An unusual association of malignant gastrointestinal neuroectodermal tumor (clear cell sarcoma-like) and Ewing sarcoma.

Very recently a new designation of "Malignant Neuroectodermal Gastrointestinal Tumor" has been proposed for an aggressive form of neuroectodermal tumor with features similar to that of Clear Cell Sarcoma of Soft Tissue, however without a melanocytic differentiation. Also known as "clear cell sarcoma-like tumors of the gastrointestinal tract", these tumors show some features strongly suggesting an origin from a gastrointestinal neuroectodermal precursor cell unable to differentiate along the melanocytic lineage. They occur mainly in young and middle-aged adults, and have a poor prognosis with a high rate of liver and lymphnode metastases. Histologically they are composed of epithelioid or oval-to spindle cells with a sheet-like or nested pattern of growth, strongly positive for neural markers (S-100, SOX10, and vimentin) and negative for the melanocytic ones. EWSR1 gene rearrangements including EWSR1-ATF1 or EWSR1-CREB1 GENE fusions are typically assessed in these tumors. Here we report a case of malignant neuroectodermal gastrointestinal tumor which immunophenotypically unusually expressed FLI-1, occurring in a 29-year-old man with a previous medical history of Ewing sarcoma. We finally suggest that this case might be a further evidence of a link between these two entities.

[Ewing/PNET sarcoma family of tumors: towards a new paradigm?]. / Tumeurs de la famille Ewing/PNET : vers un nouveau paradigme ?

Ewing sarcoma family of tumors are mainly aggressive sarcomas of bone and also arising in soft tissues, which share common features: morphological features of basophilic round cell tumors, immunohistochemical features by expression of membrane CD99 protein, and genetic features with a translocation involving EWS and FLI1 in approximately 90% of cases. The discovery of this translocation has made it possible to unify in a single entity several lesions such as PNET, neuropitheliomas, Askin tumors, Ewing sarcomas… Since then, the extensive use of molecular/genetic methods has helped to identify an increasing number of molecular anomalies in unclassified round cell sarcomas, these sarcomas often harboring an atypical morphology and a less frequent CD99 positivity. Besides the rearrangements between the FET family of genes (EWS or FUS) and the wide ETS family of genes (FLI1, ERG, FEV, ETV…), new partner genes are gradually identified: cases with EWS-non ETS partners are extremely rare, but there are more important groups which are CIC-DUX4 and BCOR-CCNB3 translocation-positive sarcomas. These findings raise the problem of the nosological borders of the Ewing/PNET entity and its links with new "Ewing-like" groups of tumors, and raise the therapeutic problems. The forward-looking identification of new round cell sarcomas should enable studies of wider series to try to answer these questions.

Glioblastoma with PNET-like components has a higher frequency of isocitrate dehydrogenase 1 (IDH1) mutation and likely a better prognosis than primary glioblastoma.

Glioblastoma with primitive neuroectodermal tumor-like components (GBM-PNET), a rare variant of glioblastoma, poses both diagnostic and therapeutic challenges. Ten patients with GBM-PNET were investigated with a median age of 51.5 years and the male to female ratio of 4:1. The majority of patients (7 out of 10) showed ring-enhancing lesions on magnetic resonance imaging (MRI), which is classic for GBMs. Restricted diffusion was noted in 7 cases where diffusion weighted imaging (DWI) was performed, which correlates with the presence of PNET-like components. CD56 and vimentin immunostaining made the diagnosis of GBM-PNET much easier. Vimentin strongly and diffusely highlighted the astrocytic components and was negative in PNET-like components, while CD56 was strongly and diffusely positive in both astrocytic and PNET-like components. Seven out of 9 cases were positive for p53 in both astrocytic and PNET-like components. Two out of 8 cases harbored isocitrate dehydrogenase 1 (IDH1) R132H mutation, while IDH2 R172 mutations were not identified. Three out of 10 patients had a median survival time of 17 months while the two patients, whose tumor carried IDH1 mutation, were still alive after 15 and 31 months of follow-up. Compared to primary GBMs, GBM-PNETs might have a better prognosis. Further large scale studies are necessary to confirm this observation.

