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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↗

Somatic mutations of WNT/wingless signaling pathway components in primitive neuroectodermal tumors.

Primitive neuroectodermal tumors (PNETs) represent the most frequent malignant brain tumors in childhood. The majority of these neoplasms occur in the cerebellum and are classified as medulloblastomas (MB). Most PNETs develop sporadically; however, their incidence is highly elevated in patients carrying germline APC gene mutations. The APC gene encodes a central component of the WNT/wingless developmental signaling pathway. It regulates the levels of cytoplasmic beta-catenin protein that plays a central role in neural development and cell proliferation. We analyzed 87 sporadic PNETs and 10 PNET cell lines for mutations of the APC gene and beta-catenin (CTNNB1) gene using single strand conformational polymorphism (SSCP) and sequencing analysis. We examined the mutation cluster region of APC (codons 1255--1641) for germline variants and somatic mutations. The medulloblastoma cell line MHH-MED-2 carried a Glu1317Gln missense germline variant and a sporadic MB sample showed a somatic Pro1319Leu substitution. Mutational analysis of exon 3 of CTNNB1 uncovered 4 PNETs (4.8%) with somatic missense mutations. These mutations caused amino acid substitutions in 3 of 80 medulloblastomas (Ser33Phe, Ser33Cys and Ser37Cys) and 1 of 4 supratentorial PNETs (Gly34Val). All mutations affected GSK-3 beta phosphorylation sites of the degradation targeting box of beta-catenin and resulted in nuclear beta-catenin protein accumulation. Deletions of CTNNB1 were not detected by PCR amplification with primers spanning exons 1--5. Our data indicate that inappropriate activation of the WNT/wingless signaling pathway by mutations of its components may contribute to the pathogenesis of a subset of PNETs.

Adenomatous Polyposis Coli Protein↗

Alternative EWS-FLI1 fusion gene and MIC2 expression in peripheral and central primitive neuroectodermal tumors.

Primitive neuroectodermal tumors (PNET) occur either in the central nervous system (CNS; central PNET, cPNET) or in the peripheral sites (peripheral PNET, pPNET). Recent molecular approaches have been defining a new concept of PNET, that is, the pPNET including Ewing's sarcoma (ES) which expresses MIC2 glycoprotein and shows the specific chimeric gene of EWS-FLI1. The expression of MIC2 and the genetic rearrangement of EWS-FLI1 are considered to be highly specific to the pPNET/ES. This study examined the expression of MIC2 and EWS-FLI1 gene by means of immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) on various small round cell tumors originating in the CNS or non-CNS organs. All peripheral PNET tested expressed MIC2 and were positive for EWS-FLI1 (11/11). In contrast, all cPNET and other blastic CNS tumors were negative for MIC2: medulloblastoma (0/3), cerebral PNET (0/2), spinal PNET (0/2), glioblastoma (0/2), retinoblastoma (0/3), and pineoblastoma (0/2). These MIC2-negative tumors were also negative for the chimeric gene product of EWS-FLI1. Interestingly, one PNET originating in the intracranial dura mater was positive for both MIC2 and EWS-FLI1 fusion gene. The results indicate that cPNET lacks any genetic or protein markers, except for a meningeal PNET which falls into the same phenotypic spectrum of pPNET.

12E7 Antigen↗

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↗

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↗

FDG PET scan in a primitive neuroectodermal tumor.

Primitive peripheral neuroectodermal tumor (PNET) is a rare tumor that often arises in soft tissue. Magnetic resonance imaging is a good diagnostic tool that can establish the extent of disease. The utility of positron emission tomography (PET) using F-18-fluoro-2-deoxy-D-glucose (FDG) in the diagnostic work-up and staging of PNET has not been well established. We present a case of PNET of the right upper extremity that did not show FDG uptake despite its large size and aggressive nature.

Adult↗

Primitive neuroectodermal tumor (PNET) in the differential diagnosis of malignant kidney tumors.

