Peripheral Primitive Neuroectodermal Tumor Research Articles

腹腔内から発生したＰｅｒｉｐｈｅｒａｌ ｐｒｉｍｉｔｉｖｅ ｎｅｕｒｏｅｃｔｏｄｅｒｍａｌ ｔｕｍｏｒの１例

We report a case of peripheral primitive neuroectodermal tumor of the abdominal cavity in a 24-year old woman. Cytology of ascites consisted of numerous individualy scattered cells and a few small clusters. Tumor cells were small to medium size, with a high nuclear/cytoplasmic ratio. Their nucleoli were prominent. The histology of abdominal tumor in the abdominal cavity showed features similar to cytologic findings. An inmmunohistochemical study showed tumor cells were positive for MIC 2, vimentin, and cytokeratin. We showed the usefulness of immunohistochemistry in the cytology of this rare case.

Adamantinoma-Like Ewingʼs Sarcoma: Usefulness of Genetic Approaches in Diagnosing Small Round Cell Tumors

A 13-year-old boy had a painful longitudinal swelling over the lateral aspect of the right calf. Radiographic studies revealed a dense fibular diaphyseal lesion with an associated soft tissue mass interpreted as probable Ewing's sarcoma. In contrast to the expected small round cell tumor appearance, the biopsy tissue was composed of nests of hyperchromatic, mildly pleomorphic cells separated by a pronounced desmoplastic reaction. Immuno-phenotyping showed that the tumor cells were strongly keratinand vimentin-immunoreactive but negative for 0-13 (MIC2). Other epithelial-like features included the presence of abundant intermediate filaments (including tonofilaments) and complex desmosomal-type intercellular junctions. These histologic, immunohistochemical, and ultrastructural findings were consistent with a diagnosis of adamantinoma, an entity that is not usually considered in the differential diagnosis of Ewing's sarcoma. Genetic analysis of this patient's tumor specimen, in addition to two cases previously described in the literature as “Ewing-like adamantinomas,” revealed the presence of the 11;22 translocation [t(11; 22)(q24;q12)] and/or the associated EWS/FLI1 fusion transcript characteristic of Ewing's sarcoma and peripheral primitive neuroectodermal tumors. This case illustrates the diagnostic challenges often encountered in bone and soft tissue tumors. Recently, recognition of specific cytogenetic and molecular genetic abnormalities in these neoplasms has significantly reduced some of the associated difficulties and has provided valuable information with respect to histopathogenesis. A review of the diagnostic and prognostic usefulness of genetic studies in Ewing's sarcoma and peripheral primitive neuroectodermal tumors is presented.

Updates on cytogenetics and molecular genetics of bone and soft tissue tumors:: Ewing sarcoma and peripheral primitive neuroectodermal tumors

Updates on cytogenetics and molecular genetics of bone and soft tissue tumors:: Ewing sarcoma and peripheral primitive neuroectodermal tumors

Thoracoabdominal peripheral primitive neuroectodermal tumors in childhood: radiological features

Peripheral primitive neuroectodermal tumors (PNET) are extremely uncommon, malignant neoplasms affecting mostly children and young adults. We retrospectively reviewed the clinical data and radiological studies of four such cases. All cases were pathologically proven. Plain films, US, and CT scans were used. The youngest child had a huge pelvic tumor and two adolescents each had a chest wall (Askin) tumor. The fourth patient had a most unusual location of the PNET in the anterior mediastinum. The CT findings are emphasized. We emphasize that the markedly abnormal CT findings are not specific for PNET.

In situ reverse-transcriptase polymerase chain reaction demonstration of the EWS/FLI-1 fusion transcript in Ewing's sarcomas and peripheral primitive neuroectodermal tumors.

It is now widely accepted that the EWS/FLI-1 fusion transcript is associated with tumors of the Ewing family. To test whether it is possible to detect the fusion transcript by means of combining polymerase chain reaction (PCR) methodology and immunohistochemistry, we investigated tumors of the Ewing family using in situ reverse transcriptase (RT)-PCR. We were able to demonstrate the t(11;22) fusion transcript in five of six cases of Ewing's sarcoma and four of four peripheral primitive neuroectodermal tumors. These results were confirmed using fluorescence in situ hybridization in seven tumor samples. In situ RT-PCR-labeled fusion transcripts were found in virtually all tumor cells within a given sample, indicating that each cell possessed the t(11;22) transcript. We conclude from these results that in situ RT-PCR can be used for the rapid detection of EWS/FLI-1 fusion transcripts in biopsy material. The findings also suggest that all cells of the tumors of the Ewing family carry the EWS/FLI-1 fusion transcript.

