Diagnosis and management of intracranial malignant peripheral nerve sheath tumors

Intracranial malignant peripheral nerve sheath tumor: A case report and comprehensive literature review

Background

Malignant peripheral nerve sheath tumors (MPNSTs) are rare malignant soft-tissue sarcomas arising from peripheral nerves. Little data exist regarding MPNST originating intracranially. Here, we present a 7th/8th nerve complex MPNST, discuss the treatment strategy and patient outcome, and provide a comprehensive review of existing literature.

Methods

Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, PubMed and crossed references were queried, yielding 37 publications from 1952 to the present. Fifty-three cases of primary intracranial and extra-axial MPNST were identified.

Results

We additionally report a 40-year-old female presented with acute onset dizziness and subsequent hearing loss with associated right-sided facial numbness. Magnetic resonance imaging revealed a 0.5 cm × 1.7 cm enhancing lesion within the right internal auditory canal extending into the cerebellopontine angle. The patient was initially treated with retro sigmoid craniotomy for tumor resection followed by a trans labyrinth approach for residual tumor resection. She completed adjuvant fractionated radiation therapy and underwent facial nerve transfer to restore complete hemifacial paralysis. The most common cranial nerves involved were V and VIII (43.4% each), with 66% of patients male and 34% female. The average age was 43.4 ± 17.4 years. The mean survival time for reported non-survivors after tissue diagnosis was 15 ± 4 months. Two-year survival for patients receiving gross total resection was 33.3% versus 22.8% with subtotal resection.

Conclusion

MPNSTs comprise a group of highly aggressive neoplasms that rarely arise intracranially. Gross total surgical resection should be pursued when feasible.

Spontaneous malignant transformation of trigeminal schwannoma: consideration of responsible gene alterations for tumorigenesis-a case report

Malignant peripheral nerve sheath tumors (MPNSTs) arising from the trigeminal nerves are extremely rare (only 45 cases, including the present case, have been published) and have been reported to develop de novo from the peripheral nerve sheath and are not transformed from a schwannoma or neurofibroma. Here, we report a case of MPNSTs of the trigeminal nerve caused by the malignant transformation of a trigeminal schwannoma, with a particular focus on genetic considerations. After undergoing a near-total resection of a histologically typical benign schwannoma, the patient presented with regrowth of the tumor 10 years after the primary excision. Histopathologic and immunochemical examinations confirmed the recurrent tumor to be an MPNST. Comprehensive genomic analyses (FoundationOne panel-based gene assay) showed that only the recurrent MPNST sample, not the initial diagnosis of schwannoma, harbored genetic mutations, including NF1-p.R2637* and TP53-p.Y234H, candidate gene mutations associated with malignant transformation. Moreover, the results of reverse transcription polymerase chain reaction showed that the fusion of SH3PXD2A and HTRA1, which has been reported as one of the responsible genetic aberrations of schwannoma, was detected in the recurrent tumor. Taken together, we could illustrate the accumulation process of gene abnormalities for developing MPNSTs from normal cells via schwannomas.

Cranial and Spinal Malignant Peripheral Nerve Sheath Tumor: A Pathological Enigma

Objective  Malignant peripheral nerve sheath tumor (MPNST) arises from nerve sheaths, mostly seen in peripheral nerves but rare in craniospinal nerves. The information available in the literature to build up treatment strategy and improve clinical outcomes is scarce. We are reviewing cases from our institute, with emphasis on radiological features for early differentiation from its benign variants.

Methods  We analyzed pathologically diagnosed cases retrospectively from January 2007 to December 2018 at our institute. Clinicoradiological details and treatment parameters were collected from medical records for evaluation. Each case was contacted telephonically for final clinical follow-up at the time of writing the manuscript.

Results  A total of seven cases of MPNST were diagnosed in the last 10 years. It included four intracranial and three spinal cases. The mean age for the cohort was 34.3 years, with five females. We could achieve gross total resection (GTR) and subtotal resection in four (57.1%) and two (28.6%) cases, respectively. We could achieve an overall survival of 57.1% in the average follow-up of 28.2 months (range: 8–84 months).

Conclusion  MPNST is a rare tumor with a bad prognosis. Radical surgical resection is the mainstay of the treatment, but it is not always possible to achieve it because of the inaccessible location and large size of lesions. Preoperative diagnosis is challenging; however, few radiological findings may give a clue toward it. As a disease entity overall, it has a poor outcome with a high rate of fatality.

First documented case of intracranial falcine malignant peripheral nerve sheath tumor: illustrative case

BACKGROUND

The authors reported the first documented case of intracranial extraaxial nonneurofibromatosis type 1-related nontriton malignant peripheral nerve sheath tumor (MPNST) originating from the falx cerebri.

