Immunohistochemistry of central nervous system tumors. Its contributions to neurosurgical diagnosis

An immunohistochemical study of neuroepithelial (colloid) cysts

Monoclonal and polyclonal antisera were used against 12 cases of neuroepithelial (colloid) cysts to determine the specific antigenic profile of the cyst epithelium. Intermediate filament markers (cytokeratin, vimentin, neurofilament, and glial fibrillary acidic protein) and epithelial markers (epithelial membrane antigen and monoclonal antibody lu-5) demonstrated that colloid cyst epithelium has a unique antigenic profile in contrast to that of choroid plexus or glial tissue. Theories raised to explain the etiology of colloid cysts have included derivation from the embryonic paraphysis, detachments of developing neuroepithelium from the tela choroidea, and remnants of respiratory epithelium; a more recent theory suggests that these cysts are products of developing choroid plexus or ependyma. The present study shows that colloid cyst epithelium is distinct from that of choroid plexus or ependyma and therefore does not represent a product of their formation, nor does it represent a form of immature glia. This finding supports the conclusion that colloid cysts in any ventricular location represent a developmental anomaly of primitive neuroectoderm in the embryo, which remains unique from other products of neuroectodermal derivation.

Immunohistochemistry of retinoblastoma. A review

Various studies which relate to the immunohistochemical identification of neuronal, glial, carbohydrate and nucleic acid associated antigens in retinoblastoma will be reviewed. The majority of these studies appear to support the concept that retinoblastomas arise, in situ, from neuron committed cells and in some cases specifically into photoreceptor-like cells. In selected cases, however, glial cell differentiation may be a feature of the tumor. In addition, the molecular biology of the retinoblastoma gene and the immunohistochemical characterization of its gene product will be discussed.

Applications of immunocytochemistry to diagnostic cytopathology

Immunohistochemical technique is now successfully applied to the cytologic materials. This review article describes details of staining procedures for immunocytochemistry at both light and electron microscopic levels. The clinical application of the technique includes aspiration biopsy cytology for breast lesions, thyroid lesions, lymph nodes, the nervous system, and others. The establishment of carcinoma cells in the body fluid by the demonstration of carcinoembyronic antigen (CEA) and the establishment of specific diagnoses in small-cell or large-cell anaplastic tumors by immunocytochemistry warrants special emphasis.

Diagnostic markers in human neurooncology. A progress report

In this progress report, some of the most commonly used antibodies are discussed in regard to their immunohistochemical application to human neurooncology. The importance of determining the spectrum of antibody immunoreactivity in a wide panel of normal, reactive, and neoplastic tissues is stressed. in atypical and aberrant cases, immunopositivity needs to be interpreted with caution and in the context of all other available data. The demonstration of a well-characterized, cell type-specific marker in a tumor reflects not so much its cytogenesis as its differentiation potential and its capacity for metaplasia. The relation of an abnormal or aberrant expression of antigenic determinants to the process of neoplasia raises a number of intriguing questions to which research in the next few years will likely provide answers.

Cerebral primitive neuroectodermal tumors in childhood

A series of 17 infants and children with cerebral primitive neuroectodermal tumors (PNETs) detected by computed tomography is presented. The pertinent literature is reviewed. Because of ongoing nosological difficulty, we include in this series only those tumors which are located in the cerebral hemisphere, and are composed of predominantly undifferentiated neuroepithelial tumor with or without glial or neuronal differentiation. The prognosis of the patients with cerebral PNETs remains poor despite treatment including surgical resection, radiation therapy and/or chemotherapy. Only two patients had a long term survival more than 4 years in this series. The histological features and the extent of surgical resection did not influence the patients survival. Nevertheless, visible total resection afforded better control of local disease of the primary site, but remote metastases along the cerebrospinal fluid pathway were frequent at relapse. The patients with cerebral PNETs appear to be best treated with radical gross total resection, postoperative radiation therapy including irradiation to the neuraxis and aggressive chemotherapy.

An immunohistological study of 66 ependymomas

Sixty-six ependymomas were examined immunohistologically to determine their distribution of glial fibrillary acidic proteins, S-100 protein and vimentin. The neoplasms were subdivided into four groups: (1) ependymomas from the cauda equina, predominantly of the myxopapillary type; (2) benign ependymomas; (3) malignant ependymomas; and (4) ependymoblastomas. Marked differences in antigen reactivity were observed between each group. The intensity of the reaction with the three antibodies was strongest in malignant ependymomas. Ependymomas from the cauda equina showed a patchy distribution of positivity for the three antigens in cells surrounding blood vessels but there was no staining of collagenous septa or the myxoid areas. In ependymoblastomas, the cells of the rosettes were negative for glial fibrillary acidic protein, but there was focal positivity for vimentin and S-100. Other areas showed tumour cells containing moderate amounts of vimentin and small amounts of S-100, and a few bands of filaments positive for glial fibrillary acidic protein. The cytogenetic and biological implications of these findings are discussed.

