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PubMed1995

Single-cell PCR performed with neurofibroma Schwann cells reveals the presence of both alleles of the neurofibromatosis type 1 (NF1) gene.

It is commonly held that Schwann cells (SC) are the progenitor cells of benign neurofibromas. To test for loss of heterozygosity (LOH) at the neurofibromatosis 1 (NF1) gene locus, three intragenic polymorphic markers were analyzed after polymerase chain reaction amplification, starting from 98 single SC isolated from primary cultures of neurofibromas, of five informative NF1 patients. The patterns obtained did not provide evidence for LOH at the NF1 gene. LOH by nondisjunction, large deletions, or somatic recombination in SC seems not to be the mechanism of generation of neurofibromas.

Alleles↗
PubMed1995

Differential expression of triiodothyronine receptors in schwannoma and neurofibroma: role of Schwann cell-axon interaction.

Regulation of gene expression in Schwann cells may be determined, at least in part, by the interaction of these cells with axons. Two peripheral nerve tumors, neurofibroma and schwannoma, represent good tools for studying Schwann cell activity in the presence or absence of axon action. In the present work we studied the expression of triiodothyronine receptors (T3R) by Schwann cells in these two tumors and also in adult normal sciatic nerve. Confirming the results of the histological examination, immunostaining of the neurofilaments showed the presence of fascicles or scattered axons in all neurofibroma sections studied. In these neurofibromas, Schwann cells did not express T3R immunoreactivity. Furthermore, in adult normal sciatic nerve, Schwann cells which ensheathed axons were devoid of any T3R expression. In contrast, in schwannoma, the complete absence of axons was demonstrated by the lack of neurofilament immunostaining. Here, Schwann cells deprived of axonal interaction displayed clear T3R immunoreactivity. In schwannoma cell cultures, Schwann cells continued to express T3R, even in cultures treated with medium that had been conditioned with rat sensory neurons. On the basis of these results, we suggest that, beside the possible regulatory mechanisms for T3R, the synthesis of T3R is regulated, at least in part, by Schwann cell-axon interaction.

Animals↗
PubMed1975

An electron microscope study of "Pacinian neurofibroma".

An electron microscope study has been made of the "Pacinian neurofibroma". Unlike the usual neurofibroma the "Pacinian neurofibroma" is characterized by a proliferation of the so-called perineurial cells. Groups of surface vesicles, the absence of mesoaxons and a fragmented basallamina differentiate these perineurial cells from Schwann cells. The formation of the perineurial cells can be traced continuously from small and wide submicroscopic cellbands and clubshaped thickenings to ribbonlike cell complexes as well as to tactile-like structures. The most developed complexes and structures are visible with the light microscope. These formations do not correspond with real tactile corpuscles, rather they can be considered as neoplastic structures of the perineurium.

Axons↗
PubMed1994

Characterization of Schwann cells from normal nerves and from neurofibromas in the bicolour damselfish.

Schwann cells are an important component of neurofibromas, one of the primary lesions encountered in neurofibromatosis type 1 in man. A central question in studies of neurofibromatosis type 1 has been whether the Schwann cells present in these tumours are intrinsically abnormal or exhibit abnormal phenotypes in response to stimuli from other cell types in these tumours. Damselfish neurofibromatosis is a naturally occurring disease in a species of marine fish, the bicolour damselfish, that is being developed as an animal model of neurofibromatosis type 1. Affected fish exhibit multiple neurofibromas and neurofibrosarcomas (malignant schwannomas). The present study compares the morphology, antigen expression and proliferative capacity in vitro of Schwann cells derived from peripheral nerves of normal, healthy fish with cells isolated from both spontaneously occurring and experimentally induced neurofibromas. Schwann cells from normal nerves expressed S100 antigens but not fibronectin or glial fibrillary acidic protein antigens and were similar in morphology and proliferative capacity to Schwann cells isolated from mammalian peripheral nerves. Tumour-derived cultures contained variable proportions (27-79%) of S100-positive cells that were identified as Schwann cells based on this feature. These tumour-derived Schwann cells exhibited a different morphology than normal Schwann cells, usually exhibited an increased reactivity to anti-S100 antibodies and were able to proliferate in vitro without added mitogens. Repeated subculturing of tumour-derived cultures led to the production of six cell lines all of which were composed exclusively of Schwann cells as indicated by S100 expression. These findings show that Schwann cells are an important component of tumours in Damselfish neurofibromatosis and that these cells are morphologically and physiologically altered in this disease. Observations of cell lines also suggest that tumour-derived Schwann cells are intrinsically abnormal and that this phenotype is not a result of stimuli from other cell types in the tumours.

