SEARCH · Search PubMed

Results for “NEUROFIBROMA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed1986

Ultrastructural localization of S-100 protein in neurofibroma.

The nature of the cells in neurofibromas was studied by electron microscopy and immunoelectron-microscopic examination of S-100 protein. Ultrastructurally, all five neurofibromas studied were found to be composed of Schwann cells, perineurial cells, and intermediate cells, which had features of both perineurial cells and fibroblasts. The Schwann cells had complex, branched cytoplasmic processes and a continuous basal lamina. The perineurial cells were distinguishable from Schwann cells by the presence of numerous pinocytotic vesicles, unbranched slender cytoplasmic processes and a discontinuous basal lamina. The intermediate cells had no basal lamina, but were topographically related to Schwann cells and had a similar fine structure to that of perineurial cells. Thus, they seemed to be modified neoplastic perineurial cells. Immunoelectron-microscopic studies showed the presence of cells with and without S-100 protein in the neurofibromas: cells with S-100 protein resembled Schwann cells ultrastructurally, and those without S-100 protein were perineurial and intermediate cells. Some Schwann cells with S-100 protein in one neurofibroma had numerous pinocytotic vesicles characteristic of perineurial cells, suggesting that Schwann cells and perineurial cells are functional variants of the same cell type. Thus this study showed that neurofibromas were composed of Schwann cells with S-100 protein and perineurial and intermediate cells, including so-called endoneurial fibroblasts, without S-100 protein. Morphological and functional transition seems to occur between Schwann cells and perineurial cells, and between perineurial cells and intermediate cells.

Adult↗

PubMed1995

Benign neurofibromas in type 1 neurofibromatosis (NF1) show somatic deletions of the NF1 gene.

Neurofibromatosis type 1 (NF1) is one of the most common human autosomal dominant diseases. NF1 is characterized by café-au-lait spots (CLS), axillary freckles and Lisch nodules of the iris. Another hallmark of NF1 is the development of neurofibromas, benign tumours that arise from peripheral nerve sheaths. NF1 patients also have an increased incidence of certain malignant tumours. Malignancies in NF1 are believed to follow the 'two-hit' hypothesis, in which one allele is constitutionally inactivated while the other allele is subsequently inactivated ('second hit') at the somatic level. This hypothesis has not, however, been fully tested in the aetiology of benign neurofibromas. This is a crucial issue since it addresses not only the basic mechanism behind the genesis of neurofibromas, but may also indicate a mechanism common to many or all NF1 features. Using both NF1 intragenic polymorphisms as well as markers from flanking and more distal regions of chromosome 17, we have investigated loss of heterozygosity (LOH) in 22 neurofibromas from five unrelated NF1 patients. Eight of these tumours revealed somatic deletions involving NF1, indicating that inactivation of NF1 is associated with at least some neurofibromas.

Adult↗

PubMed2000

Toward a survey of somatic mutation of the NF1 gene in benign neurofibromas of patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1), a common autosomal dominant disorder caused by mutations of the NF1 gene, is characterized by multiple neurofibromas, pigmentation anomalies, and a variety of other possible complications, including an increased risk of malignant neoplasias. Tumorigenesis in NF1 is believed to follow the two-hit hypothesis postulated for tumor-suppressor genes. Loss of heterozygosity (LOH) has been shown to occur in NF1-associated malignancies and in benign neurofibromas, but only few of the latter yielded a positive result. Here we describe a systematic approach of searching for somatic inactivation of the NF1 gene in neurofibromas. In the course of these studies, two new intragenic polymorphisms of the NF1 gene, a tetranucleotide repeat and a 21-bp duplication, could be identified. Three tumor-specific point mutations and two LOH events were detected among seven neurofibromas from four different NF1 patients. Our results suggest that small subtle mutations occur with similar frequency to that of LOH in benign neurofibromas and that somatic inactivation of the NF1 gene is a general event in these tumors. The spectrum of somatic mutations occurring in various tumors from individual NF1 patients may contribute to the understanding of variable expressivity of the NF1 phenotype.