Primitive neuroectodermal tumors (PNETs) of the kidney, a rare neoplastic disease of high malignancy with a tendency towards early metastasis, affect young adults (26-30 years) irrespective of the gender. Differential diagnosis from other renal tumors is very important for an effective therapy. Herein, we report on a 24-year-old male patient with a renal tumor consisting of small, round cells, and summarize the diagnostic procedures that establish the diagnosis of PNET. Light microscopy revealed not only areas containing small, round cells forming rosettes and pseudorosettes, but also areas containing spindle cells. Expression of CD 99 in combination with neural markers, such as NSE, was detected by immunohistochemistry, and further evidence of neural differentiation was provided by electron microscopy. Image cytometry revealed a peridiploid DNA-stemline. A reciprocal translocation of the chromosomes 11 and 22 [t(11;22)(q24;q12)] with expression of a EWS/FLI-1 fusion transcript was demonstrated by molecular pathology. Using these methods, the diagnosis of PNET was firmly established, and the tumor was treated by surgical resection and subsequent adjuvant chemotherapy. Eighteen months after therapy, the patient is in excellent health condition without any evidence of tumor recurrence.

Adult↗

Primitive neuroectodermal tumor of the pancreas. A case report of an extremely rare tumor.

Primitive neuroectodermal tumor (PNET) of the pancreas is extremely rare. Although the diagnosis of PNET is suggested by the light microscopic appearance of the tumor, it should be confirmed by the immunohistochemical evaluation of the c-myc expression and if possible, further determination of the particular chromosome translocation, t(11;22)(q24,q12). In this report, we present a male patient with pancreatic PPNET who had been followed up for 50 months. The related literature is also reviewed. In our case, the pathologic diagnosis was based on the positive immunoreactivity for CD99 in many of the tumor cells. The complementary cytogenetic studies were not possible in the private setting of the patient's treatment. The patient was 31 years old when first operated. Within 4 months of the first operation he had local recurrence. In the third year of his follow-up he had been discovered to have pulmonary metastases and another metastatic tumor in his lung was diagnosed the year after. The metastatic foci were primarily treated by surgical resections. He had chemotherapy after each resection of pulmonary metastatic foci. After 50 months of the initial surgical intervention, he succumbed to widespread thoracic and bone metastases. Because of the extreme rarity of PPNET in the pancreas, and its rather protracted course, we think our case may further contribute to the ever expanding database for this particular entity.

12E7 Antigen↗

Gene expression profiling of early- and late-relapse nonseminomatous germ cell tumor and primitive neuroectodermal tumor of the testis.

PURPOSE: To better understand the molecular mechanisms that underlay the development and progression of nonseminomatous germ cell tumor of testis (NSGCTT) as well as malignant transformation of teratoma and primitive neuroectodermal tumor (PNET). EXPERIMENTAL DESIGN: We studied the gene expression profiles of 17 retroperitoneal NSGCTTs (10 yolk sac tumors, 3 embryonal carcinomas, 4 teratomas) and 2 PNETs obtained from patients with two clinical outcomes. Tissue samples were obtained from the Indiana University. One group of NSGCTT and PNET patients developed metastases within 2 years (early-relapse) of initial successful treatment, and the other group developed metastases after 2 years (late-relapse). Gene expression in these groups of patients was quantified using cDNA microarrays and real-time relative quantitative PCR. RESULTS: We demonstrate that the gene expression profiles of these tumors correlate with histological type. In addition, we identify type-specific genes that may serve as novel diagnostic markers. We also identify a gene set that can distinguish between early-relapse and late-relapse yolk sac tumors. The expression differences of these genes may underlie the differences in clinical outcome and drug response of these tumors. CONCLUSION: This is the first study that used gene expression profiling to examine the molecular characteristics of the NSGCTTs and drug response in early- and late-relapse tumors. These results suggest that two molecularly distinct forms of NSGCTTs exist and that the integration of expression profile data with clinical parameters could enhance the diagnosis and prognosis of NSGCTTs. More importantly, the identified genes provide insight into the molecular mechanisms of aggressive NSGCTTs and suggest intervention strategies.

Cell Transformation, Neoplastic↗

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↗

Primitive neuroectodermal tumor of the sternum in a child: resection and reconstruction.

Pediatric primary malignancies of the sternum are rare. They represent less than 1% of all bone tumors. Primitive neuroectodermal tumor of the chest wall or Askin's tumor is more often seen in the ribs than in the sternum. Surgical treatment involves resection of the tumor followed by primary reconstruction. We report the case of a 16-year-old adolescent boy who was diagnosed to have primitive neuroectodermal tumor of the sternum and underwent resection with primary reconstruction of the anterior chest wall. We describe for the first time the use of a 2-mm Gore-Tex Dualmesh plus biomaterial (W.L. Gore and Associates, Flagstaff, Ariz) and locking mandibular multiperforated titanium plates with screws (Stryker-Leibinger, Freiburg, Germany) for primary sternal reconstruction in a child. Despite having a wide resection, he did not require postoperative ventilation and had an uncomplicated recovery. The reconstructed chest wall has a normal contour with normal pulmonary physiology.