PAX2 expression in Wilms tumors and other childhood neoplasms.

PAX2 plays an important role in kidney development; although small studies have demonstrated PAX2 expression in Wilms tumors (WT), comprehensive studies on formalin-fixed tissue are lacking. Thus, we systematically evaluated PAX2 immunohistochemical staining in a retrospective study of pediatric WT, as compared with other pediatric tumors. We stained formalin-fixed, paraffin-embedded sections from 39 WT, 6 nephrogenic rests, 8 non-Wilms renal tumors, and 43 nonrenal pediatric small round cell tumors with 2 different PAX2 polyclonal antibodies. PAX2 demonstrated strong, diffuse staining of epithelial and blastema components of WT (97% of cases). PAX2 stained WT stroma in fewer cases (23%), but 80% of anaplastic foci were positive. Nephrogenic rests, 1 case of metanephric adenoma, and 1 pediatric renal cell carcinoma were also PAX2 positive; other pediatric renal tumors were negative. Neuroblastoma, primitive neuroectodermal tumor/Ewings, and T-cell acute lymphoblastic lymphoma (ALL) were PAX2 negative. However, PAX2 weakly stained some cases of B-cell ALL rhabdomyosarcoma (RMS) was also stained, especially alveolar RMS (83%), with less staining of embryonal RMS (13%). One of the antibodies also stained maturing myoid cytoplasm of WT and RMS. This study shows that PAX2 is a sensitive marker of WT (sensitivity 97%), but PAX2 shows weak-to-moderate-intensity nuclear staining of RMS and B-cell ALL, somewhat limiting its utility. However, PAX2 may be a helpful marker in certain diagnostic situations. We speculate that RMS and B-cell ALL staining could be due to antibody cross-reactivity with PAX family members with known expression in RMS and B-cell ALL.

[An unusual adrenal tumor: Ewing tumor]. / Une tumeur surrénalienne inhabituelle : tumeur d'Ewing.

We report the case of a voluminous tumor of the adrenal diagnosed in a young pregnant woman at 26(th) week of amenorrhea. Morphologically, a soft white tumor with haemorragic areas was observed, made of sheets of monomorphous, medium sized, spindle-shaped to polygonal, with high mitotic activity. Tumorous cells expressed cytokeratins AE1/AE3, EMA, and CD99 (expression of vimentin is not relevant). Contemplated diagnoses included poorly differentiated synovialosarcoma, sarcomatoid carcinoma and Ewing tumor. Thanks to molecular biology, showing the specific transcript of Ewing/peripheral primitive neuroectodermal tumor (pPNET) EWS/FLI1, the diagnosis of this atypical tumor in an unusual location was performed. Indeed, 75% of Ewing tumors involve bones (especially, the diaphysis of long bones) and 20 to 25% soft tissues. Primitive visceral involvement is rare; less than 10 cases of adrenal involvement have been reported. The hypothesis that Ewing cell's origin is a mesenchymal stem cell, which may derive from neural crest cell, could explain the uncommon adrenal involvement. Diagnosis of Ewing tumor is based on pathologic and molecular findings, especially in atypical cases.

Peripheral primitive neuroectodermal tumour in a lumbar vertebra and the liver of a dromedary camel (Camelus dromedarius).