Adult↗

PubMed2001

Malignant peripheral nerve sheath tumour arising within neurofibroma. An immunohistochemical analysis in the comparison between benign and malignant components.

AIMS: To compare the expression of immunohistochemical variables between benign and malignant components of malignant peripheral nerve sheath tumour (MPNST) arising within neurofibroma. METHODS: Eight cases of MPNST arising within a neurofibroma, associated with neurofibromatosis type 1 (NF1), were studied. The areas of MPNST and neurofibroma were compared immunohistochemically with regard to the expression of proliferative activity (MIB-1), growth factors, p53, bcl-2, neural cell adhesion molecule (N-CAM), and CD34. RESULTS: The expression of transforming growth factor beta 1 (TGF-beta 1), TGF-beta receptor type II, hepatocyte growth factor alpha (HGF-alpha), c-met, p53, and N-CAM was higher in the areas of MPNST than in the neurofibromatous areas in four, five, five, eight, five, and three of the eight cases, respectively. CD34 expression was lower in the areas of MPNST than in the neurofibroma areas in three of the eight cases. CONCLUSIONS: On the basis of these findings, TGF-beta 1, HGF-alpha, and p53 might be involved in the malignant transformation of neurofibroma to MPNST.

Adolescent↗

PubMed2002

Neurofibromas in children with neurofibromatosis 1.

Neurofibromatosis 1 is a common autosomal dominant disease reported in approximately 1 in 3000 individuals. Although some features of neurofibromatosis 1, such as café-au-lait spots and Lisch nodules, are clinically silent, neurofibromas cause a significant degree of morbidity, mortality, and cosmetic disfigurement. Childhood through early adulthood is a vulnerable period for the growth of these lesions. Neurofibromas are a heterogeneous group of benign tumors that grow from intraneural and extraneural tissues. These tumors take on different morphology, grow at variable rates, and occur in multiple locations. Symptoms arise as neurofibromas enlarge, compressing and distorting local structures. The unpredictable nature of neurofibromas has a serious impact on the quality of life of patients with neurofibromatosis 1, and their management is challenging for physicians. Surgical removal remains the mainstay of treatment. However, advances in the understanding of the genetics and pathogenesis of neurofibromatosis 1 have led to the development of promising new biologically directed therapies. The purpose of this review is to summarize the defining characteristics, incidence, clinical course, management options, and outcome of neurofibromas in children with neurofibromatosis 1.

Adolescent↗

PubMed2005

Thoracoscopically guided transaxillary resection of adjoining intercostal plexiform neurofibromas: review of mosaicism in neurofibromatosis: technical note.

OBJECTIVE AND IMPORTANCE: The present article describes a rare presentation of Type I neurofibromatosis (NFI) involving adjoining intercostal plexiform neurofibromas, as well as the novel use of thoracoscopy to guide surgical resection. This presentation highlights the manner in which NFI may affect selective regions of the body disproportionately through genetic mosaicism. CLINICAL PRESENTATION: A 40-year-old man had intractable neuropathic anterior right chest wall pain in the distribution of T2 and T3. Magnetic resonance imaging and computed tomography of the chest revealed masses deep to the second and third ribs in the axilla. Biopsy of a subcutaneous nodule in the right chest wall revealed a small neurofibroma. An extensive workup revealed no masses outside the region of the right chest wall and no stigmata of NFI. INTERVENTION: The patient underwent right-sided thoracoscopy for identification of the intrathoracic neurofibromas and placement of spinal needles to localize the anterior and posterior extent of the masses. These landmarks were used to guide a transaxillary approach to third rib resection and nerve-sparing neurofibroma resection. CONCLUSION: Isolated adjoining intercostal plexiform neurofibroma is a unique presentation of mosaic NFI. Because of its limited penetrance, this variant may present as a regional pain syndrome. Thoracoscopy can be used effectively to guide intercostal nerve sheath tumor resection.

