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PubMed1977

Different types of benign nerve sheath tumors. Light microscopy, electron microscopy and autoradiography.

In a light-, electronmicroscopic and autoradiographic study different types of nerve sheath tumors were classified. Their cellular population was quantitatively evaluated in the electron microscope. In the neurinoma the predominant cell was found to be the Schwann cell, but in the different types of neurofibromata a variable content of connective tissue cells was noted. T-HE DIFFUSE NEUROFIBROMATA SHOWED A QUANTITATIVE CELLULAR COMPOSITION SIMILAR TO NORMAL PERIPHERAL NERVES. In the plexiform neurofibroma a large number of fibroblasts were present and in the argyrophilic neurofibroma high content of perineurial cells was found. In autoradiographic sections the tumors showed in general a low proliferation rate (L.i. 1-3.6%). In the argyrophilic neurofibrom a higher labelling index (9.5%) was found.

Adolescent↗
PubMed1992

Vascular permeability changes in tumours of the peripheral nervous system.

Vascular permeability changes were examined in 34 tumours of the peripheral nervous system by immunohistochemical demonstration of serum proteins as endogenous tracers. The blood-tumour barrier was impaired in the reticular (Antoni type B) portions of neurinomas (Schwannomas) and in cutaneous neurofibromas but was similar to the normal blood-nerve barrier in fibrillary (Antoni type A) neurinomas, in most neurofibromas, in ganglioneuromas and in anaplastic tumours. These differences in permeability are discussed in relation to aspects of pathological tumour vascularization, the histogenesis of microcystic changes, and systemic therapeutic approaches.

Adult↗
PubMed1992

Comparison of various basement membrane components in benign and malignant peripheral nerve tumours.

Immunohistochemical methods were used to analyse benign and malignant tumours of peripheral nerve tissue. We tested for the distribution of basement membrane (BM) components collagen IV, laminin, heparan sulphate proteoglycan, fibronectin, for S100 protein and for the presence of interstitial collagens III and V. Laminin was generally noted in association with Schwann cells, but collagen IV occurred with perineural cells. When tested for BM components, fibroblasts were notably non-reactive except for fibronectin. Three specific area-dependent BM patterns were observed in the benign tumours: (a) Schwann cell-like, in fascicular areas (Antoni A areas of schwannoma, central fibrous bundles of plexiform neurofibromas and central areas of cutaneous neurofibroma), (b) perineural cell-like (capsular structures of schwannoma) and (c) fibroblast-like (myxoid and fibrously transformed areas). Most malignant tissues showed a variably fragmentary focal deposition of laminin. Other BM components were present only in well-differentiated areas. Poorly differentiated tumours demonstrated fibronectin reactivity alone. Our results provide evidence that the specific staining pattern for BM components helps to differentiate the various cellular proliferations in neurogenic tumours. Schwann cells are not only distinguishable from perineural cells by S100 protein staining, but also by their specific BM staining. In addition, perineural cells can be separated from fibroblasts, which do not express BM material. The "tropism" of laminin in normal nerves and benign neural tumours--which persists in neurogenic sarcomas--indicates preferential Schwann cell differentiation in these cells.

Basement Membrane↗
PubMed1999

Primary nerve-sheath tumours of the trigeminal nerve: clinical and MRI findings.

We reviewed the clinical and MRI findings in primary nerve-sheath tumours of the trigeminal nerve. We retrospectively reviewed the medical records, imaging and histological specimens of 10 patients with 11 primary tumours of the trigeminal nerve. We assessed whether tumour site, size, morphology or signal characteristics were related to symptoms and signs or histological findings. Histological proof was available for 8 of 11 tumours: six schwannomas and two plexiform neurofibromas. The other three tumours were thought to be schwannomas, because they were present in patients with neurofibromatosis type 2 and followed the course of the trigeminal nerve. Uncommon MRI appearances were observed in three schwannomas and included a large intratumoral haemorrhage, a mainly low-signal appearance on T2-weighted images and a rim-enhancing, multicystic appearance. Only four of nine schwannomas caused trigeminal nerve symptoms, including two with large cystic components, one haemorrhagic and one solid tumor. Of the five schwannomas which did not cause any trigeminal nerve symptoms, two were large. Only one of the plexiform neurofibromas caused trigeminal nerve symptoms. Additional neurological symptoms and signs, not related to the trigeminal nerve, could be attributed to the location of the tumour in three patients.