A 9-year-old castrated male dromedary camel developed weakness and ataxia, progressing to sternal recumbency and hindlimb paralysis. Necropsy revealed multiple liver tumours and a mass in the 3rd lumbar vertebra, compressing the spinal cord. The hepatic and vertebral masses consisted of uniform sheets of primitive cells, with perivascular pseudorosettes and small numbers of neuroblastic Homer-Wright rosettes. Immunohistochemically, the tumour cells were uniformly positive for vimentin and variably positive for neuron-specific enolase and glial fibrillary acidic protein. The histopathological and immunohistochemical findings indicated a peripheral primitive neuroectodermal tumour (pPNET) exhibiting neuroblastic, glial and ependymomatous differentiation, probably reflecting the tumour's primitive multipotential neuroepithelial nature. To the authors' knowledge, this is the first reported case in the camel of a pPNET, presumably intraosseous in origin with hepatic metastasis, and morphologically similar to Ewing's sarcoma in man.

SMARCB1/INI1 protein expression in round cell soft tissue sarcomas associated with chromosomal translocations involving EWS: a special reference to SMARCB1/INI1 negative variant extraskeletal myxoid chondrosarcoma.

Several previous studies have demonstrated the lack of SMARCB1/INI1 protein expression in only the malignant rhabdoid tumor (MRT). Several sarcoma groups are associated with a tumor-specific translocation involving EWS. Moreover, the EWS and SMARCB1/INI1 genes are located on the same 22q chromosome. We analyzed the status of SMARCB1/INI1 protein expression in 93 cases of sarcomas associated with chromosomal translocation involving EWS, comprising 52 Ewing's sarcoma/primitive neuroectodermal tumors, 24 extraskeletal myxoid chondrosarcomas (EMCS), 14 clear cell sarcomas of soft tissue, 2 desmoplastic small round cell tumors, and 1 myxoid/round cell liposarcoma. In addition, we analyzed the detailed SMARCB1/INI1 gene alteration in cases, which lacked its protein expression. Consequently, 4 EMCS showed no SMARCB1/INI1 expression, and 2 of these 4 cases revealed homozygous deletion and frameshift mutation of the SMARCB1/INI1 gene, respectively. These cases showed histologic findings compatible with EMCS, according to the most recent WHO classification, but no major fusion gene transcripts were detected. Moreover, 3 out of 4 SMARCB1/INI1 negative variant EMCS disclosed rhabdoid features. Therefore, the lack of SMARCB1/INI1 protein expression may be associated with rhabdoid features. The immunohistochemical result of the SMARCB1/INI expression is not an absolute diagnostic criteria for MRT and careful histologic evaluation is required to make a precise diagnosis of MRT.

Primitive neuroectodermal tumor of the breast: immunohistochemistry and fluorescence in situ hybridization.

A case of primitive neuroectodermal tumor (PNET) that developed as a breast lump in a 47-year-old Japanese woman is reported. After fine-needle aspiration (FNA) cytology, a mastectomy was performed. The surgical specimen was a well-circumscribed tumor, 21 x 18 x 18 mm, localized in the breast. The tumor cells were small and round with scant cytoplasm, and proliferated in sheets or solid nests. No intraductal carcinoma component was present. The tumor cells were immunohistochemically positive for neural cell adhesion molecule (CD56), neuron-specific enolase and synaptophysin, and they showed membranous immunoreactivity for the MIC2 protein (CD99). Fluorescence in situ hybridization (FISH) indicated a rearrangement of the EWS region on chromosome 22, which is highly specific for Ewing's sarcoma and PNET, which are referred to as the Ewing's sarcoma family of tumors (EFT). No other lesions suggestive of the primary site of this tumor, such as bone, soft tissue, or other organs were detected. The patient has been disease free for 6 months after surgery followed by chemoradiation therapy. FISH is extremely useful for accurate diagnosis of EFT, especially in cases of unusual locations.

Medulloepithelioma masquerading as chronic anterior granulomatous uveitis.

CASE REPORT: We report a rare clinical case of unilateral ciliary body teratoid medulloepithelioma presented first with infantile cataract, subsequently masquerading as chronic granulomatous anterior uveitis, followed by appearance of a tumour over the iris surface. COMMENTS: Diagnosis of the tumour in the early stages allows proper management and avoids enucleation.

Cdk9 regulates neural differentiation and its expression correlates with the differentiation grade of neuroblastoma and PNET tumors.