Abdominal Neoplasms↗

PubMed2005

Tight junction proteins and perineurial cells in neurofibromas.

Cutaneous neurofibromas consist of axonal processes, Schwann cells, fibroblasts, perineurial cells, mast cells, and abundant extracellular matrix. The distribution and role of perineurial cells in neurofibromas has been uncertain, partly because there has not been a specific immunohistochemical marker for perineurial cells. In this study, tight junctions (TJs) of 16 neurofibromas from 12 patients with neurofibromatosis type 1 (NF1) were analyzed using electron microscopy, immunohistochemistry, and Western transfer analysis. Cell-cell contacts with typical ultrastructural morphology of TJs were seen between adjacent perineurial cells surrounding the small nerves and between contacting perineurial cell processes embedded in tumor stroma. Immunohistochemistry showed expression of claudin-1, claudin-3, and ZO-1 in the intercellular junctions of a subpopulation of tumor cells. Occludin was present mainly in perineurium and claudin-5 localized to the blood vessels. Double immunolabelings were used to identify the cell types expressing claudin-1. The results showed that claudin-1 positive cells were also positive for type IV collagen and epithelial membrane antigen but not for S-100 protein. This labeling pattern is consistent with perineurial cell phenotype. Using claudin-1 as a marker, our results showed that clusters of perineurial cells are distributed around the rudimentary nerves within cutaneous neurofibromas and at the periphery of some neurofibromas.

Blotting, Western↗

PubMed1986

Nerve growth factor receptors on dissociated neurofibroma Schwann-like cells.

Neurofibromatosis is a disorder which predominantly involves cellular elements of peripheral neural sheaths. Little is known about the regulation of differentiation and proliferation of cells comprising neurofibromas. Because nerve growth factor-like activity may be present in neurofibromas and the cells comprising neurofibromas are neural crest derivatives, we have investigated whether nerve growth factor (NGF) receptors are present on cells from dissociated dermal neurofibromas. Using 125I-NGF to measure binding to cultured cells in suspension and for autoradiography, we identified a population of cells having characteristics of Schwann cells which exhibited saturable 125I-NGF binding. This binding is characteristic of the "fast" (low affinity) NGF receptor, having a Kd of approximately 1 nM and a Bmax of at least 120 fmol/10(6) cells. Less than 20% of the bound 125I-NGF (5 ng/ml) is not displaced when transferred to 0 degrees C by an excess of unlabeled NGF (10 micrograms/ml) and is therefore bound to either "slow" (high affinity) sites or is rapidly internalized. NGF receptors with characteristics of fast sites have recently been reported on Schwann-like cells from chick dorsal root ganglia [Zimmerman, A., and Sutter, A. Beta nerve growth factor (beta NGF) receptors on glial cells. Cell-cell interaction between neurones and Schwann cells in culture of chick sensory ganglia. EMBO J., 2: 879-885, 1983]. The identification of NGF receptors on both fetal chick dorsal root ganglia and neurofibroma Schwann-like cells suggests that NGF may have a role in the regulation of Schwann cell function in both normal development and in neurofibromatosis.

Cells, Cultured↗

PubMed2004

The biology and management of laryngeal neurofibroma.

