Primary Ewing's Sarcoma of the Duodenum: A Case Report

We report a case of Ewing's sarcoma arising from the duodenum in a 20-year-old woman who presented with a rapidly progressive ulcerative lesion. The surgical specimen obtained via Whipple's operation revealed a small round-cell tumor (SRCT) in the first and second portion of the duodenum. The tumor cells revealed strong immunoreactivity for CD 99 and vimentin and focal paranuclear dot-like immunoreactivity for cytokeratin. Electron microscopy showed primitive tumor cells with few cytoplasmic organelles, but neither neurosecretory granules nor specific cell junctions were present. On Western blot study, 68-kDa EWS/FLIl fusion protein was detected. The occurrence of Ewing's sarcoma in the gastrointestinal hollow viscus has recently been recognized, and this case expands the known anatomic sites that can harbor Ewing's sarcoma by demonstrating primary duodenal involvement.

Ewing sarcoma-primitive neuroectodermal tumor of the uterus: a clinicopathologic, immunohistochemical and ultrastructural study of one case

INTRODUCTION

Ewing sarcoma-primitive neuroectodermal tumors (ES/PNET) constitute a family of neoplasms characterized by a continuum of neuroectodermal differentiation. ES/PNET of the uterus is rare. There are 43 cases published in the English literature as far as we know. We describe an additional case.

CASE REPORT

A 56-year-old woman presented with a 2-month history of irregular menopausal vaginal bleeding. After surgical excision, microscopic, immunohistochemical and electron microscopic examination suggested the diagnosis of ES/PNET. The patient underwent combined chemotherapy consisting of ifosfamide, etoposide, and cisplatin. She was alive with no evidence of recurrence or metastasis after 41 months of the initial operation.

DISCUSSION

In spite of the rarity of ES/PNET, we should consider it in the differential diagnosis of small cell neoplasms of the uterus.

Keratin-positive Ewing's sarcoma: an ultrastructural study of 12 cases

Ewing's sarcoma/primitive neuroectodermal tumor (EWS/PNET) is an aggressive neoplasm of bone and soft tissue. Histologically, it is characterized by the presence of small round blue cells, which usually express MIC-2 and FLI-1 immunohistochemically. The most specific feature for diagnosis, however, is cytogenetic or molecular evidence of a consistent abnormality, the t(11;22)(q24;q12), or variants thereof. The immunohistochemical expression of keratins in a significant proportion of these cases has been highlighted in several recent studies. The ultrastructural features of these keratin-positive tumors have not, however, been characterized in detail. In this study we analyzed the ultrastructural features of 12 well-documented EWS/PNETs that stained strongly for pankeratin by immunohistochemistry. Ultrastructurally, the tumor cells contained a few organelles, which included a small number of mitochondria, poorly developed Golgi complexes, free ribosomes, and inconspicuous rough-endoplasmic reticulum. Rudimentary cell junctions were seen in 2 tumors while prominent junctions were observed in the remaining 10. Five tumors contained intracytoplasmic filaments, and definite tonofibrils were identified in 2. Well-developed basal lamina around tumor cells were also demonstrated in 2 tumors. Follow-up information was available for all cases. Seven patients died of disease, 2 are alive with disease, and 3 have no current evidence of disease. The cohort includes 5 patients with a type-1 translocation, which has been associated with a better prognosis in some studies; 4 of these patients have died of their disease, and 1 is alive with recurrent disease. This study shows that keratin-positive EWS/PNETs have evidence of epithelial differentiation ultrastructurally, and may possibly represent a more aggressive subset of the EWS/PNET group of tumors.

Ultrastructure of the Ewing's sarcoma family of tumors

Specimens of 47 tumors diagnosed by routine light microscopy as Ewing's sarcoma of bone, and 5 similar soft tissue tumors (extraskeletal Ewing's sarcomas), were examined by transmission electron microscopy. Immunohistochemical stains were performed on all the tumors, and pre-therapy and post-therapy specimens from 5 of the patients were compared. Cell and nuclear areas were assessed in 41 cases by cytomorphometry by using low-magnification electron micrographs. DNA ploidy was determined by static cytometry on 51 of the tumors. None of the methods revealed differences between the bone and soft tissue tumors. The ultrastructural spectrum extended imperceptibly from the typical forms to markedly irregular variants, and was much broader than could be anticipated from the light microscopy. Neural features were observed but they were not common. Comparison of the Ewing's sarcomas with a group of other small round cell tumors (rhabdomyosarcoma, neuroblastoma, small cell carcinoma) using the same techniques showed that they have similar cell and nuclear areas despite the obvious differences in their immunophenotypes and ultrastructure. The collective findings are in keeping with the currently favored view that Ewing's sarcoma and peripheral primitive neuro-ectodermal tumor are the extremes in a morphologic continuum within which neural differentiation ranges from absent to prominent.

