A series of 397 peripheral neural sheath tumors: 30-year experience at Louisiana State University Health Sciences Center

High-Definition 4K 3D Exoscope (ORBEYETM) in Peripheral Nerve Sheath Tumor Surgery: A Preliminary, Explorative, Pilot Study

BACKGROUND

Surgery for peripheral nerve sheath tumors aims to preserve functional fascicles achieving gross-total resection. Increasing the visualization of anatomic details helps to identify the different layers and the tumor-nerve interface. The traditional microscope can present some limitations in this type of surgery, such as its physical obstruction.

OBJECTIVE

To present a proof-of-concept study about exoscope-guided surgery for schwannomas of the lower limbs, to analyze the advantages and disadvantages of the 4K, high-quality, 3-dimensional (3D) imaging.

METHODS

We analyzed 2 consecutive surgical cases of suspected schwannomas of the lower limbs using the ORBEYE™ exoscope (Olympus). A standard operative microscope was also available in the operating room. All procedures were performed with neurophysiological monitoring, to identify functioning nerves and to localize the tumor capsule safest entry point. The cases are reported according to the PROCESS guidelines.

RESULTS

In both cases, we achieved a gross total resection of the schwannomas; the exoscope provided an excellent view of the anatomic details at tumor-nerve interface, as visible in intraoperative images and in the 3D-4K video supporting these findings. The surgeon's position was comfortable in both cases, although if the co-surgeon positioned himself in front of the first surgeon, the comfort was slightly reduced. The 4K monitor allowed a realistic, nontiring 3D vision for all the team.

CONCLUSION

The ORBEYETM, after an adequate learning curve, can represent a feasible and comfortable instrument for nerve tumor surgery, which is usually performed in a single horizontal plane. Further and wider clinical series are necessary to confirm this first impression.

Surgery for Peripheral Nerve Sheath Tumours of the Buttocks, Legs and Feet in 90 Patients With Neurofibromatosis Type 1

BACKGROUND/AIM

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumour predisposition syndrome that can cause plexiform neurofibromas (PNFs). This study examines the surgical procedures that have been performed on large PNFs of the lower extremities.

PATIENTS AND METHODS

Surgical procedures on the lower extremity performed on 90 patients with NF1 with PNFs were evaluated. The topography of the tumours was classified according to dermatomes and functional units.

RESULTS

A total of 243 surgical interventions on the regions of interest were performed. Neurological complications were rarely noted and usually occurred temporarily. There was no preference for dermatomes affected by PNF. The proportion of patients with malignant peripheral nerve sheath tumours (MPNSTs) in this group was 4/90 (4.4%).

CONCLUSION

PNFs often require repeated local interventions to achieve the treatment goal. Local tumour recurrences are to be expected even after extensive tumour reduction. Rapid tumour growth combined with new pain sensations can be signs of a MPNST.

Intramuscular ancient schwannoma of the axillary nerve

We present the case of an adolescent with an intramuscular ancient schwannoma of the axillary nerve which, to the best of our knowledge, has not been reported before. Due to its deep location, intramuscular schwannoma has less clinical signs and hence, is difficult to diagnose. Ancient schwannoma, characterised by degeneration due to long course, is rare and can be mistaken for malignancy due to heterogeneous intensity and degeneration evident on MRI and nuclear atypia on histopathology. It is important to differentiate it from malignancy based on a clinically benign swelling with a long history, well-encapsulated mass on MRI with the split fat sign and absence of significant mitotic activity despite nuclear atypia. The aim of surgery should be enucleation of the tumour while preserving the function of the parent nerve.

A clinicopathological study of peripheral schwannomas

Aim and objective

Schwannomas are benign neoplasms of neural origin with sporadic or syndromic occurence. They are commonly seen in cranial nerves. Peripheral schwannomas occur rarely and may have unique presentations. The aim of this study is to evaluate the clinico-pathological characteristics of peripheral schwannomas.

Methods

A retrospective cross sectional study of peripheral schwannomas excluding head neck region was conducted. The study group consisted of 18 cases which were recorded over a period of seven years. The corresponding data were collected from the archives of the Department of Pathology.

Results

Male to female ratio was 1:1. The average age of the cases was 47 years. The most common site was the upper limbs (55.55%) followed by lower limbs, chest and penis. The lesions mostly presented as painless swellings (62%). Histopathological examination revealed classic features of schwannoma. Secondary changes included cystic degeneration, foam cells, epitheloid cells, hyalinization, microcystic change and collection of plasma cells. All cases were confirmed by positive S100 staining.

Conclusion

Peripheral schwannomas may be missed due to its rarity and atypical presentations. Both clinicians and pathologists should be aware of this common entity at unusual sites for the proper management of the patients. Surgery is usually the treatment of choice.

Lipomas as an Extremely Rare Cause for Brachial Plexus Compression: A Case Series and Systematic Review

Introduction  Brachial plexus lipomas are extremely rare benign tumors that may cause slow progression of neurological deficits leading to thoracic outlet syndrome. Up to now, surgery remains challenging. The aim of this study is to present our surgical treatment regime and long-term neurological outcome in three cases of giant brachial plexus lipomas and to show results of systematic review.

Patients and Methods  Retrospective analysis of our database “peripheral nerve lesion” to identify patients suffering from brachial plexus lipomas between January 1, 2012, and December 31, 2019. Systematic review was performed for literature published until March 31, 2020, analyzing PubMed, Google Scholar, Scopus, and the Cochrane Collaboration Library independently by two authors.

Results  Over the past years, three patients suffering from giant brachial plexus lipomas attended to our neurosurgical department. All patients underwent preoperative magnetic resonance imaging (MRI), ultrasound examinations, and electrophysiological testing. Tumors were removed microsurgically via anterior/posterior, supraclavicular/infraclavicular, and combined approaches. The patients were accessed postoperatively by MRI and clinical follow-up. Systematic review of the literature revealed 22 cases, which were analyzed in regard to demographics, surgical treatment, and neurological outcome.

Conclusion  Brachial plexus lipomas are an extremely rare cause for brachial plexus compression. Total microsurgical removal with intraoperative electrophysiological monitoring is the treatment of choice with excellent long-term MRI and clinical outcome.

[Granular cells tumour (Abrikossof) of the ulnar nerve at the arm. A case report and literature review]

INTRODUCTION

Granular cell tumours are extremely rare on peripheral nerves, with an incidence of 0.029% of pathologic samples. In a literature review, we found only 5 cases involving the ulnar nerve, although considered the most frequently involvement nerve.