OBJECTIVES: To review the presentation of laryngeal neurofibroma, including its association with neurofibromatosis types 1 and 2, and present guidelines for its management. DESIGN: Retrospective study. PATIENTS: Five pediatric patients with laryngeal neurofibroma, 4 girls (80%) and 1 boy (20%), were treated at a tertiary pediatric medical center from 1973 through 2003. Recorded data included age at initial presentation, sex, symptoms, significant medical and family history, preoperative evaluation, location of the tumor, surgical procedure, complications, outcome, and recurrence. RESULTS: The 5 patients presented with stridor and cafe-au-lait spots at or shortly after birth. All patients were diagnosed as having neurofibromatosis type 1 by the established criteria. Studies evaluating the disease processes included plain radiography, computerized tomography, magnetic resonance imaging, barium swallow, and laryngoscopy and bronchoscopy under anesthesia. Pathologic examination of biopsy specimens from all patients showed neurofibromas with plexiform and/or diffuse features. Treatments included tracheotomy (n = 4), carbon dioxide laser excision (n = 4), modified neck dissection (n = 3), partial pharyngectomy (n = 1), supraglottic laryngectomy (n = 1), and endoscopic hemilaryngectomy (n = 1). Three patients were successfully decannulated. Follow-up ranged from 1 to 15 years. One patient was lost to follow-up. No evidence of malignant degeneration was noted. CONCLUSIONS: Neurofibroma of the larynx is a rare condition that should be considered in the differential diagnosis of children with a submucosal laryngeal mass. In our series, all patients had associated neurofibromatosis type 1. Complete surgical excision is the treatment of choice in cases of localized small lesions. To prevent debilitating outcomes due to aggressive surgery, minimally invasive procedures (partial excision via endoscopic approach) may be preferable for larger lesions that infiltrate the surrounding vital structures. Long-term follow up of these patients is essential owing to the possibility of malignant transformation.

Adolescent↗

PubMed1997

Massive intratumor hemorrhage in facial plexiform neurofibroma.

BACKGROUND: Plexiform neurofibromatosis is a feature of von Recklinghausen's disease. Head and neck lesions may produce varying degrees of cosmetic and functional deformity. However, life-threatening hemorrhage into facial plexiform neurofibromas has not been previously reported. METHOD: We report two patients with von Recklinghausen's disease who experienced massive hemorrhage into facial neurofibromas, one following a blunt injury and the other without a known initiating event. RESULTS: Conservative management did not stop the hemorrhage into facial neurofibromas in either instance. Surgical exploration was mandated for hemorrhage control and evacuation of blood clots. Hemostasis was attained by a combination of hypotensive anesthesia and chromic catgut suture ligatures. CONCLUSIONS: These case reports demonstrate a potentially lethal complication in patients with facial plexiform neurofibroma. Where a competent and experienced interventional neuroradiologist is not available, surgical exploration should be undertaken to control bleeding.

Adolescent↗

PubMed1992

Growth of human acoustic neuromas, neurofibromas and schwannomas in the subrenal capsule and sciatic nerve of the nude mouse.

To develop a reproducible in vivo model for the growth of human acoustic neuromas and neurofibromas, we implanted tumor specimens (6 acoustic neuromas; 4 neurofibromas; 3 schwannomas arising in skin and soft tissues) from 13 different patients into the subrenal capsules of 67 nude mice and sciatic nerves of 64 nude mide. The animals were anesthetized and the tumors were microscopically implanted. Serial tumor volumes were determined at intervals up to 2 months by reopening the incision and directly measuring the tumor size with a micrometer. The percentages of acoustic neuromas that survived or grew were 57.1% in the subrenal capsule and 88.9% in the sciatic nerves; the percentages of neurofibromas that survived and grew were 50% in the subrenal capsule and 70% in the sciatic nerves; and the percentages of schwannomas that survived and grew were 57.1% in the subrenal capsule and 94.1% in the sciatic nerve. Tumors in the sciatic nerve also survived and grew for a longer period than those in the subrenal capsules. Tumor enlargement and stability correlated with neovascularity. At 1 or 2 months after engraftment, the tumors showed histologic appearances similar to the original tumors and immunohistochemical analysis of cryostat sections demonstrated staining of the tumors, but not the host mouse tissues for human beta 2-microglobulin, a species-specific marker. Furthermore, analysis of genomic DNA from implanted tumors revealed its human origin. We conclude that human acoustic neuromas, neurofibromas and schwannomas are readily grown in two sites in nude mice and that they retain their morphologic features and genomic identities. These tumors grow better and more consistently in the sciatic nerve than in the subrenal capsule. These are useful model systems for studying tumor growth and cellular modulation.

Animals↗

PubMed1993

Lectin histochemistry of normal and neoplastic peripheral nerve sheath. 2. Lectin binding patterns of schwannoma and neurofibroma.