OBSERVATIONS

A 34-year-old man with headache, short-term memory deficit, postural instability, and blurred vision presented with a large heterogenous contrast-enhanced intraventricular cystic lesion originating from the free margin of the falx cerebri. The patient received surgery using the right posterior interhemispheric approach. Gross total resection was performed, and the inferior border of the falx cerebri was resected. The postoperative course was uneventful. Histological examination revealed hypercellular foci of neoplastic spindle cells with hyperchromatic and wavy nuclei. Hence, a diagnosis of MPNST was made based on concomitant immunochemistry findings, including mouse double minute 2 homolog focal positivity and geographic loss of H3K27me3. The patient received adjuvant radiotherapy, and recurrence was not observed.

LESSONS

Intracranial MPNSTs are extremely rare tumors, typically originating from the cranial nerves in the posterior cranial fossa. An even rarer variant of these tumors, referred to as malignant intracerebral nerve sheath tumors, may directly arise from the brain parenchyma. The authors reported the first case of an intracranial MPNST originating from the dura mater of the falx cerebri, acting as an extraaxial lesion with prevalent expansion in the right ventricle.

Stem-like cells drive NF1-associated MPNST functional heterogeneity and tumor progression

NF1-associated malignant peripheral nerve sheath tumors (MPNSTs) are the major cause of mortality in neurofibromatosis. MPNSTs arise from benign peripheral nerve plexiform neurofibromas that originate in the embryonic neural crest cell lineage. Using reporter transgenes that label early neural crest lineage cells in multiple NF1 MPNST mouse models, we discover and characterize a rare MPNST cell population with stem-cell-like properties, including quiescence, that is essential for tumor initiation and relapse. Following isolation of these cells, we derive a cancer-stem-cell-specific gene expression signature that includes consensus embryonic neural crest genes and identify Nestin as a marker for the MPNST cell of origin. Combined targeting of cancer stem cells along with antimitotic chemotherapy yields effective tumor inhibition and prolongs survival. Enrichment of the cancer stem cell signature in cognate human tumors supports the generality and relevance of cancer stem cells to MPNST therapy development.

Malignant Transformation in Vestibular Schwannoma: Clinical Study With Survival Analysis

Aim

Vestibular schwannomas (VSs) are generally considered benign tumors, and malignant transformation of VSs (MTVSs) are rare findings. The clinical features, treatment strategy, outcomes and prognostic factors remain unclear. We endeavored to analyze the natural history, management, outcomes and prognostic factors of MTVSs.

Materials and Methods

The clinical features, radiologic findings, pathological investigations and surgical outcomes of 4 patients with MTVSs treated at the authors' institution between 2010 and 2019 were retrospectively collected. Related literature published until December 2019 (63 articles, 67 patients) was evaluated. The authors also made a pooled analysis to evaluate the risk factors for overall survival (OS) time.

Results

Of the 4 cases in our series, 3 cases were malignant transformation following previous treatment (surgery and radiosurgery) and 1 was primary MTVS. Of the 71 MTVSs from the literature, 27 were male and 39 were female, with the mean age of 47.2 ± 17.5 years old. Twelve patients (18.5%) were diagnosed with NF2 (15.4%) or NF1 (3.1%). Forty-three (61.4%) patients underwent previous treatment (surgery and/or radiotherapy) prior to the pathological diagnosis of MTVSs. The mean size of the MTVSs was 35.1 ± 13.2mm. The mean Ki-67 index was 30.6% ± 18.8%. Twenty-four (49.0%) patients underwent gross total resection, 25 (51.0%) patients underwent incomplete resection. Twenty-five (44.6%) underwent adjuvant radiotherapy (RT) postoperatively. During the average follow-up of 9.9 ± 9.5 months (range, 0-40 months), 37 (82.2%) patients developed a local recurrence or metastasis. Forty-seven (73.4%) patients died of tumor progression or postoperative complications. The overall 1-year and 2-year survival rate was 42.3% and 18.6% respectively. Log-rank testing for Kaplan-Meier survival analysis identified that size (P = 0.047) and adjuvant radiotherapy (P=0.001) were significant prognostic factors for OS. Multivariate analysis revealed that adjuvant RT was the only prognostic factor for longer OS (P = 0.005).

Conclusions

MTVSs are rare, fatal disease, prone to recur and metastasize rapidly, resulting in death in most of the cases. We found that GTR did not improve the survival in MTVSs but postoperative adjuvant RT can significantly improve the OS, and we recommend early postoperative RT in MTVSs regardless of extent of resection.

Malignant Peripheral Nerve Sheath Tumor of the Cerebellar Hemisphere: An Unusual Location and Multiple Intracranial Parenchyma Metastases

Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue malignancies that can occur in any part of the body. The most common sites are the proximal limbs and trunk. Intracranial MPNSTs are rare; most originate from the auditory, trigeminal, and other cranial nerves, and occurrence within the brain parenchyma is rarer. Here, we describe a malignant peripheral schwannoma in the cerebellar hemisphere of the brain parenchyma. To our knowledge, this is the first case of brain parenchymal metastasis of an MPNST. We observed no effects on the tumor after the application of multiple chemotherapy drugs; thereafter, we explored the literature surrounding the condition.