Ewing's sarcoma family of tumor arising in the adrenal gland--possible diagnostic pitfall in pediatric pathology: histologic, immunohistochemical, ultrastructural, and molecular study

We present an adrenal Ewing's sarcoma family of tumor (ESFT) arising in an 11-year-old Japanese boy. Although intensive chemoradiotherapy and radical surgery were performed, the patient died of obstinate disease 1 year and 3 months after the initial presentation. The primary site (adrenal gland) with radiologic findings (with foci of calcification), high titer of serum neuron specific enolase, and sheets of monotonous primitive rounded cells on histology mostly favored neuroblastoma. However, a diagnosis of ESFT was confirmed by immunohistochemical profile, including MIC2-positivity and molecular study disclosing EWS-FLI1 chimera gene verified by direct sequencing. Recognition of adrenal ESFT and use of newly developed diagnostic techniques are required for differential diagnosis of undifferentiated small round cell tumor of the adrenal gland.

Immunohistochemical and ultrastructural investigation of neural differentiation in Ewing sarcoma/PNET of bone and soft tissues

The authors evaluated the role of immunohistochemistry and electron microscopy in defining neural differentiation in 28 cases of Ewing sarcoma/PNET. The panel of primary antibodies used included vimentin, MIC-2, NSE, S-100 protein, leu7, neurofilaments, GFAP, and chromogranin A. Cases were considered undifferentiated when neural markers were absent, poorly differentiated if one neural marker was present, and well differentiated if two or more markers were observed. Cases were also evaluated for the presence of cytoplasmic processes, microtubules, and neurosecretory granules as ultrastructural features of neural differentiation: the tumor was classified as well differentiated if two of these features were present; and poorly differentiated if one was evident; all other cases were considered undifferentiated. According to immunohistochemistry, 10 cases (35.7%) were undifferentiated, 12 cases (42.9%) were poorly differentiated, and 6 (21.4%) were well differentiated. According to the ultrastructural analysis, 10 tumors were undifferentiated (35.7%), 14 poorly differentiated (50%), and 4 well differentiated (14.3%). The overall concordance between the two techniques was low (35.7%), and both modalities were concordant in classifying only 1 well-differentiated, 5 poorly differentiated, and 4 undifferentiated tumors. In conclusion, the authors suggest that investigations devoted to test the prognostic significance of neural differentiation in these neoplasms should employ both immunohistochemistry and electron microscopy, separately and in combination, to assess what is the most effective choice for predicting the clinical course.

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.

EWS/ETS fusion genes induce epithelial and neuroectodermal differentiation in NIH 3T3 fibroblasts

Ewing's sarcoma is the least differentiated member of the peripheral primitive neuroectodermal (pPNET) tumor family. Chromosomal translocations involving the EWS gene and five different Ets family transcription factor genes create fusion genes encoding aberrant transcription factors and are implicated in the vast majority of Ewing's sarcoma cases. Here, NIH 3T3 fibroblasts were infected with control (tk-neo or RAS) and two different EWS/ETS-expressing retroviruses. In vitro studies of established polyclonal lines expressing the two EWS/ETS genes, either EWS/FLI1 or EWS/ETV1, showed induction of cytokeratin 15 gene expression. Both fusion genes also caused characteristic gross morphologic, histologic, and ultrastructural changes in NIH 3T3 cells when transformed cell lines were injected into CB-17-scid mice. Native NIH 3T3 cells with a spindled cell morphology were converted to polygonal cells with high nucleo-cytoplasmic ratios that continued to express abundant cytokeratin. Extracellular collagen deposition was abolished, rough endoplasmic reticulum was markedly diminished, and rudimentary cell-cell attachments appeared. Most strikingly, neurosecretory-type dense core granules like those seen in pPNET were now evident. This murine model, created in mesenchyme-derived NIH 3T3 cells, demonstrated new characteristics of both neuroectodermal and epithelial differentiation and resembled small round cell tumors microscopically.

Ovarian small cell tumors: an electron microscopic review

Small cell tumors of the ovary are uncommon but represent an important group to recognize in the differential diagnosis of primary and metastatic ovarian neoplasms. In some cases the correct diagnosis cannot be confidently made on the basis of clinical setting, routine light microscopy, and immunohistochemistry, and electron microscopy may be supportive or definitive in establishing cell type. The cell type is often important in choosing optimal therapy and in predicting prognosis. The authors performed electron microscopy on a moderate number of ovarian small cell tumors and here describe and illustrate the diagnostic features of representative examples of various types. The ultrastructural features of the metastatic tumors, such as embryonal rhabdomyosarcoma, neuroblastoma, and melanoma, are identical to those of their respective primary tumors, are well known, and usually pose no problem in diagnosis. On the other hand, the ultrastructural features of some primary ovarian small cell tumors may present a more difficult differential diagnosis, because they have features that are subtle and/or in common. Exemplary of tumors in this category are diffuse adult granulosa cell tumor, endometrial stromal sarcoma, and small cell carcinomas of the hypercalcemic and pulmonary (oat cell) types. Distinguishing among them may be difficult but is possible, and electron microscopy may be a valuable supplement to the diagnostic information obtained from the clinical presentation, light microscopy, immunohistochemistry and, in some tumors, cytometric analysis of these neoplasms.

Primary endocervical extraosseous Ewing's sarcoma/PNET

A 36-year-old woman presented with intermenstrual spotting and was found to have a cystic mass involving the uterine cervix on a pelvic ultrasound examination. A necrotic and hemorrhagic tumor was excised by hysterectomy and processed for light and electron microscopic investigation and molecular analysis. Microscopic examination revealed a small round cell tumor that immunohistochemical studies (including staining for the highly restricted surface antigen p30/32MIC2) and ultrastructural studies indicated was an extraosseous Ewing's sarcoma (EES)/primitive neuroectodermal tumor (PNET). This diagnosis was established by detection of EWS/ERG fusion transcript through reverse transcription polymerase chain reaction (RT-PCR) with nested primers. Full body computed tomography failed to detect any extrauterine tumor, and the patient is clinically free of disease 18 months after hysterectomy. This case represents the first report of a primary EES/PNET arising in the uterine cervix.

