Benign Peripheral Nerve Sheath Tumors Research Articles

Peripheral Nerve Sheath Tumors of Head and Neck: Imaging-Based Review of World Health Organization Classification.

We aim to review the imaging appearance of peripheral nerve sheath tumors (PNSTs) of head and neck according to updated fourth edition of World Health Organization classification. Peripheral nerve sheath tumor can be sporadic or associated with neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis. Schwannoma is the most common benign PNST that can be intracranial or extracranial and appears heterogeneous reflecting its histologic composition. Melanotic schwannoma is a different entity with high prediction of malignancy; it shows hypointense signal on T2-weighted image. Neurofibroma can present by localized, plexiform, or diffuse lesion. It usually appears homogeneous or shows a characteristic target sign. Perineurioma can be intraneural seen with the nerve fiber or extraneural appearing as a mass. Solitary circumscribed neuroma and neurothekeoma commonly present as dermal lesions. Nerve sheath myxoma may exhibit high signal on T1 weighted image. Benign triton tumors can be central, aggressive lesion, or peripheral nonaggressive lesion. Granular cell tumor shows hypointense signal on T2 weighted image. Neuroglial heterotopia most commonly occurs in the nasal cavity. Ectopic meningioma arises from ectopic arachnoid cells in the neck. In hybrid PNST, combined histological features of benign PNST occur in the same lesion. Malignant PNSTs are rare with an aggressive pattern. Computed tomography and magnetic resonance imaging are complementary studies to determine the location and extent of the tumor. Advanced magnetic resonance sequences, namely, diffusion-weighted imaging and dynamic contrast enhancement, can help in differentiation of benign from malignant PNST.

A Rare Case of Malignant Peripheral Nerve Sheath Tumor of Larynx.

Malignant peripheral nerve sheath tumors are highly aggressive tumors and they arise either de novo or from preexisting benign schwannoma or neurofibromatosis. Malignant peripheral nerve sheath tumor of the larynx is an extremely rare neoplasm, for which accurate diagnosis is difficult and the therapy is usually delayed. Although wide surgical excision is the mainstay of treatment, radiation therapy also plays an important role in the control and treatment of locally recurrent disease and non resectable cases. Here we are reporting a case of malignant peripheral nerve sheath tumor of the larynx without definite evidences of von Recklinghausen's disease or preexisting benign peripheral nerve sheath tumor.

Surgical Excision of Dumbbell-shaped Vagus Nerve Schwannoma: A Case Report

Schwannoma is a benign peripheral nerve sheath tumour that arises from the uncontrolled proliferation of Schwann cells. Intracranial and extracranial vagus nerve schwannoma is an extremely rare entity that poses a surgical challenge due to its delicate location in the cerebrum and parapharyngeal space adjacent to major neck vessels. This report describes a unique case of a 42 years old female with left dumbbell vagus nerve schwannoma, involving both the intracranial and extracranial portion of the left vagus nerve, extending into the parapharyngeal space. She underwent a two-stage surgery in which intracranial vagus schwanomma was debulked initially, and excision of the extracranial schwanomma in the parapharyngeal space was performed in a later setting via a transcervical approach.

Common peroneal nerve schwannoma, a rare cause of sciatica - Case report & review of literature

Schwannoma typically a slow-growing tumour that bears the reputation of the most common benign peripheral nerve sheath tumour. Sciatic nerve schwannoma is rare (1%) tumour that can manifest with symptoms of sciatica (1). Diagnosis of schwannoma is often delayed, notably when presents with symptoms of sciatica (1- 4).

Peripheral nerve sheath tumor: differentiation of malignant from benign tumors with conventional and diffusion-weighted MRI.