Adolescent↗
PubMed2003

Imaging tumours of the brachial plexus.

Tumours of the brachial plexus are rare lesions and may be classified as benign or malignant. Within each of these groups, they are further subdivided into those that are neurogenic in origin (schwannoma, neurofibroma and malignant peripheral nerve sheath tumour) and those that are non-neurogenic. Careful pre-operative diagnosis and staging is essential to the successful management of these lesions. Benign neurogenic tumours are well characterized with pre-operative MRI, appearing as well-defined, oval soft-tissue masses, which are typically isointense on T1-weighted images and show the "target sign" on T2-weighted images. Differentiation between schwannoma and neurofibroma can often be made by assessing the relationship of the lesion to the nerve of origin. Many benign non-neurogenic tumours, such as lipoma and fibromatosis, are also well characterized by MRI. This article reviews the imaging features of brachial plexus tumours, with particular emphasis on the value of MRI in differential diagnosis.

Brachial Plexus↗
PubMed2006

Midline cutaneous lumbosacral lesions: not always a sign of occult spinal dysraphism.

OBJECTIVE: The authors report two unusual cases of extraspinal midline lumbosacral lesions that resembled the usual skin markers of occult spina bifida. PATIENTS AND METHODS: The pathological diagnosis of the masses was plexiform neurofibroma and mastocytoma, respectively. RESULTS: Some lesions, as those we are reporting, although occurring at the lumbosacral midline, do not necessarily belong to occult spinal dysraphism, as was initially suspected. Plexiform neurofibroma and skin mastocytoma are very rare indeed in this spinal location. CONCLUSION: The two cases represent an important addition to the differential diagnosis of a congenital dorsal midline mass.

Child↗
PubMed2001

Diagnosis and management of neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder whose major feature is the occurrence of multiple neurofibromas, which are benign tumors of the nerve sheath. It affects an estimated one in 3000 to 4000 individuals. In addition to neurofibromas, there are many other clinical manifestations, including malignant tumors such as gliomas or malignant peripheral nerve sheath tumors, and nontumor effects such as skeletal dysplasia and learning disability. Diagnosis is established on the basis of clinical criteria. Molecular genetic testing is feasible, but the large size of the gene and wide range of pathogenic mutations have so far impeded the development of a clinical diagnostic test. Insights into pathogenesis have followed from identification of the NF1 gene and the development of animal models. The major function of the gene product appears to be regulation of the ras protein. Tumors are believed to arise by the loss of function of the NF1 protein, suggesting that NF1 behaves as a tumor suppressor gene. Heterozygous effects on some cell types are also likely, however. The role of ras in the pathogenesis of tumors in NF1 has suggested an approach to treatment using ras inhibitors, some of which are likely to begin in clinical trials in NF1 patients in the near future.

Animals↗
PubMed1987

Apolipoprotein E synthesis in neurofibrosarcoma and schwannoma cell cultures from two individuals with neurofibromatosis.

Apolipoprotein E is expressed in neurofibrosarcoma and Schwannoma cell cultures derived from two patients with different types of neurofibromatosis, but not in six cell cultures derived from the benign neurofibromatosis neurofibromas. In addition, a cell culture derived from a nonneurofibromatosis human malignant astrocytoma showed apolipoprotein E expression. Although all cells in either the neurofibrosarcoma or Schwannoma cultures appeared morphologically similar (suggesting homogeneity), apolipoprotein E was immunochemically detected in the perinuclear region of only half of the cells. Thus, production of apolipoprotein E in neurofibromatosis-associated neurofibroma tumors may be a marker for a specific subclass of transformed cells. The expression of apolipoprotein E in glial cell neoplasms is possibly related to an alteration in their lipid metabolism.