Pineoblastoma with neuronal differentiation--immunohistochemical and immunocytochemical studies

Immunohistochemical and immunocytochemical studies were performed on a specimen obtained at operation from a 4 year-old female with intracranially spread pineal tumor in the right temporal lobe. Microscopically, it was a highly cellular tumor, and the cells contained chromatin-rich round or oval nuclei and scanty cytoplasms. There were numerous mitotic figures. Rosettes were not detected. Both immunohistochemical staining of paraffin-embedded sections and immunocytochemical staining of short-term cultured cells disclosed a subgroups of cell positive for NSE and 68K-NF (neurofilament). No cells were positive for GFAP, S-100 protein or HCG. From these findings, the tumor was thought to be pineoblastoma, which is an undifferentiated tumor that rarely shows divergent differentiating potential. This is the first report of pineoblastoma with the differentiation only toward the neuronal line confirmed by the analysis of immunohistochemistry and immunocytochemistry.

Uveal malignant melanoma and von Recklinghausen's neurofibromatosis

A case of uveal malignant melanoma with extensive spread to the central nervous system occurring in a 63-year-old woman with peripheral-type von Recklinghausen's neurofibromatosis was studied by light microscopy. The tumor histologically consisted of large, loosely coherent epithelioid cells with abundant eosinophilic cytoplasm and large, irregular nuclei with prominent nucleoli. The tumor cells contained variable amounts of melanin pigment and exhibited positive immunohistochemical staining for S-100 protein and neuron-specific enolase. A review of the literature disclosed only ten previous cases of uveal malignant melanoma associated with von Recklinghausen's neurofibromatosis. A predominance of women and of the peripheral variant of von Recklinghausen's neurofibromatosis was noticed in the cases reported.

Late recurrence of primitive neuroectodermal tumor/medulloblastoma

The period of risk for recurrence of primitive neuroectodermal tumor/medulloblastoma (PNET/MB) is not clearly defined. With current treatment since more than 50% of children with PNET/MB can be expected to survive for at least 5 years after diagnosis, determining the evidence of "late" recurrence is of increasing concern. Collins has stated that patients with embryonal tumors who survive, disease free, for a period of time equal to the age at diagnosis plus 9 months can be declared cured. This, so-called Collins' law has been applied to patients with PNET/MB. To determine the incidence of "late" recurrence, factors which impact on recurrence and applicability of Collins' law, the authors studied all patients diagnosed with PNET/MB at the Children's Hospital of Philadelphia, Hospital of the University of Pennsylvania, Philadelphia, and Geisinger Medical Center, Danville, Pennsylvania, between 1970 and 1984. For the 44 patients in this study, the disease-free survival at 5, 10, and 12 years was 54%, 41% and 30%, respectively. For children surviving 5 years, the actuarial survival at 10 years was 75% and at 12 years, 51%. Age, sex, dose of radiotherapy, chemotherapy, or extent of surgery were not predictive of late relapse. Recurrence in three of seven patients (43%) occurred outside the "period of risk" as predicted by Collins. It appears that the "period of risk" for recurrent central nervous system tumors after PNET/MB is as yet undefined and probably indefinite.

S-100 immunoreactivity in primary and metastatic carcinoma of the breast: a potential source of error in immunodiagnosis

Immunoreactivity for S-100 protein, typically a marker for malignant melanoma and neural-derived tumors, was observed in neoplastic cells of 57 of 68 cases (84%) of formalin-fixed, paraffin-embedded primary and/or metastatic carcinoma of the breast of various histologic types. The extent of S-100 immunoreactivity varied, with only a minor proportion of positive tumor cells noted in some cases. An awareness of this staining profile for S-100 protein, particularly in metastatic poorly differentiated neoplasms with unknown primaries, is imperative for accurate immunohistochemical interpretation. Using a panel of reagents which includes antibodies to keratin proteins and epithelial membrane antigen, the epithelial nature of S-100-positive carcinomas may be readily defined. Tumor cells in all cases of primary and metastatic carcinoma of the breast evaluated in this study exhibited strong staining for both of these tissue markers. To preclude misinterpretation of tumor type due to anomalous staining patterns for a specific antibody, eg, S-100 protein, a panel of antibodies is recommended for assessment of metastatic poorly differentiated tumors.

Immunocytochemical analysis of intermediate filaments in human ependymal tumors

The peroxidase anti-peroxidase technique was used for localization of glial fibrillary acidic protein (GFAP) and vimentin (VM) in 19 ependymal tumors in order to determine if a unique pattern of intermediate filament (IF) expression could be demonstrated. Cytokeratin (CK) immunoreactivity was examined in a subgroup of 7 tumors with papillary pattern. Nineteen non-ependymal neuroectodermal tumors were used as controls. Ependymomas, subependymomas and astrocytomas were positive for both IF. Oligodendrogliomas, oligodendroglial portions of mixed gliomas and the majority of medulloblastomas were negative for GFAP and VM. Areas of poor differentiation in all tumors demonstrated little expression of any IF. A composite ependymoma/choroid plexus papilloma showed the presence of GFAP, VM and CK in the papillomatous portion only. Four papillary ependymomas were negative for CK. This study emphasizes the parallel distribution of GFAP and VM in well differentiated ependymomas and other glial tumors and casts doubt upon the concept of VM as a marker for de-differentiation in neuroectodermal neoplasia.

Intracranial olfactory neuroblastoma mimicking carcinoma: report of two cases

Two cases of olfactory neuroblastoma which presented clinically as intracranial lesions are described. Prominent features of epithelial differentiation were present, which led to initial diagnoses of poorly differentiated carcinoma. The true nature of the lesions was only established subsequently by careful histological examination, immunohistochemistry and electron microscopy. The potential towards epithelial differentiation in such tumours was emphasized and certain new histological features were described, including a biphasic epithelial and stromal pattern, papillae formation and positive staining for cytokeratin. These two cases underline the importance of exhaustive examination of poorly differentiated epithelial-like lesions of the frontal lobes by conventional histology, immunohistochemistry and electron microscopy.