CASE REPORT

A 32 year-old female from the French West Indies presented a severe arm pain with deficit of interosseous hand muscles. Imaging studies were in favour of a Schwanoma, but during surgery, we found an unremovable intra-neural tumour. Nerve biopsy revealed a granular cell tumour. Initial decision was observation only. However, within two years, tumour increased in size, along with pain aggravation and functional deficit. We performed a nerve resection (with adequate margins) with reconstruction using sural nerve graft associated with a neurotisation of the motor branch with the anterior interosseus nerve. At two years follow-up, no recurrence was observed. The scar is hypersensitive with moderate neuropathic pain. There is a sensory reinnervation of the fourth finger, with no motor recovery of the hand. We observed a slight recovery of flexor profundus tendons, which, in turn increased the claw hand.

DISCUSSION

The five cases described in the literature were managed differently (biopsy only, excision, excision with reconstruction), with modest results. There is no recommended treatment. Our case is the first at arm level. We were able to perform complete resection, but functional result is poor.

CONCLUSION

Granular cell tumours require treatment if symptomatic (pain, function loss), but, at the moment, there is no recommended treatment.

Surgical Management of Sporadic Peripheral Nerve Schwannomas in Adults: Indications and Outcome in a Single Center Cohort

Simple Summary

Peripheral nerve sheath tumors are associated with significant morbidity. Clinical presentation, tumor location, and therapeutic strategies are variable. We aim to provide high-quality data concerning the results of interdisciplinary operative approaches for surgical resection of schwannomas. Understanding the anatomical and functional challenges of surgical interventions in the peripheral nervous system can help to enhance the outcomes of these therapies. We aim to highlight the need for interdisciplinarity and provide evidence for both excellent functional outcomes, as well as improved quality of life for patients undergoing sporadic schwannoma surgery.

Abstract

Most sporadic peripheral nerve sheath tumors in adults are schwannomas. These tumors usually present with significant pain but can also cause neurological deficits. Symptomatology is diverse, and successful surgical interventions demand interdisciplinarity. We retrospectively reviewed 414 patients treated between 2006 and 2017 for peripheral nerve sheath tumors. We analyzed clinical signs, symptoms, histology, and neurological function in the cohort of adult patients with schwannomas without a neurocutaneous syndrome. In 144 patients, 147 surgical interventions were performed. Mean follow-up was 3.1 years. The indication for surgery was pain (66.0%), neurological deficits (23.8%), significant tumor growth (8.8%), and suspected malignancy (1.4%). Complete tumor resection was achieved on 136/147 occasions (92.5%). The most common location of the tumors was intraspinal (49.0%), within the cervical neurovascular bundles (19.7%), and lower extremities (10.9%). Pain and neurological deficits improved significantly (p ≤ 0.003) after 131/147 interventions (89.1%). One patient had a persistent decrease in motor function after surgery. Complete resection was possible in 67% of recurrent tumors, compared to 94% of primary tumors. There was a significantly lower chance of complete resection for schwannomas of the cervical neurovascular bundle as compared to other locations. The surgical outcome of sporadic schwannoma surgery within the peripheral nervous system is very favorable in experienced peripheral nerve surgery centers. Surgery is safe and effective and needs a multidisciplinary setting. Early surgical resection in adult patients with peripheral nerve sheath tumors with significant growth, pain, neurological deficit, or suspected malignancy is thus recommended.

Management of benign nerve sheath tumors of the brachial plexus: relevant diagnostic and surgical features. About a series of 17 patients (19 tumors) and review of the literature

Brachial plexus (BP) tumors are rare, potentially difficult-to-manage lesions. The method is retrospective chart analysis. Among the 17 patients, four had neurofibromatosis and one schwannomatosis (NF +). The latter has bilateral BP tumors that remain stable on MRI at a 6.5 year follow-up. Another NF + patient has bilateral non-operable BP plexiform neurofibromas. The complaints of the 15 operated patients were radiated pain, a mass, local pain, paresthesia, a neurological deficit (n = 15, 12, 7, 10, 7). On MRI, the tumors appeared as nodular or ovoid large masses. Four operated tumors were proximal, reaching the foramen. The FDG-PET scan (n = 4) always showed tumor hypermetabolism. A preoperative percutaneous biopsy was done in three patients before neurosurgical consultation; one of them developed neurogenic pain and a sensory deficit following two percutaneous biopsies for a misinterpreted cervical lymphadenopathy. Surgery was performed using a supra-, infra-, supra- + infra-clavicular or posterior subscapular approach (n = 8, 3, 3, 1). Intraoperative electrophysiology was used in all patients. Complete or gross total resection was achieved in 14 patients. Two patients had fascicle reconstruction with grafts. Pathology revealed 13 schwannomas and two neurofibromas. Neurogenic pain transiently developed or worsened after surgery in five patients. At last follow-up, a mild deficit remained in four patients (preexisting in three). No recurrence had occurred. We conclude that a thorough examination of any patient with a cervical or axillary mass is crucial to avoid misinterpretation as a lymphadenopathy. MRI is the best imaging modality. Most BP benign tumors can be completely and safely resected through the use of microsurgical techniques and intraoperative electrophysiology.

Schwannoma with Psammoma Body

We present a case of a 59-year-old male veteran with a chronic history of right foot soft-tissue mass that was causing pain in his shoes, but not functional or neurologic symptoms. Excision of the mass and pathologic evaluation resulted in multidisciplinary involvement and evaluation. In this example, the mass was found to be either an unusual schwannoma that happens to be psammoma body-rich or an unusual psammomatous melanocytic schwannoma that deviates from conventional examples, as a diagnostic consensus was unable to be reached. Schwannomas are an uncommon finding in the foot, and even more uncommon are those that contain psammoma bodies. Although rare, these tumors can be concerning for more systemic, life-altering diseases such as Carney complex, for which our patient refused genetic testing.

Brachial plexus tumors extending into the cervicothoracic spine: a review with operative nuances and outcomes

BACKGROUND

The rarity and anatomical complexity of brachial plexus tumors (BPTs) impose many challenges onto surgeons performing surgical resections, especially when these tumors invade the cervicothoracic spine. Treatment choices and surgery outcomes heavily depend on anatomical location and tumor type.