Animals↗
PubMed1995

Small ileal neurofibroma causing intussusception in a non-neurofibromatosis patient.

Neurofibromas in the small intestine are usually accompanied by von Recklinghausen's disease (neurofibromatosis), and usually originate in the intramuscular plexus of Auerbach. We present here a solitary neurofibroma, which caused an ileocolic intussusception, originating in the submucosal plexus of Meissner in a non-neurofibromatosis patient. To our knowledge, there is no previous report of a neurofibroma originating in the plexus of Meissner. This condition was clearly confirmed by macroscopic and microscopic evaluation.

Adult↗
PubMed1998

[Tumor reduction of plexiform neurofibroma in the craniofacial and neck area].

Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary disease of high penetrance and variable expression. Epidemiologic data on craniofacial manifestations are still lacking. Up until now 74 patients with NF1 have been treated at the Department of Oral and Maxillofacial Surgery of the University of Hamburg. Forty-two patients presented periorbital and orbital neurofibromas varying in extension and in the severity of findings of the affected site. Surgical therapy is mainly based on tumour reduction, frequently combined with face-lifting. In our experience neurofibromas of the neck tend to be pseudo-encapsulated, facilitating the preparation of the tumour. On the other hand, identification and preparation of diffuse infiltrating neurofibromas in the trigeminal nerve region are difficult and local recurrence must be expected.

Adult↗
PubMed2006

MRI growth patterns of plexiform neurofibromas in patients with neurofibromatosis type 1.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with an incidence of 1:3000. Approximately 30% of NF1 patients develop plexiform neurofibromas (PNF) which often cause severe clinical deficits. We studied the growth patterns of 256 plexiform neurofibromas (PNF) by magnetic resonance imaging (MRI) and associated disfigurement and functional deficits to determine whether there are definable growth types of these tumors. Retrospectively, we evaluated MRI scans obtained during 1997 to 2003 of 256 plexiform neurofibromas from 202 patients with NF1. Clinical investigation was carried out at the same time as the MRI scans. We identified three growth patterns: superficial in 59, displacing in 76, and invasive growth in 121 tumors. The majority (52%) of invasive PNF were found in the face, head and neck area. While superficial PNF primarily caused aesthetic problems, displacing PNF led in most cases to aesthetic problems and pain, while invasive PNF led mainly to functional deficits and disfigurement. Our study demonstrates that PNF have different growth patterns that are associated with specific clinical features. Classification of PNF may open new opportunities in clinical management, especially regarding decisions and options associated with surgical intervention.

Adolescent↗
PubMed2004

Solitary intraosseous neurofibroma of the tibia.

A solitary intraosseous neurofibroma is rare and mostly occurs in the mandible. We report a case of a solitary intraosseous neurofibroma of the tibia. The radiographic findings were nonspecific and showed an eccentrically located, osteolytic lesion with a thin sclerotic border in the diaphysis of the left proximal tibia. The entity of intraosseous neurofibroma is briefly reviewed.

Adult↗
PubMed2005

A case of solitary neurofibroma of the nasal dorsum: resection using an external rhinoplasty approach.

A 7-year-old girl had suffered from progressive swelling of the nasal dorsum over 2 years. Computed tomography and magnetic resonance imaging showed a large soft tissue density in the nasal dorsum. Tc-99m DTPA cisternography and brain SPECT showed a restricted mass in the nasal dorsum without intracranial connection. The mass was resected using an external rhinoplasty approach, and the pathologic diagnosis was of neurofibroma. Furthermore, the nasal dorsum was identified as the origin of the neurofibroma without the stigma of neurofibromatosis. Here, we present this case and discuss the clinical and pathological aspects of neurofibroma arising in the nasal dorsum.

Child↗
PubMed2000

Neurofibroma of the auriculotemporal nerve.

Despite the extensive branching of the trigeminal nerve, solitary neurofibromas along its branches are a rare finding. We report our management of a neurofibroma of the right auriculotemporal nerve in a 46-year-old women. A chain of small nodules palpable in the right postauricular region was associated with increasing pain radiating into the postauricular and temporoparietal regions of her head. Magnetic resonance imaging and computed tomography showed several small ovoid lesions extending from the postauricular region to the infratemporal fossa. The lesions were removed surgically. The facial nerve adhered to the dorsal side of the largest nodule, but this could be removed without sequelae. The auriculotemporal nerve was identified as the nerve of origin and was removed together with the lesions. Histopathological examination was consistent with a neurofibroma with early plexiform cell formations. Clinical findings are discussed.