Glioblastoma multiforme as a secondary malignancy following stereotactic radiosurgery of a meningioma: case report

The documentation and exact incidence of stereotactic radiosurgery (SRS)-induced neoplasia is not well understood, with most literature restricted to single case reports and single-center retrospective reviews. The authors present a rare case of radiosurgery-induced glioblastoma multiforme (GBM) following radiosurgical treatment of a meningioma. A 74-year-old patient with a sporadic meningioma underwent radiosurgery following surgical removal of a WHO grade II meningioma. Eighteen months later she presented with seizures, and MRI revealed an intraaxial tumor, which was resected and proven to be a glioblastoma. As far as the authors are aware, this case represents the third case of GBM following SRS for a meningioma. This report serves to increase the awareness of this possible complication following SRS. The possibility of this rare complication should be explained to patients when obtaining their consent for radiosurgery.

Treatment and survival differences across tumor sites in malignant peripheral nerve sheath tumors: a SEER database analysis and review of the literature

Background

Currently, literature is scarce on differences across all possible tumor sites in malignant peripheral nerve sheath tumors (MPNSTs). To determine differences in treatment and survival across tumor sites and assess possible predictors for survival, we used the Surveillance, Epidemiology, and End Results (SEER) database.

Methods

MPNST cases were obtained from the SEER database. Tumor sites were recoded into: intracranial, spinal, head and neck (H&N), limbs, core (thorax/abdomen/pelvis), and unknown site of origin. Patient and tumor characteristics, treatment modalities, and survival were extracted. Overall survival (OS) was assessed using univariable and multivariable Cox regression hazard models. Kaplan-Meier survival curves were constructed per tumor site for OS and disease-specific survival (DSS).

Results

A total of 3267 MPNST patients were registered from 1973 to 2013; 167 intracranial (5.1%), 119 spinal (3.6%), 449 H&N (13.7%), 1022 limb (31.3%), 1307 core (40.0%), and 203 unknown (6.2%). The largest tumors were found in core sites (80.0 mm, interquartile range [IQR]: 60.0-115.0 mm) and the smallest were intracranial (37.4 mm, IQR: 17.3-43.5 mm). Intracranial tumors were least frequently resected (58.1%), whereas spinal tumors were most often resected (83.0%). Radiation was administered in 35.5% to 41.8%. Independent factors associated with decreased survival were: older age, male sex, black race, no surgery, partial resection, large tumor size, high tumor grade, H&N site, and core site (all P < .05). Intracranial and pediatric tumors show superior survival (both P < .05). Intracranial tumors show superior OS and DSS curves, whereas core tumors have the worst (P < .001).

Conclusion

Superior survival is seen in intracranial and pediatric MPNSTs. Core and H&N tumors have a worse prognosis.

Case of an Intracranial Malignant Peripheral Nerve Sheath Tumor in the Setting of Pacer-dependent Heart Block

Intracranial malignant peripheral nerve sheath tumors (MPNSTs) are an extremely rare entity with only a handful of cases reported in the literature. MPNSTs typically occur in the extremities and the trunk. The treatment algorithm includes, when possible, gross-total resection as these tumors are extremely aggressive. When these tumors occur intracranially, they are termed malignant intracerebral nerve sheath tumors. The diagnosis hinges on immunohistochemistry and pathological features and often the diagnosis can be delayed for this reason. In this setting, it is critical to utilize intraoperative navigation, thus necessitating the use of fine-cut magnetic resonance imaging (MRI). This report presents a patient who presented with symptoms of obstructive hydrocephalus secondary to an intracranial mass. The patient underwent a full and extensive metastatic workup that was ultimately negative. To complicate things, the patient was fully pacemaker dependent. In this report, we review the literature surrounding this type of tumor, along with a detailed presentation of the case mentioned including the difficulties of cardiac pacing in the setting of MRI.

Five-Year-Old Boy With Behavioral Changes and Papilledema

A 5-year-old boy had initial symptoms of behavioral changes, nausea, vomiting, headache, weight loss, and progressive vision failure. Brain MRI revealed abnormal signal intensity in both optic nerves, the optic chiasm, the right medial temporal lobe, and tissues surrounding the right supraclinoid internal carotid artery with associated leptomeningeal and spinal cord enhancement. After nondiagnostic dural and spinal arachnoid biopsies, a temporal lobe biopsy was diagnostic for a rare malignant peripheral nerve sheath tumor.

Malignant nerve sheath tumor involving glossopharyngeal, vagus and spinal nerve with intracranial-extracranial extension and systemic metastases in a patient with type 1 neurofibromatosis: A case report

INTRODUCTION

Intracranial malignant peripheral nerve sheath tumors are an extremely rare pathology with a high morbidity and mortality. Epidemiological, clinical and prognostic data are scarce and with little certainty in the literature. The aim of this paper is to report for first time in English literature, the case of a patient with type 1 neurofibromatosis, who presented a malignant peripheral nerve sheath tumor that involved the left glossopharyngeal, vagus and spinal nerves with intracranial and extracranial extension through jugular foramen and systemic metastases.