[Clinico-pathologic study of Ewing's sarcomas of bone and soft tissue and peripheral primitive neuroectodermal tumors]

OBJECTIVE

To study the diagnosis and differentiation of EW and PNET.

METHODS

Fourteen cases of Ewing's sarcomas (EW) and peripheral primitive neuroectodermal tumors (PNET) were studied by light microscopy, immunohistochemistry and electron microscopy (EM). Twelve cases were followed up. Schmidt criterion was used for the differential diagnosis of EW and PNET.

RESULTS

There were 6 cases of EW and 8 cases of PNET. Six of 8 PNET cases had Homer-Wright (H-W) rosettes. In this series, 12/14 cases were positive for O13 (HBA71) staining. NSE was positive in 3 cases of EW. All PNET cases were positive for neural markers, and 5 of them were positive for more than two of these markers. Electronmicroscopically, there were neurosecretory granules (4/4 cases), nerve-like protrusions and microfilaments (1/4 case) in PNET. In 3 of 6 EW and 1 of 6 PNET, PAS staining was positive. During the follow-up period from 2 months to 5 years, 3 cases with intraosseous EW remain alive and free of tumor. The remaining patients are dead or having their tumors metastasized.

CONCLUSION

EW is more primitive in cell differentiation, while PNET has more neural differentiation. The presence of H-W rosettes is an important morphologic feature of PNET. To differentiate EW from PNET is of clinical significance O13 is a useful marker for the diagnosis of EW/PNET.

Differentiating small round cell sarcomas of the soft parts by an innovative immunogold labeling method: an ultrastructural study

A new immunoelectron microscopy procedure was developed by remaking the fixed-frozen tissue specimens into LR White resin blocks suitable for postembedding colloidal gold immunolabeling, and used to examine 16 cases of small round cell soft tissue sarcomas. In rhabdomyosarcoma, ultrastructural double-immunogold staining demonstrated a coexpression of muscle specific actin and desmin in the same tumor cell. In both Ewing's sarcoma and peripheral neuroepithelioma, the heterogeneous expression of MIC2 gene product (p30/32MIC2) in each tumor cell was demonstrated as well. In peripheral neuroepithelioma, the colloidal gold immunolabeling for neurofilament demonstrated the intermediate filaments surrounding microtubules. The procedure for ultrastructural colloidal gold immunolabeling using fixed-frozen tissue is thus considered to be useful not only for tumor diagnosis, but also for investigating various subcellular structures.

Appraisal of the comparative utility of immunohistochemistry and electron microscopy in the diagnosis of childhood round cell tumors

To provide an objective assessment of the comparative utility of fluorescence- and peroxidase-based immunohistochemistry and electron microscopy, an observer blinded study was conducted under realistic study conditions utilizing a large sampling of poorly differentiated pediatric round cell tumors. Working independently, using a single ancillary technique of particular expertise, each of three investigators attempted to render a specific diagnosis with regard to 50 diagnostically challenging tumors. The results were compared against the subsequent "file diagnosis" established by consensus with all relevant information made available. A grading scheme was applied wherein points were awarded based on the accuracy and confidence of diagnosis. A comparative efficiency rating, expressed as a percentage, was formulated by dividing the number of points awarded each technique by the total number of points theoretically available. Electron microscopy proved superior overall, with an efficiency rating of 89%. Immunoperoxidase and immunofluorescence studies yielded efficiency ratings of 71 and 61%, respectively. Used in combination, the techniques achieved an efficiency rating of 95%. Application of these ancillary techniques resulted in a revision of the provisional diagnosis in 11 of 50 cases, and left only two cases without a firm specific diagnosis.

Histology, immunohistochemistry, and electron microscopy of small round cell tumors of bone

Small round cell tumors (SRCTs) of the bone make up a family of primary bone sarcomas with morphologically, biologically, and clinically specific features. Among them, Ewing's sarcoma (ES) is the most common entity, but several varieties such as atypical ES, large cell ES, and ES with neuroectodermal differentiation (peripheral primitive neuroectodermal tumor of the bone or neuroepithelioma of the bone) have been identified recently. Histology and electron microscopy together with the variable expression of several epitopes (as shown by immunohistochemistry, mainly HBA/71 [Mic2 antigen]) provide the basis for characterizing the group within the context of neuroectodermal-derived neoplasms. A number of other ES-like tumors with small round cells, mimicking those previously described, have been characterized; Askin's tumor of the thoracopulmonary region will be considered as an ES similar to those already described, but within a particularly anatomic location. On the other hand, the presence of an endothelial appearance within a poorly differentiated neoplasm may be present in some ES-like SRCTs (atypical ES with endothelial features). The differential diagnosis with other sarcomas defined by small round to spindle cell contours might prove difficult. Particular attention must be paid to small cell osteosarcoma and mesenchymal chondrosarcoma. Likewise, "primitive sarcoma of bone" is considered in this study because it is a very rare neoplasm differing from the formerly discussed types; its pluripotentiality provides this tumor a blastemic character and a multiphenotypic expression. Malignant non-Hodgkin's lymphoma is an unusual presentation when primary to the bone, previous to any other anatomic location. Several subtypes have been considered within a histology that encompasses that seen in lymph nodes.