The Ewing Sarcoma (EWS)/Peripheral Primitive Neuroectodermal Tumours (pPNET) in Chinese children: A review of the Hong Kong experience

The Ewing Sarcoma (EWS)/Peripheral Primitive Neuroectodermal Tumours (pPNET) in Chinese children: A review of the Hong Kong experience

Fine Needle Aspiration Cytology of the Ewing’s Sarcoma Family of Tumors

To study the cytomorphologic features of the Ewing's sarcoma (ES) family of tumors. During a period of eight years (1990-1997), 123 soft tissue tumors and 65 bone tumors were evaluated by fine needle aspiration cytology (FNAC); 14 cases were diagnosed as in the ES family of tumors. The ages of the patients ranged from 8 to 30 years. All the cases were histologically confirmed. Of 14 cases of the ES family of tumors, 7 were ES, 3 extraosseous ES (EOE), 2 peripheral primitive neuroectodermal tumor (PPNET) and 2 Askin tumor. Cytologically, smears from all the cases showed round tumor cells with a high nuclear/cytoplasmic ratio. On detailed examination, subtle differentiating features were observed. The cells in ES had finer nuclear chromatin in comparison to those of PPNET and Askin tumor, and punched-out clear cytoplasmic vacuoles were present. PPNET showed nuclear molding, unipolar cytoplasmic tags and Homer-Wright rosettes. Histologically, all cases of ES and EOE and one case of Askin tumor showed periodic acid-Schiff-positive inclusions. FNAC features coupled with clinical findings enable a rapid diagnosis of the ES family of tumors, from which treatment modalities can be determined.

Ganglioside patterns in neuroepithelial tumors of childhood.

To elucidate a relationship between neuronal anaplasia, tumor proliferation, and ganglioside contents, we quantified gangliosides by HPTLC in tumors of neuroepithelial tissues at different grade, i. e. peripheral primitive neuroectodermal tumor (PPNET, grade IV), ependymoma (EPEN, grade III), neuroblastoma (NB, grade IV), and dysembryoplastic neuroepithelial tumor (DNT, grade I). PPNET, the most undifferentiated tumor examined had lowest concentration of total lipid-bound sialic acid. GM3 was the major ganglioside in all undifferentiated tumors (46-72.7% of total lipid-bound sialic acid). GD3 was an another component in PPNET and EPEN (7.2-17.3%). Concentration of a complex gangliosides GM1 was decreased in all tumor tissues and those of GT1a, GD1b and GT1b were decreased in tumors of high grade. The results suggest that the composition of gangliosides could be of considerable value in refining the classification of neuroepithelial tumors in infancy and childhood.

Peripheral primitive neuroectodermal tumour of the cervix

Peripheral primitive neuro-ectodermal tumours (PNET) of the cervix are very rare. Here, we report the clinical, pathological, immunohistochemical and genetic features of a case of a PNET located in the cervix. Hysterectomy revealed a cervical tumour. On microscopic examination, a vaguely lobular arrangement of uniformly appearing neoplastic cells, with round to oval nuclei, distinct nuclear membranes and a clear, moderately glycogen-rich cytoplasm was seen. Cells stained positive for LEU 7, S 100, monoclonal NSE and particularly for MIC2. Neurogenic differentiation was also seen by electron microscopic examination. The genetic hallmark of PNET, a 22q12 rearrangement was demonstrated by fluorescence in situ hybridisation experiments, supporting the diagnosis. Awareness of the existence of primary PNET of the cervix is important to avoid confusion with other tumours of the cervix.