PRESENTATION OF CASE

A 37 years-old female patient with malnutrition and Villaret́s syndrome. It was confirmed by brain magnetic resonance imaging and PET-CT the presence of a neoplasic lesion which was radiologically compatible with malignant peripheral nerve sheath tumor with systemic metastases. Partial surgical resection was performed; the patient postoperative course was without significant clinical improvement but with added peripheral facial palsy. The patient did not accept adjuvant management because of personal reasons.

DISCUSSION AND CONCLUSION

Behavior therapy is unclear due to the low frequency of the disease and the lack of case series, representing a challenge for the physician in its approach and a poor prognosis for the patient.

Surgical treatment of rare giant malignant tumors of the scalp: A report of 3 cases with different tumor types

The scalp is the most frequent site of occurrence of malignant tumors. As an area that is generally neglected by the patient and not closely monitored during physical examinations, scalp tumors can go unnoticed until they become malignant. The present study reports 3 cases of rare giant malignant tumors of the scalp, namely a peripheral nerve sheath tumor, a fibrous tumor and a malignant proliferating trichilemmal tumor, that were treated at The First Bethune Hospital of Jilin University (Changchun, China). Vascularized free anterolateral thigh flap surgery was performed in 2 of the 3 cases. A local flap repair was applied to the third case. The implanted skin grafts remained viable post-operatively and wound repair was uneventful. No signs of malignancy were detected on the edge of the pathological section upon closer pathological examination. In the follow-up period, no recurrence was detected in any of the cases.

Late malignant transformation of vestibular schwannoma in the absence of irradiation: case report

Late malignant transformation of vestibular schwannoma (VS) following irradiation has previously been reported 29 times in the literature. Here, the authors report the first late malignant transformation of VS unrelated to neurofibromatosis or radiation exposure. After undergoing a near-total excision of a histologically benign VS, the patient developed malignant regrowth of the tumor remnant 42 months after the primary excision. This case challenges the dogmatic belief of absolute causality between radiation exposure and late malignant transformation of VS, and has important implications regarding future counseling and consent for the treatment of patients with VS.

Evaluation of Reported Malignant Transformation of Vestibular Schwannoma: De Novo and After Stereotactic Radiosurgery or Surgery

OBJECTIVE

To critically analyze each reported case of malignant transformation of vestibular schwannoma (VS) after either stereotactic radiosurgery (SRS) or microsurgery (MS).

DATA SOURCES

We searched the Pubmed/Medline database using the relevant key words vestibular schwannoma, acoustic neuroma, malignant, transformation, radiation, induced, stereotactic, radiosurgery, malignancy, GammaKnife, and CyberKnife and combinations thereof.

STUDY SELECTION

Inclusion criteria for malignant transformation of VS after SRS included histopathology of initially benign VS, subsequent histopathology confirming malignant VS, reasonable latency period between malignancy and benign diagnoses.

DATA EXTRACTION

A neurotologist and a skull base neurosurgeon independently assessed each case report for quality, entry, exclusion criteria, and comparability of extracted data.

DATA SYNTHESIS

We calculated median age, latency times, and survival times for each case report.

RESULTS

Malignant transformation has been documented to occur after either SRS or MS. Eight cases were included that showed histopathologic evidence of malignant transformation after SRS and MS. Four cases of malignant transformation were included that demonstrated malignant transformation after MS only. Malignant transformation of VS can also occur de novo, and de novo malignant VSs are also encountered, which can confound a causal inference from either SRS or MS. Eighteen cases of primary malignant VS were included. Studies that were identified but not included in the review are summarized and tabulated. We found 12 studies of malignant transformation associated with NF2.

CONCLUSION

The potential mechanism leading to malignant transformation of VS seems more obvious for SRS and is less understood for MS. Given a low incidence of de novo malignant schwannoma, the possibility that these are spontaneous events in either setting cannot be ruled out. Risk of malignant transformation of VS after either SRS or MS is not zero; however, the magnitude of this risk is probably minimal based on the evidence from eight histopathologically confirmed cases.

Malignant peripheral nerve sheath tumors of the eighth cranial nerve arising without prior irradiation

