Composition of free amino acids in brain tumors

The composition of the free amino acid pools in various brain tumors and in normal brains obtained at surgery or at autopsy is determined with an automatic amino acid analyzer and the results statistically evaluated. The tumors have lower ratios of GABA in the pools than the normal brain; tumors with higher GABA ratios are found in those which are in close contact with and have an invasive nature to brain tissue. In gliomas, the more malignant a tumor becomes, the more different the composition in that tumor is from that in normal brain tissue. But conversely, the ratio of GABA is highest in glioblastoma. The composition of the pool in oligodendroglioma is not significantly different from that in the normal brain. Metastatic brain tumors show the highest ratios of phenylalanine, tyrosine and methionine in the pool among the tumors and the normal brain. From the viewpoint of the composition of the free amino acid pools, like from that of the histological aspects, brain tumors seem to be classified into four groups: glioma, neurinoma, meningioma and metastatic tumors.

Melanotic schwannoma of the sympathetic ganglia: pathological and clinical characteristics

Reports of melanin-producing tumors of Schwann cell origin are extremely rare. Reports of only 9 such tumors arising from sympathetic ganglia have been published previously. Two new cases of melanotic schwannoma of sympathetic ganglia are reported. The pathological and clinical characteristics of these unusual melanotic tumors are discussed.

Solitary malignant Schwannoma: clinical aspects, immunohistochemistry and ultrastructure

Solitary malignant Schwannoma is a rare tumor derived from cells of the nerve sheath, the Schwann cells. During the past 6 years we have treated six patients with this tumor, four males and two females ranging in age from 18 to 69 years. Five of them had their tumors located on the trunk, which is associated with a bad prognosis. In four of the six patients ultrastructural examination played an important role in making the diagnosis of malignant Schwannoma. Light microscopy alone is insufficient because the spindle-shaped cells growing in fascicles often closely resemble other sarcomatous tumors. Ultrastructural typical findings of Schwannomas are cytoplasmic processes, intercellular junctions and basal lamina. Surgery was the sole treatment in three patients. One patient only received chemotherapy because of disseminated disease. The other two were treated with surgery combined with radiotherapy. Four patients developed distant metastases for which chemotherapy was given, but all patients died within 3 years after their initial treatment. Only two patients are free of disease 56 and 72 months after treatment. Solitary malignant Schwannoma is a tumor with a grave prognosis, for which ultrastructural and immunohistochemical examination plays an important role in order to establish the diagnosis.

Congenital neural hamartoma ("fascicular schwannoma"). A light microscopic, immunohistochemical, and ultrastructural study

A previously undescribed form of a congenital neural hamartoma composed entirely of Schwann cells in a fascicular pattern was found on the leg of a male infant. The lesion was thought to be an unusual variant of plexiform Schwannoma or a newly recognized unencapsulated form of Schwannoma. On light microscopic examination, the lesion, which measured 5 x 4 cm when it was surgically removed when the infant was 7 months old, showed an unencapsulated dermal mass composed of fascicles of spindle cells with frequent Verocay body-like structures. The intervening stroma was collagenous and contained an increased number of mast cells. Special stains did not demonstrate any axons in the tumor. There was a strongly positive immunohistochemical reaction for S-100 protein and collagen type IV in the spindle cells. These cells were weakly or focally positive for Leu-7 and vimentin, and completely negative for neural filaments, neuron-specific enolase, glial fibrillary acidic protein, epithelial membrane antigen, desmin, and muscle-specific actin. On electron microscopic examination, the spindle cells were found to be surrounded by basal lamina and showed frequent cytoplasmic invagination filled with collagen bundles. No unmyelinated nerve fibers were identified.

Cellular schwannoma. A clinicopathologic study of 29 cases

A series of 29 cellular schwannomas is described in terms of their clinical presentation and course, light and electron-microscopic appearance, immunohistochemical properties and cytogenetics. The study indicates that cellular schwannoma can be defined as a subtype of classical schwannoma, characterized by spindle cells forming a compact fascicular, sometimes fibrosarcoma-like growth pattern, a low mitotic activity, a generally moderate nuclear and cellular polymorphism and a high degree of Schwann cell differentiation as seen by electron microscopy and immunohistochemistry. The tumour is characteristically located close to the vertebral column, in the mediastinum or retroperitoneum and has a benign course. Occasionally bone destruction and neurological symptoms develop. The clinical appearance together with the high cellularity, fascicular pattern and mitotic activity had led to the erroneous diagnosis of a soft tissue sarcoma in a few cases, and cellular schwannoma may thus be considered to be a pseudosarcoma. Immunohistochemically, cellular schwannomas appear to deviate from classical schwannomas and malignant peripheral nerve sheath tumours by their expression of glial fibrillary acidic protein. The chromosome analysis revealed a normal diploid stemline karyotype, with a variety of abnormal clones, including one with monosomy 22.

Characterization of glycoconjugates found in granular cell tumors, with special reference to keratan sulfate

Nine granular cell tumors (GCTs) were studied using the immunoperoxidase technique with a mouse monoclonal antibody to keratan sulfate and a polyclonal antibody to S-100 protein. Various lectins and basic dye stains were also employed. Schwannomas benign and a malignant, a neurofibroma, a leiomyoma, two examples of nevus pigmentosus and a congenital epulis were similarly examined to compare the histochemical reactivities. Tumor cells of all the GCTs reacted intensely with the antibodies to keratan sulfate and S-100 protein. Peripheral nerve bundles and other neurogenic tumors showed stained for S-100 protein but not for keratan sulfate. Basic dye stain indicated the presence of sulfated glycoconjugates in GCTs. Lectin stains demonstrated that GCTs were rich in glycoconjugates but the reactivity patterns for 14 lectins differed between GCTs and normal tissue components. None of the lectins used in this study was specific for GCTs. These results indicate that GCTs contain abundant glycoconjugates and that the monoclonal antibody to keratan sulfate may be an immunohistochemical marker for GCT.