A novel chimera gene between EWS and E1A-F, encoding the adenovirus E1A enhancer-binding protein, in extraosseous Ewing's sarcoma

Ewing's sarcoma/PNET, a tumor of the bone and soft tissue, is one of the most common causes of tumor death among youths. This tumor does not have specific phenotypes, but does have characteristic chromosomal translocations. Furthermore, the expression of EWS/FLI-1 or EWS/ERG chimeric genes was found to be generated through a t(11;22)(q24;q12) or a t(21;22)(q22;q12) translocation. In this study, we identified a new chimera gene between the transactivation domain of EWS and E1A-F, encoding the adenovirus E1A enhancer-binding protein. Since E1A-F is known to activate matrix metalloproteinase genes, the chimera gene may possibly be involved in tumor progression and could be a novel tumor marker for Ewing's sarcoma/PNET.

Osteosarcoma and Ewing's sarcoma in a retinoblastoma patient

Retinoblastoma, though uncommon, frequently is associated with other second malignant neoplasms, especially bone sarcomas. These second neoplasms can occur in sporadic cases of retinoblastoma, though they more commonly are associated with genetic forms of the disease. This is the first known report of 2 histologically distinct bone sarcomas in a patient with retinoblastoma.

Diagnostic value of electron microscopy in rare malignant musculoskeletal tumors. Experience from an orthopedic tumor center

Rare musculoskeletal tumors can be difficult to diagnose by light microscopy or immunohistochemistry. Electron microscopy can be of diagnostic assistance especially if histotype specific ultrastructural features exist. In particular, electron microscopy for uncommon sarcomas such as alveolar soft part sarcoma, parachordoma, atypical Ewing's sarcoma and epithelioid sarcoma may be the diagnostic modality of choice.

[Cytodiagnosis of Ewing sarcoma]

Pelvic Ewing's sarcomas were studied by fine needle aspiration biopsy in two young male patients. Local pain, subfebrility, high ESR had occurred in both cases. X ray examination showed osteolytic lesions in both patients. The differential diagnostic question was, are the lesions osteomyelitis or malignant tumors? Fine needle aspiration biopsies and cytological examinations were performed in order to determine the nature of the lesions. The aspirates consisted of monotonous population of small undifferentiated tumor cells. The nuclei were monomorph with small nucleoli and finely granular chromatin. The tumor cells contained large amounts of PAS positive diastase-digestible granular cytoplasmic glycogen. The aspirated material was examined by immunocytochemistry and electronmicroscopy in one of the cases. Both of these methods had diagnostic value in our patients in the detection of Ewing's sarcoma.

An autopsy case of extraskeletal Ewing's sarcoma followed up for 24 years

A long-term (24 years) follow-up case of extraskeletal Ewing's sarcoma is reported. The light microscopic examination showed features hardly indistinguishable from Ewing's sarcoma of the bone, that is, the tumor cells were diffusely arranged and uniform in size and shape, and possessed glycogen in the cytoplasm. Homer-Wright rosettes were found only in the autopsy material. An immunohistochemical study using a neural marker (neuron-specific enolase) demonstrated positive staining in most tumor cells. An ultrastructural study revealed intracytoplasmic glycogen particles and incomplete neural characters as follows: the cytoplasmic processes resembled neural processes without neurosecretory granules, microtubules or neurofilaments. These findings suggest that this case finally acquired an incomplete neural character with repeated recurrence. This tumor was diagnosed extraskeletal Ewing's sarcoma, but in future it may be categorized as primitive neuroectodermal tumor (PNET).

Lymphoglandular bodies in lymphoid lesions and non-lymphoid round cell tumours: a quantitative assessment

Lymphoglandular bodies (cytoplasmic fragments) were counted in 10 high power fields (HPF) of the smears in 35 cases of non-Hodgkin lymphoma (NHL), 26 Hodgkin's disease (HD), 36 reactive lymphadenitis, 24 non-lymphoid round cell tumors, and 20 cases of secondaries in lymph nodes. The number of lymphoglandular bodies in both May-Grünwald-Giemsa (MGG) and hematoxylin-eosin (H&E) stained smears in NHL, HD, and reactive lymphadenitis were significantly higher compared to non-lymphoid round cell tumors (P < 0.001). In H&E stained smear 92.5% of NHL, 86.2% of reactive lymph nodes, and 66.7% of HD cases had > 100 lymphoglandular bodies per 10 HPF. In MGG stained smears 100% NHL, 89.7% of reactive lymphadenitis, and 66.7% of HD cases contained > 100 lymphoglandular bodies per 10 HPF. On the other hand only 4.8% of non-lymphoid round cell tumors crossed this level in both H&E stained and MGG stained smears. Number of lymphoglandular bodies was also significantly higher in MGG stained smears compared to H&E stained smears (P < 0.05 to < 0.01) and in fine-needle aspiration (FNA) smears compared to imprint smears (P < 0.01 to < 0.001) in cases of NHL, HD, and reactive lymphadenitis.