To evaluate potential of conventional MRI and diffusion-weighted imaging (DWI) for differentiating malignant from benign peripheral nerve sheath tumors (PNSTs). Eighty-seven cases of malignant or benign PNSTs in the trunk or extremities that underwent conventional MRI with contrast enhancement, DWI, and pathologic confirmation between Sep. 2014 and Dec. 2017 were identified. Of these, 55 tumors of uncertain nature on MRI were included. Tumor size, signal, and morphology were reviewed on conventional MRI, and apparent diffusion coefficient (ADC) values of solid enhancing portions were measured from DWI. Patient demographics, MRI features, and ADC values were compared between benign and malignant tumors, and robust imaging findings for malignant peripheral nerve sheath tumors (MPNSTs) were identified using multivariable models. A total of 55 uncertain tumors consisted of 18 malignant and 37 benign PNSTs. On MRI, tumor size, margin, perilesional edema, and presence of split fat, fascicular, and target signs were significantly different between groups (p < 0.05), as were mean and minimum ADC values (p = 0.002, p < 0.0001). Most inter-reader agreement was moderate to excellent (κ value, 0.45-1.0). The mean ADC value and absence of a split fat sign were identified as being associated with MPNSTs (odds ratios = 13.19 and 25.67 for reader 1; 49.05 and 117.91 for reader 2, respectively). The C-indices obtained by combining these two findings were 0.90 and 0.95, respectively. Benign and malignant PNSTs showed different features on MRI and DWI. A combination of mean ADC value and absence of split fat was excellent for discriminating malignant from benign PNSTs. • It is important to distinguish between malignant peripheral nerve sheath tumors (MPNSTs) and benign peripheral nerve sheath tumors (BPNSTs) to ensure an appropriate treatment plan. • On conventional MRI and diffusion-weighted imaging (DWI), MPNSTs and BPNSTs showed significant differences in tumor size, margin, presence of perilesional edema, and absence of split fat, fascicular, and target signs. • Absence of a split fat sign and mean apparent diffusion coefficient (ADC) values were robust imaging findings distinguishing MPNSTs from BPNSTs, with a C-index of > 0.9.

Multiple spinal neurofibromas with cervical and lumbar cord compression In neurofibromatosis 1 - A rare presentation

Neurofibromatosis is a multi system genetic condition with a wide range of neurological manifestations. It is clinically characterized by neurofibromas (benign peripheral nerve sheath tumours), skin involvement, visual complaints along with cardiopulmonary and gastrointestinal complaints. On the basis of affected gene and chromosome, neurofibromatosis may be divided into Type I (Chr. 17) and Type II (Chr. 22). Cervical cord compression due to cervical root neurofibromas represents an important clinical problem in patients with neurofibromatosis type 1 (NF 1), but is rarely reported. 1,2 We report here a rare case, who in addition to classical features of NF-1, had multiple spinal neurofibromas in cervical as well as lumbar spine leading to quadriparesis. Keywords: Neurofibromatosis, Neurofibromatosis type 1, Cervical cord compression, Neurofibroma, Recklinghausen’s disease.

Case Report of Schwannomas: Benign Tumour of the Peripheral Nerve Sheath

Schwannomas, also known as neurilemmomas, are benign peripheral nerve sheath tumours arising from the Schwann cells surrounding the nerve. Incidence of peripheral nerve sheath benign tumours occurring in the lower extremities is rare (1–10%). The authors present two cases with solitary schwannomas from the peripheral nerves. In one case, the schwannoma arose from the sural nerve and in the other, from the tibial nerve. They were successfully surgically removed with the aid of a surgical microscope, with no intraoperative or postoperative complications.

Genetic basis of neurofibromatosis type 1 and related conditions, including mosaicism.

Neurofibromatosis type 1 (NF1) is a frequent autosomal dominant disorder characterised by café-au-lait maculae (CALM), skinfold freckling, iris Lisch nodules and benign peripheral nerve sheath tumours (neurofibromas). The NF1 gene is a tumour suppressor gene and NF1 individuals have an increased risk for a long list of tumours, all resulting from a second hit in the normal copy of the NF1 gene. Remarkably, some non-tumour phenotypes such as CALM and pseudarthrosis are also caused by a "second hit". Germline mutations inactivating the NF1 gene show a large variability in genetic mechanisms ranging from single-nucleotide substitutions and somatic mosaicism to large deletions affecting neighbouring genes. Molecular confirmation of the clinical diagnosis is becoming increasingly more important to differentiate NF1 from other syndromes such as Legius syndrome, to investigate genotype-phenotype correlations relevant in 10% of cases and to detect somatic mosaicism. Some degree of learning difficulties, attention deficit and social problems are observed in most children and affect quality of life. There is a large individual variability in complications and the evolution of the disease is difficult to predict. Specialised outpatient clinics for children have been widely established and are important for surveillance and guidance. Regular surveillance is also important for adolescents and adults because many tumour complications can be detected by whole-body MRI and treated even before symptoms develop and irreversible damage occurs. Recent data on nodular plexiform neurofibromas with continued growth in adolescents and young adults show that many of these tumours are premalignant lesions called atypical neurofibromatous neoplasm of uncertain biological potential (ANNUBP). Specific surveillance and timely local resection of these benign peripheral nerve sheath tumours might be important to prevent malignant degeneration. In the last years, targeted therapy with MEK inhibitors has shown promise to treat unresectable and symptomatic plexiform neurofibromas. Many more challenges remain to find the best way to monitor children and adults for potential complications and to find a satisfying cure for many complications in this disorder.