METHODS

The authors performed an extensive review of the published literature (PubMed) focusing on "brachial plexus tumors" that identified invasion of the cervicothoracic spine.

RESULTS

The search yielded 2774 articles pertaining to "brachial plexus tumors". Articles not in the English language or involving cervicothoracic spinal invasion were excluded.

CONCLUSIONS

Recent research has shown that the most common method used to resect tumors of the proximal roots is the dorsal subscapular approach. Despite its association with high morbidity rate, this technique offers excellent exposure to the spinal roots and intraforaminal portion of the spinal nerve. The dorsal approach is used to resect recurrent lower trunk tumors and dumbbell-shaped neurofibromas, yet it is also the least common overall approach used in brachial plexus tumor resections. The ventral or anterior technique is commonly used to resect tumors at the cord to division level, and root to trunk level. Motor complications, transient nerve palsy, and bleeding are among the most common complications of the anterior supraclavicular approach. Further controlled studies are needed to fully determine the optimal surgical approach used to obtain the best outcomes and least complications for each type of brachial plexus tumor.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Surgical Strategy for Sacral Tumor Resection

PURPOSE

This study aimed to present our experiences with a precise surgical strategy for sacrectomy.

MATERIALS AND METHODS

This study comprised a retrospective review of 16 patients (6 males and 10 females) who underwent sacrectomy from 2011 to 2019. The average age was 42.4 years old, and the mean follow-up period was 40.8 months. Clinical data, including age, sex, history, pathology, radiographs, surgical approaches, onset of recurrence, and prognosis, were analyzed.

RESULTS

The main preoperative symptom was non-specific local pain. Nine patients (56%) complained of bladder and bowel symptoms. All patients required spinopelvic reconstruction after sacrectomy. Three patients, one high, one middle, and one hemi-sacrectomy, underwent spinopelvic reconstruction. The pathology findings of tumors varied (chordoma, n=7; nerve sheath tumor, n=4; giant cell tumor, n=3, etc.). Adjuvant radiotherapy was performed for 5 patients, chemotherapy for three, and combined chemoradiotherapy for another three. Six patients (38%) reported postoperative motor weakness, and newly postoperative bladder and bowel symptoms occurred in 5 patients. Three patients (12%) experienced recurrence and expired.

CONCLUSION

In surgical resection of sacral tumors, the surgical approach depends on the size, location, extension, and pathology of the tumors. The recommended treatment option for sacral tumors is to remove as much of the tumor as possible. The level of root sacrifice is a predicting factor for postoperative neurologic functional impairment and the potential for morbidity. Pre-operative angiography and embolization are recommended to prevent excessive bleeding during surgery. Spinopelvic reconstruction must be considered following a total or high sacrectomy or sacroiliac joint removal.

Imaging of non-neurogenic peripheral nerve malignancy-a case series and systematic review

OBJECTIVE

To evaluate the frequency, clinico-pathologic and imaging features of malignant tumors in peripheral nerves which are of non-neurogenic origin (non-neurogenic peripheral nerve malignancy-PNM).

MATERIALS AND METHODS

We retrospectively reviewed our pathology database for malignant peripheral nerve tumors from 07/2014-07/2019 and performed a systematic review. Exclusion criteria were malignant peripheral nerve sheath tumor (MPNST). Clinico-pathologic and imaging features, apparent diffusion coefficient (ADC_min), and standard uptake values (SUV_max) are reported.

RESULTS

After exclusion of all neurogenic tumors (benign = 196, MPNST = 57), our search yielded 19 non-neurogenic PNMs (7%, n = 19/272), due to primary intraneural malignancy (16%, n = 3/19) and secondary perineural invasion from an adjacent malignancy (16%, n = 3/19) or metastatic disease (63%, n = 12/19). Non-neurogenic PNMs were located in the lumbosacral plexus/sciatic nerves (47%, n = 9/19), brachial plexus (32%, n = 6/19), femoral nerve (5%, n = 1/19), tibial nerve (5%, n = 1/19), ulnar nerve (5%, n = 1/19), and radial nerve (5%, n = 1/19). On MRI (n = 14/19), non-neurogenic PNM tended to be small (< 5 cm, n = 10/14), isointense to muscle on T1-W (n = 14/14), hyperintense on T2-WI (n = 12/14), with enhancement (n = 12/12), low ADC_min (0.5-0.7 × 10-3 mm²/s), and variable metabolic activity (SUV_max range 2.1-13.1). A target sign was absent (n = 14/14) and fascicular sign was rarely present (n = 3/14). Systematic review revealed 89 cases of non-neurogenic PNM.

CONCLUSION

Non-neurogenic PNMs account for 7% of PNT in our series and occur due to metastases and primary intraneural malignancy. Although non-neurogenic PNMs exhibit a non-specific MRI appearance, they lack typical signs of neurogenic tumors such as the target sign. Quantitative imaging features identified by DWI (low ADC) and F¹⁸-FDG PET/CT (high SUV) may be helpful clues to the diagnosis.

Cauda Canis: Variation of a Tinel's Sign for a Sciatic Nerve Tumor

A patient with a prior history of intradural schwannoma and disc herniation presented with radicular pain after being hit in the thigh by a dog's tail. She was worked up and found to have a tumor of her right sciatic nerve. The tumor was resected and histology was consistent with schwannoma. The dog's tail acted as a Tinel's sign maneuver and led to timely identification of her peripheral nerve tumor. Peripheral nerve schwannomas can present in unusual forms, and Tinel's maneuver may be a useful tool in diagnosis.

The effect of ozone injection within a common peroneal nerve schwannoma: A mistreatment due to a misdiagnosis

Background:

Peripheral schwannomas can be misdiagnosed or mistreated as they can mimic other subcutaneous lesions, leading to wrong diagnosis and, therefore, to improper treatment.

Case Description:

A 23-years-old male presented a painful growing nodule at the left popliteal fossa, with distally irradiated pain. A first magnetic resonance imaging depicted a heterogeneous lesion between common peroneal and sural nerves but, surprisingly, the patient was submitted to perilesional injection of ozone-oxygen mixture, causing the onset of intense neuropathic pain. A second MRI showed a morphological change of tumor characteristics. He finally underwent surgery but, intraoperatively, inter-fascicular fibrous adherences were noticed, making the tumor removal more difficult and riskier. The histopathological diagnosis was of schwannoma with areas of foreign body reaction.