Comparison of Ewing's sarcoma of bone and peripheral neuroepithelioma. An immunocytochemical and ultrastructural analysis of two primitive neuroectodermal neoplasms

Ewing's sarcoma of bone (ESB) and peripheral neuroepithelioma (PN) are frequently considered to be different tumors. Some researchers have suggested that PN is morphologically a neuroectodermal Ewing's sarcoma. We sought to determine the extent of neuroectodermal features in conventional ESB on direct patient material (25 cases) and to compare these tumors with a similar group of readily diagnosed PNs (10 cases). Light microscopic, ultrastructural, and immunophenotypic parameters were assessed and compared for both groups. The avidin-biotin complex method was used. All tumors were antigenically intact since all stained for vimentin or at least one marker. Neuroectodermal antigens (neuron-specific enolase, Leu-7 [HNK-1], neurofilament 200 kd, and S100) were found in nine of 10 cases of PN and in 17 of 25 cases of ESB. In ESB, an atypical light microscopic appearance correlated with the presence of neuroectodermal features in most cases, but neuroectodermal phenotype was more frequent (68%) than morphological evidence of neuroectodermal differentiation (36%). These data support the concept that ESB and PN are both peripheral primitive neuroectodermal neoplasms, differing only in extent of neuroectodermal phenotype and morphological differentiation.

Patterns of differentiation in extraosseous Ewing's sarcoma cells. An in vitro study

BACKGROUND

In vitro, tissue culture-associated differentiation assays have facilitated the identification of multiple tumor-cell types.

METHODS

We have investigated the capability of differentiation of three extraosseous Ewing's sarcoma cell lines toward a neural and muscular direction by in vitro stimulation with dibutyryl cyclic adenosine-monophosphate (db cAMP) and 5-azacytidine, respectively.

RESULTS

Elongation of cytoplasmic processes and increase of neural markers chromogranin, S-100 protein, and glial fibrillary acidic protein were observed after db cAMP treatment of these lines and neurosecretory granules as well as myelin figures were demonstrated ultrastructurally. These results support the existence of several pathways of neural differentiation in vitro--neuroblastic, Schwannian, and central glial--in stages of maturation more advanced than those previously reported in Ewing's sarcoma of bone. The cell lines showed no definitive myoblastic differentiation after 5-azacytidine treatment.

CONCLUSIONS

These data suggest that these three extraosseous Ewing's sarcoma cell lines configurate a heterogeneous group of tumors with respect to capability of differentiation into the neural lineage, arrested at more advanced stages of neural crest development than Ewing's sarcoma of bone and without capability of myoblastic differentiation with 5-azacytidine.

Electron microscopy in the diagnosis of small round cell tumors of bone

Small round cell tumors involving bone can present problems in differential diagnosis by light microscopy. In exploring the role of electron microscopy in this situation, seven small cell osteosarcomas and seven mesenchymal chondrosarcomas were examined by electron microscopy and compared with typical and atypical Ewing's sarcomas. There is much overlap in the ultrastructural features of these tumors, but electron microscopy is helpful to establish or confirm a diagnosis of typical Ewing's sarcoma and, if representative matrix is present, of small cell osteosarcoma.

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.

Morphometrical investigation of medulloblastoma nuclei by S.A.M. (Shape Analytical Morphometry) software system

In order to characterize medulloblastomas and to get over the difficulties sometimes encountered in differential diagnosis, a double morphometric procedure has been applied to its nuclei. The first consisted of size measurements (maximum diameter, area and perimeter), the latter is represented by S.A.M. (Shape Analytical Morphometry) software-system specifically implemented to describe shape of biological structure by analytical parameters. Analytical and dimensional parameters submitted to Hotelling's multivariate discriminant analysis gave the best results when used together in convenient discriminant subsets, thereby allowing a good distinction between medulloblastoma in comparison with neuroblastoma, Ewing's tumor, lymphoblastic and lymphocytic lymphoma. These results underline the usefulness of morphometric characterization also for practical diagnostic purposes.

Type I and type II insulin-like growth factor receptors and their function in human Ewing's sarcoma cells

Binding studies using recombinant human 125I-labelled insulin-like growth factor I ([125I]IGF-I) revealed IGF-I receptors in three Ewing's sarcoma cell lines with Kd ranging from 74 x 10(-12) M to 100 x 10(-12) M and Bmax = 36-63 fmol/mg cell protein. [125I]IGF-I binding was displaced by IGF-I, IGF-II and insulin with IC50 values of 1.5 nM, 6.3 nM and 0.7 microM respectively. Recombinant human [125I]IGF-II radioligand-binding assays in the cell lines disclosed specific binding sites for IGF-II with Kd = (110-175) x 10(-12) M and Bmax varying from 21 fmol/mg to 72 fmol/mg cell protein. Neither IGF-I nor insulin displaced [125I]IGF-II binding. IGF-I was found to increase basal glucose transport by maximally 1.5 times with EC50 = 0.9 nM IGF-I. The efficacy and potency of IGF-II on glucose uptake were comparable to those of IGF-I whereas insulin was ineffective. IGF-I and IGF-II also provoked stimulation of glycogen synthesis in Ewing's sarcoma cells. The maximal glycogenic response was reached at 0.01 microM IGF-I and 0.1 microM IGF-II, the EC50 value being approximately 1 nM IGF-I and 2 nM IGF-II. Insulin did not significantly influence glycogen formation. IGF-I and IGF-II but not insulin increased DNA synthesis in Ewing's sarcoma cells. The maximal mitogenic response was obtained with 10 nM IGF-I or IGF-II with an EC50 value of about 0.7 nM for both peptides. alpha-IR-3, a monoclonal antibody specific for the IGF type I receptor, effectively blocked IGF-I- and IGF-II-mediated metabolic responses. In conclusion, the data show that IGF-I and IGF-II induce rapid and long-term biological responses in Ewing's sarcoma cells exclusively through interaction with IGF type I receptors.