Ependymal and choroid plexus tumors. Cytokeratin and GFAP expression

Twenty-six ependymal and 15 choroid plexus tumors were examined with monoclonal antibody against cytokeratin using the avidin-biotin-peroxidase complex (ABC) technique. Serial sections were examined with antisera to glial fibrillary acidic protein (GFAP). In five ependymal tumors (one ependymoma, two papillary ependymomas, and two primitive neuroectodermal tumors [PNET] with ependymal cells), a variable number of cytokeratin-positive cells were present. Most tumor cells (except two PNET) were positive with GFAP antisera. Many cytokeratin-positive cells were present in all choroid plexus tumors. GFAP-positive cells were present focally in six of 11 papillomas and in one of four carcinomas. Although their staining patterns and distribution were clearly different, focal coexistence of cytokeratin and GFAP was observed in six papillomas and two ependymal tumors. Thus, some ependymal tumors (especially papillary ependymomas and occasional PNET) and many choroid plexus tumors have demonstrable positivity with antibody to cytokeratin, suggesting a transitional cell type with features of both ependyma and choroid plexus.

Mixed oligodendroglioma and astrocytoma: fine structural and immunohistochemical studies of four cases

Four mixed oligodendrogliomas and astrocytomas were investigated by electron microscopy and immunohistochemistry (GFAP, NSE and MBP). GFAP-positive oligodendroglioma cells and their transitional cells to GFAP-negative oligodendroglioma cells were present, suggesting successive morphological changes of astrocytic tumor cells. NSE-positive cells, suggestive of residual neurons, also exhibited round nuclei and perinuclear halos. On electron microscopy, oligodendroglioma cells that showed glial filaments, vascular end-feet and zonulae adherentes were occasionally present. The tumor cells with or without astrocytic characteristics showed common features of cytoplasmic organelles. These findings suggest that most oligodendroglioma cells in mixed gliomas are of an astrocytic nature and that characteristic microscopic features of oligodendroglioma are of a common cellular form that can be taken by various types of cells under certain circumstances.

Melanotic medulloblastoma. A case report with immunohistochemical and ultrastructural examination

A melanotic medulloblastoma is reported with electron microscopic and immunohistochemical findings. The cerebellar tumor had seeded through the cerebrospinal fluid to cerebrum and spinal cord, spread through the dura, and metastasized to the lungs. It consisted of (i) anaplastic cells with slight neuronal differentiation, but without the fibrillary background of neuroblastomas, and (ii) epithelial islands pigments with melanin. The latter participated in the spread through the subarachnoid space, but did not extend beyond the dura. Electron microscopy revealed in the pigmented cells tight junctions and oculo-cutaneous melanin, including premelanosomes. The anaplastic cells had undistinguished organelles and only small junctions. On immunohistochemistry, the cytoplasm of the anaplastic cells was positive for neuron-specific enolase and neurofilament, and some of the nuclei were positive to S-100, confirming neuronal differentiation. The cells did not stain for glial fibrillary acidic protein, carcinoembryonic antigen, cytokeratin, alpha fetoprotein, vimentin, and epithelial membrane antigen. The melanotic cells were negative to all reagents tested, even to S-100 protein. The presence of oculo-cutaneous melanin and of neuronal elements indicate a neuroectodermal or neural crest origin.

Retinal S-antigen immunoreactivity in medulloblastomas

A series of 16 cerebellar medulloblastomas were studied immunohistochemically using a four-step immunoperoxidase (PAP) method and a monoclonal antibody (MAbA9-C6) which defines an epitope of the retinal S-antigen, a protein known to occur in retinal photoreceptor cells and pinealocytes of the pineal gland as well as in retinoblastomas, pineocytomas and pineoblastomas. Immunopositivity was demonstrated in a variable number of tumor cells in 50% of the cases. This finding may be an indication of a differentiation potential of medulloblastomas along the photoreceptor cell lineage. Alternatively, it may simply indicate the non-specificity of the retinal antigen in the neoplastic state.

Gamma-enolase and glial fibrillary acidic protein in nervous system tumors. An immunohistochemical study using specific monoclonal antibodies

A large series of central and peripheral nervous system tumors was studied for the presence of glial fibrillary acidic protein (GFAP) and gamma-enolase (neuron-specific enolase, NSE), using specific monoclonal antibodies (mAbs). Occurrence in and specificity of GFAP to glial and mixed tumors was confirmed and depended on the malignancy grade and features such as meningeal invasion. Using a well-characterized mAb, gamma-enolase was demonstrated in neuronal, as well as in a whole range of non-neuronal tumors. This lack of specificity of gamma-enolase prohibits its use as an exclusive neuronal marker. Nevertheless quantization or comparison with other types of enolases could still prove to be useful in well-defined situations. The advantages inherent to mAbs and a highly sensitive detection system turn GFAP stainings into a specific and readily reproducible technique.

