Nucleolar organizer regions in small cell tumours of childhood

A silver colloid technique for nucleolar organizer regions (AgNORs) was applied to paraffin sections of 50 small cell tumours of childhood. These comprised 20 neuroblastomas, 10 Ewing's sarcoma, and 20 rhabdomyosarcomas, including spindle cell, myxoid, and round cell variants. On the basis of the number of AgNORs, one could differentiate between the three groups. The differences observed were statistically significant (P = 0.01-0.001). The subtypes of rhabdomyosarcoma could not be distinguished from one another on the basis of AgNOR counts. We suggest that this simple histochemical technique may be a useful adjunct to the range of special techniques now available to assist the pathologist in the diagnosis of small round cell tumours.

Immunocytochemical analysis of Ewing's tumors. Patterns of expression of intermediate filaments and desmosomal proteins indicate cell type heterogeneity and pluripotential differentiation

Examples of classical Ewing's tumors ("Ewing's sarcomas") of both skeletal and extraskeletal locations were analyzed for the expression of intermediate filament (IF) and cell junction proteins, with the use of immunofluorescence and immunoelectron microscopy as well as gel electrophoresis. In all 11 tumors examined vimentin filaments were abundant. A type of plaque-bearing small cell junction, which is common in these tumors but difficult to classify by morphologic criteria, was identified by antibodies to desmoplakins as true desmosomes. These were found in all cases, although in a very variable proportion of cells. Some of these junctions were associated with vimentin IFs. In addition, 9 of the cases examined showed scattered or clustered cells expressing the simple-epithelium type cytokeratins 8 and 18. Moreover, 3 cases displayed dispersed or clustered cells producing neurofilaments. The value of these observations, notably the cell type heterogeneity, for the diagnosis of tumors of this group is discussed. The results further indicate that Ewing's tumors are derived from a primitive, pluripotential cell that may differentiate, in variable proportions, into cells with mesenchymal, epithelial, and, more rarely, even neural features, suggesting that this tumor should be regarded as a blastoma, rather than as a true sarcoma.

[An ultrastructural analysis of malignant soft tissue tumors]

The differential diagnosis of malignant soft tissue tumors constitutes a major problem in surgical pathology. A distinction among sarcomas is sometimes difficult, but this is a situation in which histologic examination of representative tissue will give a diagnosis in the majority of cases. Electron microscopy sometimes contributes to the proper diagnosis of sarcomas. For electron microscopy, fresh samples from 110 cases of sarcoma filed at the Department of Pathology, Faculty of Medicine, Kyushu University, were examined. The distinguishing ultrastructural appearance of the following tumors are discussed: Spindle cell sarcomas (leiomyosarcoma 10 cases, malignant Schwannoma 5, fibrosarcoma 5, monophasic synovial sarcoma 7). Round cell sarcomas (rhabdomyosarcoma 10 cases, extraskeletal Ewing's sarcoma 1, malignant neuroepithelioma 1, malignant rhabdoid tumor of soft parts 3, monophasic synovial sarcoma 9). Pleomorphic sarcomas (malignant fibrous histiocytoma 24 cases, pleomorphic liposarcoma 1). Myxoid sarcomas (myxoid malignant fibrous histiocytoma 8 cases, myxoid liposarcoma 8, extraskeletal myxoid chondrosarcoma 4). Sarcomas with a specific pattern. Using electron microscopy, general analysis of cellular morphology and detection of specific structures are helpful for evaluating these sarcomas. Nevertheless, poorly differentiated sarcomas may still pose a diagnostic dilemma, since their specific features are poorly represented.

Small-cell pediatric tumors: histology, immunohistochemistry, and electron microscopy

Histology, immunohistochemistry, and electron microscopy give an account on what is known of the correlation between histologic appearance and prognosis in this important group of tumors. Ultrastructural and immunohistochemical findings are presented that frequently are useful in establishing a diagnosis, but also serve to elucidate the histogenesis of some tumors, especially those that lack characteristic features.

Characterization of intermediate filaments expressed by Ewing tumor cell lines

The histogenesis of Ewing sarcoma is still controversial; we therefore studied the expression of intermediate filaments (IF) in cell lines derived from Ewing tumors since identification of IF in tumor cells is considered a reliable marker of tissue origin and differentiation. All nine lines studied expressed vimentin IF; in addition, a small number of Ewing cells from three lines expressed keratin filaments. After treatment with phorbol esters, a high percentage of cells from these three lines synthesize keratin IF identified by immunoblotting as keratin 8 and 18 polypeptides, which are expressed by single epithelia and epithelial cells in early embryonic development. Furthermore cells from a fourth line synthesize keratins after transplantation in nude mice. These data indicate that, under certain conditions, undifferentiated Ewing cells may acquire an IF phenotype related to that of epithelial cells.