SPONTANEOUS APOPTOSIS AND RETINOIC ACID RECEPTOR INCIDENCE IN NEUROBLASTOMAS AND PERIPHERAL NEUROECTODERMAL TUMORS

Twelve cases of neuroblastoma (NB) (7 boys and 5 girls) and 4 cases of primitive peripheral neuroectodermal tumor (PNET) (3 boys and 1 girl) were investigated for the presence of apoptosis and retinoic acid receptor (RAR) by immunhistochemical method. The apoptotic index in NB was zero or 1% in 8 children and relatively low (2-4.8%) in the other 4 cases, while it was higher (4.1-10.5%) in PNET. The RAR index determined by immunoperoxidase reaction in NB was zero or 3% in 5 cases and 9-34% in 7 children. RAR index in PNET was 16-68% in all the 4 cases. Good correlation (r=.47 according to Pearson-Bravis) was found between the number of RAR and spontaneus apoptosis. These results suggest that the RAR index in untreated NB and PNET shows great individual variation since its determination is necessary for the evaluation of the efficacy of retinoic acid treatment.

Apoptotic responsiveness of the Ewing's sarcoma family of tumours to tumour necrosis factor-related apoptosis-inducing ligand (TRAIL).

We investigated the cytotoxic responsiveness of 40 cell lines derived from representatives of the Ewing's sarcoma family of tumours (ESFT), i.e., Ewing's sarcoma (ES), peripheral primitive neuroectodermal tumour (pPNET) and Askin tumour (AT), to tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). Incubation with TRAIL at 100 ng/ml induced cell death at 24 hr in 19 of 26 ES, 11 of 12 pPNET and 2 of 2 AT cell lines. Half-maximal cell death concentrations (IC(50) values) varied from 0.1 to 20 ng/ml. TRAIL displayed potent cytotoxic activity against freshly derived ESFT cell isolates. Cytotoxicity was associated with phosphatidylserine expression and internucleosomal DNA fragmentation, features characteristic of apoptosis. The apoptotic programme in the sensitive ESFT VH-64 cell line revealed TRAIL-induced activation of FLICE/MACH1 (caspase-8) and CPP32/Yama/apopain (caspase-3) and processing of the prototype caspase substrate poly(ADP-ribose) polymerase. In addition, TRAIL provoked a collapse of the mitochondrial transmembrane potential (DeltaPsi(m)), parallelled by a reduction in ATP levels and release of cytochrome c from mitochondria into the cytosol. Inhibition of caspase-8 and caspase-3 by zIETDfmk and zDEVDfmk, respectively, substantially prevented TRAIL-induced apoptosis. However, zIETDfmk, but not zDEVDfmk, reduced TRAIL-mediated DeltaPsi(m) dissipation, indicating that TRAIL causes mitochondrial dysfunction through caspase-8 acting upstream of mitochondria. While macromolecule synthesis inhibitors (actinomycin D, cycloheximide) augmented susceptibility to TRAIL in TRAIL-responsive cell lines, these agents did not render TRAIL-resistant cell lines susceptible to TRAIL. However, the proteasome inhibitor MG132 sensitised to TRAIL in resistant cell lines. Collectively, these results show that TRAIL initiates effective death in the vast majority (80%) of cell lines derived from ESFT. Since TRAIL provoked cell death in ESFT ex vivo, this cytokine may be a promising drug for the treatment of ESFT in vivo.

Peripheral Primitive Neuroectodermal Tumor: Report of a Case

Peripheral primitive neuroectodermal tumor (pPNET) is a rare tumor. We present a patient who was diagnosed as pPNET. An 11-year-old boy had complained of pain and swelling in his left leg for one year. Imaging studies revealed an osteolytic lesion in his left distal tibia. Histopathology and immunohistochemistry results led to the diagnosis of pPNET. The treatment of the tumor consisted of a combination of chemotherapy with hematopoietic growth factor support and local radiotherapy. Complete remission was achieved after completion of treatment. After a brief review of the literature, we found that PNETs are unusual and highly aggressive neoplasms. In general, the prognosis of patients with PNETs is poor and new treatment strategies are necessary for patients with these rare tumors.

Clinically critical impact of molecular genetic studies in pediatric solid tumors.