Cdk9 is a member of the Cdc2-like family of kinases. Its cyclin partners are members of the family of cyclin T (T1, T2a and T2b) and cyclin K. The Cdk9/Cyclin T complex appears to be involved in regulating several physiological processes. Recently, Cdk9 has been identified as a regulator of the differentiation program of several cell types, such as muscle cells, monocytes and lymphocytes, suggesting that it may have a function in controlling specific differentiative pathways. We analyzed whether Cdk9 and Cyclin T1 may be involved in the regulation of neuron and astrocyte differentiation. Cdk9 and Cyclin T1 expression levels were monitored during the differentiation program of neuroblastoma and astrocytoma cell lines. Our results suggest that Cdk9/Cyclin T1 complex may be required for neuron differentiation induced by retinoic acid, because the expression level of the complex varies during differentiation, but no significant changes were observed in its expression in the astrocytoma cell line. In addition, the expression of Cdk9 and Cyclin T1 was evaluated by immunohistochemistry in samples of neuroblastoma, PNET (Primary Neuroectodermal Tumor) and astrocytoma tumors of different grades, in order to assess whether there was a correlation between Cdk9 expression and tumor grading. Our results show that in neuroblastoma and PNET tumor samples Cdk9 is more expressed the more differentiated the tumor is. Conversely, no significant alteration of Cdk9 expression was observed in astrocytoma tumor samples of different grades, thus confirming the results obtained for the cell lines.

Immunohistochemical analysis of hSNF5/INI1 in pediatric CNS neoplasms.

Atypical teratoid/rhabdoid tumor (AT/RT) may be misdiagnosed as primitive neuroectodermal tumor/medulloblastoma (PNET) and occasionally as other tumors. Molecular genetic analysis of AT/RT demonstrates deletion and mutation of the hSNF5/INI1 gene in most cases, with decreased or absent expression at the RNA or protein level. Immunohistochemistry with an antibody to INI1 was performed to determine whether this would be a sensitive and specific means of assessing INI1 loss in pediatric brain tumors. Fifty-three tumors consisting of 20 AT/RTs, 10 PNETs, and 23 other central nervous system tumors were examined. No nuclear staining was found in all 20 AT/RTs. Most other central nervous system tumors demonstrated nuclear staining. Eight cases in which classification as AT/RT or PNET was difficult were also examined. Seven cases had no chromosome 22 deletion or INI1 mutation; INI1 antibody showed nuclear staining in these cases. One case was a recurrent tumor with features consistent with an AT/RT. INI1 immunostaining was negative in this case, and a mutation in INI1 was subsequently identified. Immunohistochemical staining with an INI1 antibody correlates with molecular findings in AT/RT and may be useful in confirming the histologic diagnosis. INI1 immunostaining may have particular utility in the analysis of tumors with indeterminate histologic features or atypical immunophenotypic profiles.

Heterogeneity of extraparenchymal primitive neuroectodermal tumors within the craniospinal axis.

Four cases of primitive neuroectodermal tumors (PNETs) with unusual localization (three intraspinal extramedullary and one pontocerebellar) are reviewed. Histologically, they were small round blue cell tumors with diverse patterns. Immunohistochemically, all tumors were positive for at least two neuronal markers, two cases were Mic-2 positive and one showed glial differentiation. The paraffin-embedded tumor specimens were examined by interphase FISH using dual-color probes specific for EWS, HER-2 and BCR loci. Molecular cytogenetic study revealed the presence of EWS rearrangement in two cases and the presence of i(17q) in one tumor. Three tumors exhibited 22 disomy and one was 22 polyploid. Extraparenchymal PNETs within craniospinal axis are heterogeneous from the clinical, histological, immunohistochemical and molecular point of view. These PNETs can be of a central or peripheral type. Multidisciplinary approach is of a basic importance in differential diagnosis of such cases.