OBJECTIVE Malignant peripheral nerve sheath tumors (MPNSTs) of the eighth cranial nerve (CN) are exceedingly rare. To date the literature has focused on MPNSTs occurring after radiation therapy for presumed benign vestibular schwannomas (VSs), while MPNSTs arising without prior irradiation have received little attention. The objectives of the current study are to characterize the epidemiology, clinical presentation, disease course, and outcome using a large national cancer registry database and a systematic review of the English literature. Additionally, a previously unreported case is presented. METHODS The authors conducted an analysis of the Surveillance, Epidemiology, and End Results (SEER) database, a systematic review of the literature, and present a case report. Data from all patients identified in the SEER database with a diagnosis of MPNST involving the eighth CN, without a history of prior radiation, were analyzed. Additionally, all cases reported in the English literature between January 1980 and March 2015 were reviewed. Finally, 1 previously unreported case is presented. RESULTS The SEER registries identified 30 cases between 1992 and 2012. The average incidence was 0.017 per 1 million persons per year (range 0.000-0.0687 per year). The median age at diagnosis was 55 years, and 16 (53%) were women. Thirteen cases were diagnosed upon autopsy. Of the 17 cases diagnosed while alive, the median follow-up was 118 days, with 3 deaths (18%) observed. When compared with the incidence of benign VS, 1041 VSs present for every 1 MPNST arising from the eighth CN. Including a previously unreported case from the authors' center, a systematic review of the English literature yielded 24 reports. The median age at diagnosis was 44 years, 50% were women, and the median tumor size at diagnosis was 3 cm. Eleven patients (46%) reported isolated audiovestibular complaints typical for VS while 13 (54%) exhibited facial paresis or other signs of a more aggressive process. Treatment included microsurgery alone, microsurgery with adjuvant radiation, or microsurgery with chemoradiation. Sixty-one percent of patients receiving treatment experienced recurrence, 22% of which were diagnosed with drop metastases to the spine. Ultimately, 13 patients (54%) died of progressive disease at a median of 3 months following diagnosis. The ability to achieve gross-total resection was the only feature that was associated with improved disease-specific survival. CONCLUSIONS MPNSTs of the eighth CN are extremely rare and portend a poor prognosis. Nearly half of patients initially present with findings consistent with a benign VS, often making an early diagnosis challenging. In light of these data, early radiological and clinical follow-up should be considered in those who elect nonoperative treatment, particularly in patients with a short duration of symptoms or atypical presentation. These data also provide a baseline rate of malignancy that should be considered when estimating the risk of malignant transformation following stereotactic radiosurgery for VS.

Malignant transformation in vestibular schwannoma: report of a single case, literature search, and debate

OBJECT

The significance of radiation in the induction of malignancy in vestibular schwannomas (VSs) after radiosurgery is unclear despite an increasing number of case reports. The authors describe a new case of verified malignant transformation in a vestibular schwannoma (MTVS) and provide a new evaluation of such cases previously reported in the literature.

METHODS

A 46-year-old woman underwent subtotal resection of a right-sided VS in 2004. The histological characteristics of the lesion were typical and benign. In early 2007 Gamma Knife surgery (GKS) was performed to treat a residual enlarging remnant. The radiosurgery parameters included the following: target volume 3.5 cm(3), prescription dose 12 Gy, prescription isodose 45%, maximum dose 26.7 Gy, and coverage 97%. At 2 years' follow-up the lesion was enlarged to 5.2 cm(3), but by 5 years it had decreased to 2.3 cm(3). Six months later the lesion was 8.4 cm(3). Repeated surgery was performed, and a histological analysis revealed a malignant peripheral nerve sheath tumor. The case was further managed with repeated GKS performed in the spring of 2013. At that time, the radiosurgery parameters included the following: target volume 3.5 cm(3), prescription dose 16 Gy, prescription isodose 45%, maximum dose 35.6 Gy, and coverage 91%. This Gamma Knife Department has treated a total of 205 patients with VS (local incidence of MTVS 0.49%). A search of the literature published up to and including 2013 was performed using PubMed as well as more informal search methods.

RESULTS

This patient is the 29th reported case of MTVS after radiation therapy. Of these cases, 40.7% were patients with neurofibromatosis (NF). In those cases in which histology showed tumors with previously benign characteristics, totally conforming to the criteria for MTVS, the mean delay to malignant expression was 68 months (median delay 72 months). The authors also retrieved papers reporting 30 cases of malignant VS in patients who had not undergone radiation treatment. Five of those cases were malignant transformation of a benign entity, and in 4 of them histology had verified that the initial disease was benign. In those 4 cases, there was a mean delay to malignant expression of 7.2 months (median delay 8 months).

CONCLUSIONS

Despite more frequent reports of MTVS after radiation treatment recently, there has been no accurate quantification of the risk, except in patients with NF, in whom the incidence of malignancy is high in relation to the numbers treated. The present analysis indicates that the risk of malignancy over 20 years in cases in which no radiation treatment has occurred is 1.32-2.08 per 100,000, and this risk decreases to 1.09-1.74 per 100,000 if cases of NF are excluded. After radiation treatment, the overall risk over 20 years is 25.1 per 100,000, and this risk decreases to 15.6 per 100,000 if cases of NF are excluded. Radiation treatment increases the risk by approximately 10 times in non-NF cases.