A case of primary intrapulmonary neurilemoma and review of the literature

In this paper, we present an extremely rare case of a primary intrapulmonary neurogenic tumor, in which localization of S-100 protein, neuron specific gamma-enolase (NSE) and CEA was investigated using immunohistochemical staining. The patient, who was a 39-year-old man, experienced no symptoms; however, a routine chest X-ray revealed a round tumor-like shadow in the infrahilar area of the right lung. As the tumor appeared to be gradually increasing in size, surgery was performed and histopathological examination of the excised tumor revealed it to be a primary intrapulmonary neurilemoma. Immunohistochemical staining demonstrated the presence of S-100 protein in the tumor cells but NSE and CEA were not detected. For the 2 years following his operation, the patient has been in good health and is now under careful observation.

[Differential immunohistochemical characteristics of meningiomas and other neoplasms of the central nervous system]

We present an immunohistochemical study of 16 meningiomas and 19 CNS tumors including gliomas, neurinomas and metastatic carcinomas, in order to establish a histopathologic differential diagnosis, using formalin-fixed and paraffin-embedded material. The antibodies analysed included vimentin, GFA-protein, cytokeratin, S-100 protein and epithelial membrane antigen. Meningiomas always express vimentin as marker, and occasionally cytokeratin and EMA. The most constant antigens demonstrated in astrocytomas were GFA-protein and vimentin, and occasionally we were able to detect S-100 protein. Neurinomas proved positive to S-100 protein, and metastases presented cytokeratin and EMA reactivity. Our results confirm the existence of diverse immunohistochemical patterns within CNS tumors, a fact that can be useful in routine differential diagnosis.

Glial fibrillary acidic protein and keratin expression by benign and malignant nerve sheath tumors

Formalin-fixed, paraffin-embedded sections of 59 ultrastructurally confirmed nerve sheath tumors (NSTs) that included 27 benign schwannomas, five neurofibromas, and 27 malignant schwannomas were studied by the avidin-biotin-peroxidase complex method using antibodies directed against glial fibrillary acidic protein (GFAP), keratin, S-100 protein, vimentin, and desmin. GFAP was expressed by 33% of the benign schwannomas, 40% of the neurofibromas, and 7% of the malignant schwannomas. Keratin was expressed by 7% of the benign schwannomas and 4% of the malignant schwannomas. S-100 protein was expressed by 100% of the benign NSTs and by 40% of the malignant schwannomas. Vimentin was observed in 100% of the benign NSTs and in 85% of the malignant schwannomas. None of the cases stained for desmin. GFAP and cytokeratin expression could not be predicted on the basis of tumor light microscopy or ultrastructure. These findings are of practical importance in routine surgical pathology, particularly with respect to the differential diagnosis of gliomas located in the central nervous system and in immunohistochemical studies of peripherally located, poorly differentiated neoplasms.

Noninvasive differentiation of tumors with use of localized H-1 MR spectroscopy in vivo: initial experience in patients with cerebral tumors

A recently developed method for image-selected localized hydrogen-1 magnetic resonance (MR) spectroscopy was assessed in the differential diagnosis of nine primary and secondary cerebral tumors, including four gliomas, two meningiomas, one neurilemoma, one arachnoid cyst, and one metastasis of breast cancer. Well-resolved H-1 MR spectra of these tumors were obtained in vivo with a conventional 1.5-T whole-body MR imaging system. All tumor spectra were remarkably different from spectra from normal brain tissue. Spectra obtained from different tumors exhibited reproducible differences, while histologically similar tumors yielded characteristic spectra with only minor differences. The observed spectral alterations reflect variations in concentrations and relaxation times of the H-1 MR sensitive pool of free (mobile) metabolites within the tissues. In most cases, the concentrations of N-acetyl-aspartate and creatine/phosphocreatine are reduced below detectability, whereas choline-containing compounds are generally enhanced. The spectral differences between the tumors are mainly due to the differing concentrations of lipids, lactic acid, and carbohydrates. Localized H-1 MR spectroscopy may become an important clinical tool for the differentiation of tumors as well as for therapeutic control.

Lipocortin-1 immunoreactivity in central and peripheral nervous system glial tumors

We examined the cellular distribution of lipocortin-1 (L-1), a major physiologic substrate for the epidermal growth factor receptor/kinase, in 122 central nervous system (CNS) and peripheral nervous system (PNS) neoplasms using the peroxidase-antiperoxidase technique with a polyclonal antibody specific for L-1. Extensive L-1 immunoreactivity was demonstrated in many CNS tumors; in 11 of 21 glioblastoma multiformes, in five of 12 anaplastic astrocytomas, and in five of 14 astrocytomas. Significant numbers of immunoreactive ependymocytes or astrocytes were also seen in six of 13 ependymomas. In contrast, no immunostaining was detected in the oligodendrocytes in any of ten oligodendrogliomas. PNS tumors, found in two of five malignant nerve sheath tumors, 13 of 15 schwannomas, 13 of 17 neurofibromas, and 14 of 15 traumatic neuromas, also contained considerable L-1 immunoreactivity in Schwann cells or mast cells. These findings raise the possibility that L-1 may participate in the proliferation or subsequent differentiation of neoplastic astrocytes, ependymocytes, and Schwann cells.

[Immunohistochemical study of c-myc oncogene product in human brain tumors]

C-myc oncogene is widely distributed in eukaryotic cells and is supposed to play an important role in the cellular proliferation and differentiation. Enhanced expression of this oncogene is reported in many kind of tumors, which is often associated with increased malignancy. It seems, therefore, important to study the expression of this oncogene in analyzing the cell biologic features of brain tumors. In the present paper we investigated the distribution of this oncogene product in paraffin-embedded tissue of various kind of brain tumors with a monoclonal antibody to synthetic c-myc peptide. The results demonstrated that c-myc product was detectable in most of the astrocytoma lineage. The immunoreaction within the cell nuclei was more intense in grade 3 and grade 4 astrocytomas than in grade 2 tumors. The expression in grade 4 tumors was, however, rather weaker that in grade 3 tumors. In benign, non-glial tumors like meningiomas and neurinomas, the nuclear immunoreaction was usually absent or only weak, although it was enhanced in a case of acoustic and spinal neurinomas associated with von Recklinghausen's disease.