Standard cytogenetic techniques are time-consuming and often not informative with solid tumors. In contrast, the reverse transcriptase-polymerase chain reaction (RT-PCR) is a readily available technique that can rapidly detect tumor-specific chromosomal rearrangements, even in small biopsy specimens. We present cases depicting the importance of including molecular diagnostic studies in the routine evaluation of pediatric solid tumors. We used RT-PCR to detect chimeric transcripts specific for major pediatric solid tumors, including peripheral primitive neuroectodermal tumor (pPNET), alveolar rhabdomyosarcoma (ARMS), and desmoplastic small round-cell tumor (DSRCT). We reviewed six recent cases in which the initial diagnosis was changed by the results of RT-PCR. Highly unusual or nonspecific clinical and/or histopathologic findings led to the initial diagnoses of neuroblastoma in three patients and DSRCT, leukemia, and carcinoma in one patient each. The final diagnoses after RT-PCR studies were pPNET in three patients, ARMS in two patients, and DSRCT in one patient. RT-PCR results led to early corrections in the diagnosis in two patients, but four patients received treatment not considered optimal for the neoplasms ultimately diagnosed, including three who, despite presenting with localized tumors that have a >70% cure rate with standard therapy, have died or are dying of disease. Molecular genetic studies on solid tumors can clarify the diagnosis in seemingly straightforward as well as in overtly problematic cases. These diagnostic distinctions are now critical as disease-specific and risk-directed therapies have emerged.

Ewing's Sarcoma and Peripheral Primitive Neuroectodermal Tumor of Bone and Soft Tissue

The histological diagnosis of Ewing's sarcoma (Es) continues to be a difficult task for pathologists. A number of new Es varieties has been described, leading to further complexity. Conventional Es, atypical Es, and peripheral neuroectodermal tumor (pPNET), including peripheral neuroepithelioma, belong genetically to the same family of neoplasms, displaying common chromosomal rearrangements and analogous gene reorganizations. The main translocations are t(11;22) and t(21;22), with genes EWS, FLI-1 and ERG being involved, as well as other members of the ETS family of transcription factors. The prevalence of morphology should be maintained with the use of conventional histological techniques and supported with the analysis of the expression of CD99 Mic2 (HBA 71, 0.13) antigen, which is present in over 90% of cases, as well as with FLI-1 rearranged gene derived protein. Moreover, FISH and RT-PCR in paraffin-embedded tumor tissue may be of use in extremely difficult cases for differential diagnosis. Nevertheless, a number of mixed tumor types, such as primitive sarcoma or biphenotypic sarcoma, may show structural and genetic diversity, thus rendering their diagnosis even more complex.

Repression of the gene encoding the TGF-beta type II receptor is a major target of the EWS-FLI1 oncoprotein.

Chromosomal translocations resulting in the expression of chimaeric transcription factors are frequently observed in tumour cells, and have been suggested to be a common mechanism in human carcinogenesis. Ewing sarcoma and related peripheral primitive neuroectodermal tumours share recurrent translocations that fuse the gene EWSR1 (formerly EWS) from 22q-12 to FLI1 and genes encoding other ETS transcription factors (which bind DNA through the conserved ETS domain). It has been shown that transduction of the gene EWSR1-FLI1 (encoding EWS-FLI1 protein) can transform NIH3T3 cells, and that mutants containing a deletion in either the EWS domain or the DNA-binding domain in FLI1 lose this ability. This indicates that the EWS-FLI1 fusion protein may act as an aberrant transcription factor, but the exact mechanism of oncogenesis remains unknown. Because ETS transcription factors regulate expression of TGFBR2 (encoding the TGF-beta type II receptor, TGF-beta RII; Refs 9,14), a putative tumour suppressor gene, we hypothesized that TGFBR2 may be a target of the EWS-FLI1 fusion protein. We show here that Ewing sarcoma [corrected] (ES) cell lines with the EWSR1-FLI1 fusion have reduced TGF-beta sensitivity, and that fusion-positive ES cells and primary tumours both express low or undetectable levels of TGFBR2 mRNA and protein product. Co-transfection of FLI1 and the TGFBR2 promoter induces promoter activity, whereas EWSR1-FLI1 leads to suppression of TGFBR2 promoter activity and FLI1-induced promoter activity. Introduction of EWSR1-FLI1 into cells lacking the EWSR1-FLI1 fusion suppresses TGF-beta RII expression, whereas antisense to EWSR1-FLI1 in ES cell lines positive for this gene fusion restores TGF-beta RII expression. Furthermore, introduction of normal TGF-beta RII into ES cell lines restores TGF-beta sensitivity and blocks tumorigenicity. Our results implicate TGF-beta RII as a direct target of EWS-FLI1.