Does malignant small round cell tumor of the thoracopulmonary region (Askin tumor) constitute a clinicopathologic entity? An analysis of 30 cases with immunohistochemical and electron-microscopic support treated at the Institute Gustave Roussy

The morphology and clinical outcome of 30 patients with malignant small round cell tumors located in the thoracopulmonary region (Askin tumor) are reported. Histologically, all tumors had similar patterns, with small round-to-oval cells and a lobulated stroma. Immunohistochemical analysis always resulted in positive staining for one or several neural markers. No significant differences were found compared with the immunomarkers in 26 typical Ewing's sarcomas located outside the thoracic wall. In three specimens, electron microscopy confirmed the presence of membrane-bound neurosecretory granules. It was confirmed that there is a remarkable similarity among all malignant small round cell tumors, including Askin tumor and Ewing's sarcoma. Overall survival was poor with a 2-year rate of 38% and a 6-year rate of 14%.

Atypical primitive neuroectodermal tumors. Comparative light and electron microscopic and immunohistochemical studies on peripheral neuroepitheliomas and Ewing's sarcomas

Recently, primitive neuroectodermal tumors (PNETs) have been shown to cover a wide spectrum of small round cell sarcomas, probably including some Ewing's sarcomas (ESs) and extraskeletal Ewing's sarcomas (EESs), in addition to classical peripheral neuroepitheliomas (PNs). In studies of small cell sarcomas, we found a group of undifferentiated tumors resembling PNETs with some features of neuroectodermal differentiation, but possessing areas of relatively large, pleomorphic cells. To clarify the nature of these tumors and their relationship to PNETs, we examined the variety of histological, immunohistochemical and ultrastructural features of 11 small cell sarcomas. Five of these tumors were composed of uniform, small round cells and were classified as PNs because of the presence of definite Homer-Wright rosettes and fibrillary processes. The presence of well developed neurite-like processes containing neurosecretory granules and immunoreactivities for various neural markers suggested that these PNs showed more advanced neuronal differentiation. Two tumors, with the classical features of ES, showed no ultrastructural evidence of neuronal differentiation, although only gamma-gamma neuron-specific enolase (NSE) positivity was detected. Four undifferentiated tumors with atypical features, included in this study as an atypical PNET group, showed certain neuroectodermal characteristics, such as ganglion cell differentiation, perivascular pseudorosettes, and gamma-gamma NSE reactivity. It is concluded from this study that PNETs may include small round cell tumors showing different degrees of neuro-ectodermal differentiation and some histological variations.

The ultrastructure of small-cell osteosarcoma, with a review of the light microscopy and differential diagnosis

Small-cell osteosarcoma is a rare form of osteosarcoma and often poses difficulty in differential diagnosis when tissue samples do not include any diagnostic osteoid. By light microscopy, it may be difficult to distinguish small-cell osteosarcoma from other small-cell neoplasms, especially Ewing's sarcoma and mesenchymal chondrosarcoma. Relatively little has been reported about the ultrastructural characteristics of small-cell osteosarcoma, whereas electron microscopic examination has proven very useful in the diagnosis of most other small-cell neoplasms. We have studied four proven small-cell osteosarcomas in detail at the electron microscopic level and found their common features to be a high nucleocytoplasmic ratio, poorly differentiated cytoplasm, numerous free ribosomes and mitochondria as the next most prevalent organelle, small junctions, and envelopment of individual and groups of cells by matrix. Beyond these characteristics, cytoplasmic organelles and nuclear features varied, and no single pathognomonic ultrastructural picture was observed. However, within the range of possible ultrastructure of small-cell osteosarcoma, most small-cell neoplasms can be ruled out. Only certain examples of Ewing's sarcoma and mesenchymal chondrosarcoma may be indistinguishable from it when osteoid is not present in the sample.

Scanning electron microscopic evidence for neural differentiation in Ewing's sarcoma cell lines

A number of recent studies have suggested a relationship between Ewing's sarcoma (ES) and other small round cell tumours of childhood such as peripheral neuroepithelioma (PN). We report scanning electron microscopic studies on the character of induced neural differentiation in ES, neuroblastoma, PN, osteosarcoma and colon carcinoma. We found evidence of neural differentiation in both neural lines and in one of two Ewing's lines before treatment. After differentiation, both Ewing's and neural lines developed neuritic processes with varicosities and little arborization, except for the initially undifferentiated Ewing's line (A4573) which displayed extensive lateral sprouting from neuritic processes after differentiation. Neither treated nor untreated osteosarcoma or colon carcinoma displayed any evidence of neural differentiation. Further, neuroblastoma cells are easily distinguished from ES and PN by virtue of their single, unbranched neurites and lack of lateral sprouting or filopodia. These results provide further evidence for the neural character and close relationship between ES and PN.