Ependymoblastoma: a histological, immunohistological and ultrastructural study of five cases

Five ependymoblastomas were studied by means of routine histological techniques, immunohistology and electron microscopy. The tumours were characterized histologically by medium sized, poorly differentiated cells with round or oval nuclei frequently in mitosis and by ependymoblastic rosettes. Reactions for cytokeratin and neurofilament were negative and tubular material positive for glial fibrillary acidic protein was scanty. All five tumors demonstrated positivity for vimentin and S-100 protein. Electron microscopy showed poorly differentiated cells with high nucleo-cytoplasmic ratio and scanty cytoplasmic organelles. Sparse rosettes were present and the cells were united by junctional complexes. Frequent rudimentary or incomplete cilia, a few basal bodies and a few short intercellular glial-like filaments were seen. Features differentiating ependymomas and anaplastic ependymomas from ependymoblastomas are discussed and the need for a definite category separating ependymoblastomas from the former tumours is emphasized.

An immunocytochemical demonstration of calcineurin in human nerve cell tumors. A comparison with neuron-specific enolase and glial fibrillary acidic protein

Human central and peripheral nerve cell tumors were examined in detail using antibodies to calcineurin, glial fibrillary acidic protein (GFAP) and neuron-specific enolase (NSE). Forty-eight formalin-fixed and paraffin-embedded specimens of human neuronal tumors, including 27 medulloblastomas, were examined. Calcineurin-positive cells were found in all peripheral nerve cell tumors and the two gangliogliomas, whereas 20 of the 27 medulloblastomas and one of the two cerebral neuroblastomas did not contain calcineurin-positive cells. Differentiation of cells along the neuronal lines was positively correlated with calcineurin immunoreactivity. NSE-positive cells were found in all of the tumors with the exception of the one cerebral neuroblastoma. NSE immunoreactivity was not invariably consistent with calcineurin immunoreactivity and non-neuronal cells were often positive. Calcineurin-positive cells were all devoid of GFAP, but NSE-positive cells expressed GFAP in some tumors. GFAP-immunoreactive cells were found only in central nerve cell tumors, and not in peripheral tumors. In addition, GFAP-positive cells in some tumors such as retinoblastoma and medulloblastoma morphologically revealed not only neoplastic but also reactive astrocytic features.

Immunocytochemistry of intracranial meningiomas

Fifty meningiomas of four major histological types have been examined by immunocytochemical methods applied to formalin fixed paraffin embedded material and using readily available commercial antisera. The expression of GFAP, S100, NSE, vimentin, cytokeratin, fibronectin and desmoplakin was investigated. The majority of tumours contained NSE (86%) and S100 (78%), and all irrespective of histological type, contained vimentin and fibronectin. The epithelial marker cytokeratin was found in 56% of cases, but showed only focal expression. The relevance of these findings to histogenesis and metabolism is discussed and it is suggested that intermediate filament typing provides valuable information on meningiomas structure and function. The possible role of NSE and S100 in meningeal neoplasm is discussed.

Antidesmosomal monoclonal antibody in the diagnosis of intracranial tumours

Immunocytochemistry has been applied extensively to the diagnosis of intracranial tumours, but meningiomas still present a diagnostic problem. However, desmosomes have been shown by electron microscopy to be present in meningiomas, and this distinguishes them from gliomas. This paper describes a new monoclonal antibody, 11-5F, against desmosomal proteins 1 and 2 (desmoplakins) and assesses its usefulness in the diagnosis of meningiomas and other intracranial tumours. A total of 74 surgically removed intracranial tumours were examined by fluorescent antibody staining with 11-5F on frozen sections. In addition, a panel of antibodies against cytokeratin, vimentin, glial fibrillary acidic protein, and S100 protein was used. 11-5F stained 30/30 meningiomas and 14/14 metastatic carcinomas but 0/30 gliomas, thus distinguishing meningiomas and metastatic carcinomas from gliomas. The distinction between meningiomas and metastatic carcinomas on the basis of intermediate filaments staining was more difficult because neither the anticytokeratin nor the antivimentin antibody was specific for either tumour type. This study emphasizes the value of antidesmosomal antibodies as an important adjunct to the diagnosis of intracranial tumours.

Effect of sodium butyrate on S-100 protein levels and the cAMP response

Sodium butyrate (NaB), when added to cell cultures, produces a variety of morphological and biochemical changes. We examined its effects, in nM concentrations, on the expression of two glioma cell-associated proteins, glial fibrillary acidic protein (GFAP) and S-100 protein in human glioma-derived cell line (RF), and of S-100 protein in the C6 rat glioma cell line. GFAP levels decreased by about 50% in the RF cell line, and S-100 protein levels decreased protein levels decreased by about 40% after treatment with 1 mM NaB for 48 h. In the C6 rat glioma cell line, isoproterenol with theophylline was found to increase S-100 levels by two-fold over basal levels. NaB was found to inhibit the induction of S-100 protein but exhibited no effect on the basal levels of the protein. Other short chain fatty acids, including sodium propionate and sodium isobutyrate, exhibited partial inhibitory activity. NaB, at an EC50 of 1 mM, was also found to inhibit both the beta-adrenergic and the forskolin-mediated increase in cAMP levels in these cells. This suggests that NaB may inhibit cells from expressing S-100 protein by attenuating cAMP levels.

Contribution to the problem of giant cell astrocytomas

Histological, immunocytochemical, and biological features of 38 giant cell gliomas were investigated. The invasion of these tumors and its giant cells by histiocytes, lymphocytes, plasma cells, and especially by eosinophilic granulocytes is viewed as an immune response, which may explain a favorable clinical course. Fifty-three percent of the patients were younger than 45 years at the time of surgery. The average postoperative survival of 27.4 months was clearly longer than in glioblastoma. These biological features suggest a differentiation from glioblastoma multiforme. The classification of this entity as "monstrocellular astrocytoma" is proposed.