Cranial Nerve Neoplasms↗
PubMed2004

Mediastinal neurofibroma originating from the left intrathoracic phrenic nerve: report of a case.

We report a case of mediastinal neurofibroma originating from the left phrenic nerve in a 42-year-old woman who was referred to us after a routine chest X-ray showed a smooth, round abnormal shadow in the left middle lung field adjacent to the heart. We resected a 25 x 20 x 20-mm tumor by video-assisted thoracic surgery. Histopathological examination confirmed that the lesion was a mediastinal neurofibroma originating from the left phrenic nerve without von Recklinghausen's disease. Neurogenic mediastinal tumors originating from the phrenic nerve are very rare, and to the best of our knowledge, no other case of a mediastinal neurofibroma originating from the phrenic nerve in a patient without von Recklinghausen's disease has ever been reported.

Adult↗
PubMed2002

Bilateral cervicomediastinal neurofibroma originating from the vagal nerve in a patient with von Recklinghausen's disease: report of a case.

A 19-year-old woman with von Recklinghausen's disease was admitted with symptoms of hoarseness. A computed tomography scan showed a bilateral cervicomediastinal tumor. An extirpation of the left cervicomediastinal tumor was performed for the purpose of diagnosis and treatment. On thoracotomy, the tumor, which measured 9 x 8 x 4 cm in size, arose from the intrathoracic vagal nerve and the left tumor was resected with a segment of the vagal nerve and recurrent nerve. The pathological diagnosis of the tumor was a neurofibroma. The tumor on the right side was left untreated due to concerns about possibly causing palsy of the bilateral recurrent nerve and also because of the asymptomatic state of the right tumor. Mediastinal neurofibroma in a patient with von Recklinghausen's disease often arises from the intrathoracic vagal nerve. To our knowledge, this is the first report of bilateral cervicomediastinal neurofibroma originating from the vagal nerves.

Adult↗
PubMed1987

Subglottic neurofibroma in a child.

Reported here for the first time is a case of subglottic neurofibroma in an infant which was removed by laryngofissure. Neurofibromas are ubiquitous in distribution, but very rare in the larynx and also extremely rare in infancy. Only 9 cases had been reported in children under 9 years of age. In the present case, H.T., a boy aged 2 years and 7 months, complaining of inspiratory stridor since the beginning of December 1985, was admitted to our hospital on Jan. 21, 1986. The tumor was completely removed by laryngofissure and pathological diagnosis showed it to be a neurofibroma. Laryngeal neurofriboma cases are reviewed and discussed.

Child, Preschool↗
PubMed2005

Pigmented neurofibroma: review of Japanese patients with an analysis of melanogenesis demonstrating coexpression of c-met protooncogene and microphthalmia-associated transcription factor.

Pigmented neurofibroma (PNF) is a rare variant of neurofibroma showing melanin production. To clarify the clinicopathologic features of PNF and to characterize melanogenesis in PNF, 12 cases of PNF were examined in comparison with schwannoma (SCH, n = 16) and neurofibroma (NF, n = 26). The PNF patients were all Japanese including 7 men and 5 women, and patient age ranged from 11 to 71 years (median, 23.5 years). They showed strong a predisposition for neurofibromatosis type 1. Their tumor size was large, and tumors arose from various sites of skin. Histologically, clusters of epithelioid, dendritic, and spindle melanin-producing cells with faint pigmentation had a tendency to locate in deep dermis and subcutis, which seems to be a characteristic pattern of melanogenesis. There was a transition between melanin-producing cells and Schwann cells. Immunohistochemical examination included known melanogenic markers, microphthalmia-associated transcription factor (MITF), which is a key regulator of melanogenesis, and 2 tyrosine kinase receptors, c-Met and c-Kit, which regulate the development of melanocytes. In PNF, melanin-producing cells were S100 (+), MITF (+), Melan-A (+), tyrosinase (+/-), HMB45 (+/-), c-Met (+), and c-Kit (-). Schwann cells were S100 (+), MITF (-), Melan-A (-), tyrosinase (-), HMB45 (-), c-Met (-), and c-Kit (-), and intermediate spindle cells were S100 (+), MITF (+), Melan-A (+), tyrosinase (-), HMB45 (-), c-Met (+), and c-Kit (-). When compared with SCH and NF, MITF was weakly expressed in a part of tumor cells of SCH, whereas no definite staining was found in NF. c-Met expression was very weak in a scattered manner in SCH (10/15 cases) and NF (10/26 cases). These results suggest that PNF is a unique tumor that shows differentiation toward mature melanin production, but ability of melanin synthesis seems to be impaired. There may be a close relationship between up-regulated MITF and c-Met and the peculiar melanogenic nature of PNF, and both of these are useful diagnostic tools for distinguishing PNFs with less melanin production from NFs.