Conclusion:

The injection of ozone or other substances within a subcutaneous swelling should be avoided, before a complete imaging assessment; because of such swelling could be a peripheral nerve schwannoma. The correct assessment of a lesion of the limbs determining radiating pain should be carefully demanded to a thorough history, clinical examination, and appropriate imaging technique. To avoid incorrect management, the treatment of such tumors should be performed in the first place by dedicated equips with proven expertise in this field.

Perineural spread to the brachial plexus: a focused review of proposed mechanisms and described pathologies

BACKGROUND

Perineural spread (PNS) is an emerging mechanism for progressive, non-traumatic brachial plexopathy. We aim to summarize the pathologies (tumor and infection) shown to have spread along or to the brachial plexus, and identify the proposed mechanisms of perineural spread.

METHODS

A focused review of the literature was performed pertaining to pathologies with identified perineural spread to the brachial plexus.

RESULTS

We summarized pathologies currently reported to have PNS in the brachial plexus and offer a structure for understanding and describing these pathologies with respect to their interaction with the peripheral nervous system.

CONCLUSIONS

Perineural spread is an underrepresented entity in the literature, especially regarding the brachial plexus. It can occur via a primary or secondary mechanism based on the anatomy, and understanding this mechanism helps to support biopsies of sacrificial nerve contributions, leading to more effective and timely treatment plans for patients.

Sural nerve schwannoma: A case report

A 54-year old female with lateral ankle and foot pain was referred to an orthopaedic specialist clinic. Examination and investigations revealed a painful mass surrounding the sural nerve. Surgical excision confirmed the diagnosis of a sural nerve schwannoma. The following case report discusses this patient's presentation in further depth, as well as information about schwannomas, their frequency in the lower limb, and recommendations for investigation and management. LEVEL OF CLINICAL EVIDENCE: 6.

Safe marginal resection of atypical neurofibromas in neurofibromatosis type 1

OBJECTIVE

Patients with neurofibromatosis type 1 (NF1) are predisposed to visceral neurofibromas, some of which can progress to premalignant atypical neurofibromas (ANFs) and malignant peripheral nerve sheath tumors (MPNSTs). Though subtotal resection of ANF may prevent malignant transformation and thus deaths with no neural complications, local recurrences require reoperation. The aim of this study was to assess the surgical morbidity associated with marginal resection of targeted ANF nodules identified via preoperative serial volumetric MRI and 18F-FDG-PET imaging.

METHODS

The authors analyzed clinical outcomes of 16 NF resections of 21 tumors in 11 NF1 patients treated at the NIH Clinical Center between 2008 and 2018. Preoperative volumetric growth rates and 18F-FDG-PET SUVMax (maximum standardized uptake value within the tumor) of the target lesions and any electromyographic or nerve conduction velocity abnormalities of the parent nerves were measured and assessed in tandem with postoperative complications, histopathological classification of the resected tumors, and surgical margins through Dunnett's multiple comparisons test and t-test. The surgical approach for safe marginal resection of ANF was also described.

RESULTS

Eleven consecutive NF1 patients (4 male, 7 female; median age 18.5 years) underwent 16 surgical procedures for marginal resections of 21 tumors. Preoperatively, 13 of the 14 (93%) sets of serial MRI studies and 10 of the 11 (91%) 18F-FDG-PET scans showed rapid growth (≥ 20% increase in volume per year) and avidity (SUVMax ≥ 3.5) of the identified tumor, respectively (median tumor size 48.7 cm3; median growth rate 92% per year; median SUVMax 6.45). Most surgeries (n = 14, 88%) resulted in no persistent postoperative parent nerve-related complications, and to date, none of the resected tumors have recurred. The median length of postoperative follow-up has been 2.45 years (range 0.00-10.39 years). Histopathological analysis confirmed significantly greater SUVMax among the ANFs (6.51 ± 0.83, p = 0.0042) and low-grade MPNSTs (13.8, p = 0.0001) than in benign neurofibromas (1.9).

CONCLUSIONS

This report evaluates the utility of serial imaging (MRI and 18F-FDG-PET SUVMax) to successfully detect ANF and demonstrates that safe, fascicle-sparing gross-total, extracapsular resection of ANF is possible with the use of intraoperative nerve stimulation and microdissection of nerve fascicles.

Schwannomas of Uncommon Peripheral Locations: Analysis of Imaging Findings of 21 Cases

BACKGROUND

Schwannomas are benign slow-growing tumors most often associated with the cranial nerves. Schwannomas often originate from the eighth cranial nerve. They may also originate from the peripheral nervous system of the neck and extremities. However extracranial peripheral schwannomas are considered a rare entity.

OBJECTIVES

The knowledge of rare localizations and typical imaging findings will lead to a successfulradiological diagnosis. Therefore, in this study, we present the clinical findings and MRI characteristics of schwannomas with a rare localization involving the peripheral, lower and upper extremity and intramuscular regions.

MATERIALS AND METHODS

The hospital database was screened for patients with an extracranial soft tissue mass. Twenty-one cases of schwannomas were found in rare localization. We analyzed the MR images of these patients retrospectively. The MR images were evaluated in terms of tumor location, signal intensity, and enhancement pattern. The histological examination of all the patients confirmed the diagnosis of schwannoma.

RESULTS

In 21 patients, the schwannomas were peripheral, localized to upper (n = 6) and lower extremities (n = 11). The remaining four patients had intramuscular schwannomas. The patients diagnosed with intramuscular schwannomas had schwannomas in sternocleidomastoid, gastrocnemius, triceps muscle and lateral wall of the abdomen. The average long-axis diameter of the tumor was 27.7 mm and the average short-axis diameter was 16.4 mm. The contrast pattern was diffused in eight tumors and peripheral in 13.

CONCLUSION

In this study, we present clinical findings and MRI characteristics of schwannomas with a rare localization involving the peripheral, lower and upper extremity and intramuscular regions.

Multiple recurrent neurofibromas in the abdominal wall: A case report

BACKGROUND

Neurofibroma can be a clinical manifestation of neurofibromatosis, which is a benign neurogenic tumor that occurs sporadically. Neurofibromas in the abdomen usually appear in the retroperitoneal space. Reports on neurofibromas in the abdominal wall are rare, and multiple recurrent neurofibromas in this area have not yet been reported.

CASE SUMMARY

This is a case of a 73-year-old man who suffered from multiple recurrent neurofibromas in the abdominal wall for 16 years and received 13 surgical treatments.