Immunohistochemical characterization of human retinoblastomas in situ with multiple markers

We studied paraffin-embedded specimens from 18 surgically enucleated eyes with retinoblastoma by peroxidase-antiperoxidase immunohistochemistry with antibodies against glial fibrillary acidic protein, S-100 protein, Leu 7 epitopes, neuron-specific enolase, the 200-kilodalton subunit of the neurofilament triplet polypeptide, and retinal S-antigen. We found that (1) glial fibrillary acidic protein, S-100 protein, and Leu 7 epitopes were detected only in well-differentiated glial cells that were interpreted as reactive and not neoplastic, (2) undifferentiated neoplastic cells expressed both neuron-specific enolase and retinal S-antigen immunoreactivity, and (3) differentiated cells forming Flexner-Wintersteiner rosettes were found to express neuron-specific enolase, retinal S-antigen, and, occasionally, neurofilament protein. These results support the view that retinoblastomas are composed of neuron-committed cells and favor the origin of these tumors from photoreceptor progenitor cells. We did not find any morphologic or immunohistochemical evidence of glial differentiation from tumor cells that would support the concept that retinoblastoma arises from a primitive neuroectodermal cell capable of divergent differentiation along neuronal and glial lines.

Erythropoietin in haemangioblastoma: immunohistochemical and electron microscopy studies

Immunohistochemical studies for erythropoietin were carried out in six capillary haemangioblastomas, three of which were also studied by electron microscopy. The immunohistochemical studies showed that positively stained cells were scattered in the vicinity of capillaries, and that neither endothelial cells nor stromal cells were stained. In their morphology and distribution, the positively stained cells were identical to mast cells as observed by electron microscopy. In one case, erythropoietin was demonstrated in the cyst fluid of the tumour. These findings suggest that mast cells with abundant secreting granules in haemangioblastomas are capable of producing erythropoietin.

Medulloblastomas in childhood: histological factors influencing patients' outcome

Sixty-five medulloblastomas in infancy and childhood treated from 1965 through 1981 were reviewed, and the correlation between histological findings of medulloblastomas and clinical course of the patients was studied. Thirty-five patients died but the remaining 30 are alive and without clinical evidence of recurrence 5 years or more after surgery. Certain histological features on light microscopic examinations (e.g., pleomorphism of tumor cells, nuclear-cytoplasmic ratio, mitotic index, degree of vascularity and endothelial proliferation) do influence patient outcome with statistical significance (P less than 0.05). Thirty out of 65 medulloblastomas were examined further, using immunohistochemical methods with glial fibrillary acidic protein (GFAP), neuron specific enolase (NSE), and factor VIII/vW factor (F VIII/vWF). GFAP stain was negative in 20%, NSE stain in 13.3% and F VIII/vWF stain in 16.7% of the medulloblastomas studied. "Desmoplastic" medulloblastomas showed a strong tendency toward positive NSE and GFAP staining in the glomerular portion. There was no correlation between patient outcome and the results of applied immunohistochemical studies. Our data indicate that certain histological features may influence patient outcome, but the degree and pattern of cellular differentiation do not predict outcome.

Embryonal central neuroepithelial tumors: current concepts and future challenges

While the embryonal central neuroepithelial tumors present complex conceptual and clinical problems, advances in cell type identification by special neurohistological, immunohisto- and immunocytochemical techniques have permitted discrimination of distinct cytomorphogenetic entities. These are based in part on their resemblance to the normal phases of neurocytogenesis. Four of these tumors, medulloepithelioma, desmoplastic infantile ganglioglioma, pineoblastoma and medulloblastoma, are designated as multipotential in light of their capacity to undergo divergent differentiation. Cytomorphogenetic, clinical and experimental data implicate fetal neural cell targets for transformation and raise the possibility that aberrant developmental regulatory mechanisms may contribute to the biologic behavior of these tumors. Growth factors and some neuroregulatory neurotransmitters (such as serotonin) are known to act as modulators of normal neuromorphogenesis. They could play a regulatory role in central neuroepithelial tumors on the hypothesis that the aberrant behavior of the embryonal neoplasms could either be modified by functional receptor responses or result from abnormal receptor responses to these substances. Future challenges include the definition of new cytomorphogenetic entities and subgroups of the currently defined forms of embryonal CNS tumors based on the presence of specific growth factors and neuroregulatory neurotransmitters, or their receptors, the characterization of neoplastic receptor responses mediating any modulatory role of the presently known growth factors or neuroregulatory neurotransmitters on the growth and maturation potential of the embryonal central neuroepithelial tumors and the further definition of developmental, stage-specific modulators that might be operative in these tumors.

Immunohistochemical demonstration of glial markers in retinoblastomas

Twenty retinoblastomas were studied immunohistochemically in order to visualize glial cells. In the retina, the glial cells in the ganglion cell layer and the Müller cells were GFAP positive, while only the glial cells of the ganglion cell layer expressed S-100 reactivity. In the tumours S-100/GFAP positive glial cells were found in areas near the retina and along many tumour vessels. Some S-100 reactive cells previously interpreted as tumour cells were refound in a few tumours. In areas with Flexner-Winterstein rosettes and in areas with light cells showing photoreceptor-like differentiation, glial cells reactive for both S-100 and GFAP were demonstrated. The latter findings may represent differentiation in a glial direction in the more mature parts of retinoblastoma.