Ewing's sarcoma lines synthesize laminin and fibronectin

Immunoelectron microscopy was employed to detect laminin and fibronectin cell surface expression on five Ewing's sarcoma lines plus a normal fibroblast line as control. Monospecific antibodies to both glycoproteins were detected on tumour cell and fibroblast layers with colloidal gold--protein A conjugates. All five tumour lines were positive for fibronectin and/or laminin, whereas the fibroblast line expressed fibronectin only, as expected. Fibronectin displayed a dense granular pattern, typically in the cell-cell and cell-matrix adhesion areas; laminin displayed a punctate pattern. 3H-leucine metabolical labelling was also used to demonstrate laminin and fibronectin synthesis. The labelled proteins released in the culture media were separated by molecular weight on SDS-PAGE and identified by immunoprecipitation with the monospecific antibodies. The results substantiated the immunoelectron microscopy data. These findings indicate that Ewing's sarcoma lines produce a complex extracellular matrix including fibronectin and laminin, in addition to the collagens described by other workers. Histogenetic classification of this tumour in terms of extracellular matrix proteins synthesis is thus more difficult than has been supposed. The same complexity must also be borne in mind when using the matrix components as an aid to Ewing's sarcoma differentiation from other childhood tumours.

Embryonic ultrastructure as a guide in the diagnosis of tumors

The purpose of this article has been to illustrate the applications and limitations of comparing the ultrastructural morphology of certain poorly differentiated neoplasms with normal human embryonic tissues. The examples used--embryonal rhabdomyosarcoma, Wilms' tumor, and fibrous mesothelioma, in comparison with embryonic mesoderm and its early derivatives--are but a few of the entities that can be investigated in this manner. Ewing's sarcoma was included in the report because of the long-standing and unsolved mystery concerning its histogenesis and because we believe it probably fits into the same category of poorly differentiated mesodermal neoplasms as the other lesions described. However, unlike the other more definite examples of primitive neoplasms manifesting focal markers of secondary mesenchymal differentiation, Ewing's sarcomas exhibit no ultrastructural evidence for myogeneous, nephrogenic, or mesothelial lines of maturation. Nor are there any morphologic indications of ectodermal or endodermal differentiation. The questions arise as to whether the category of Ewing's sarcoma has been perpetuated by so classifying all small-cell neoplasms having no recognizable line of differentiation, and whether this category may include cells of more than one type, that is, cells that are biologically determined to develop along several different pathways. This concept would be one explanation for the occurrence of Ewing's tumors in soft tissue as well as in bone, and we know that the cells contained in somites are ultrastructurally very similar to the least-differentiated cells making up the myotomes and sclerotomes. Apparently, questions such as these cannot be answered by morphologic studies alone. However, a number of other useful diagnostic and academic points of information can be gleaned.

Epithelioid hemangioendothelioma of bone. A clinicopathologic, ultrastructural, and immunohistochemical study

In a review of 29 cases of solitary and multicentric hemangioendothelial sarcomas of bone, 14 were found to have histologic features of epithelioid hemangioendotheliomas. These were characterized by the presence of epithelioid or "histiocytoid" endothelial cells that were either round or spindle-shaped. Intracytoplasmic vacuolization was noted, and some showed nesting of cells, mimicking metastatic adenocarcinoma. The presence of a myxoid matrix suggested the diagnosis of chondrosarcoma in some cases. Some of the tumors strongly resembled the lesions formerly designated as intravascular bronchioloalveolar tumor, angioglomoid tumor of bone, or malignant myxoid angioblastoma of bone. Factor VIII-related antigen was detected in five of the six cases examined, and ultrastructural study in five cases confirmed the endothelial nature of the tumor cells; Weibel-Palade bodies were present in three cases. There were 11 men and three women, and the tumors were seen predominantly in patients who were under 30 years of age (10 cases). Four cases involved solitary tumors, and nine were multicentric in bone. The multicentric tumors had a predilection for the bones of one lower extremity (five cases). The total series had a protracted clinical course, and the multicentric tumors appeared to follow a less aggressive course.

Extraskeletal Ewing's sarcoma arising in the broad ligament

The necessity for ultrastructural and immunohistochemical examination in establishing the diagnosis of extraskeletal Ewing's sarcoma is reemphasized by the unusual presentation of such a tumor in the broad ligament of a 41-year-old woman. Implications for therapy are discussed.