[Malignant peripheral nerve sheath tumour of the infra-orbital nerve]

A malignant peripheral nerve sheath tumour (MPNST) is an uncommon neoplasm that rarely involves the head and neck region. It is even more infrequent for these tumours to affect cranial nerves. We report the case of a 53-year-old man who presented a MPNST involving the infra-orbital nerve, which extended through the orbit and the base of the skull, progressing intracranially. Histological studies identified the tumour as an MPNST. Response to radiotherapy was not complete and radical surgical resection was impossible, so the patient died 10months later. This rare case of MPNST with intracranial involvement illustrates the dismal prognosis for patients with these lesions. Prognosis is poor because of the difficulty of performing radical surgery with free margins in these locations.

A long-term survival case of a primary malignant intracerebral nerve sheath tumor

We report a long-term survival case of a primary malignant intracerebral nerve sheath tumor (MINST) occurring in the right frontal lobe of a 13-year old boy. After the gross total resection (GTR), we have performed radiation therapy but it recurred 50 months after the surgery, so the second GTR was performed. Later, second tumor recurrence was found 4 months after the second surgery. Subsequently the third GTR, radiotherapy, and chemotherapy were carried out. At present, the patient has been remaining alive for 77 months without evidence of tumor recurrence. According to the previous reports, the primary MINST is very rare : there are only 8 cases reported. It is also a fast-growing, invasive tumor with poor outcome. This is the first case that had no recurrence for 50 months after the surgery among the reported cases that had been followed up for more than 5 years. It is supposed that a period of recurrence free survival after GTR and low mitotic activity are associated with the patient's prognosis. A GTR followed by adjuvant radiation therapy and chemotherapy will be recommended to patients of MINST.

Secondary neoplasms after stereotactic radiosurgery

OBJECTIVE

The use of medical radiation has increased 6-fold in the past 30 years. Within neurosurgery, the advent of stereotactic radiosurgery (SRS) has significantly altered the treatment paradigm for both benign and malignant central nervous system diseases. With this increased reliance on radiation has come a responsibility to identify the long-term risks, including the potential development of radiation-induced neoplasms. Although the data regarding traditional radiation exposure and its subsequent risks are well-defined, the data for SRS is less developed.

METHODS

We reviewed the published literature to more accurately define the risk of developing secondary neoplasms after stereotactic radiosurgery.

RESULTS

A total of 36 cases of SRS-induced neoplasms were identified. More than half of the cases had an initial diagnosis of vestibular schwannoma. Overall, the risk of developing an SRS-induced neoplasm is approximately 0.04% at 15 years.

CONCLUSION

The risk of developing an SRS-induced neoplasm is low but not zero. Thus, long-term surveillance imaging is advised for patients treated with SRS.

Clinical, radiological, and pathological features of 26 intracranial and intraspinal malignant peripheral nerve sheath tumors

Object

Intracranial and intraspinal malignant peripheral nerve sheath tumors (MPNSTs) are rarely reported because of their extremely low incidence. Knowledge about these tumors is poor. In this study the authors aimed to analyze the incidence and clinical, radiological, and pathological features of intracranial and intraspinal MPNSTs.

Methods

Among 4000 cases of intracranial and intraspinal PNSTs surgically treated between 2004 and 2011 at Beijing Tiantan Hospital, cases of MPNST were chosen for analysis and were retrospectively reviewed. To determine which parameters were associated with longer progression-free survival (PFS) and overall survival (OS), statistical analysis was performed.

Results

Malignant PNSTs accounted for 0.65% of the entire series of intracranial and intraspinal PNSTs. Twenty-four (92.3%) of these 26 MPNSTs were primary. Radiologically, 26.9% (7 of 26) of the MPNSTs were misdiagnosed as nonschwannoma diseases. Twenty-one patients were followed up for 1.5 to 102 months after surgery. Twelve patients experienced tumor recurrence, and median PFS was 15.0 months. The 2- and 3-year PFS rates were 47.7% and 32.7%, respectively. Five patients died of tumor recurrence, and median OS was not available. The 2- and 3-year OS rates were 74.7% and 64.0%, respectively. Univariate analysis revealed that female sex, total tumor removal, and primary MPNSTs were significantly associated with a better prognosis. Multivariate analysis revealed that only total removal was an independent prognostic factor for both PFS and OS.

Conclusions

Malignant PNST within the skull or spinal canal is a rare neoplasm and is seldom caused by benign schwannomas. Radiologically, intracranial or intraspinal MPNST should be differentiated from meningioma, chordoma, fibrous dysplasia of bone, and ear cancer. Total resection whenever possible is necessary for the prolonged survival of patients, especially males.

Malignant peripheral nerve sheath tumour following radiotherapy for pituitary adenoma

Intracranial malignant peripheral nerve sheath tumour (MPNST) is an extremely rare lesion. We report a patient with an MPNST in the sellar region following radiotherapy for pituitary adenoma.

Updates on the diagnosis and treatment of intracranial nerve malignant peripheral nerve sheath tumors

Background:

Malignant peripheral nerve sheath tumors (MPNSTs) are rare entities and MPNSTs of intracranial nerves are even more sporadic. MPNSTs present diagnosis and treatment challenges since there are no defined diagnosis criteria and no established therapeutic strategies.

