antigen enhancement. Patterns of differentiation were then compared with patient relapse-free survival. Multivariate analysis of PNET immunohistochemistry and clinical variables indicated GFAP expression conferred a 6.7-fold greater risk of relapse than tumors that did not express GFAP or NFPs. Increased risk of relapse was directly related to the amount of GFAP expression. Tumors exhibiting clumps or sheets of GFAP-staining cells were associated with a 3.0-fold increased risk of relapse compared with tumors that did not express GFAP, irrespective of immunohistochemical evidence of other differentiation, while scattered GFAP staining was not associated with increased risk of relapse. These findings indicate that expression of GFAP in PNETs has prognostic power comparable with the most significant clinical factors currently used to predict clinical outcome.

Adolescent↗
PubMed2000

Mutations of the INI1 rhabdoid tumor suppressor gene in medulloblastomas and primitive neuroectodermal tumors of the central nervous system.

Germ-line and somatic mutations of the hSNF5/INI1 gene have been reported in atypical teratoid/rhabdoid tumors (AT/RTs) of the brain, consistent with its role as a tumor suppressor gene. In the present study, we determined the frequency of deletions and mutations of INI1 in 52 children whose original diagnosis was medulloblastoma (MB) or primitive neuroectodermal tumor (PNET) of the central nervous system. Mutations were detected in DNA isolated from four tumors, all from children less than 3 years of age at diagnosis. Two of the four were reviewed and reclassified as atypical teratoid tumor, whereas there was insufficient material to establish this diagnosis in the two remaining cases. The relatively low frequency of mutations, even in a large series of infants, suggests that loss of sequences from chromosome 22 and/or mutations of INI1 do not account for the poor prognosis of children with MB or PNET who are less than 3 years of age at diagnosis. Nevertheless, chromosome 22 deletion and INI1-mutation analysis of infants with MB/PNET should be considered for all children who are less than 1 year of age. Detection of these mutations suggests that the child has an AT/RT, rather than a MB/PNET, a finding with important prognostic value.

Adolescent↗