Unexpected high frequency of neurofibroma in the celiac ganglion of German cattle

In a study originally designed to find potential risk factors for bovine spongiform encephalopathy (BSE) we examined tissues from 403 Holstein Frisian cattle in total. These included 20 BSE cattle and their 236 birth- and feeding cohort animals plus 32 offspring, 103 age, breed and district-matched control cattle and further twelve cattle with neurological signs. In addition to the obex, we examined the celiac ganglion, cervical cranial ganglion, trigeminal ganglion and proximal ganglion of the vagus nerve using histological techniques. Unexpectedly, we found a high number of neurofibroma, a benign peripheral nerve sheath tumor consisting of Schwann cells, fibroblasts and perineural cells. The neurofibroma were present only in the celiac ganglion and found during histologic examination. With a frequency of 9.91% in BSE cattle and their cohorts (case animals) and 9.09% in the age, breed and district matched control animals there seems to be no correlation between the occurrence of BSE and neurofibroma. Benign peripheral nerve sheath tumors have been described more often in cattle than in other domestic animals. Usually, they are incidental macroscopic findings in the thoracic ganglia during meat inspection. To our knowledge, there are no previous systematic histologic studies including bovine celiac ganglia at all. The high incidence of celiac ganglia neurofibroma may play a role in the frequently occurring abomasal displacements in Holstein Frisian cattle as the tumors might cause a gastrointestinal motility disorder. At present a genetic predisposition for these neoplasms cannot be ruled out.

Diffusion tensor imaging and tractography for preoperative assessment of benign peripheral nerve sheath tumors

PurposeTo evaluate the diagnostic value of fiber tractography and diffusivity analysis generated from 3D diffusion-weighted (DW) sequences for preoperative assessment of benign peripheral nerve sheath tumors. MethodMR imaging at 3 T was performed in 22 patients (mean age 41.9 ± 17.1y, 13 women) with histologically confirmed schwannomas (N = 18) and histologically confirmed neurofibromas (N = 11), including a 3D DW turbo spin echo sequence with fat suppression. Diffusion tensor parameters were computed and fiber tracks were determined. Evaluation was performed by two radiologists and one orthopedic surgeon blinded for final diagnosis. Mean diffusivity was computed to allow further assessment of tumor microstructure. Preoperative fascicle visualization was graded, fascicles were categorized regarding anatomical location and amount of fascicles surrounding the tumor. The agreement of imaging findings with intraoperative findings was assessed. ResultsOn 78.3 % of the DTI images, the fascicle visualization was rated as good or very good. Tractography differences were observed in schwannomas and neurofibromas, showing schwannomas to be significantly more often located eccentrically to the nerve (94.8 %) than neurofibromas (0 %, P < 0.01). Fascicles were significantly more often continuous (87.5 %) in schwannomas, while in neurofibromas, none of the tracks was graded to be continuous (0 %, P = 0.014). A substantial agreement between fiber tracking and surgical anatomy was found regarding the fascicle courses surrounding the tumor (κ = 0.78). Mean diffusivity of schwannomas (1.5 ± 0.2 × 10−3 mm2/s) was significantly lower than in neurofibromas (1.8 ± 0.2 × 10−3 mm2/s; P < 0.001). The Youden index showed an optimal cutoff at 1.7 × 10−3 mm2/s (sensitivity, 0.91; specificity, 0.78; J = 0.69). ConclusionsPreoperative diffusion tensor imaging allowed to accurately differentiate between schwannomas and neurofibromas and to describe their location in relation to the nerve fascicles for preoperative planning.