Methods:

We reviewed literature for MPNST-related articles. We found 45 relevant studies in which 60 cases were described.

Results:

We identified 60 cases of intracranial nerve MPNSTs. The age ranged from 3 to 75 years old. Male to female ratio was 1.5:1. The most involved cranial nerves (CNs) were CN VIII (60%), CN V (27%), and CN VII (10%). Most of the MPNSTs reported (47%) arose sporadically, 40% arose from a schwannoma, 8% arose from a neurofibroma, and 6% arose from an unspecified nerve tumor. Twenty patients had a history of radiation exposure, four patients had neurofibromatosis type 1 (NF1), four patients had neurofibromatosis type 2 (NF2), and NF2 was suspected in two other patients. Twenty-two patients were treated with radiotherapy and presented a higher survival rate. Seventy-two percent of patients died of their disease while 28% of patients survived. One-year survival rate was 33%. Forty-five percent of tumors recurred and 19% of patients had metastases.

Conclusion:

MPNSTs involving CNs are very rare. Diagnosis is made in regards to the histological and pathological findings. Imaging may help orient the diagnosis. A preexisting knowledge of the clinical situation is more likely to lead to a correct diagnosis. The mainstay of treatment is radical surgical resection with adjuvant radiotherapy. Since these tumors are associated with a poor prognosis, a close follow-up is mandatory.

Imaging diagnosis-malignant peripheral nerve sheath tumor presenting as an intra-axial brain mass in a young dog

A 3-year-old Labrador retriever was presented with acute onset seizures. Magnetic resonance imaging demonstrated an intra-axial mass affecting the right temporal lobe of the brain. Surgical resection and histopathological findings were most consistent with a malignant peripheral nerve sheath tumor. After initial recovery, deterioration 3 months post surgery prompted euthanasia. Post-mortem revealed a mass protruding from the ventral surface of the temporal lobe, encroaching upon the optic chiasm and invading the brain. Histopathology findings were again consistent with malignant peripheral nerve sheath tumor. Although rare, this tumor should be included as a possible differential diagnosis for intra-axial brain masses in dogs.

Malignant peripheral nerve sheath tumor of the trigeminal nerve: clinicopathologic features in a young adult patient

Malignant peripheral nerve sheath tumors (MPNSTs) arising from cranial nerves are rare and usually affect adults. Here we report the clinicopathologic features of a young adult patient with a trigeminal nerve MPNST, in whom another tumor involving the oculomotor nerve on the contralateral side was evident. The patient, an 18-year-old woman, had suffered recurrent paroxysmal sharp stabbing pain over her cheek and forehead on the right side for 1 month. A brain MRI study disclosed a mass, 35 mm in diameter, in the right Meckel's cave, and another mass, 10 mm in diameter, involving the intracranial portion of the left oculomotor nerve. Following gadolinium administration, the former and latter tumors exhibited strong and weak enhancement, respectively. The patient had no clinical stigmata characteristic of neurofibromatosis type 1. Following a tentative diagnosis of schwannoma, total resection of the trigeminal nerve tumor was performed. Histologically, the tumor consisted of highly cellular, spindle-shaped cells arranged in a fascicular pattern, with occasional mitotic figures, nuclear pleomorphism and necrosis. Immunohistochemically, the tumor cells showed variable intensities and frequencies of reactivity for S-100 protein, myelin basic protein, CD34, podoplanin and p53, but no reactivity for Smarcb1. Thus, the tumor exhibited features of MPNST. This case appears to provide information that is useful for accurate diagnosis and surgical planning in patients with bilateral or multiple cranial nerve tumors.

Malignant peripheral nerve sheath tumor of the abducens nerve and a review of the literature

BACKGROUND

Malignant peripheral nerve sheath tumors are rare, and intracranial occurrences are even more rare. Treatment strategies have varied widely. This article reports the first case of a malignant peripheral nerve sheath tumor of the abducens nerve and provides a literature review that includes 61 cases of intracranial malignant peripheral nerve sheath tumors. Data were analyzed based on age, sex, treatment, survival, immunohistochemical staining, location, tumor grade, and neurofibromatosis association. These tumors more often affect male persons, and the patients affected have a mean age of 39 years. Most patients underwent subtotal or gross total resection and radiation. Intracranial location varied, but most tumors occurred in the cerebellopontine angle. The literature shows that intracranial malignant peripheral nerve sheath tumors are a heterogeneous group. Their association with neurofibromatosis is less clear than that of their extracranial counterparts. Prognosis is poor, but surgical resection and radiation can enhance chances for longer survival. Our aim was to elucidate information about these tumors.

CASE DESCRIPTION

A 30-year-old woman presented with a 6-month history of headaches and diplopia.

RESULTS

Neurological examination revealed no focal deficit. Imaging revealed a heterogeneously enhancing retroclival mass without bony destruction. The tumor originated from the ipsilateral abducens nerve and extended into the Dorello canal; it adhered to the brainstem and cranial nerves. Pathology was consistent with low-grade malignant peripheral nerve sheath tumor.