Extraosseous Ewing's sarcoma versus primitive rhabdomyosarcoma: diagnostic criteria and clinical correlation

A light and electron microscopic study of 51 cases of Ewing's sarcoma of bone (ESB) and 33 soft tissue sarcomas (carrying a variety of light microscopic diagnoses, including primitive rhabdomyosarcoma) in children and young adults was performed to clarify the similarities and differences among these tumors. Ultrastructural criteria were developed to evaluate the neoplasms. Remarkable ultrastructural uniformity was found in the cases of ESB. In contrast, the soft tissue sarcomas could be divided into two distinct groups on the basis of the ultrastructural criteria: those closely resembling primitive areas of otherwise differentiated rhabdomyosarcomas, and those indistinguishable from ESB. It is proposed that the diagnosis of soft tissue Ewing's sarcoma be reserved for lesions identical to ESB by both light and electron microscopy. The first group of sarcomas may be histogenetically related to rhabdomyosarcoma and should be distinguished from extraosseous Ewing's sarcoma, as their clinical behavior appears to be quite different.

Primary Ewing's sarcoma of the base of the skull

The authors report a case of primary Ewing's sarcoma of the petrous bone. The radiological features, including the computed tomographic scan and angiographic findings, are described in detail.

Extraskeletal Ewing's sarcoma: a clinical, morphological and ultrastructural analysis of five cases with a review of the literature

In 1969 it was recognised that tumors with light microscopic appearances indistinguishable from Ewing's sarcoma of bone may arise in extraskeletal sites (extraskeletal Ewing's sarcoma). Here, we review the available literature and report five new cases. All five received combined modality therapy with combination chemotherapy and radiotherapy to the primary site followed by surgical excision in two. All attained complete remission; after a median follow-up of 26 months, three remain disease-free but two have relapsed and died. Our experience, in accord with previous series, suggests that extraskeletal Ewing's sarcoma compared with its bony counterpart tends to occur in older subjects, has a similar incidence in males and females, usually presents with a painless mass and readily responds to combined modality therapy. We detected no light or electron microscopic features to denote a histogenetic origin. However, we suspect extraskeletal Ewing's sarcoma may occur more frequently than previously supposed.

Extraskeletal Ewing's sarcoma with cutaneous involvement

We report the case of a 13-year-old girl with extraskeletal Ewing's sarcoma involving the skin and subcutaneous tissue of the upper back. The patient underwent wide local excision and right axillary node dissection, and received chemotherapy with vincristine, actinomycin D, and cyclophosphamide. There was no evidence of recurrence or metastasis in eight months of follow up. Light and electron microscopic features were typical for this neoplasm. Tumor cells contained abundant glycogen, but failed to stain for desmin, keratin, neuron-specific enolase, or S-100 protein. We discuss the differential diagnosis of extraskeletal Ewing's sarcoma as well as theories of its histogenesis.

Cutaneous extraskeletal Ewing's sarcoma

Extraskeletal Ewing's sarcoma has been recognized as being histologically indistinguishable from Ewing's sarcoma of bone. Although the occurrence of extraosseous Ewing's sarcoma in deep soft tissues has been well described, such cutaneous lesions are rare. We report the clinical history, histopathologic findings, and results of ultrastructural study of this rare variant occurring in a 12-year-old girl. She presented with a dermal and subcutaneous tumor of the left third toe, without osseous involvement. The lesion was composed of masses of round-oval cells, with perilobular fibrosis, focal hemorrhage, ill-defined pale cytoplasm containing glycogen, and absent pericellular reticulin. Ultrastructural study showed a monotonous cell population, with focal thickening of apposing membranes, high nuclear/cytoplasmic ratio, copious intracytoplasmic glycogen, and paucity of organelles except mitochondria. We present this case along with discussion of the literature and problems concerning differential diagnosis of small cell malignancies in the skin.

Aspiration cytology of Ewing's sarcoma. Light and electron microscopic correlations

Fine-needle aspiration biopsy specimens from 15 histologically proven cases of Ewing's sarcoma of the bone were studied by both light and electron microscopy. Large glycogen deposits in the Ewing's sarcoma cells could be easily recognized in smears stained routinely with Diff-Quik (American Scientific Product, McGraw Park, IL). These deposits appeared as punched-out clear spaces in the cytoplasm. Ultrastructurally the tumor cells could be divided into chief cells and dark cells. The chief cells were further categorized based on their nuclear morphologic features into cleaved, noncleaved, and intermediate cells. The dominant cell was noncleaved in eight, cleaved in three, and intermediate in four cases. All five tumors with abundant glycogen were composed predominantly of noncleaved cells. The tumor cells in aspiration material appeared to be irregular in shape, and some had cytoplasmic processes. In one tumor these processes were quite prominent; this caused some difficulty in differentiation from neuroblastoma.