Neural differentiation in Wilms' tumor

Immunoperoxidase studies using antibodies to neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), and S100 were used to confirm the presence of neural differentiation identified histologically in five cases of Wilms' Tumor. These observations invite reappraisal of Masson's proposed neuroectodermal histogenesis of Wilms' tumor because they are difficult to reconcile with the currently accepted metanephrogenic blastematous origin. They also provide a stimulus to examine the expression of neural markers during normal renal development and differentiation.

Primitive neuroectodermal tumour of the central nervous system associated with malignant rhabdoid tumour of the kidney: report of a case

Malignant rhabdoid tumour of the kidney is a recently reported tumour presenting in young children. Irrespective of stage and despite intensive chemotherapy these tumours have a poor prognosis, with death usually occurring within a matter of months. A recent report has shown the association of second embryonal tumours of the central nervous system occurring in patients with the renal tumour; most of these second tumours have occurred in the posterior fossa. We report here an infant who presented with a mass in the right groin, showing features of a poorly differentiated sarcoma, possibly rhabdomyosarcoma. Further investigations revealed a tumour in the lower pole of the right kidney which was subsequently shown to be a malignant rhabdoid tumour. The child was given chemotherapy but re-presented at 10 months of age with hydrocephalus, irritability and spasms leading to death. At autopsy a large tumour was found filling the right lateral and third ventricles; histology showed a primitive neuroectodermal tumour with focal astrocytic differentiation. Residual rhabdoid tumour was restricted to a few para-aortic lymph nodes and focal lymphatic micrometastases in lungs. The association of two embryonal neoplasms of possible similar histogenesis is discussed.

Calcineurin as a neuronal marker of human brain tumors

Calcineurin is one of the calmodulin binding proteins and a Ca2+-dependent and calmodulin-stimulated phosphoprotein phosphatase. We used antisera to the calcineurin as a cell-type-specific marker in order to identify neuronal cells in the rat brain and human neoplasms. In normal rat brain slices, basal ganglia were stained macroscopically, and other areas such as cerebral cortex, corpus callosum, cerebellar cortex, granular layer and pyramidal tract of the spinal cord were lightly identified as well. Under the light microscope, it was found that only the neuronal cells were stained, and astrocytes, oligodendrocytes, ependymal cells and vessels were not. Intracellular distribution of the staining showed various patterns and staining intensity of varying degree. Using the PAP method, localization of the calcineurin in formalin-fixed, paraffin-embedded tissues were studied in 65 human intracranial neoplasms, and in 11 human extracranial neoplasms. The neuronal elements of neuroblastoma, ganglioglioma, ganglioneuroma and retinoblastoma were clearly stained. In contrast, glioblastoma, astrocytoma, oligodendroglioma, ependymoma, meningioma, neurinoma, pituitary adenoma, craniopharyngioma, hemangioblastoma, hamartoma, lymphoma and mesenchymal tumor were all negative. Two cases out of 5 medulloblastomas were stained, but others were not. Although positive tumors disclosed various staining patterns and intensities, these results indicated that calcineurin could be a new neuronal marker in human brain tumors.

Central neural antigens: detection and diagnostic application

During the last few years, methods have been developed which permit practical use of biochemical research on the nervous system. In the central nervous system, proteins have been identified for astrocytes (glial fibrillary acidic protein and vimentin) and oligodendroglia (myelin basic protein and other glycoproteins). For certain classes of nerve cells, the neurofilament proteins and neuron-specific enolase (a glycolytic isoenzyme) have been identified. Detection of some of these substances in body fluids is possible via radioimmunoassays (RIA) and in tissue sections using the peroxidase-antiperoxidase immunohistochemical method.

Primary cerebral neuroblastomas. A clinicopathological study of one adolescent and five adult patients

Neuronal differentiation was demonstrated by light microscopy, immunohistochemistry and electron microscopy in the cerebral neoplasms of one adolescent and five adult patients. The tumours exhibited a wide spectrum of cellular differentiation from low to high grade malignancy which seems to correlate well with their biological behaviour. The natural history of these 6 cerebral neuroblastomas is rather long compared to that of other malignant primary cerebral neoplasms of adulthood; however, 2 patients died, one survived about 5 yr after initial symptoms whilst an untreated patient survived more than 12 yr. It is suggested that morphological grading along the lines of Kernohan's system may be useful in determining the prognosis and postoperative management of patients with cerebral neuroblastomas.

Astroblastoma revisited: a report of three cases

The very existence of astroblastoma has been a question of considerable controversy, although there appears now to be sufficient documentation to establish it as a tenable entity. Due to the rarity of this tumor, little information exists in the literature as to its natural history, efficacy of therapy and its pathological and radiological appearance. We report three cases of astroblastoma, describing their natural history, the response to therapeutic interventions and their light microscopic, ultrastructural and immunohistochemical characteristics.