Adult↗
PubMed1977

Intraosseous benign neural sheath neoplasms of the jaws. Report of seven new cases and review of the literature.

Benign neural sheath neoplasms occurring centrally within the jaws are most uncommon. Our search of the English-language literature revealed twenty-eight previously reported cases. Seven additional cases--five neurofibromas and two neurilemmomas--are newly described here. Most cases have not been associated with multiple neurofibromatosis. These tumors occur predominantly in females, in patients under 45 years of age, and in the posterior mandible. The tumors generally present as asymptomatic radiolucencies, but some are associated with pain and/or swelling. Neurofibromas tend to recur more often than neurilemmomas when treated by conservative local excision.

Adult↗
PubMed1989

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.

Desmin↗
PubMed2005

Role for the epidermal growth factor receptor in neurofibromatosis-related peripheral nerve tumorigenesis.

Benign neurofibromas and malignant peripheral nerve sheath tumors are serious complications of neurofibromatosis type 1. The epidermal growth factor receptor is not expressed by normal Schwann cells, yet is overexpressed in subpopulations of Nf1 mutant Schwann cells. We evaluated the role of EGFR in Schwann cell tumorigenesis. Expression of EGFR in transgenic mouse Schwann cells elicited features of neurofibromas: Schwann cell hyperplasia, excess collagen, mast cell accumulation, and progressive dissociation of non-myelin-forming Schwann cells from axons. Mating EGFR transgenic mice to Nf1 hemizygotes did not enhance this phenotype. Genetic reduction of EGFR in Nf1(+/-);p53(+/-) mice that develop sarcomas significantly improved survival. Thus, gain- and loss-of-function experiments support the relevance of EGFR to peripheral nerve tumor formation.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed2005

Giant nerve sheath tumour: report of six cases.

Giant nerve sheath tumour is a rare tumour originating from the nerve sheath. It differs from the conventional nerve sheath tumour only by the size these tumours can reach. There are two main type of tumours that occur in the nerve sheath which include neurofibroma and schwannoma. The current views are that schwannomas arise from the progenitor of the schwann cell. Whereas the neurofibroma series probably arise from a mesenchymal origin closer to a fibroblast. We report on six cases of nerve sheath tumour that occur in the spinal and paraspinal region that presented to us over a 5 year period.

Adolescent↗
PubMed2004

Case studies for illustration and discussion: peripheral nerve tumors.

This article gives a presentation of a variety of surgical cases of peripheral nerve tumors for illustration and discussion. The first three cases include a schwannoma, a neurofibroma, and a desmoid tumor of the brachial plexus region. Case 4 is that of a patient with a common peroneal ganglion cyst, and case 5 is that of a patient with an angiolipoma of the forearm. Cases 6 through 8 illustrate a plexiform neurofibroma, a malignant peripheral nerve sheath tumor, and a metastatic carcinoma to the brachial plexus region. In case 9, a patient with schwannomatosis was treated for multiple spinal schwannomas.

Adult↗
PubMed1989

Retroperitoneal neural sheath tumors: Cleveland Clinic experience.

Retroperitoneal neural sheath tumors are a rare clinical entity with a variable and nonspecific presentation, whose accurate preoperative diagnosis often can be difficult. Since July 1984, 9 retroperitoneal neural sheath tumors, including 3 benign schwannomas, 3 malignant schwannomas and 3 neurofibromas, were evaluated at our institution. Preoperative evaluation included a computerized tomography scan in all patients and magnetic resonance imaging in 4. Magnetic resonance imaging offered better resolution and anatomical definition in certain cases. Preoperative computerized tomography-guided needle biopsy, performed in 3 patients, yielded inaccurate or inconclusive results. The 6 patients with surgically resected benign schwannomas and neurofibromas had no local recurrences and all 6 had no evidence of disease (mean followup 17.3 and 14 months, respectively). Malignant tumors, especially when associated with von Recklinghausen's disease, offered a poor prognosis. Surgical considerations include complete tumor excision with free margins of resection and proper pathological evaluation to determine biological potential.