[A case of retroperitoneal schwannoma]

A 39-year-old man, who had been pointed out to have a lower abdominal mass, was admitted to our hospital. Physical examination revealed a child-head-sized mass with smooth surface in the middle part of the lower abdomen. Computerized tomographic scan showed the non-cystic mass located in the retroperitoneal space from the level of L5 to S5. An open biopsy was performed and pathological diagnosis was benign schwannoma (Antoni A and B type). Radical operation could not be performed because of his refusal. In addition to this case, 40 cases of retroperitoneal schwannoma reported in Japan are reviewed and discussed.

Meningioma, meningeal hemangiopericytoma (angioblastic meningioma), peripheral hemangiopericytoma, and acoustic schwannoma. A comparative immunohistochemical study

The relationship between meningeal hemangiopericytoma (angioblastic meningioma), meningiomas of meningothelial derivation, and peripheral hemangiopericytoma is controversial; and immunohistochemical studies have yielded conflicting results. Likewise, immunohistochemistry has been touted as a reliable means of differentiating fibrous meningioma from acoustic schwannoma. By the immunoperoxidase method, we studied 40 meningiomas (11 meningotheliomatous, four transitional, 11 fibrous, three secretory, four metaplastic, one xanthomatous, one papillary, four atypical, one malignant), five arachnoid granulations, 13 angioblastic meningiomas, nine peripheral hemangiopericytomas, and seven acoustic schwannomas. Antisera to vimentin, epithelial membrane antigen (EMA), keratin, S-100 protein, carcinoembryonic antigen (CEA), desmin, factor VIII, Ulex europeaus, and glial fibrillary acidic protein (GFAP) were utilized. All meningiomas and arachnoid granulations stained for vimentin and EMA; 15% and 12% of meningiomas were S-100 and keratin positive, respectively. The latter was noted primarily in areas of secretory (pseudopsammomatous) differentiation. In contrast, all angioblastic meningiomas stained for only vimentin. This profile of immunoreactivity was also seen in the peripheral hemangiopericytomas, with the exception of single cases that stained focally for EMA and S-100 protein, respectively. Acoustic schwannomas all stained positively for S-100 protein, vimentin, and were variably reactive for EMA, a pattern not distinct from meningioma. We conclude that (a) meningiomas express both epithelial and mesenchymal markers as do arachnoid granulations, (b) that angioblastic meningiomas demonstrate only mesenchymal markers, (c) that angioblastic meningiomas express identical markers to peripheral hemangiopericytoma and should thus be considered a variant thereof, (d) among meningiomas, CEA and keratin appear to be relatively specific markers for the "secretory" variant, and (e) because of overlap in S-100 and EMA reactivity, these markers are unreliable in differentiating meningioma from acoustic schwannoma.

Immunohistochemical evaluation of intermediate filament expression in canine and feline neoplasms

Specimens of neoplastic tissues from 19 dogs and 4 cats were examined immunohistochemically for intermediate filament expression, using commercially available antibodies. Staining was observed in a wide range of tumor tissues and in normal internal controls by use of antibodies to vimentin, desmin, glial fibrillary acidic protein, and low and high molecular weight cytokeratins. Intermediate filament expression was found to be consistent with light and/or electron microscopic findings, and hence believed to be an accurate indicator of tumor histogenesis in cats and dogs. Three fixatives were evaluated for their relative abilities to preserve antigenicity. Absolute alcohol was superior to B5 fixative and both were superior to formalin. Some tissues that clearly displayed intermediate filament antigens with alcohol and B5 fixative failed to stain when fixed in formalin.

Immunohistochemical studies on the tissue localization of collagen types I, III, IV, V and VI in schwannomas. Correlation with ultrastructural features of the extracellular matrix

The distinctive tissue localization of collagen types in typical schwannomas with Antoni type A and B areas was demonstrated immunohistochemically using affinity-purified antibodies against types I, III, IV, V and VI collagen and comparative ultrastructural studies were made on the extracellular matrix components. Antoni type A tissue, which was composed of tightly packed spindle cells with long cytoplasmic processes surrounded by a continuous basement membrane and a few fibrillar components of the extracellular matrix, was almost exclusively immunoreactive for type IV collagen, presumably representing the basement membrane. Verocay bodies, which are organoid structures of Antoni type A tissue, had a variety of more abundant extracellular fibrous components, such as banded collagen fibrils, fibrous long-spacing fibrils and microfibrils. These were positive for type I and III, as well as type IV collagen. In Antoni type B areas, where two types to tumor cells designated Schwann cell-like and fibroblast-like were scattered in large amounts of amorphous extracellular matrix containing microfibrils and thick banded collagen fibrils, type VI collagen as well as types I, III and IV collagen were consistently detected. Type V collagen was localized in dense fibrous tissue areas and around blood vessels. These findings indicate that the differently organized cellular patterns of schwannomas, identified as Antoni types A and B, are characterized not only by the ultrastructural features of the extracellular matrix, but also by the distinctive collagen types produced by neoplastic Schwann cells.