Peripheral medulloepithelioma: an immunohistochemical, ultrastructural, and cytogenetic study of a rare, chemotherapy-sensitive, pediatric tumor.

A case of peripheral medulloepithelioma, a rapidly growing tumor involving the pelvic cavity of a 12-year-old girl, is presented. The diagnosis was supported by expression of vimentin, nestin, alpha-internexin, neurofilaments, and microtubule-associated protein 5 and by characteristic ultrastructure that included absence of cilia or microvilli. Trisomy of chromosomes 2 and 8 was the only detectable chromosomal abnormality. Combination chemotherapy resulted in complete remission. Because some of these rare tumors are sensitive to chemotherapy, their recognition and separation from other neuroectodermal tumors are advisable for better understanding of their biology and determination of optimal treatment.

Unusual aberration involving the short arm of chromosome 11 in an 8-month-old patient with a supratentorial primitive neuroectodermal tumor.

An 8-month-old baby girl with a supratentorial primitive neuroectodermal tumor showed an unusual aberration involving the short arm of chromosome 11. Seven abnormal metaphase cells had 49 chromosomes with trisomies of chromosomes 9 and 13, and partial trisomies of 1q and 18p. One homologue chromosome 11 was strikingly abnormal showing a long acrocentric-like form, which was composed of the long arm of chromosome 1 and an addition to the short arm of chromosome 11. This was characterized by fluorescence in situ hybridization using a partial arm chromosome-painting probe.

Drug resistance in epilepsy: human epilepsy.

The basis of drug resistance in human epilepsy is not understood. Parallels with resistance in cancer suggest that drug resistance proteins may have a role. To examine this possibility, we have studied human brain tissue containing pathologies capable of causing refractory epilepsy. Using immunohistochemistry for P glycoprotein (Pgp) and multidrug resistance-associated protein 1 (MRP1), we examined both pathological tissue and control tissue. We demonstrate expression of Pgp and MRP1 in glia from cases of malformation of cortical development studied both before and after the onset of epilepsy, as well as in cases of hippocampal sclerosis and dysembryoplastic neuroepithelial tumours. In one particular type of malformation, we also demonstrate that dysplastic neurons express MRP1. The pattern of immunolabelling suggests overexpression is concentrated particularly around vessels in most of the pathologies. The timing shows that expression may be constitutive in some pathologies. These findings suggest that drug resistance proteins may contribute to drug resistance in refractory epilepsy.

C-kit expression in pediatric solid tumors: a comparative immunohistochemical study.

The stem cell factor/c-kit tyrosine kinase receptor pathway has been shown to be important for tumor growth and progression in several cancers, including mast cell diseases, gastrointestinal stromal tumor, acute myeloid leukemia, small cell lung carcinoma, and Ewing sarcoma. Studies using the oral agent STI-571 (Gleevec, Novartis), an inhibitor of the tyrosine kinases bcr-abl, c-kit, and PDGFR, have shown significant responses in patients with chronic myelogenous leukemia and gastrointestinal stromal tumor. With the aim of identifying additional groups of tumors that may use the stem cell factor/c-kit pathway and secondarily may be responsive to STI-571 treatment, this study surveyed 151 primary tumors from patients treated at St. Jude Children's Research Hospital for immunohistochemical expression of c-kit. Formalin-fixed, paraffin-embedded sections were stained with rabbit polyclonal anti-human c-kit (CD117, Dako) using standard avidin-biotin-peroxidase complex technique, antigen retrieval, and an automated stainer. Strong, diffuse staining for c-kit was seen in a proportion of synovial sarcomas, osteosarcomas, and Ewing sarcomas. Strong, diffuse staining was less common in neuroblastomas, Wilms' tumors, and rhabdomyosarcomas and was negative in alveolar soft part sarcomas and desmoplastic small round cell tumors. Tumors with strong, diffuse staining for c-kit in a pattern similar to gastrointestinal stromal tumor may represent suitable targets for new therapeutic agents.