CONCLUSION

We need to pay due attention to its treatment, and primary surgery should be designed thoroughly.

Fungating malignant peripheral nerve sheath tumor arising from a slow-growing mass in the forearm: a case report and review of the literature

Background

Malignant peripheral nerve sheath tumor is a rare and aggressive form of sarcoma that arises from a peripheral nerve, mostly in association with neurofibromatosis type 1. Half of the cases were reported in the extremities, with the lungs being the most common site of metastasis. We report a rare case of successful limb salvage surgery performed for a large exophytic malignant peripheral nerve sheath tumor of the right forearm with wide surgical margins followed by split-thickness skin graft and later a flexor carpi radialis tendon transfer to extensor digitorum communis tendon.

Case presentation

A 51-year-old Bedouin Arabic man presented to our institution with an incompletely excised, large, fungating, malignant peripheral nerve sheath tumor occupying most of his right forearm. Staging imaging showed multiple lung nodules. He underwent wide local excision followed by skin graft and tendon transfer as a palliative measure to preserve the function of his dominant limb. The operation was performed without any complications, and the patient had an excellent postoperative result. Afterward, he was started on multiple lines of chemotherapy that failed because of disease progression, and the patient died 7 months after the operation.

Conclusion

Clinicians must consider the possibility of soft tissue sarcoma even in a patient with a small, slow-growing, superficial mass. Furthermore, a wrong open biopsy or nononcological surgical procedure may lead to possible contamination and ultimately a more radical procedure than would have originally been necessary, where this can be prevented by an early referral to a highly specialized sarcoma center.

Malignant triton tumor below the peritoneal reflection: a case report

Malignant triton tumor (MTT) is a rare subtype of malignant peripheral nerve sheath tumors (MPNSTs) histologically defined by rhabdomyoblastic differentiation. MTTs are primarily found in the head, neck, extremities and trunk, but rare cases of MTT within the buttock, the mediastinum and the retroperitoneum have also been documented. We present the case of a 47-year-old male patient who initially presented with right flank pain and hematuria in July 2019, who was found to have a large pelvic mass below peritoneal reflection. Complete resection of the mass was performed, and pathology identified the mass as a MTT.

Diagnostic and management considerations in incidental common peroneal intraneural haemangioma

Intraneural haemangiomas are rare tumours that can affect peripheral nerves. We describe a case of a 10-year-old female with an incidental finding of a common peroneal nerve lesion following knee injury. MRI demonstrated avid heterogeneous enhancement and peri-lesional oedema, and an open biopsy was performed revealing haemangioma on histopathological analysis. The patient was managed with observation and remains intact at 24-month follow-up.

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

PURPOSE

To 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.

METHOD

MR 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.

RESULTS

On 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).

CONCLUSIONS

Preoperative 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.

Angioleiomyoma of the hand with nerve compression

OBJECTIVE

This study was performed to analyze the clinical, radiographic, and pathological features of hand angioleiomyoma causing nerve compression and assess the outcomes of surgical excision.

METHODS

This case series included three men and one woman (mean age, 53.3 years; range, 49-56 years). The patients' chief complaint was numbness of the fingers. The patients' medical histories were reviewed, and the diagnosis of angioleiomyoma with nerve compression was confirmed by means of imaging examination and pathological analysis.

RESULTS

Three tumors occurred in the palm and one in the finger, and the average maximum tumor diameter was 1.8 cm (range, 0.8-2.6 cm). Preoperative magnetic resonance imaging demonstrated well-defined masses with isointense signals on T1 sequences, hyperintense signals on T2 sequences, and strong heterogeneous enhancement after injection of contrast material. All tumors were located near nerves, leading to nerve compression. The diagnosis of angioleiomyoma was confirmed by postoperative pathology. Finger sensation recovered and no recurrence was found during an average follow-up of 37 months (range, 25-59 months).

CONCLUSIONS

Angioleiomyoma should be considered among the differential diagnoses of hand tumors and timely resection should be performed, particularly if the mass is causing numbness and/or pain with positive Tinel's sign and/or tenderness.

Giant Pelvic Schwannoma: Case Report and Review of the Literature

INTRODUCTION

Pelvic schwannomas are rare, mostly benign tumors. They are usually asymptomatic until their massive growth compresses adjacent organs. We describe the case of a 53-year-old man with a pelvic schwannoma who initially complained of constipation and urinary retention.

AREAS COVERED

We analyzed the clinical presentation, histopathology, diagnostic imaging tools, and the treatment options for pelvic schwannomas, compared with the few other cases reported in the literature.

EXPERT COMMENTARY

Pelvic schwannomas are masses that can grow to considerable size, producing symptoms over time. Due to their size and localization, surgery, although difficult, is the only available treatment.

Malignant peripheral nerve sheath tumor of the parapharyngeal space arising from cervical sympathetic chain: A rare entity

Malignant peripheral nerve sheath tumors (MPNSTs) of parapharyngeal space are rare and if present are most often in association with neurofibromatosis type 1 (NF-1). Only a few cases of MPNST have been reported in the literature without coexisting NF. We report one such case of an MPNST of parapharyngeal space tumor in a 35-year-old female with no associated features of NF-1. She presented with right-sided neck swelling and ptosis. Magnetic resonance imaging showed a 7 cm × 8 cm × 11 cm irregular swelling in the right parapharyngeal space with invasion of surrounding muscles. The mass was excised using a transcervical approach. Postoperative histopathological examination of the specimen revealed MPNST possibly arising from the cervical sympathetic chain.

Benign peripheral nerve sheath tumor of digit versus major-nerve: Comparison of MRI findings

Objective

To compare the symptoms and magnetic resonance imaging (MRI) findings between digital peripheral nerve sheath tumor (PNST) and major-nerve PNST.

Methods

A total 36 cases with benign PNSTs (16 digital, 20 major-nerve) were enrolled. Chief complaint and Tinel sign were reviewed. Five classic MRI features of PNST, the signal intensity (SI), the enhancement, and the shape of tumor were evaluated on MRI.