Intraspinal pigmented schwannoma with malignant progression

A case with recurrent pigmented intraspinal tumour with malignant progression is presented. The primary tumour grew around the nerve roots T9 and T10, was attached to dura and infiltrated the vertebral bone tissue. On light microscopy it was comprised of monomorphic cells with large amount of cytoplasmic pigment and many large pigmented globoid bodies. Mitoses were not observed. On electron microscopy, in addition to cytoplasmic melanosomes of regular size, macromelanosomes were numerous. The tumour cells were surrounded partially by basement membrane like material. On these bases a histological diagnosis of benign pigmented tumour of neural crest origin was suggested (a possible pigmented meningioma or pigmented schwannoma). The patient got a recurrence one year after the primary operation. Biopsy from the re-operation showed histologically the same type of tumour with more pleomorphic cells. Subsequently, the tumour grew progressively and metastases were observed in the lungs and in the skin. The patient died two years after the primary operation. The malignant progression of the tumour and other reports on similar tumours was most consistent with a diagnosis of malignant pigmented schwannoma and this was confirmed later on with immunohistochemical staining showing positive staining for basement membrane components, collagen type IV and laminin as well as a positive staining for S-100 protein. The present findings show that despite benign histological features these tumours can behave very aggressively and stress the need of more information on this type of tumour.

Pheochromocytoma combined with malignant schwannoma: unusual neoplasm of the adrenal medulla

A 38-year-old woman was operated on to remove a large tumor that replaced the left adrenal gland. The tumor was encapsulated and showed small areas typical of pheochromocytoma, and spindle cell or undifferentiated round cell sarcoma in most areas. Metastases of primitive round cell appearance were operated from the abdominal cavity and abdominal wall shortly after the initial surgery. Eighteen months after the first operation, the patient was alive with metastases in liver and retroperitoneal space. The pheochromocytomalike component showed a typical ultrastructural and immunohistochemical profile of pheochromocytoma and was positive for neurofilaments, synaptophysin, neuron-specific enolase, and S-100 protein in the sustentacular cells. The sarcomatous areas showed fibroblastoid spindle cells that were often surrounded by a basal lamina. Immunohistochemistry revealed S-100 protein positivity in many spindle cells, but markers of pheochromocytoma or epithelial differentiation were absent. The metastases lacked all markers except for vimentin, and the cells were undifferentiated by electron microscopy. These findings suggest that the neoplasm was a compound tumor with a typical pheochromocytoma component and a sarcoma resembling a malignant schwannoma. Neoplastic proliferation of the S-100 protein-positive Schwann-cell-like sustentacular cells of the pheochromocytoma would be an explanation for the genesis of this sarcoma associated with pheochromocytoma.

Malignant epithelioid schwannoma: a light microscopic and immunohistochemical study

Malignant epithelioid schwannoma is a rare variant of malignant nerve sheath tumor that can be confused with both other neuroectodermal neoplasms and carcinomas. The light microscopic and immunohistochemical findings of a malignant epithelioid schwannoma arising in the mandibular region of a 27-year-old female are described. The differential diagnosis of this unusual neoplasm from malignant melanoma and poorly differentiated carcinoma is discussed.

Immunocytochemical demonstration of glial fibrillary acidic protein in imprint smears of human brain tumors

Papanicolaou-destained imprint smears from 24 brain tumors were investigated by means of avidin-biotin-peroxidase complex method (ABC) with the use of monoclonal antibodies against glial fibrillary acidic protein (GFAP). Positive staining reaction to GFAP antibody has been demonstrated in cells from the following tumors: astrocytoma, anaplastic astrocytoma, glioblastoma multiforme, mixed glioma, and ependymoma. The reaction for GFAP was negative for the following tumors: medulloblastoma, neurilemmoma, melanoma, hemangioblastoma, and metastatic tumors. In astrocytoma, the cell bodies and processes were positive with delicate fibrillary patterns; in anaplastic astrocytoma, cytoplasm and the processes were intensively stained. In glioblastoma multiforme, the staining patterns were also mixed, and the short, thickened processes were characteristic. Use of both a smear preparation and the immunoperoxidase staining technique is of great value in diagnosis of tumors of the central nervous system.

Immunohistochemical evaluation of Leu-7, myelin basic-protein, S100-protein, glial-fibrillary acidic-protein, and LN3 immunoreactivity in nerve sheath tumors and sarcomas

The collective expression of five antigens produced in immature or mature myelin-producing glia was evaluated in nerve sheath tumors and spindle cell sarcomas with histologic features of schwannomas. Myelin-associated glycoprotein (Leu-7), myelin basic-protein (MBP), S100-protein, and, in most cases, glial-fibrillary acidic-protein (GFAP) and HLA-DR/Ia (LN3) immunoreactivity were evaluated immunohistochemically using commercially available antibodies on 53 benign nerve sheath tumors and 12 sarcomas. Leu-7 immunoreactivity was detected by a monoclonal antibody in 12 of 16 schwannomas, 12 of 20 neurofibromas, and 17 of 17 traumatic neuromas. No Leu-7 positivity was seen in the sarcomas. Distinct heavy MBP immunoreactivity, assessed using polyclonal antibodies, was identified only in all 17 traumatic neuromas. Extensive S100-protein positivity was seen in 15 of 16 schwannomas, 17 of 20 neurofibromas, and 17 of 17 traumatic neuromas. Extensive LN3 immunoreactivity was seen in Schwann cells of 50% of the nerve sheath tumors analyzed; however, it was also present in associated interdigitating reticulum cells; GFAP immunoreactivity was not detected. These data suggest that Leu-7 is an important marker of Schwann cell neoplasms, although it is not superior to S100 protein. Moreover, combined immunohistochemical evaluation of potential Schwann cell markers including Leu-7, MBP, GFAP, and LN3 using commercially available antibodies offers no advantage over analysis of S100-protein immunoreactivity alone.

Expression of glial fibrillary acidic protein (GFAP) in peripheral nerve sheath tumors. A comparative study of immunoreactivity of GFAP, vimentin, S-100 protein, and neurofilament in 38 schwannomas and 18 neurofibromas

Immunoreactivity of glial fibrillary acidic protein (GFAP) in 38 schwannomas and 18 neurofibromas was evaluated and compared with the reactivity of vimentin, S-100 protein, and neurofilament protein. All cases were positive for vimentin and S-100 protein. GFAP was positively stained in the neoplastic cells of 15 of 38 schwannomas (38%) and in two of 18 neurofibromas (11%). The extensively stained GFAP-positive tumors tended to be deeply situated in the body. The GFAP-positive cells were usually spindle-shaped and appeared preferentially in the perivascular region of hyalinized, thick blood vessels.