An unusual banded structure in Ewing's sarcoma

In a largely haemorrhagic and necrotic specimen of Ewing's sarcoma we found banded structures (periodicity of banding about 250 nm) of a type hitherto not known to occur in any normal or pathological tissue. Morphological appearances suggested that these structures had evolved from the fibrin which was always closely associated with them. However, this idea was abandoned because the periodicity of banding of these structures is about ten times greater than the known periodicity of banding of fibrin. These structures have the same periodicity of banding as fibrous long-spacing collagen produced in vitro and about twice the periodicity of banding of fibrous long-spacing collagen found in vivo. However, they lack the fine striations or minor bands of the in vitro fibrous long-spacing collagen. We therefore conclude that the banded structures in this tumour represent a new form of fibrous long-spacing collagen which shares the features of in vitro and in vivo types of fibrous long-spacing collagen.

Cell interaction with the extracellular matrices produced by endothelial cells and fibroblasts

The extracellular matrices (ECM) produced by cultured bovine corneal endothelial cells and chick embryo fibroblasts were compared for their induction of cell attachment, proliferation and differentiation. The corneal endothelial ECM (cECM) induced a comparable and rapid attachment and flattening of both human Ewing's sarcoma and colon carcinoma cells which utilize fibronectin and laminin as adhesive glycoproteins, respectively. In contrast, the ECM produced by fibroblasts (fECM) readily supported the attachment and flattening of Ewing's sarcoma cells but had only a small effect on the carcinoma cells. Vascular endothelial cells were stimulated to proliferate by both types of matrices, but to a lesser extent by the fECM. In contrast, the formation of a closely apposed, non-overlapping and contact-inhibited endothelial cell monolayer was only dictated by the cECM. Vascular endothelial cells cultured on fECM grew on top of each other and incorporated [3H]thymidine even late at confluency. Neurite outgrowth (ciliary ganglion cells) and network formation (adult rat oligodendrocytes) were promoted by both types of matrices but in a more consistent manner with the cECM. It is likely that the small amounts of laminin deposited by chick embryo fibroblasts into their ECM are responsible for its efficient induction of neurite outgrowth and for the limited degree of carcinoma cell attachment and flattening. It is thus demonstrated that differences in chemical composition and supramolecular arrangement between cECM and fECM result not only in differences in the attachment, spreading and proliferative responses of cells but also in the expression of their characteristic morphological appearance and differentiated functions.

Small round cell neoplasms: can electron microscopy and immunohistochemical studies accurately classify them?

The answer to the question posed in the title, "Small Round Cell Neoplasms: Can Electron Microscopy and Immunohistochemical Studies Accurately Classify Them?", is obviously "yes"; but a qualified yes--generally yes, perhaps with expertise usually yes, but never just plain yes. Some cases certainly will defy the best attempts even of the most expert in the application of these "special" techniques. And embarrassing as it may be for those of us infatuated with the latest technology to admit, it is with the difficult case especially that old-fashioned technology so often must be depended upon. In his excellent recent appraisal of the role of a variety of special techniques in this application, Triche offers the following comment: "Overall, electron microscopy is probably the most universally useful of all diagnostic techniques other than light microscopy in round cell tumors." The data from our studies certainly point to the same conclusion. With each of the tumors, electron microscopy demonstrated itself to be more reliable than immunohistochemistry. Electron microscopy offers not only greater sensitivity and specificity, but also greater versatility. Immunohistochemistry allows hypothesis testing only. Electron microscopy, on the other hand, can provide answers even when the right questions are not being asked. For example, if a particular small round cell tumor under investigation happens in actuality to represent something other than the neuroblastoma which it is being considered (e.g., a granulocytic sarcoma, liposarcoma, Wilm's tumor, etc.), electron microscopy can reveal this fact, but a neuron-specific enolase stain cannot. Parenthetically, it should also be said that electron microscopy has proven particularly well suited to the examination of fine-needle aspiration specimens. The two spare many patients in our institution the need for a major operative procedure to establish a secure tissue diagnosis. Immunohistochemistry does have a role to play but it is, at least in our opinion, clearly secondary to that of electron microscopy. The concept of replacing electron microscopy with a battery of immunostains has often been advocated as an economic measure, but this argument begins quickly to lose its weight as the number stains included in the battery is increased to cover the diagnostic possibilities. Giving consideration to the capriciousness of some of these stains, there exists with this also an increasing possibility of a spurious or misinterpreted result leading to an errant diagnosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Epithelioid haemangioendothelioma of the bone tissue

An epithelioid haemangioendothelioma arising in a 43-year-old Japanese woman is presented. The patient first complained of severe back pain and neurogenic disturbances due to compression fracture of the spinal bone. Radiographically the tumour masses showed osteolytic lesions without reactive new bone formation. Similar lesions were noted in other bones. Biopsy and surgical specimens showed the features of epithelioid haemangioendothelioma. A lymphocyte associated antigen, HLA-DR which has been regarded as a B lymphocyte marker was detected in the tumour cells. The importance of this finding was emphasized with respect to the identification or classification of vascular tumours.