Results

Half of each group showed tenderness. Tinel sign was less frequent in digital PNST (12.5%) than major-nerve PNST (95.0%, P < 0.001). Split fat sign, entering and exiting nerve, target sign, and thin hyperintense rim were only observed in major-nerve PNST (P = <0.001, <0.001, 0.492, and 0.002, respectively). Fascicular sign was found in digital PNSTs (31.3%), but more frequent in major-nerve PNST (P < 0.001). In digital PNSTs, mild hyperintense SIs (56.2%) on T1-weighted images (T1-WI) was noted, but none in major-nerve PNST (P < 0.001). Both groups showed hyperintense SIs on T2-WI (P = 0.371). Homogeneity on T2-WI was noted in 43.8% of digital PNSTs, but none in major-nerve PNSTs (P = 0.004). Both groups showed heterogeneous enhancement (P = 0.066), but four (25%) digital PNSTs showed homogeneous enhancement. Lobulated shape was noted in 50% of digital PNSTs but none of major-nerve PNSTs (P = 0.001). Digital nerve was involved at 81.3% of digital PNSTs. Three foot cases showed unusual manifestations: bone destruction, skin thickening, and subungual location.

Conclusion

In digital PNSTs, Tinel sign is not commonly found and classic MRI findings is insufficient. In addition, some digital PNSTs show different SI and enhancement from major-nerve PNSTs. However, digital soft tissue tumor involving digital neurovascular bundle and especially representing a fascicular sign should be considered the possibility of a digital PNST.

Oncologic Accuracy of Image-guided Percutaneous Core-Needle Biopsy of Peripheral Nerve Sheath Tumors at a High-volume Sarcoma Center

OBJECTIVES

Peripheral nerve sheath tumors (PNSTs) are clinically heterogenous, comprising benign (BPNST) and malignant (MPNST) variants. BPNSTs can be managed with nerve-sparing excision or observation. MPNSTs require radical resection and multidisciplinary oncologic management (1, 15). Image-guided core-needle biopsy (IGCNBx) is the well-established standard to obtain preoperative tissue diagnosis of soft tissue tumors. However, there has been resistance to performing IGCNBx of PNSTs because of the presumed risk of nerve injury and unknown accuracy in determining malignancy. We sought to define the accuracy and safety of IGCNBx in PNSTs.

MATERIALS AND METHODS

All patients that underwent both IGCNBx and surgical resection of a PNST at our institution between 2002 and 2016 were analyzed. The accuracy of IGCNBx in determining malignancy was calculated, including subgroup analyses by histologic subtype and neurofibromatosis 1 status. Complication data were collected and analyzed.

RESULTS

Among the 78 PNSTs with IGCNBx and postresection surgical pathology, 76% (n=59) had BPNST and 24% (n=19) had MPNST on postresection surgical pathology. IGCNBx accurately determined malignancy in 94% of cases. IGCNBx demonstrating schwannoma or MPNST were 100% accurate in determining malignancy. IGCNBx demonstrating neurofibroma or indeterminate results were 33% and 57% malignant on postresection surgical pathology, respectively. There were no long-term complications, including sensory or motor deficits, from IGCNBx.

CONCLUSIONS

Percutaneous IGCNBx demonstrates 94% accuracy in differentiating benign from malignant PNSTs. IGCNBx demonstrating neurofibroma or indeterminate pathology should be interpreted with caution because of risk of malignant reclassification on surgical pathology. Our results reaffirm the safety of IGCNBx, as no patients experienced long-term complications.

Oncological Treatment Considerations Differ across Surgical Subspecialties Treating Malignant Peripheral Nerve Sheath Tumors: An International Survey

Background

Malignant peripheral nerve sheath tumors (MPNSTs) are rare and aggressive soft tissue sarcomas (STS) that, because of their origin, are operated by several surgical subspecialties. This may cause differences in oncologic treatment recommendations based on presentation. This study investigated these differences both within and between subspecialties.

Methods

A survey was distributed among several (inter)national surgical societies. Differences within and between subspecialties were analyzed by χ²-tests.

Results

In total, 30 surgical oncologists, 30 neurosurgeons, 85 plastic surgeons, and 29 “others” filled out the survey. Annual caseload, tumor sites operated, and fellowship training differed significantly between subspecialties. While most surgeons agreed upon preoperative use of MRI, the use of radiological staging and FDG-PET use differed between subspecialties. Surgical oncologists agreed upon core needle biopsies as an ideal type of biopsy while other subspecialties differed in opinion. On average, 53% of surgeons always consider preservation of function preoperatively, but 42% would never perform less extensive resections for function preservation. Respondents agreed that radiotherapy should be considered in tumor sizes >10 cm, microscopic, and macroscopic positive margins. A preferred sequence of radiotherapy administration differed between subspecialties. There was no consensus on indications and sequence of administration of chemotherapy in localized disease.

Conclusion

Surgical oncologists generally agree on preoperative diagnostics; other subspecialties do not. Considering the preservation of function differed among all subspecialties. Surgeons do agree on some indications for radiotherapy, yet the use of chemotherapy in localized MPNSTs lacks consensus. A preferred sequence of multimodal therapy differs between and within surgical subspecialties, but surgical oncologists prefer neoadjuvant radiotherapy.

Predictive factors of postoperative deficit and functional outcome after surgery for upper limb schwannomas: Retrospective study of 21 patients

Schwannomas are the most frequent benign tumors of the peripheral nerves. Tumor enucleation is the traditional surgical treatment. The incidence of neurological complications after surgery varies and predictive factors for these complications are not clearly defined. The aim of this study was to find predictive factors of postoperative neurological deficit after surgical treatment of schwannomas of the upper limb. Twenty-four schwannomas removed from 21 patients were analyzed retrospectively. The patients' mean age was 45.4years and the mean follow-up was 64.4months. Clinical parameters studied were age, gender, nature of preoperative symptoms, duration of symptoms, type of surgery performed, tumor location and size, nerve involved, QuickDASH and DN4 scores. Postoperative neurological deficits occurred in 14 patients (67%), with 11 having a sensory deficit and 7 a motor weakness. Eleven did not exist before surgery (6 sensory, 5 motor). In the postoperative deficit subgroup, 6 schwannomas involved the brachial plexus, 4 the ulnar nerve, and 4 the median nerve. All patients who had a fascicular resection because tumor enucleation was not feasible were in the postoperative deficit subgroup. Ten patients had either unchanged or worse QuickDASH and/or DN4 scores after surgery. Surgical treatment of schwannomas can lead to postoperative complications. Although none of our findings were statistically significant, advanced age, large tumor size, more than 16months between the first symptoms and surgery, and brachial plexus location seem to be more frequently observed in those with a postoperative neurological deficit.