Esthesioneuroblastoma is not a member of the primitive peripheral neuroectodermal tumour-Ewing's group.

Esthesioneuroblastoma (ENB) is a rare, site-specific, locally aggressive neuronal malignancy so far thought to belong to primitive peripheral neuroectodermal tumour-Ewing's tumour (pPNETs-ETs). Its anatomical location, in addition to morphologic, immunophenotypic and ultrastructural features, suggests its origin in the neuronal or neuroendocrine cells of the olfactory epithelium. However, the cytogenetic and molecular data currently available appear controversial on the presence of the typical translocation t(11;22)(q24;q12) and of trisomy 8, chromosomal changes that characterize the tumours belonging to the pPNETs-ETs. Herein we have analysed five ENB tumour specimens for trisomy 8 by fluorescence in situ hybridization (FISH), for the presence of EWS gene rearrangements by FISH, reverse transcription polymerase chain reaction and Southern blot analyses, as well as for the expression of the Ewing sarcoma-associated MIC2 antigen by immunohistochemistry. Neither EWS/FLI-I, EWS/ERG and EWS/FEV fusion genes nor MIC2 expression were found in any tumour, whereas trisomy 8 was found in one case only. Moreover, DNA from three cases analysed by Southern blot did not show EWS gene rearrangements. Our results support the evidence that ENB is not a member of the pPNETs-ETs. © 1999 Cancer Research Campaign

Relation of neuroglial marker expression and EWS gene fusion types in MIC2/CD99-positive tumors of the Ewing family

The Ewing family of tumors (EFT) is characterized by high MIC2/CD99 expression and specific EWS/ETS gene rearrangements, resulting in different chimeric transcripts. Further division into peripheral primitive neuroectodermal tumors and Ewing's sarcoma is still debated and, in the absence of distinct morphological parameters, has been based on the reactivity with neuroglial markers (NgM). We investigated 44 EFT in terms of a possible correlation between the type of EWS chimeric transcripts and reactivity with the following NgM: polyclonal and monoclonal neuron-specific enolase (NSE), S-100, chromogranin A, synaptophysin, Leu-7, glial fibrillary acid protein, and neurofilament. EWS/Fli1 fusion type 1 was detected in 30 of 44 and type 2 in 11 of 44 tumors. Three tumors, presenting with an uncommon morphology, carried rare chimeric transcripts. Our results indicate an association of lack of NgM staining with type 1 EWS/Fli1 translocations, found in 16 of 18 tumors with no NgM expression as detectable by any of the antibodies we applied. Using the monoclonal NSE antibody, 21 of 26 tumors without NgM staining expressed type 1 EWS/FLI1 chimeric RNA, whereas in the groups with 1 or more and 2 or more NgM, only 9 of 17 and 1 of 5 tumors, respectively, carried type 1 EWS/Fli1 fusion transcripts. Despite this association of increased NgM expression with a non-type 1 EWS/Fli1 gene fusion, a strict correlation between the extent of NgM expression and certain EWS fusion types was not evident. This fortifies the concept to consider EFT as a spectrum of tumors and suggests the type of EWS fusion transcripts as one, but not the only parameter influencing the extent of differentiation.

Neuroectodermal differentiation in Ewing's sarcoma family of tumors does not predict tumor behavior