An immunohistochemical study of glial and neuronal markers in primary neoplasms of the central nervous system

Paraffin-embedded tissues from 56 primary neoplasms of the central nervous system and seven cases of non-neoplastic reactive astrocytosis were examined by immunoperoxidase techniques on serial sections using monoclonal antibodies to glial fibrillary acidic protein (GFAP) and the 68 kDa neurofilament subunit and monospecific polyclonal antibodies to alpha- and gamma-enolase. gamma-Enolase was present in all neoplasms of neuronal origin, but was also present in anaplastic gliomas (particularly in giant cells), in some well-differentiated astrocytomas and reactive astrocytes. The cells containing gamma-enolase in these cases appeared morphologically identical to those containing alpha-enolase and GFAP in adjacent serial sections. No relationship was found between gamma-enolase immunoreactivity and cellular anaplasia in the gliomas studied. Subependymal neoplasms from patients with tuberose sclerosis exhibited evidence of both astrocytic and neuronal differentiation, sometimes in morphologically distinct cell populations, consistent with their suggested origin from a primitive cell line.

Non-glial specificities of immunocytochemistry for the glial fibrillary acidic protein (GFAP). Triple expression of GFAP, vimentin and cytokeratins in papillary meningioma and metastasizing renal carcinoma

In an extensive immunocytochemistry study for glial fibrillary acidic protein (GFAP) of human neuropathological biopsy or autopsy tissue specimens examined for diagnostic or research purposes, rare non-glial specificities of the GFAP immunostain were observed: Schwann cells of some small nerves in salivary gland, renal capsule, and in epidural fat adjacent to a metastatic carcinoma, Schwann and satellite cells in a spinal ganglion invaded by tumor, chondrocytes of epiglottic cartilage, few cells of a malignant pleomorphic adenoma of salivary gland, most cells of a recurrent papillary meningioma with areas similar to the hemangiopericytic variant, and many cells of a renal carcinoma metastatic to brain; the primary renal tumor had been operated 4 years earlier and focally contained some GFAP-positive cells. To ascertain the specificity of such unexpected immunoreactivities for GFAP and to exclude possible crossreactivities with other intermediate filament (IF) proteins, a panel of different antibodies was used for immunocytochemistry with the peroxidase-antiperoxidase (polyclonal antisera) or labeled biotin-avidin (monoclonal antibodies) techniques: two monoclonal and four polyclonal anti-GFAP, three monoclonal and one polyclonal anti-cytokeratins (CK), and two monoclonal anti-vimentin (VIM) antibodies. Triple expression of GFAP, VIM and CK was found in the papillary meningioma (in patterns suggesting frequent co-localization), in the metastatic carcinoma (in patterns suggesting little co-localization), and in the pleomorphic adenoma (only few GFAP-positive cells). Co-expression of GFAP and VIM was seen in epiglottic chondrocytes and reactive astroglia; another metastatic carcinoma was labeled only for CKs. In the light of previous reports on non-glial specificities of the GFAP immunostain, and of the consistency of our immunostaining results obtained by all monospecific anti-GFAP antibodies as well as the lack of immunocytochemically evident crossreactivity with other IF proteins, authentic GFAP production by some rare non-glial tissues and tumors is suggested.

Histopathologic and immunohistochemical study of malignant tumors of peripheral nerve sheath (malignant schwannoma)

Histologic and immunochemical analyses were performed on 38 cases and 33 cases of malignant tumors of the peripheral nerve sheath, respectively. The histologic features consisted of either closely packed or loosely arranged interlacing fascicles of slender spindle cells that showed a wavy pattern. Although no characteristic findings indicative of neurogenic differentiation could be confirmed with anti-S-100-protein, a fair number of positive cells were seen in the area where the tumor cells were loosely arranged and displayed a wavy pattern. When anti-neuron-specific enolase (NSE) and anti-neurofilament antibody (68K, 200K) were applied, they were found to be positive in cells differentiating to ganglion cells and in epithelial cells. Since S-100-protein-positive cells indicate a differentiation to Schwann cells and NSE-positive cells and neurofilament-positive cells to nerve cells, it was concluded that immunohistochemistry can serve as an effective supplementary method for the diagnosis of malignant tumors of the peripheral nerve sheath.

Immunohistochemical study of placental alkaline phosphatase in primary intracranial germ-cell tumors

Indirect immunoperoxidase staining by the peroxidase-antiperoxidase (PAP) technique was carried out on 23 human primary intracranial germ-cell tumors (17 germinomas, one embryonal carcinoma, one yolk-sac tumor, three teratomas, and one teratoma with embryonal carcinoma) and on six human primary pineal non-germ-cell tumors (one pineocytoma, two pineoblastomas, two astrocytomas, and one glioblastoma multiforme). The technique used specific rabbit antisera against placental alkaline phosphatase (PLAP), alpha-fetoprotein (AFP), and human chorionic gonadotropin (HCG). Thirteen of 17 intracranial germinomas (76.5%) showed positive staining for PLAP mainly on the tumor cell membrane. In six primary intracranial non-seminomatous germ-cell tumors, there was weak positive staining indicating the presence of PLAP in only a few cells of one embryonal carcinoma, and in some glandular epithelial cells of one teratoma; this staining was limited to the cytoplasm. None of the other six primary pineal non-germ-cell tumors showed any positive PLAP reaction. From these results, PLAP was shown to be very useful in histopathology as a diagnostic tumor marker of intracranial germinoma. Positive AFP staining was seen in several yolk-sac tumor cells and a few embryonal carcinoma cells. However, no intracranial germinomas and non-germ-cell tumors of the pineal region showed positive reaction. As for HCG, only one suprasellar germinoma and one pineal embryonal carcinoma among 29 specimens contained a few positive-staining tumor cells.