Interdisciplinary approach allows minimally invasive, nerve-sparing removal of retroperitoneal peripheral nerve sheath tumors

Purpose

En bloc resection of retroperitoneal peripheral nerve sheath tumors (PNST) is advocated by a variety of surgical disciplines. Yet, microsurgical, nerve-sparing tumor resection might be better suited to improve symptoms and maintain neurological function, especially in cases where patients present with preoperative neurological deficits. However, neurosurgeons, versed in nerve-sparing techniques to remove PNST, are generally unfamiliar with the visceral approaches to retroperitoneal PNST.

Methods

We retrospectively evaluate a series of 16 patients suffering from retroperitoneal PNST. Patients were treated by a unique interdisciplinary approach, combining the visceral surgeon’s skills to navigate the complex anatomy of the retroperitoneal space and the neurosurgeon’s familiarity with microsurgical, nerve-sparing tumor removal. Specifically, we assess whether our interdisciplinary approach is suited to improve preoperative symptoms and maintain neurological function and study whether oncological outcome, surgical morbidity, and operative times are comparable to those reported for “classical” retroperitoneal PNST resection. In addition, we study two cases of suspected PNST that were diagnosed as malignant peripheral nerve sheath tumors (MPNST) after surgery.

Results

Total macroscopic tumor resection was achieved in 14/16 PNST patients. Mean intraoperative blood loss was 680.6 ml (95% CI, 194.3–1167.0 ml) and mean operative time was 162.5 min (95% CI, 121.6–203.4 min). We did not record any major postoperative surgical or neurological complications. A total of 8/11 patients with preoperative pain symptoms reported long-lasting improvement of their symptoms. In terms of oncological outcome, all patients that had been subjected to total tumor removal and for whom follow-up was available, were tumor-free after a mean follow-up of 761.9 days (95% CI, 97.6–1426.0 days). One of the two MPNST patients, who presented with tumor progress 15 months after initial surgery, was subjected to radical re-resection.

Conclusions

Interdisciplinary, nerve-sparing removal of retroperitoneal PNST is well suited to improve preoperative symptoms and maintain neurological function, while achieving an oncological outcome and a surgical morbidity similar to previously reported results for radical retroperitoneal PNST resection. Radical re-resection was feasible in a patient with post hoc MPNST diagnosis.

Median Nerve Schwannoma of the Hand and Wrist: 3 Cases

Tumors of the median nerve are difficult to diagnose and median nerve schwannomas are rare. During a ten-year period, we treated eleven median nerve schwannomas found on the hand (nine) and wrist (two). All the tumors were treated by enucleation under loupe magnification and tourniquet application. All had a favorable result at a mean follow up of five years. We present three of our most typical cases, with schwannomas found on the wrist, palm and thumb. We also review the literature offering a wider view on the pathology, diagnosis and treatment of schwannomas in general.

Anterior knee schwannoma

Peripheral nerve tumors are relatively uncommon with schwannomas being the most common type. Schwannomas are usually benign encapsulated tumors composed of neoplastic Schwann cells that generally do not transform to malignancy. Many are discovered incidentally as solitary tumors. The cause is unknown. Most occur spontaneously, while some develop in association with genetic disorders such as neurofibromatosis type 2 or schwannomatosis. Schwannomas can occur anywhere in the body. They affect all ages, with peaking incidence between ages 20 and 50 years, without predilection to sex or race. Many are asymptomatic; however, presenting signs and symptoms, such as paresthesia and pain, are due to mass effect and direct nerve invasion. Diagnosing includes combinations of thorough physical examination, imaging modalities such as magnetic resonance imaging and surgical biopsy. Treatment depends on factors such as location of the tumor and severity of symptoms. Asymptomatic patients are treated conservatively while symptomatic patients undergo surgical resection with favorable prognosis.

Benign peripheral nerve tumors

Benign peripheral nerve tumors encompass a wide range of neoplasms and non-neoplastic tumor like lesions. Some of these lesions if not encountered in the setting of genetic syndromes, are occurring sporadically. The principles of oncology should be respectfully followed in every step of diagnostic approach and surgical management. Albeit, classified as benign, some of them do have different level of malignant potential, thus the treating physicians should be aware of that to avoid possible pitfalls with devastating outcomes. This article reviews the most common benign peripheral nerve tumors discussing the clinicopathological findings, imaging appearance and the current trend in their approach.

Extracapsular dissection in peripheral nerve schwannoma surgery using bright light and fluorescein sodium visualization: case series

BACKGROUND

Schwannomas are the most frequent peripheral nerve sheath tumors and are treated by surgical resection when symptomatic. Tumor removal is performed by intraneural dissection and enucleation. In order to safely remove the tumor from the nerve, the use of sodium fluorescein has recently been proposed to distinguish the tumor from the adjacent normal nerve fibers, before incision of the tumor pseudocapsule and during intraneural tumor dissection.

METHODS

We report a consecutive case series of 5 peripheral nerve schwannomas operated in 4 patients, in which we evaluate the usefulness of sodium fluorescein compared to usual visual landmarks, at each step of the surgical procedure.

RESULTS

After exposition of the schwannoma, sodium fluorescein helped with the localization of intracapsular en passant nerve fascicles in only one case. Hence, the definition of a safe entry zone for capsular incision relied mainly on nerve monitoring and direct visualization of en passant nerve fascicles under microscope. During intraneural dissection, there was a sharp contrast between the fluorescent tumor and the non-fluorescent adjacent pseudocapsule in most cases but the colorimetric variation between tumor and normal tissue induced by fluorescence did not outperform the natural contrast between the yellow true capsule and the gray-red layers of the pseudocapsule.

CONCLUSION

Based on these results, we consider that the limited additional value of sodium fluorescein in primary peripheral nerve schwannoma surgery does not warrant its use in daily clinical practice. Additional studies are needed to assess its usefulness during the surgery of recurrences and tumors which are intertwined with several fascicles of origin such as neurofibromas.

Minimally invasive resection of a lumbar extradural schwannoma: how I do it

BACKGROUND

Complete surgical resection of a foraminal lumbar schwannoma may require an extended surgical exposure and facetectomy and thus secondary instrumentation. The minimally invasive technique through the use of tubular retractors may represent a valid surgical alternative.