The observation that neuroectodermal differentiation imparts a worse prognosis to the Ewing family of tumors has been suggested by some studies and refuted by others. To assess whether the diagnosis of Ewing's sarcoma versus peripheral primitive neuroectodermal tumor (PNET) affects prognosis, we analyzed tumors from 63 analogously treated pediatric and young adult patients from the National Cancer Institute and St Jude Children's Research Hospital and retrospectively compared the results with clinical outcomes. The tumors were assessed using standard light microscopy and immunohistochemical stains for neuron-specific enolase, CD57, S100 protein, neurofilament protein, and synaptophysin with or without antigen retrieval. Ultrastructural evaluation was also performed in 39 tumors. Classification was performed using Kiel criteria as well as a modified classification. Kaplan-Meier analyses, with Mantel-Haenzel evaluation of the significance of the differences, were performed separately for localized or metastatic tumors. Using the Kiel classification on a subset of 60 cases, 39 tumors qualified as PNET and 21 as Ewing's sarcoma. Using the modified classification on a subset of 61 cases, 14 were classified as PNET, 21 as atypical Ewing's sarcoma, and 26 as Ewing's sarcoma. The addition of electron microscopy to the diagnostic armamentarium significantly increased the likelihood of identifying PNET. No significant differences in event-free or overall survival were seen using either the modified or Kiel classification, regardless of the ancillary diagnostic techniques employed. In this exploratory analysis, neuroectodermal differentiation did not play a role in clinical outcome. Confirmation of this finding will require a larger, separate study of similarly treated patients, and it may not apply to older patients.

The Ewing family of tumors and the search for the Achilles' heel.

The ideal cancer therapy would accomodate the specific biology of a tumor and be based upon understanding the mechanisms of malignancy. This vision has been the driving force in cancer research. However, the story of success in clinical cancer management is a story of empirie largely independent from progress in basic research. For the Ewing family of tumors (EFT) comprising Ewing's sarcoma and peripheral primitive neuroectodermal tumor, significant insights into the molecular basis have appeared recently. Some of last year's discoveries may have taken us closer to the identification of the Achilles' heel in this disease. The first clue has been obtained to the mechanism of chromosomal translocation, which constitutes a rate-limiting step in EFT pathogenesis. Also, researchers have progressed in understanding the control of EFT cell proliferation, differentiation, and death. A major role in these processes has been attributed to the EWS-ets gene rearrangement. Specific growth factor circuits appear to be involved in deregulated tumor cell growth. By analogy to heterologous cellular systems, it is possible to postulate an important functional role for CD99(MIC2) as it contributes to the malignant phenotype of EFT. In vitro, as well as the first in vivo, experimental evidence suggests that tumor cell expansion and spread can be counteracted by breaking these physiological pathways. Still, we are far from a tailored biological therapy of EFT. Before this goal may be achieved, we must seek further improvements and diversification of today's standard and intensified treatment regimens.

Diagnosis and Classification of the Small Round-Cell Tumors of Childhood

The small-round-cell tumors of childhood include neuroblastoma, the Ewing family of tumors, rhabdomyosarcoma, lymphoma, and desmoplastic small-round-cell tumor. Although classical histological features are generally highly suggestive of tumor type, on occasion these tumors may be indistinguishable by light microscopy, making a definitive diagnosis difficult. Accurate diagnosis of pediatric small-round-cell tumors has become increasingly crucial, as disparate approaches to therapy are used for distinct tumor types. In addition, because for many pediatric cancers, therapy is also tailored according to patient risk, it has become important to further classify tumors biologically, using cytogenetic or molecular studies to identify chromosome translocations, gene amplification, gene expression patterns, and/or mutations. In this issue of The American Journal of Pathology, Gilbert and colleagues used a reverse transcriptase polymerase chain reaction (RT-PCR) assay to analyze the expression of two genes involved in the catecholamine biosynthetic pathway, tyrosine hydoxylase and dopa decarboxylase, in 84 pediatric malignancies. 1 Their studies demonstrate that the expression of these two genes is highly specific for neuroblastoma. Of the 29 non-neuroblastoma tumor samples examined, only pheochromocytomas expressed clearly detectable levels of the genes. These results suggest that analysis of tyrosine hydoxylase and dopa decarboxylase expression may help distinguish neuroblastoma from other small-round-cell childhood tumors. Despite recent advances in immunohistochemistry and molecular pathology, some cases of small-round-cell tumors of childhood remain diagnostically problematic. Thus, additional diagnostic tools, such as the ones described by Gilbert and co-workers, are needed to ensure that every child with a small-round-cell tumor is diagnosed correctly. The value and limitations of current immunohistochemical, cytogenetic, and molecular studies as diagnostic aids for the small-round-cell tumors of childhood are highlighted below.