Revision of the World Health Organization classification of brain tumors for childhood brain tumors

A classification for childhood brain tumors based upon revision of nomenclature of all brain tumors published by the World Health Organization (WHO) in 1979 is proposed. Applicability of the WHO classification scheme was tested in a combined study of the clinical and pathologic features of approximately 3300 brain tumors in children. It was found to be adequate for many of the neoplasms but unsuitable for a significant proportion, including a number of complex cerebral tumors for which there was no appropriate name. Nomenclature of poorly differentiated or densely cellular neuroepithelial tumors was simplified to reflect the current state of knowledge of neuroembryology and neuro-oncology, although the Committee members recognized that such a proposal would likely perpetuate the long-standing and continuing controversy relative to the nature and origin of these neoplasms.

The "ideal" classification of pediatric central nervous system neoplasms

The "ideal" classification of pediatric brain tumors will depend on a full characterization of pathologic variables and their influence on prognosis. Currently available information about these variables remains incomplete, even for traditional histologic and cytologic features, and certainly for those studied by the newer methods that will continue to appear. In light of the multiplicity and specialized nature of some of the techniques that are or will become available, it is suggested that specific pediatric central nervous system neoplasms be targeted for study by groups of pathologists according to a protocol that delegates specific studies to specific individuals. In light of the large number of cases required, as well as the need to control for effects of different treatments, such studies are most readily done within the framework of large cooperative clinical trials. Such organizations provide the mechanism to test the biologic significance of pathologic findings that can then be used in the ideal classification.

Application of markers in the diagnosis of soft tissue tumours

In this review we describe the application of markers which are useful for the diagnosis of soft tissue tumours in paraffin sections. Detection of intermediate filament proteins appears to be most useful for first screening of these neoplasms because all, except neuroblastomas, express vimentin; cytokeratin is expressed in synovial sarcomas, epithelioid sarcomas and mesotheliomas; desmin in myogenic tumours and glial fibrillary acidic protein in astrocytomas and gliomas. Tissue-specific markers are: factor VIII--related antigen-endothelial cells; myoglobulin and skeletal muscle myosin--skeletal muscle cells; neuron specific enolase--neurons and cells of the APUD systems; and leukocyte-associated antigen--leukocytes. Markers which are present in a variety of cell types and therefore do not serve as tissue-specific markers are; S-100 proteins, alpha-1-antichymotrypsin, creatine kinase M and actin. The S-100 antigens have been detected in melanomas, granular cell tumours, chondrosarcomas and in some schwannomas and liposarcomas. Alpha-1-antichymotrypsin has been found in fibrohistiocytic and 'true' histiocytic tumours and creatine kinase M and actin in myogenic tumours. No specific markers have, as yet, been described for fibrosarcomas, Ewing's sarcomas and hemangiopericytomas.

Simultaneous expression of glial fibrillary acidic (GFA) protein and neuron-specific enolase (NSE) by the same reactive or neoplastic astrocytes

In normal cells of the central nervous system (CNS), glial fibrillary acidic (GFA) protein is demonstrable by immunohistochemistry in fibrillated astrocytes, and neuron-specific enolase (NSE) in neurons and their processes. However, it has been shown that NSE may also be expressed in reactive astrocytes and in various neoplastic cells of non-neuronal origin, including those of astrocytomas and glioblastomas. In the present study, a double-labelling technique using immunoperoxidase (PAP) and immunofluorescence (FITC) was employed to determine whether GFA protein and NSE could be expressed simultaneously by the same cell. This was found to be the case in some, but not in all reactive astrocytes in the human brain. In glial tumours, many of the neoplastic cells in the glioblastomas and astrocytomas examined demonstrated either GFA protein or NSE, but usually not both. However, occasional neoplastic cells in those gliomas were found to show both proteins. Because of the relatively low sensitivity of the FITC technique, the percentage of cells expressing both proteins could not be determined, but it is clearly possible for a single reactive or neoplastic astrocyte to demonstrate both GFA protein and NSE.

Myxopapillary ependymoma. A clinicopathologic and immunocytochemical study of 77 cases

The study involved 77 myxopapillary ependymomas of the spinal cord encountered during a 60-year period (1924-1983). This variant of ependymoma was, with few exceptions, limited to the lumbosacral region, particularly the filum terminale. The male:female ratio was 1.7:1, and the mean age at diagnosis was 36.4 years (range, 6-82); at presentation, 15 (19%) of the patients were in the first two decades of life. The duration of symptoms ranged from 1 month to 30 years; the most frequent complaint was low-back pain, and eight patients had undergone prior "disc surgery." Generally, myelographic block was disclosed. Preoperative cerebrospinal fluid protein levels averaged 2462 mg/dl. Myxopapillary ependymomas are slow-growing tumors that show no significant tendency to histologic dedifferentiation. Despite some variation in cytologic features and the presence of atypia and modest mitotic activity in most cases, the gross characteristics of the tumors appear to be of greater prognostic significance than the histologic features. Tumors that were encapsulated (25%) and amenable to intact, total surgical removal had a recurrence rate of 10%, whereas those that were removed either piecemeal (34%) or subtotally (41%) had recurrence rates of 19%. Overall survival, however, was more closely related to residual disease; total removal of tumor, whether intact (encapsulated) or piecemeal, resulted in longer survival (19 years) than did subtotal resection (14 years). Patients who died (6.5%) did so after a prolonged course marked by multiple recurrences. Radiotherapy may be of particular benefit to patients whose tumors are not amenable to intact total removal.