Lectin binding patterns of 31 schwannomas and 6 neurofibromas were examined using 12 lectins, and the results were compared with those of normal peripheral nerves. Tumors obtained from 10 cases of neurofibromatosis and 4 recurrent schwannomas were included. Changes of glycoconjugates were observed in association with a neoplastic transformation of Schwann cells; Arachis hypogaea (PNA) staining after neuraminidase treatment seen in normal Schwann cells was reduced in schwannoma of Antoni type A, and bindings with Glycine max (SBA) and Helix pomatia (HPA) after sialic acid removal, which were not seen in normal Schwann cells, appeared in schwannoma cells. Intensities of staining of tumor cells with each lectin were higher in Antoni type B than those in Antoni type A. No differences in lectin binding patterns were observed between schwannomas in patients with neurofibromatosis or recurrent schwannomas and ordinary, primary schwannomas in patients without stigmata of neurofibromatosis. Lectin binding patterns of Schwann cells and perineurial cells in neurofibroma were almost similar to those in normal peripheral nerves with an exception of faint stain of Schwann cells with HPA after neuraminidase pretreatment. This result suggests differences in extent of differentiation between schwannoma cells and neoplastic Schwann cells in neurofibroma. Specific PNA binding to perineurial cells in neurofibroma indicates the significance of this lectin as a marker of these cells.

Glycoconjugates↗

PubMed2006

[Solitary intraparotid neurofibroma of the facial nerve. Symptomatology, biology and management].

Neurogenic neoplasms of the parotid gland are extremely uncommon. We present the case of a solitary intraparotid neurofibroma of the N. facialis occurring in a 55-year-old female who noted a painless left-side enlargement in the region of the parotid gland over a period of 2 years. Facial function was normal. Magnetic resonance imaging revealed a well-demarcated round mass within the left parotid. At surgery, a tumor was found involving the main trunk of the facial nerve, histopathologically representing a neurofibroma. Since solitary intraparotid neurofibromas are characterized by a very slow growth lacking the propensity for malignant transformation, the tumor was left to preserve facial nerve function. The clinical course over months or even years and the non-specific symptomatology are characteristic of intraparotid facial neurofibromas. Surgical management depends on the clinical setting in the individual case. Conservative treatment based on facial nerve preservation and leaving the tumor in situ is recommended, rather than radical tumor removal with resection of the segment of the N. facialis involved.

Biomarkers, Tumor↗

PubMed2005

Solitary subglottic neurofibroma: a report of an unusual manifestation.

Neurofibromas of the larynx are extremely rare, especially in the subglottic part. Most of the patients with neurofibromas suffer from neurofibromatosis type 1 (NF1, von Recklinghausen's disease), which is characterized by cafe-au-lait spots and neurofibromas of any type. We present a case of a solitary neurofibroma in the subglottic region that relapsed 4 years after the primary diagnosis. The clinical findings, histological results and therapy are discussed.

Adult↗

PubMed2001

Somatic NF1 mutational spectrum in benign neurofibromas: mRNA splice defects are common among point mutations.

Neurofibromas, benign tumors that originate from the peripheral nerve sheath, are a hallmark of neurofibromatosis type 1 (NF1). Although loss of heterozygosity (LOH) is a common phenomenon in this neoplasia, it only accounts for part of the somatic NF1 mutations found. Somatic point mutations or the presence of "two hits" in the NF1 gene have only been reported for a few neurofibromas. The large size of the NF1 gene together with the multicellular composition of these tumors has greatly hampered their molecular characterization. Here, we present the somatic NF1 mutational analysis of the whole set of neurofibromas studied by our group and consisting in 126 tumors derived from 32 NF1 patients. We report the identification of 45 independent somatic NF1 mutations, 20 of which are reported for the first time. Different types of point mutations together with LOH affecting the NF1 gene and its surrounding region or extending along the 17q arm have been found. Among point mutations, those affecting the correct splicing of the NF1 gene are common, coinciding with results reported on germline NF1 mutations. In most cases, we have been able to confirm that both copies of the NF1 gene are inactivated. We have also found that both somatic and germline mutations can be expressed at the RNA level in the neoplastic cells. Furthermore, we have observed that the study of more than one tumor derived from the same patient is useful for the identification of the germline mutation. Finally, we have noticed that the culture of neurofibromas and their fibroblast clearance facilitates LOH detection in cases in which it is difficult to determine.