The Risk of Peripheral Nerve Tumor Biopsy in Suspected Benign Etiologies.

Peripheral nerve sheath tumors (PNSTs) are tumors with unique clinical and imaging features that present to a variety of physicians. These lesions are often referred for biopsy, which can put nerve fascicles at risk. Preoperative biopsy may cause distortion of normal anatomic planes, making definitive resection difficult. To evaluate the neurological risks of preoperative biopsy in benign PNSTs. Surgical cases collected retrospectively using a prospectively established database of PNSTs treated by a single surgeon between 1997 and 2019. Patients were dichotomized depending on preoperative biopsy. The effects of biopsy were assessed via history and physical examination both pre- and postdefinitive resection. A total of 151 cases were included. Only 23.2% (35) of patients underwent preoperative biopsy, but 42.9% of these experienced new or worsening neurological examination immediately following biopsy. After definitive resection, the rate of neurological deficit was significantly different between the 2 groups with 60% of biopsy patients and 19% of those patients not biopsied experiencing decline in examination (F=25.72, P<.001). Odds ratio for any postoperative deficit for biopsy was 6.40 (CI [2.8, 14.55], P<.001). Univariate logistic regression of neurological deficit with patient age, sex, tumor type, and biopsy status showed that only biopsy was associated with the occurrence of any postoperative deficit. Biopsy of benign PNSTs is associated with a high rate of neurological deficit both immediately following the procedure and after definitive resection. Careful selection is imperative prior to proceeding with biopsy of nerve sheath tumors exhibiting benign features given the unacceptably high rate of neurological decline.

Modern treatment of perineuriomas: a case-series and systematic review

BackgroundPerineuriomas are rare benign peripheral nerve sheath tumours of perineurial cell origin and can be classified into intraneural and extraneural perineuriomas. They most commonly present a mononeuropathy of gradual onset and slow progression, resulting in progressive neurological deficits like hypoesthesia or motor weakness. Therapy is still variable. Aim of the study was to compare our surgical treatment and our follow-up regime including high-resolution nerve sonography with the current literature to evaluate best treatment of perineuriomas.MethodsRetrospective analysis of our dataset “peripheral nerve lesion” to identify patients suffering from perineuriomas between 01.01.2012 until 31.12.2018. Surgical treatment and the follow-up examination of three patients were described. Additionally, a systematic review including PubMed, the Cochrane Collaboration Library, Scopus and Google Scholar was performed for literature published between January 1, 1990 and October 31, 2019 independently by 2 authors.ResultsIn the first case, the left ulnar nerve was affected. In the second case, the left peroneal nerve and in the third case the right median nerve was affected. High-resolution nerve sonography was performed in each case. All patients underwent interfascicular neurolysis combined with a targeted fascicular biopsy under electrophysiological monitoring. Neurological deficits improved subsidized by rehabilitation. Surgical therapy and the neurological outcome were compared with literature. Systematic review revealed 22 articles, which met the inclusion criteria. Therefore, demographics, surgical treatment and neurological outcome of 77 patients were analysed.ConclusionsPerineuriomas are rare benign nerve sheath tumours with a slow progression, sometimes difficult to diagnose. Decompression and neurolysis may improve neurological deficits. High resolution nerve sonography might serve as a helpful additional diagnostic tool in this process.

Intramuscular peripheral nerve sheath tumors: schwannoma, ancient schwannoma, and neurofibroma.