Extra-skeletal Ewing's sarcoma of the nasal fossa

Extraskeletal Ewing's sarcoma is rarely found arising in the head and neck region. An unusual case arising in the nasal fossa in a young child is reported and the differential diagnosis, pathology and treatment discussed.

Acridine orange--RNA histofluorescence of sarcomas and small round cell tumors of childhood

Forty-nine pediatric malignant neoplasms were stained with acridine orange (AO) fluorochrome to qualitatively evaluate cytoplasmic RNA content. The application of AO as a supplementary stain in surgical pathologic diagnosis is based on the premise that specific neoplastic cell types characteristically and consistently contain few or many cytoplasmic ribosomes. Primitive tumors such as Ewing's sarcoma and primitive neuroectodermal tumors showed negative or low-intensity AO-RNA cytoplasmic staining. Differentiated sarcomas such as rhabdomyosarcomas and lymphomas exhibited moderate to strong AO-RNA cytoplasmic fluorescence. Acridine orange--RNA staining provides an easy, convenient, and inexpensive adjunct in the histopathologic differential diagnosis of sarcomas. It is particularly useful for distinguishing Ewing's sarcomas from other small round cell sarcomas of childhood.

Ultrastructural and immunohistochemical study of epithelioid hemangioendothelioma of bone: coexpression of epithelial and endothelial markers

Four cases of epithelioid hemangioendothelioma of bone--a borderline malignant tumor of vascular origin--were studied ultrastructurally and immunohistochemically. The epithelioid tumor cells were positive for vimentin, polyclonal and monoclonal cytokeratins, and the endothelial markers factor VIII-related antigen (FVIII:RAg) and Ulex europaeus agglutinin I. The coexpression of polyclonal cytokeratin and FVIII:RAg was demonstrated by means of step sections in the same tumor cells. The endothelial origin of epithelioid tumor cells was supported ultrastructurally by identification of Weibel-Palade bodies.

[Ultrastructure of hemangio-endothelioma of the bone]

Specimens of hemangio-endothelioma of bone from 3 patients were prepared and scrupulously analyzed with light and electron microscopes. The main findings are summarized as follows: (1) The tumour cells are of endothelial nature to form vascular spaces lined with atypical endothelial cells which bulge into the lumen. (2) Most tumour cells have a good number of organellae, especially plasmic vesicles and filaments in cytoplasm. (3) Many tumour cells are closely opposite with bridging granules in between. These features are the differentiating points of hemangio-endothelioma from other bone tumours. The plasmic vesicles are of particular interest in their function which has not yet been made clear. They may either be a structure for transporting large molecular substance including endocytosis, intracytosis and exocytosis, or a temporary storage of membrane or of plasma.

Neuroectodermal differentiation in "extraskeletal Ewing's sarcoma"

A small round cell tumor of soft tissue arising in the retroperitoneum of an 18-year-old woman is reported. The light and electron microscopic features of the tumor were mostly indistinguishable from Ewing's sarcoma of the bone and in some parts from differentiating neuroblastoma with mature neurons and Schwann cells. An immunohistochemical study using anti-NSE antibody showed many widespread NSE-positive cells lying singly and, more often, in clusters including the undifferentiated areas. The tumor was not anatomically related to the paravertebral sympathetic ganglia or adrenal glands. The present findings strongly suggest that certain extraskeletal Ewing's sarcomas are very primitive neuroectodermal tumors.

Comparative study of neuroectodermal tumor and Ewing's sarcoma of the bone. Histopathologic, immunohistochemical and ultrastructural features

We carried out a histologic, immunohistochemical and ultrastructural study of 19 tumors, previously classified as Ewing's sarcoma of the bone (ESB). The tumors were categorized histologically into four groups according to the presence or absence and the distribution of Homer-Wright rosettes, together with the immunohistochemical and ultrastructural features: 1) neuroectodermal tumor of bone (NTB) with diffusely dispersed rosettes (4 cases), 2) conventional ESB totally lacking the rosettes (9 cases), 3) intermediate-type tumor with characteristics of both NTB and ESB (4 cases), and 4) spindle cell-type tumor with focal rosettes (2 cases). Ultrastructurally, NTB contained neurotubules and neurosecretory granules, whereas ESB consisted of only undifferentiated cells. Immunoreactivity with antineural antibodies, such as Leu-7, and those against synaptophysin, NSE, neurofilament, and chromogranin, was detected in the majority of NTB, in intermediate- and spindle cell-type tumors and in two of the nine cases of ESB. In view of these findings, we propose that use of the term "neuroectodermal tumor of the bone" should be restricted to tumors with an extensive distribution of rosettes, and that those without unequivocal rosettes should be classified as ESB, although ESB may be the most undifferentiated form of NTB and some overlap may occur between the two tumor types.