Heterogeneity of malignant schwannomas

Six malignant schwannomas were studied by electron microscopy and immunohistochemistry for S-100 protein at the light and electron microscopic levels to clarify the nature of the tumor cells. Three tumors (group A) were composed of poorly differentiated tumor cells and showed no immunoreactivity for S-100 protein. One tumor (group B) was composed of perineurial cells that were S-100 protein-negative. Two tumors (group C) consisted of both Schwann cells and fibroblastic cells like neurofibromas, and only the former were found to contain S-100 protein. Thus, this study showed the heterogeneous nature of the malignant schwannomas and suggested that these tumors might arise from multipotential Schwann cells or different cellular components of peripheral nerve or primitive cells.

Immunohistochemical observation of S-100 protein and neuron specific enolase in the tumour cells of granular cell tumour

An immunohistochemical technique for the detection of S-100 protein, neuron specific enolase (NSE), carcinoembryonic antigen (CEA) and muramidase (lysozyme) was applied to a case of the granular cell tumour. S-100 protein was detected both in the nuclei and cytoplasma of the granular cells, and NSE was weakly positive in their cytoplasms. CEA and lysozyme were negative in the tumour cells. Our results supports the concept that granular cell tumours are derived from Schwann cells.

Leiomyoma and neurilemoma: report of two unusual non-epithelial tumours of the thyroid gland

Two primary spindle cell tumours of the thyroid are described showing light microscopic features of leiomyoma and neurilemoma respectively. The origin from smooth muscle and nerve sheath was confirmed by both immunohistochemical reactions and ultrastructural findings. Review of the literature reveals only one case of leiomyoma and three cases of neurilemoma reported as developing within the thyroid gland. Our observations further support the view that leiomyoma and neurilemoma may occur at this unusual site and are recognizable entities.

GFA protein reactivity in nerve sheath tumors: a polyvalent and monoclonal antibody study

We studied glial fibrillary acidic (GFA) protein immunoreactivity in 30 schwannomas, including two intracerebral examples, 26 neurofibromas and 12 neuromas using the immunoperoxidase method with a polyvalent antiserum (PVAS) and three well-characterized monoclonal antibody (MAb) preparations. Twelve of the schwannomas, including both intracerebral tumors, two of the neurofibromas and none of the neuromas immunostained with PVAS. Except for one schwannoma, all the PVAS-positive tumors were positive with two of the MAb preparations. While both of the intracerebral schwannomas were positive with the third MAb, none of the extracerebral tumors were. Our results suggest that: 1) human nerve sheath tumors contain cells having polypeptides that share epitopes with GFA protein, but 2) these polypeptides differ from astrocytic GFA protein by at least one epitope, and 3) the location of the tumors in relation to the central nervous system may influence GFA protein immunoreactivity.

Distribution and biochemical characterization of somatostatin receptors in tumors of the human central nervous system

Fifty-two brain tumors, consisting of 17 astrocytomas, 4 oligodendrogliomas, 20 glioblastomas, 3 neurinomas, 2 ependymomas, 1 neurofibroma, 1 ganglioneuroblastoma, 1 medulloblastoma, 1 plexus papilloma, 1 teratoma, and 1 germinoma, were tested for their content of specific somatostatin receptors using autoradiographic techniques or in vitro binding assays with membrane homogenates. Somatostatin receptors were found in most of the differentiated glia-derived tumors such as astrocytomas and oligodendrogliomas whereas the poorly differentiated glioblastomas were usually free of receptors. Tumors originating from neuroblasts, i.e., ganglioneuroblastoma and medulloblastoma, contained a high density of somatostatin receptors, whereas neurinomas and neurofibromas as well as the ependymomas, one teratoma, and one plexus papilloma were lacking such receptors. In one germinoma, low amounts of somatostatin receptors were observed over the lymphocytic elements. Receptor-positive tumors had saturable and high affinity receptors with pharmacological specificity for somatostatin and somatostatin analogues resembling that of normal human central nervous system tissue. In most instances, they could be labeled with two different iodinated radioligands, a somatostatin octapeptide derivative (204-090) or a somatostatin-28 analogue. This is the first time that somatostatin receptors have been shown to exist not only on neuronal structures of the central nervous system but also on glial elements. The precise function of such somatostatin receptors on glial cells, which may be different from neurotransmission, remains to be determined.

Association of laminin with heparan and chondroitin sulfate-bearing proteoglycans in neurite-promoting factor complexes from rat schwannoma cells

The present studies were undertaken to confirm the presence and identity of a putative proteoglycan associated with laminin in neurite-promoting factor complexes isolated from rat schwannoma cell conditioned medium. Sucrose density gradient centrifugation of the complex resolved two laminin-associated Na2[35S]O4-labeled peaks which were termed Pools A and B. Both pools had nearly all their [35S] cpms associated with glycosaminoglycan, contained heparan sulfate-proteoglycan core protein antigen and displayed a similarly high neurite promoting potency relative to their laminin contents. However, Pool A contained about twice as many [35S] cpms and twice as much proteoglycan core protein per laminin than Pool B. Seventy percent of Pool A cpms was associated with heparan sulfate and 30% with chondroitin sulfate whereas the inverse was true for Pool B. Treatment with heparitinase and/or chondroitinase ABC caused laminin in either pool to elute at lower salt concentrations from DEAE cellulose. In SDS-PAGE the [35S] cpms of both pools ran with the same mobility as laminin but could be separated from laminin under reducing conditions. The Pool A cpms remained at 900 KD and the Pool B cpms spread over the 200-900 KD range. By rotary shadowing electron microscopy, Pool B fractions contained primarily cross-shaped laminin images, often associated with proteoglycan-like images. Pool A fractions contained i) dense, aggregated images including intact laminin from which emanated proteoglycan-like strands, ii) circular images bearing globular domains and less commonly, iii) distorted cross-shaped laminin-like images. These studies support the existence of at least two forms of laminin-proteoglycan complexes which differ in biochemical, immunochemical and ultrastructural characteristics.