To analyze the prevalence of classic magnetic resonance imaging (MRI) findings of intramuscular peripheral nerve sheath tumors (PNSTs), including schwannoma, ancient schwannoma, and neurofibroma. Thirty pathologically confirmed benign intramuscular PNSTs (24 schwannomas, 3 ancient schwannomas, and 3 neurofibromas) were retrospectively reviewed. Classic MRI findings of PNSTs including split fat sign, fascicular sign, target sign, entering and exiting nerve, and thin hyperintense rim were assessed for each intramuscular PNST. Denervation change of the affected muscle was also assessed. In ancient schwannoma and neurofibroma, the signal intensity (SI) and enhancement pattern were analyzed. All intramuscular schwannomas revealed two more classic MRI findings. Eight of the 24 intramuscular schwannomas revealed affected muscle denervation change. All intramuscular ancient schwannomas showed only split fat sign. All intramuscular ancient schwannomas showed denervation change of the associated muscle. All intramuscular neurofibroma showed split fat sign and one case with target sign was detected. Ancient schwannomas were isointense SI on T1-weighted image (T1WI) and one case had hyperintense foci. They showed heterogeneously hyperintense SI on T2-weighted image (T2WI) with heterogeneous enhancement. Neurofibromas were isointense SI (2/3) and slight hyperintense SI (1/3) on T1WI and heterogeneously hyperintense SI on T2WI with heterogeneous enhancement. One ancient schwannoma showed conglomerated calcifications. Intramuscular schwannomas were easily diagnosed based on MRI. In the case of intramuscular ancient schwannoma and neurofibroma with only split fat sign among the classic MRI findings, they might be distinguished from other intramuscular soft tissue tumors based on muscle denervation change or typical crescent split fat sign.

Go for the Gold: A "Plane" and Simple Technique for Resecting Benign Peripheral Nerve Sheath Tumors.

Intraneural dissection is a useful technique for achieving gross total resection and preserving functional fascicles for peripheral nerve tumors. Finding the correct tissue plane is the critical step for safe successful enucleation. The authors hypothesized that the yellow color of benign nerve tumors can be used to identify surgical planes. To describe a technique to find the correct intraneural dissection plane based on a quantified yellow appearance during resection of benign peripheral nerve sheath tumors. Intraoperative photographs were reviewed to determine the percentage of yellow that tumors appeared at different phases of surgery. A technique was developed to quantitatively measure the amount of yellow using Photoshop. Previously published journal articles containing color images of peripheral nerve tumor resections were also analyzed for yellow tumor color. There were 24 patients with suitable images to permit measurement of color for 3 steps of the procedure. The average percentages of yellow for tumor exposure, tumor resection, and removed specimen were 36.5%, 59.1%, and 80.4%, respectively (P<.001). Three publications were found that contained high-quality images of at least 2 phases of the surgery with average yellow content of 47.4% and 84% (P<.01). The simple observation that a benign nerve sheath tumor is yellow in color can be used to guide surgical resection and achieve excellent outcomes. Intraneural dissection through the pseudocapsule should be pursued layer by layer until a yellow true capsule is found. By sparing functional nervous tissue within the pseudocapsule, this technique may lead to improved neurological outcomes.

Benign peripheral nerve sheath tumors of the extremities: a study of one hundred patients.

Benign peripheral nerve sheath tumors of the extremities: a study of one hundred patients.

An unusual localization of neurofibromas in a patient with neurofibromatosis type-1: The great auricular nerve

Neurofibromatosis type 1 (NF-1) is an autosomal dominant disorder characterized by café au lait macules, axillary freckling, neurofibromas, Lisch nodules, skeletal abnormalities, and a tendency to develop neoplasms. Neurofibromas are benign peripheral nerve sheath tumors that occur commonly in individuals with NF-1. Neurofibromas originating from the vagus nerve and spinal nerves are rarely reported in the literature. Here, we report an interesting case of NF-1 with a striking cutaneous presentation and bilateral localization in the great auricular nerve with bilateral vagal and multiple spinal neurofibromas. This is the first report of an NF-1 case with bilateral symmetric localization in the great auricular nerve.

Pelvic plexiform neurofibromatosis presenting with genital numbness

Neurofibromatosis type I is a common autosomal dominant inherited disorder of neural crest origin, affecting 1 in 3000 people.1 Plexiform neurofibromas, benign peripheral nerve sheath tumours, are considered pathognomonic of...

Fluorescein-guided removal of peripheral nerve sheath tumors: a preliminary analysis of 20 cases.