Adolescent↗

Germ cell tumor associated primitive neuroectodermal tumors.

PURPOSE: This retrospective review was done to assess the prognosis and response in patients presenting with primitive neuroectodermal tumor admixed with germ cell tumor. MATERIALS AND METHODS: Of the 40 patients treated at our institution from 1984 to 1999, 15 had initial stage I and 25 had initial metastatic disease. Median followup after the diagnosis was 25 months (range 4 to 142). RESULTS: Of the 40 patients 15 presented with clinical stage I disease, including 9 treated with retroperitoneal lymph node dissection and 6 who elected surveillance. Seven of the 9 patients had normal lymph nodes and all continuously had no evidence of disease. Two of the 9 patients had lymph nodes involved with teratoma with or without primitive neuroectodermal tumor. Retroperitoneal relapse in 5 of the 6 patients on surveillance was treated with cisplatin based chemotherapy followed by post-chemotherapy retroperitoneal lymph node dissection. Residual primitive neuroectodermal tumor was noted in 4 of the 5 patients and only 3 of 6 are currently without disease at a median followup of 17 months (range 15 to 69). A total of 25 patients presented with metastatic disease, of whom 23 underwent cisplatin based chemotherapy. Only 3 patients achieved complete remission with chemotherapy alone and 2 of the 3 subsequently relapsed. Of the remaining 20 patients 16 underwent post-chemotherapy retroperitoneal lymph node dissection, including 11 with primitive neuroectodermal tumor in the resected specimen. Two of these 11 patients have continuously had no evidence of disease, while an additional 3 currently have no evidence of disease after further therapy. Teratoma was present in the resected specimen in 5 of 16 patients, of whom 2 have continuously had no evidence of disease, while an additional 2 currently have no evidence of disease after further surgical resection. Therefore, 11 of 25 patients who presented with metastatic disease currently have no evidence of disease at a median followup of 19 months (range 2 to 111). CONCLUSIONS: Primitive neuroectodermal tumor in the orchiectomy specimen has adverse prognostic significance. This condition in the retroperitoneum is potentially curable by retroperitoneal lymph node dissection but rarely eradicated by chemotherapy. Therefore, we recommend retroperitoneal lymph node dissection for all clinical stage I cases with primitive neuroectodermal tumor in the orchiectomy specimen. Patients who present with metastatic primitive neuroectodermal tumor should be treated aggressively with surgical resection as an integral part of the therapeutic strategy.

Adolescent↗

A novel splice mutation in the TP53 gene associated with Leydig cell tumor and primitive neuroectodermal tumor.

A 20-month-old boy presented with precocious puberty due to a Leydig cell tumor, and at the age of 6 years with a primitive neuroectodermal brain-tumor (PNET). A novel splice site mutation of the TP53-gene, likely to be associated with a nonfunctional protein, was found in the proband, his father and younger sister, but only the proband has so far developed malignancy. The clinical phenotype in the boy is suggestive of Li-Fraumeni syndrome, but the family does not strictly conform to the canonical definition.

Adult↗

[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↗

Cervical primitive neuroectodermal tumor.

BACKGROUND: Primitive neuroectodermal tumors (PNETs) are rare and potentially aggressive malignancies. CASE: A 24-year-old woman in her eighth week of pregnancy presented with a cervical mass. Tissue biopsy demonstrated poorly differentiated carcinosarcoma with neuroendocrine features. Immunohistochemical studies confirmed the diagnosis of PNET. Treatment included alternating courses of cyclophosphamide, adriamycin, vincristine (CAV) and ifosfamide, etoposide (IE). A radical hysterectomy with bilateral ovarian transposition and periaortic lymphadenectomy was performed with postoperative chemotherapy and radiotherapy. The patient remains disease free 2 years from therapy. CONCLUSION: This is a rare case of cervical PNET occurring in a pregnant patient. A review of the literature indicates that cervical PNET is distinguishable from uterine PNET. This tumor affects younger women and may have a different histogenesis. Pregnancy should not delay diagnosis of this potentially aggressive tumor.

Adult↗