Immunohistochemical staining for apolipoprotein B in human sarcomas

A study of immunocytochemical staining for apolipoprotein B (apo B) in 52 human sarcomas and eight benign soft-tissue tumors is described. A peroxidase-antiperoxidase technique was employed using a rabbit anti-apo B antiserum. All 27 liposarcomas examined were positive for apo B, and 23 of these tumors showed at least 2-plus staining on a scale of 0 to 3 plus. Of the ten myxoid liposarcomas within this group, seven showed 2-plus or 3-plus staining, while the other three stained 1 plus. By contrast, 11 of 13 malignant fibrous histiocytomas were negative for apo B; the remainder showed 1-plus staining. Myxoid areas present in three of these cases were negative for apo B. Five of seven rhabdomyosarcomas stained at least 2 plus for apo B. Both benign and malignant peripheral nerve sheath tumors showed no consistent pattern of staining. We conclude that apo B immunocytochemical staining tends to be high in tumors whose normal tissue counterparts exhibit relatively large numbers of low-density lipoprotein receptors. Furthermore, immunoperoxidase staining for apo B should be a useful adjunct in the evaluation of soft-tissue sarcomas, particularly in cases with myxoid differentiation.

Malignant peripheral nerve sheath tumor. An immunohistochemical study of 62 cases

Malignant peripheral nerve sheath tumor (MPNST) commonly presents a diagnostic challenge and may resemble a variety of other soft tissue neoplasms microscopically. The authors have examined 62 examples of MPNST immunohistochemically, using antibodies to S-100 protein, myelin basic protein (MBP), and Leu-7, all of which are potential neural markers. Sixty-eight percent of all cases expressed at least one of these three determinants, representing a higher rate of immunoreactivity than that seen for single nervous system antigens in previous studies. Conjoint reactivity for S-100/Leu-7, S-100/MBP, and MBP/Leu-7 was seen in 34%, 34%, and 24% of cases, respectively. This coexpression of antigens is important, because none of them in isolation is immunospecific for nerve sheath tumors. In addition, stains for epithelial membrane antigen were reactive in two epithelioid tumors in this series, and eight spindle-cell neoplasms demonstrated desmin positivity. Analyses for cytokeratin, carcinoembryonic antigen, and Factor VIII-related antigen were negative in all cases. These results indicate an overlap between the immunocytochemical attributes of malignant peripheral nerve sheath tumors and other soft tissue sarcomas and emphasize the desirability of assessing multiple neural markers in such cases.

The distribution of alpha and beta subunits of S-100 protein in malignant schwannomas arising from neurofibromatosis of von Recklinghausen's disease

The immunohistochemical localization of the alpha and beta subunits of S-100 protein in 4 cases of the malignant Schwannomas arising from von Recklinghausen's disease was investigated by the indirect immunoperoxidase method. S-100 alpha-positive cells were few in presumably normal peripheral nerves, moderate in numbers in plexiform neurofibromas and numerous in malignant Schwannomas. In contrast, S-100 beta immunoreactivity, abundantly detected in normal peripheral nerves and plexiform neurofibromas, was completely negative in all of 4 cases of malignant Schwannoma. In addition, double immunostaining method for both subunits revealed their simultaneous existence in cells in the normal nerves and neurofibroma. These results suggest that malignant change of Schwann cells convert their subunit composition of S-100 protein from beta to alpha in these malignant cells. Although the mechanisms for the proportional conversion of the subunits are as yet undetermined, the immunoreactivity of S-100 alpha subunit may be a useful marker for Schwannoma in malignancy.

Cellular schwannoma: a distinct pseudosarcomatous entity

Eighteen cases of cellular schwannoma, a recently delineated benign entity, are described. These tumours present most often in middle-aged adults of either sex and show a predilection for the paravertebral region of the mediastinum and retroperitoneum. More than half the tumours macroscopically arose from a nerve but none was associated with von Recklinghausen's disease. The light microscopic features are remarkably consistent but are not immediately recognizable as neural in type. Means of distinction from a malignant nerve sheath tumour and from a variety of other soft tissue tumours are discussed. Immunohistochemical positivity for S-100 protein has been demonstrated in 17 of the 18 cases. Prolonged follow-up has revealed local recurrence in only one case; none has metastasized.

The intermediate filament complement of the spectrum of nerve sheath neoplasms

The intermediate filament complement of the spectrum of nerve sheath neoplasms including 12 typical benign schwannomas, 1 ancient schwannoma, 2 cellular schwannomas, 6 neurofibromas and 4 malignant schwannomas was investigated by immunofluorescence microscopy, two dimensional electrophoresis, and immunoblot analysis. Studies were performed on freshly frozen tumor tissue samples; a broad spectrum of antibodies against all classes of intermediate filaments was utilized. Samples were also studied by electron microscopy, and immunohistochemically for S-100 protein and desmoplakins. By immunofluorescence microscopy, all nerve sheath neoplasms revealed intense positivity for vimentin throughout the cytoplasm while 2 benign schwannomas displayed co-expression of vimentin and glial filament proteins. Two-dimensional gel electrophoresis and immunoblot analysis confirmed the presence of vimentin and showed that it was the predominant protein in all tumors. Electrophoretic analysis of the 2 benign schwannomas that immunostained for glial filament proteins confirmed the presence of this protein which was shown to comigrate with a known human control sample. Neither immunofluorescence microscopy nor biochemical analyses revealed cytokeratin polypeptides, neurofilament proteins, desmin, or desmoplakin in any of the tumors. We conclude that while vimentin is the predominant intermediate filament expressed by the entire spectrum of nerve sheath neoplasms, at least occasional benign schwannomas are capable of co-expressing glial filament proteins. It remains to be determined whether the subgroup of nerve sheath neoplasms that co-expresses vimentin and glial filament proteins is otherwise distinguishable from their more frequent counterparts that express vimentin exclusively.