Benign peripheral nerve sheath tumors (PNSTs) include mainly schwannomas-the most common tumors arising from peripheral nerves-and neurofibromas. Due to their origin, distinguishing between functional intact nerve and the fibers from whence the PNST arose may not always be easy to perform. The introduction of intraoperative tools to better visualize these tumors could be helpful in achieving a gross-total resection. In this study, the authors present a series of patients harboring PNST in which the surgery was performed under fluorescein guidance. Between September 2018 and February 2019, 20 consecutive patients with a total of 25 suspected PNSTs underwent fluorescein-guided surgery performed under microscopic view with a dedicated filter integrated into the surgical microscope (YELLOW 560) and with intraoperative monitoring. All patients presented with a different degree of contrast enhancement at preoperative MRI. Fluorescein was intravenously injected after intubation at a dose of 1 mg/kg. Preoperative clinical and radiological data, intraoperative fluorescein characteristics, and postoperative neurological and radiological outcomes were collected and analyzed. Six patients were affected by neurofibromatosis or schwannomatosis. There were 14 schwannomas, 8 neurofibromas, 1 myxoma, 1 reactive follicular hyperplasia, and 1 giant cell tumor of tendon sheath. No patient experienced worsening of neurological status after surgery. No side effects related to fluorescein injection were found in this series. Fluorescein allowed an optimal intraoperative distinction between tumor and surrounding nerves in 13 of 14 schwannomas and in all neurofibromas. In 6 neurofibromas and in 1 schwannoma, the final YELLOW 560 visualization showed the presence of small tumor remnants that were not visible under white-light illumination and that could be removed, obtaining a gross-total resection. Fluorescein was demonstrated to be a feasible, safe, and helpful intraoperative adjunct to better identify and distinguish PNSTs from intact functional nerves, with a possible impact on tumor resection, particularly in diffuse neurofibromas.

Peranan Radiologi dan Radioterapi pada Penatalaksanaan Malignant Peripheral Nerve Sheath Tumor

Malignant peripheral nerve sheath tumor (MPNST) is biologically an aggressive tumor of soft tissue sarcoma. MPNSTs represent 5–10% of all soft-tissue sarcomas. They correspond to malignant forms of neurofibromas and schwannomas. The main clinical symptoms of MPNST are increasing size of tumors, local or radicular pain, paraparesis, and paresthesia and/or weakness of extremities.Radiological imaging is important to determine the site and extension of the tumor, especially before surgery. Magnetic resonance imaging (MRI) is the imaging modality of choice. To some extent, MPNSTs share basic imaging characteristics with benign peripheral nerve sheath tumor, although there are some evidence of malignant transformation. Diagnosis may be challenging because there are no specific immunohistochemical or molecular markers. However, Histopathological examination is needed for definitive diagnosisThe mainstay of treatment is surgical resection. The goal of the operation is to achieve complete surgical excision of the tumor with negative (wide) margins. Together with wide surgical excision, radiation therapy offers the best outcome of local and overall survival rates.

Immunohistochemical Distinguishing between Canine Peripheral Nerve Sheath Tumors and Perivascular Wall Tumors

Abstract Peripheral nerve sheath tumors (PNSTs) comprise a heterogeneous group of neoplasms originating from the elements of the nerve sheath. They are divided into two forms: benign and malignant PNST. Both benign and malignant PNSTs are not very common in domestic animals but they are reported in different animal species. Histologically, PNSTs are composed predominantly of spindle cells arranged in bundles, whorls and sheets, with a different number of pleomorphic cells and mitotic figures. The aim of this study was a reclassification of 17 dog tumor samples initially diagnosed with peripheral nerve sheath tumors using histopathological analysis. The main criterion for reclassification was immunohistochemical positivity for various antigens. PNSTs are often histologically very similar to other spindle cell tumors and immunohistochemistry is required for differential diagnosis. PNSTs generally express vimentin, S-100 protein, glial fibrillary acidic protein (GFAP), collagen IV and laminin. Four tumor samples were positive to muscular marker α-SMA and vimentin and negative for S-100 protein and desmin. The spindle cells whirling around some blood vessels were observed in these tumors so they were reclassified as perivascular wall tumors (PWTs). The other 13 tumors were S-100 protein and vimentin positive and α-SMA and desmin negative, thus classified as PNST. The use of the immunohistochemical panel is necessary for distinguishing PNSTs from PWTs in routine diagnostics.