Adolescent↗
PubMed2006

Single stage near total resection of massive pediatric head and neck plexiform neurofibromas.

OBJECTIVE: Plexiform neurofibromas of the head and neck in neurofibromatosis type 1 (NF 1) carry a significant morbidity with substantial loss of function as well as significant cosmetic problems. We describe our experience with early aggressive surgical intervention in such patients in order to avert these problems. METHODS: Retrospective review of four consecutive pediatric patients with massive head and neck plexiform neurofibromas who underwent single stage near total or sub-total tumor resections. RESULTS: All four patients were referred for obstructive airway symptoms. Each patient experienced complete relief of symptoms and return of function without additional neurological deficits. There were two minor complications and no major complications of surgical resection. There have been no recurrences to date, with follow-up ranging from 15 months to 5 years. CONCLUSIONS: Early surgical intervention of NF 1 patients with plexiform neurofibromas of the head and neck with a goal of near total resection avoids the loss of function associated with these tumors, such as tracheostomy dependence, swallowing difficulty, and speech problems, and prevents the inexorable progression of substantial cosmetic deformity. Successful management of these complex lesions requires detailed preoperative planning, advanced surgical techniques, and vigilant postoperative care.

Adolescent↗
PubMed1999

Deletions of the INK4A gene occur in malignant peripheral nerve sheath tumors but not in neurofibromas.

The INK4A gene, a candidate tumor suppressor gene located on chromosome 9p21, encodes two protein products, p16 and p19(ARF). p16 is a negative cell cycle regulator capable of arresting cells in the G1 phase by inhibiting cyclin-dependent kinases 4 (Cdk4) and 6 (Cdk6), thus preventing pRB phosphorylation. p19(ARF) prevents Mdm2-mediated neutralization of p53. Loss of INK4A is a frequent molecular alteration involved in the genesis of several neoplasms, including tumors of neuroectodermal origin. This study investigated the frequency of INK4A gene alterations in a series of malignant peripheral nerve sheath tumors (MPNSTs) and neurofibromas (NFs). INK4A gene and the p19(ARF)-specific exon 1beta were studied in 11 MPNST samples from 8 patients and 7 neurofibromas. Presence of INK4A deletions was assessed by Southern blotting hybridization and by a multiplex polymerase chain reaction (mPCR). INK4A point mutations were examined by single-strand conformation polymorphism (SSCP) and sequencing. The p16 promoter methylation status was determined by PCR amplification of bisulfite-treated DNA. Homozygous deletions of exon 2, thus affecting both p16 and p19(ARF), were identified in MPNSTs from 4 of 8 patients. Deletions, mutations, or silencing by methylation were not identified in the neurofibromas analyzed. Based on our results, we conclude that INK4A deletions are frequent events in MPNSTs and may participate in tumor progression. Silencing of p16 by methylation, which occurs often in several tumor types, is uncommon in MPNSTs.

Blotting, Southern↗
PubMed2002

Endotracheobronchial neurofibromas.

Among benign tracheobronchial neoplasms, neurofibromas of neurogenic origin are exceedingly rare. In a search world literature, only 23 cases of endotracheobronchial neurofibromas in 21 series were found. We report another case of a 52-year-old man who presented to our hospital with the symptoms of intermittent productive cough and fever. Bronchoscopy revealed a round tumor obstructing the lumen of the right main bronchus. Right sleeve pneumonectomy was performed, and neurofibroma was confirmed by pathologic examination. The literature is reviewed.

Bronchial Neoplasms↗
PubMed1998

Diffuse neurofibroma of the ankle.

PURPOSE: To correlate the imaging and histological findings in diffuse neurofibroma. PATIENTS AND METHODS: Retrospective review of clinical, imaging and histological findings in two patients with diffuse neurofibroma. RESULTS: CT demonstrates diffuse infiltration of the deep and subcutaneous fat, isodense to muscle. Magnetic resonance imaging shows extensive infiltration of the subcutaneous and deep fat that envelops tendons and vessels but does not involve bone. Superficial masses enhance homogeneously after intravenous gadolinium. The reticular nature of the deep infiltration is seen on all sequences but is most conspicuous on post-gadolinium T1-weighted images which show tumour enhancement and non-enhancing hypointense soft tissue strands. Magnetic resonance angiography and Doppler ultrasound may show enlarged vessels, high blood flow and vascular pools. CONCLUSION: Diffuse neurofibroma has a characteristic appearance on magnetic resonance that is best shown on post-gadolinium T1-weighted images.

Adolescent↗