CONCLUSIONS

At 3-month follow-up, the patient walked with a cane with no further deficits except mild ataxia, which resolved within 6 months. Magnetic resonance imaging revealed a small residual tumor adherent to the basilar artery. At 1-year follow-up and after ocular surgery to correct lateral rectus palsy, the patient was neurologically intact.

Plan robustness in proton beam therapy of a childhood brain tumour

INTRODUCTION

The concern of secondary cancer induction and normal tissue complications have motivated a more frequent use of protons in radiotherapy (RT) of children. However, proton RT is likely to be less robust to anatomical changes occurring during therapy. In this study we present a recent clinical case to illustrate this issue.

MATERIAL AND METHODS

A five-year-old boy with a highly proliferating malignant intracranial nerve sheath tumour underwent a partial resection prior to RT and developed a post-surgery oedema close to the surgical cavity. RT was delivered with volumetric modulated arc therapy (VMAT) to a total tumour dose of 61.2 Gy. The most critical organs at risk (ORs) were the right optical nerve, brainstem and chiasm. Proton plans were constructed for the purpose of this study. In order to simulate a worst-case scenario, the extent of the oedema observed in the last part of the treatment was used to modify the oedema on the planning computed tomography (CT). Both the photon and proton plans were then re-calculated, as follows: Scenario A: Treatment planning based on the planning CT with oedema and dose calculated as if it was delivered without oedema. Scenario B: Treatment planning on the modified planning CT without oedema, but re-calculated with oedema. These two scenarios were compared to the situation where the oedema was present at treatment planning and unchanged during RT.

RESULTS

Total dose to critical ORs remained unchanged for the photon plans, with changes within 0.3 Gy for the normal tissues and nearly identical target coverage. For protons, scenario A led to increased maximal doses in all critical ORs, 5.1 Gy in the brainstem, 6.1 Gy in the chiasm and 6.4 Gy in the right optical nerve. For scenario B the proton plans resulted in a loss in target coverage.

CONCLUSION

This case study shows that RT with protons were far less robust to anatomical changes than when treated with photons, emphasising the increased need for adaptive approaches in RT with protons.

Malignant Peripheral Nerve Sheath Tumor of the Vestibulocochlear Nerve and Brainstem

BACKGROUND AND IMPORTANCE

Malignant peripheral nerve sheath tumors are the most common malignant mesenchymal tumors of soft tissues, but they are very rare when found to arise from a cranial nerve and when not in association with neurofibromatosis. These tumors are highly malignant and carry a poor prognosis with survival usually less than 6 months.

CLINICAL PRESENTATION

The authors report the case of a 23-year-old female with no history of phakomatoses, previous irradiation, or known genetic disorders, who presented with a malignant peripheral nerve sheath tumor of the vestibulocochlear nerve and brainstem. Multiple staged skull base approaches were carried out with maximal possible resection. Adjunctive therapies including standard radiation therapy, intensity-modulated radiation therapy, and stereotactic gamma knife radiosurgery were used with an ultimate patient survival of 27 months.

CONCLUSION

To our knowledge, this is the first report describing a patient with a malignant peripheral nerve sheath tumor of the vestibulocochlear nerve and brainstem treated with staged surgical approaches in conjunction with multiple forms of radiotherapy and having a significant survival of more than 2 years.

Factors of influence upon overall survival in the treatment of intracranial MPNSTs. Review of the literature and report of a case

BACKGROUND

Intracranial malignant peripheral nerve sheath tumors are rare entities that carry a poor prognosis. To date, there are no established therapeutic strategies for these tumors.

METHODS

We review the present treatment modalities and present the current therapeutic dilemmas. We perform a statistical analysis to evaluate the prognostic factors for Overall Survival of these patients. Additionally, we present our experience with a 64-year-old man with a MPNST of the left cerebellopontine angle.

RESULTS

To our best knowledge, forty three patients with intracranial MPNSTs, including our case, have been published in the international literature. Our analysis showed gross total resection, radiotherapy and female gender to be beneficial prognostic factors of survival in the univariate analysis. Gross total resection was recognized as the only independent predictor of prolonged Overall Survival. In our case, we performed a gross total resection followed for the first time by stereotactically guided radiotherapy.

CONCLUSION

Considering the results of the statistical analysis and the known advantages of the stereotaxy, we suggest aggressive surgery followed by stereotactically guided radiotherapy as therapy of choice.

[Peripheral nerve tumors]

Peripheral nerve tumors are most often benign tumors of the nerve sheath; uncommonly they come from the nerve cells or are metastatic tumors. A precise diagnosis is required for well-adapted and effective treatment, as is good knowledge of fibromatosis diseases. In some cases, the diagnosis of the nerve tumor will lead to a diagnosis of phakomatosis. Surgical treatment must be clearly discussed, which, in case of schwannomas gives very good functional results. Primitive malignant tumors remain an unsolved therapeutic problem.