Immunocytochemical and ultrastructural studies of the histogenesis of Ewing's sarcoma and putatively related tumors

The histogenesis of Ewing's sarcoma (EW) and extraskeletal Ewing's sarcoma (EEW) is still disputable. Their relationship to the so-called Askin's tumor, neuroectodermal tumor of bone, and peripheral neuroblastoma remains to be established. In an attempt to clarify these points, immunocytochemical and ultrastructural studies were done on tissues from 14 cases of EW, 4 cases of EEW, and 9 cases of primitive neuroectodermal tumor (PNET) and compared with neuroblastoma and olfactory neuroblastoma. Six tumors categorized initially as EW and EEW on biopsy, turned out to be PNET by extensive histologic and/or ultrastructural observations. Abundant glycogen was recognized not only in 16 of 18 cases of EW and EEW, but also in seven of nine cases of PNET. Fine fibrillar cell processes were seen between tumor cells, at least in limited areas even in cases of EW and EEW. Immunocytochemically, neuron-specific enolase (NSE), neuroblastoma cell surface antigen (NBCA), neuron cell surface antigen (NCSA), and neurofilament (NF) were demonstrated not only in neuroblastoma, but also frequently in cases of EW, EEW, and PNET. The results seem to suggest that EW and EEW represent the most immature forms of neuroectodermal tumor. Electron microscopic study showed predominantly primitive cells with occasional areas of cell processes, neurosecretory granules, and microtubules, suggesting a neuroectodermal origin.

Primitive neuroepithelial tumours of soft tissues and of bone: further ultrastructural and immunocytochemical clarification of 'Ewing's sarcoma', including freeze-fracture analysis

The ultrastructural appearances of 7 primitive neuroepithelial tumours (PNETs) originating in soft tissues and bone are described. Three of the tumours represented primary soft tissue lesions, while locally recurrent tumour or pulmonary metastases were studied from the 4 skeletal tumours, all of which had been diagnosed previously as Ewing's sarcomas. Rosettes were present in one of the soft tissue lesions and although not seen in the primary skeletal neoplasms, they were identified by light microscopy (LM) in 2 of 3 pulmonary metastases, one of which had the morphology of a neuroepithelioma, with innumerable Homer Wright rosettes. Conventional TEM revealed cytoplasmic processes in all cases and rosettes in varying stages of development were also evident, but the appearances did not achieve the level of cellular organization seen in neuroblastoma: microtubules were few, while dense-core granules varied in number but were generally sparse and pleomorphic, resembling lysosomes. However, typical neurosecretory granules were found in one lung metastasis; the neoplastic cells comprising the same tumour also had epithelial markers in the form of well constructed desmosomes, while freeze-fracture analysis demonstrated elaborate tight junctions. In thin sections, junctions in the other tumours appeared rudimentary, but freeze-fracture of a further case revealed small collections of membrane particles suggesting extremely poorly developed desmosomes. Immunocytochemical study of 4 tumours (2 originating in soft tissue and 2 in bone) demonstrated weak to moderate immunostaining for neurone-specific enolase and with several monoclonal antibodies reactive with neuroblastomas, but there was no evidence of immunolabelling for tyrosine hydroxylase.(ABSTRACT TRUNCATED AT 400 WORDS)

Electron microscopy of fine needle aspiration biopsies of mediastinal and paramediastinal lesions

The ultrastructural cytologic study of fine needle aspiration (FNA) biopsies from eight cases with mediastinal and paramediastinal lesions is reported. In these cases, electron microscopy (EM) was essential in cytologically determining the correct type of the cancer cells. The results in these cases suggest that portions of FNA biopsies from deep sites, where aspiration is difficult or requires computed tomographic scanning, should be routinely processed for plastic embedding, so that EM examination can be performed if the cells are undifferentiated, scanty or poorly preserved by light microscopic examination. The proper cytologic identification of the cell might, in fact, have a major bearing on the therapeutic choices and on the prognosis.

A case of Ewing's sarcoma diagnosed by fine needle aspiration. Light microscopy, electron microscopy and chromosomal analysis

A Ewing's sarcoma of the thigh in a 9-year-old boy was diagnosed by light microscopy, electron microscopy, and chromosomal analysis performed on fine needle aspirates.

Primary Ewing's sarcoma of the orbit presenting with visual loss

A case of primary Ewing's sarcoma of the orbit and paranasal sinuses in a 6-yearold boy is reported. The child presented with headaches and unilateral visual loss. Loss of vision as a result of optic nerve involvement with primary Ewing's sarcoma is extremely rare.

Malignant round cell tumor of bone with neural differentiation (neuroectodermal tumor)

A malignant round cell tumor primary in bone is reported in a young girl, showing histologically rosette formation and pseudoalveolar spaces. Vimentin, NSE, and S-100 were positive. Electron microscopy demonstrated abundant glycogen and neural features such as cell processes, microtubules, and occasional dense-core granules. Whether this neuroectodermal tumor represents a separate entity or is a variant of Ewing's sarcoma should wait for further experience, in the light of recent evidence suggesting that Ewing's sarcoma arises from primitive multipotential cells.

Ewing's sarcoma with epithelial differentiation: fine structural and immunocytochemical study

A femoral Ewing's sarcoma from a 13 1/2-year-old girl with otherwise typical clinical and pathological features showed epithelial differentiation by electron microscopy and immunocytochemistry. The expression of keratin and the presence of tonofilaments in cells of this Ewing's sarcoma may enforce the hypothesis that Ewing's sarcoma derives from a multipotential primitive stem cell.