Alleles↗

PubMed2006

The role of high-resolution computed tomography and magnetic resonance imaging in the evaluation of isolated orbital neurofibromas.

PURPOSE: To analyze the imaging findings in patients diagnosed with isolated orbital neurofibromas. DESIGN: Retrospective observational case series. METHODS: Computed tomographic (CT) and magnetic resonance imaging (MRI) findings were reviewed in five patients with orbital neurofibromas in the absence of systemic neurofibromatosis in this multicenter study. The main outcome measures were bony and soft tissue abnormalities involving the orbit and surrounding anatomic spaces. RESULTS: Patient age ranged from 36 to 43 years (mean, 41 years); three patients were men and two were women. Duration of symptoms ranged from three to 20 years. Radiologic findings included intraconal and extraconal soft tissue masses in all patients, bony orbital abnormalities in three patients, and intracranial extension in two patients. In addition, MRI studies in one patient revealed the previously unreported presence of neurofibromas involving extraocular muscle. CONCLUSIONS: Isolated orbital neurofibromas may present with differing radiologic appearances. The combined use of high-resolution CT and MRI may be of benefit in the preoperative diagnosis of these uncommon orbital tumors.

Adult↗

PubMed2005

Hybrid peripheral nerve sheath tumors: Schwannoma-perineurioma and neurofibroma-perineurioma. A report of three cases in extradigital locations.

We present three cases of subcutaneous tumors with hybrid features of schwannoma-perineurioma (one case) and neurofibroma-perineurioma (two cases), which occurred in two women aged 50 and 52 years and one man aged 52. Locations included the scapular area, skin overlying breast and knee area. The tumors were 1.5, 4 and 5 cm in largest diameter. None of the patients had signs of neurofibromatosis. All tumors were surgically removed, and patients remained disease-free for 1 to 4 years. The classification of the lesion into schwannoma-perineurioma and neurofibroma-perineurioma rested on histopathological and immunohistochemical findings. An ultrastructural study was performed in one case of neurofibroma-perineurioma. All cases were studied for mutation of the NF2 gene, and in one case (neurofibroma-perineurioma) a point mutation was detected in exon 15 of the gene.

Base Sequence↗

PubMed2006

Diagnostic delay of NF1 in hemifacial hypertrophy due to plexiform neurofibromas.

Benign tumors of the peripheral nerve sheath, termed neurofibromas, are the hallmark feature of neurofibromatosis type 1 (NF1). These tumors can result in hypertrophy of a limb or another anatomic region. Hemifacial hypertrophy due to an underlying neurofibroma is a typical manifestation of NF1 in young children although the overall frequency of facial involvement is low. We retrospectively studied all patients, which were referred to our outpatient clinic because of hemihypertrophy or swelling of the face for initially unknown reason with a final diagnosis of NF1. A total number of six patients were identified. Clinical and radiological characteristics of these patients were analyzed. In all patients, diagnosis of NF1 could be established based on the typical clinical criteria. However, despite other typical NF1-associated features (e.g. multiple café-au-lait spots) diagnosis of a plexiform neurofibroma as underlying cause for the hemifacial hypertrophy was significantly delayed in all patients. MRI scans were misinterpreted in all of the cases as lymphangioma because plexiform neurofibromas can resemble mesenchymal tumors or lymphangiomas. NF1 has to be considered in the differential diagnosis of hemifacial hypertrophy. A thorough clinical examination of affected patients should focus on typical disease-defining features. Early diagnosis of NF1 can prevent unnecessary treatment at least in some patients.

Cheek↗