Adult↗
PubMed2000

Neurogenic tumors of the neck.

Neurogenic tumors of the neck occur in children and adults. Important parameters to aid in the differential diagnosis are age at presentation, location, and a history of NF or multiple endocrine neoplasia. Schwannoma is the most common solitary neurogenic tumor in the neck and is usually seen in patients between 20 and 50 years of age. The plexiform neurofibroma and multiple localized neurofibromas are characteristic of NF1. MPNSTs are uncommon aggressive lesions that can arise de novo in patients with NF (10% to 30%) and postirradiation. Neuroblastic tumors consist of neuroblastoma, ganglioneuroblastoma, and ganglioneuroma. These tumors typically arise in the chest and abdomen but occasionally present as a primary neck mass. A neck mass with a histologic diagnosis of neuroblastoma is, however, more commonly metastatic from an abdominal neuroblastoma.

Adult↗
PubMed1999

Neurogenic tumors of the head and neck in children.

Soft tissue tumors make up 63% of all tumors in children. Tumors of the sympathetic chain make up 7.4% of tumors arising in children (nine new cases a year for every million children in USA) while neurofibrosarcomas make up 3.4% (2.4 new cases per year for every million children). There is a certain difference between the frequency of benign forms (rather elevated) and that of malignant forms (rather low). Diagnosis is possible by echo-scan, computed tomography, magnetic resonance imaging and fine-needle aspiration biopsy. As regards therapy, surgical resection represents the treatment of choice. In our experience, 35 neurogenic tumors in pediatric patients (8-16 years), arising in head and neck spaces, were observed and treated in the period 1976 and 1995. Twenty-six cases were schwannomas, six were neurofibromas and three were olfactory neuroblastomas. All the patients underwent surgery. Sacrifice of the affected nerve was necessary in 12 cases (all neurofibromas and eight neurinomas). In one case of olfactory aesthesioneuroblastoma a combined approach (extra-intracranial approach) was employed. Two patients are alive and disease-free with 5 and 7 years follow-up. As regards dysfunctional pathology following surgical resection, we report definitive facial nerve palsy in two cases, permanent laryngeal palsy in six cases, tongue dysfunction in one case and cheek hypoaesthesia in one case.

Adolescent↗
PubMed1981

Maxillofacial deformities in neurofibromatosis.

Four patients with neurofibromatosis are described: all displayed the feature of an increased depth of the sigmoid notch probably due to an expansive growing neurofibroma of the inferior alveolar nerve. One patient had a local neurofibroma with an invasive growth pattern and only this patient shows hyperplasia of the bone. The suggestion is made, contrary to what is found in the literature, that only the invasive growth type gives rise to hyperplasia and this type is always concomitant with a localized form of neurofibromatosis.

Adolescent↗
PubMed1992

Mast cell frequency in soft tissue tumors. Relation to type and grade of malignancy.

A high content of mast cells (MC) is considered characteristic of neurofibromas but not of malignant schwannomas and neurilemmomas. We examined the extent and reliability of this finding by counting MC in 61 peripheral nerve sheath tumors and in 103 non-neurogenic soft tissue sarcomas. We furthermore investigated correlations between the amount of MC and various features of the tumors (e.g. grades of malignancy). Neurofibromas had very high mast cell counts. However, this result only applied to about 70% of these tumors. Malignant schwannomas, malignant fibrous histiocytomas and leiomyosarcomas had remarkably high median values of MC counts with a wide dispersion within the histological groups. Synovial sarcomas were the only group that contained MC in every case, though often in small numbers. In univariate analyses the number of MC was negatively correlated to grades of malignancy, cellularity and mitotic activity of the sarcomas and tended to correlate positively to the amount of myxoid and collagenous connective tissue and lymphocytic infiltrates. Multiple linear regression analysis revealed a significant correlation to the grade of malignancy and the amount of connective tissue.

Cell Count↗