Estrogen and progestin receptors in acoustic and spinal neurilemmomas. Clinicopathologic correlations

Estradiol and progestin receptors were studied in 20 patients with neuraxial Schwann cell tumors, and their presence was correlated to the clinicopathologic features and the amount of preoperative corticosteroid therapy. Based on an arbitrary cutoff value of 200 fmol per gram of tumor as indicative of a positive receptor value in breast cancer, 4 and 13 of the neurilemmoma tissue samples could be considered as positive for estrogen and progesterone receptors, respectively. Whereas there was no convincing correlation between the estrogen and progestin receptor activity and the age, sex, or menopausal status of the patients, overweight patients had significantly higher estrogen and progestin binding values. The correlation between the amount of preoperative prednisone therapy and the amount of [3H]estradiol and [3H]promegestone binding revealed no dose relationship. Correlating [3H]estradiol and [3H]promegestone content with the histologic type of the schwannomas (Antoni types A and B, respectively), we were not able to draw conclusions, because of the predominance of Antoni type A over Antoni type B tissues in our material. The necessity of nuclear receptor assays, ligand specificity testing, and in vitro studies is stressed as a prerequisite for answering the questions whether neurilemmomas contain genuine sexual steroid hormone receptors and whether these receptors are regulated via an estrogen-estrogen-receptor system as is the case in classical sexual steroid hormone target tissues.

Epithelioid neurilemmoma of the trigeminal nerve: an immunohistochemical and ultrastructural study

A 50-year-old male presented with facial pain due to an extrinsic intracranial tumour involving pontine nerve roots. Biopsy and subsequent partial surgical excision indicated origin from the trigeminal nerve. Histologically the tumour had features of a neurilemmoma but in addition contained a population of epithelioid cells. Immunohistochemical studies demonstrated S100 protein in the non-epithelioid component but no reaction in the epithelioid cells, whilst vimentin was present in both cell types. Ultrastructurally the epithelioid cells showed features consistent with a Schwann cell nature and may represent a less well differentiated cell population derived from a Schwann cell precursor. The significance of these findings in relation to the cell of origin of neurilemmomas is discussed.

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.

Isolation and characterization of rat schwannoma neurite-promoting factor: evidence that the factor contains laminin

Rat RN22 schwannoma cells in vitro release into their growth medium a macromolecular factor that, when bound to polyornithine-coated culture substrata, will stimulate neuritic regeneration from axotomized peripheral and central neurons. During the purification of this factor, the neurite-promoting activity co-purifies with laminin immunoreactivity as measured by an enzyme-linked immunoadsorbent assay. The purified factor has an immunoreactivity per milligram of protein similar to that of purified rat yolk sac tumor laminin. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions, the purified factor exhibits a major band at 200 kilodaltons (kD) and two minor ones at about 130 and 35 kD. The 200-kD band comigrates with the 200-kD band of purified rat laminin. After SDS-PAGE under non-reducing conditions, the rat schwannoma factor and rat laminin both exhibit a band in the 900-kD range with the schwannoma factor band migrating slightly faster than the laminin one. The 200-kD (reducing conditions) and 900-kD (non-reducing conditions) bands of both the schwannoma factor and laminin are stained by immunoblotting with antisera raised against rat and human laminin and against a partially purified preparation of the schwannoma factor. On immunoblots the 400-kD band of laminin (a band not seen in the schwannoma factor preparation) also stains with all three antisera. When the antibodies from each of the three antisera are immobilized on protein A-agarose beads, the beads will completely remove from solution the neurite-promoting activities of both the schwannoma factor and laminin. Antibodies raised against rat laminin fail to block the neurite-promoting activity of the purified schwannoma factor but totally block that of rat laminin. In contrast, antibodies raised against the schwannoma factor will block the neurite-promoting activities of both the schwannoma factor and laminin. By rotary shadowing electron microscopy the schwannoma factor preparation exhibits cross-shaped images similar but not identical to those previously reported for rat and mouse laminin. In addition, the schwannoma factor preparation contains images resembling proteoglycans.

[DNA cytofluorometric analysis of nerve sheath tumors]

The present study was undertaken to clarify the ploidy patterns of peripheral nerve sheath tumors by determining nuclear DNA content of the individual tumor cells using PI-DNA cytofluorometry (NIKON SPM-RF1-D), and to investigate the relation between the ploidy patterns and histopathological findings. Most of the solitary neurilemmomas and neurofibromas studied were found to be associated with euploid-polyploidization, almost without DNA synthetic cells. It was also shown that the number of polyploid cells increased in accordance with an increase in the frequency of cells having large, atypical nuclei in histological picture, regardless of the natures of cellular arrangements. Malignant schwannomas, however, were composed of many polyploid and aneuploid cells with an increase of DNA synthetic cells, indicating their active cell proliferation. Thus, the ploidy patterns of nerve sheath tumors were remarkably different between benign and malignant ones. Furthermore, a case of multiple schwannoma suspected to be a variant of von Recklinghausen's disease, showed euploid-polyploidization with many DNA synthetic cells, indicating a ploidy pattern intermediate between benign and malignant tumors. This tumor thus appears to be a premalignant tumor or in the early stages of malignancy.

The pattern of distribution of laminin in neurogenic tumors, granular cell tumors, and nevi of the oral mucosa

Oral tumors of presumably neuroectodermal origin were stained with anti-laminin antibody by a double layered immunofluorescence technique. A marked positive staining for laminin was found in neurofibromas and neurilemmomas although the pattern of laminin distribution was slightly different. Accentuated staining was seen in Verocay bodies. In granular cell myoblastomas (GCM), small groups of tumor cells were encircled by laminin-positive material, whereas individual tumor cells were unstained. In nevi, diffusely spread nevus cells were surrounded by a rim of laminin, whereas when arranged in nests whole groups of cells were encircled by laminin as seen in the GCM. Ordinary oral fibromas included as controls were negative except for the expected positive staining of basement membranes normally occurring in the tissues. Immunohistochemical demonstration of laminin seems to be a valuable aid in differential diagnosis of soft tissue tumors and may provide useful information about the pathogenesis of various lesions.

[Malignant schwannoma arising in Recklinghausen's disease--report of 4 cases]

Four cases of malignant schwannoma arising in Recklinghausen's disease are described. The 4 patients, aged 38, 41, 44 and 38, 2 men and 2 women, had up to child-head-sized tumors in the neck, back, axilla and retroperitoneum. Oncostatic chemotherapy and irradiation were ineffective against the malignant schwannoma. In three, surgically tumor-resected cases, local recurrence and rapid tumor growth occurred. Histologically, malignant schwannoma was characterized by the presence of a few collagen fibers among the tumor cells, but abundant argentaffin fibers. Numerous mast cells are frequently seen in neurofibroma, but almost never in malignant schwannoma. In Case 3, with mild atypism, tumor cells were positive for S100 protein.

Morphology of early stages of ENU-induced brain tumors in rats

Tumors were induced in experimental animals in order to investigate early tumor growth with conventional histology and gliofibrillary acid protein (GFAP) demonstration with the peroxidase-antiperoxidase (PAP) method. In one experiment, the animals were killed after transplacental ENU administration, when microtumors were suspected; in the second experiment, the animals were followed up to their natural death and microtumors found at random were used for analysis. Conventional histology revealed 3 types of microtumors: growth restricted to the subventricular matrix, growth in the neighbourhood of the ventricles with obvious or probable connection to the ventricular zones and small tumors observed exclusively in the white matter. The latter tumors by conventional staining were composed of small round cells, considered to be oligodendrocytes. They did not contain GFA-protein positive cells within the tumor. The tumor in presumable and visible connection with the ventricular lining did contain GFAP-positive astrocytes. In the very small subventricular tumors, the small round cells (oligodendrocytes) were in continuous contact with the identical interfascicular glial cells, while GFAP positive astrocytes seemed to stem from the subventricular astrocytes (tanycytes, ependymoglia). The ependyma itself was always preserved. A twofold origin of these experimental tumors with probable development into one common cytological glial type is assumed.

Solitary pelvic neural tumors with high steroid receptor content

Two pelvic benign neural tumors, a neurofibroma and a neurilemmoma, were found to have high levels of cell nuclear estrogen receptors and both cytoplasmic and nuclear progestin receptors. A review of the literature reveals that neurogenic tumors occur predominantly in young women. This observation together with the recent findings of elevated sex steroid receptor proteins in meningiomas supports a hypothesis for the common hormonal dependence of neoplasms arising from the neural supporting tissues.

Hormones and tumours in central nervous system (CNS): steroid receptors in primary spinal cord tumours

On the basis of the studies reported on steroid receptors in brain tumours, cytoplasmic and nuclear estrogen (ER) and progesterone (PR) receptors have been examined in forty primary spinal cord tumours: fifteen neurinomas, three neurofibromas, nine meningiomas, nine ependymomas, two astrocytomas, one oligodendroglioma and one hemangiopericytoma with the exchange method in the presence of sodium thiocyanate for ER and using the synthetic progestin R5020 for PR. Regardless the type of the tumour, ER have been detected with a higher incidence in male than in female patients (78% versus 59%). PR had the same incidence in male and in female patients. The neurinoma was the oncotype more constantly provided with steroid receptors: nuclear ER, in fact, has been found with an incidence of 75% in male and of 43% in female patients. This oncotype is usually provided in both sexes with PR. Ependymomas is spinal tumour with the highest incidence of cytosol ER both in male and in female patients. On the basis of the above results reported it can be assumed that hormonal factors might be involved in the occurrence as well as in the growth of spinal cord tumours. Therefore it can be hypothesized that hormonal treatment might favourably be used as an adjuvant therapy in some selected patients with receptor positive spinal tumours.

Canine malignant melanotic schwannomas: a light and electron microscopic study of two cases

Malignant, melanotic schwannoma of the spinal cord was diagnosed in two two-year-old dogs. The neoplastic spindle cells were arranged in a herringbone or storiform pattern; the intracytoplasmic melanin varied in amount in different areas of the two neoplasms. Ultrastructural features including cytoplasmic lamellar premelanosomes and melanosomes, rudimentary cell junctions, scattered pinocytotic vesicles, and remnants of external lamina supported the diagnosis of melanotic schwannoma.

Malignant "triton" tumors: a clinicopathologic and immunohistochemical study of nine cases

Nine cases of malignant "triton" tumors, based on the coexistence of rhabdomyoblasts and Schwann cell elements, were analyzed clinicopathologically and immunocytochemically. All tumors were stained for myoglobin and S-100 protein by the immunoperoxidase technique. Six of the nine patients were in the third or fourth decade of life. Six cases were associated with von Recklinghausen's disease, and the tumors in two cases grew along nerve trunks. The malignant tumors showed a predilection for the thigh and buttock. Six of the seven deaths occurred within two years of the initial treatments. Strongly positive staining for S-100 protein was observed in three tumors, with transitional zones between the sarcomas and peripheral neurofibroma-like areas, as well as in two tumors composed predominantly of rhabdomyoblastic elements. In four other cases the tumors were only weakly positive for protein S-100. Intracytoplasmic myoglobin was present in all cases. Tumors composed predominantly of rhabdomyosarcomatous elements occurred in four patients, including two children with von Recklinghausen's disease. These results, considered with other findings, suggest that malignant "triton" tumors may not be as rare as previously believed.