METHOD

We describe the resection of a foraminal lumbar schwannoma through the use of tubular retractors, along with its advantages and limitations. A limited medial facetectomy was performed and no stabilization was needed.

CONCLUSION

Minimally invasive surgery is suitable for an efficient and safe resection of foraminal schwannomas and may help in avoiding stabilization when a limited facetectomy is performed.

Fluorescein-guided resection of plexiform neurofibromas: how I do it

BACKGROUND

Plexiform neurofibromas (PN) can determine pain, nerve function impairment, and, when extremely large, also deformity. Surgical is often partial, with possible recurrence, and the risk of malignant transformation.

METHOD

We describe the surgical strategy in a case of huge multiple plexiform neurofibromas of the left arm. We attempted to achieve a safe resection under the intraoperative guidance of fluorescein, with a dedicated microscope filter (YELLOW560). This technique can be also applied to other locations.

CONCLUSION

Fluorescein-guided surgery, coupled with intraoperative neurophysiological monitoring, increases the safe resection rate, considering the risks of neurological deficits and the possible malignant transformation.

An Unusual Case of Median Neuropathy: Application of Short Segmental Sensory Nerve Stimulation

A 55-year-old woman presented with an 18-month history of intermittent left-hand paresthesias affecting her first, second, and third digits. A small, immobile, nontender midline mass on the volar aspect of the left wrist was also present. Evaluation included normal routine nerve conduction studies and needle electromyography. An ultrasound was performed in the electromyography laboratory, verifying median nerve involvement of the mass within the proximal carpal tunnel. This finding guided the electromyographer to perform the unconventional technique of sensory nerve short segmental stimulation across the carpal tunnel, which confirmed focal slowing across the lesion, achieving electrodiagnostic confirmation of median nerve impairment. This case of atypical carpal tunnel syndrome due to a median nerve schwannoma demonstrates both the utility and specificity of short segmental sensory stimulation in some cases of median neuropathy at the wrist and the value of sonography in the electromyography laboratory.

Rare Schwannoma Nerve Tumor in a Lesser Toe: A Case Report

A schwannoma is a solitary benign tumor composed of Schwann cells occurring anywhere in the peripheral nervous system. The diagnosis of a schwannoma is often difficult to make by clinical presentation and advanced imaging modalities. We present a case report of a 61-year-old Hispanic woman with a left-foot, third-digit, soft-tissue mass. The diagnosis of a schwannoma of the proper digital nerve was made postsurgically by means of histopathologic and immunohistochemistry parameters. This is a rare location for a schwannoma, and neurogenic tumor should be included in the differential diagnosis of soft-tissue mass, as there have been prior case reports.

Interfascicular Resection of Benign Peripheral Nerve Sheath Tumors

Background

Interfascicular resection is a surgical technique used to safely treat benign peripheral nerve sheath tumors through careful dissection of functional neural elements off the tumor surface^1,2.

Description

Proper operative technique is essential to improving symptoms, preserving neurologic function, and minimizing the chance for recurrence. Accurate tumor localization, ideal patient positioning, and placement of a longitudinal incision permit adequate exposure. Prior to tumor resection, normal nerve should be identified proximally and distally and controlled with vessel loops. This allows functional fascicles streaming around the tumor in the pseudocapsule to be visualized during resection. A fascicle-free window is identified on the tumor surface through visual inspection and intraoperative neurophysiology monitoring if desired. The pseudocapsule layers are divided with a sharp instrument until a smooth and shiny true capsule layer is found. This plane should have minimal resistance and is developed circumferentially until the tumor can be enucleated in toto. At the poles of the tumor, a single nonfunctional nerve fascicle that courses into the tumor is typically found. If there is >1 fascicle running into the tumor, further pseudocapsule layers should be undermined to sweep fascicles off the true capsule surface. The entering-exiting fascicle can be tested for function and is cut sharply. The specimen should be sent to pathology for permanent sectioning. The sides of the pseudocapsule are spread in opposite directions to evaluate for residual tumor, and any remaining tumor is removed if it can be done safely. Meticulous hemostasis is achieved, and the surgical site is closed in anatomical layers.

Alternatives

Pain is the most common presenting symptom, and neuroleptic medications should be used in escalating dosage prior to surgical intervention. Nonoperative medical therapy does not typically result in symptom freedom, and patients often opt for resection. For tumors that are suspected of being malignant, an image-guided percutaneous or open biopsy and staging (positron emission tomography and/or computed tomography scans of the chest, abdomen, and pelvis) are recommended prior to treatment planning. For symptomatic benign extremity lesions, surgical resection is the treatment of choice, and adjuvant therapies like radiation and/or chemotherapy are not recommended. For malignant lesions, more aggressive surgery (wide resection or amputation) and preoperative, intraoperative, or postoperative radiation with or without chemotherapy are often utilized.

Rationale

The treatment approach depends on a variety of presenting features such as onset, progression, symptom severity, tumor size, location, imaging features, presence of a syndrome, and patient age. There is little benefit from the resection of an incidentally found, small, nongrowing lesion. The most common reasons for removal of extremity lesions are a painful mass and/or radiating "nerve" pain. There is a high likelihood of relieving the symptoms and minimizing the risk of recurrence, and a relatively low risk of causing neurologic injury. The procedure provides a definitive diagnosis. For patients with severe pain, progressive weakness, rapid tumor growth, or concerning imaging characteristics, biopsy should be considered to determine malignant potential.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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 &lt; .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 &lt; .01).

CONCLUSION

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.

Peripheral nerve injuries in the pediatric population: a review of the literature. Part III: peripheral nerve tumors in children

INTRODUCTION

Peripheral nerve tumors type, inciedence and treatment in the pediatric population should be analyzed.

METHODS

We have performed an extense literature review of this subject.

RESULTS

incidence and distribution are similar to those observed in adults. The most common peripheral nerve tumors in children are neurofibromas and schwannomas. Malignant peripheral nerve sheath tumors are also observed, specially associated with genetic syndromes, like neurofibromatosis and Carney complex.

CONCLUSION

In this review, peripheral nerve tumors have been divided into three categories to aid with understanding: reactive and hyperplastic lesions, benign tumors, and malignant tumors. The most frequent lesions have been described.

Diffusion-weighted imaging and diffusion tensor imaging as adjuncts to conventional MRI for the diagnosis and management of peripheral nerve sheath tumors: current perspectives and future directions

Peripheral nerve sheath tumors (PNSTs) account for ~ 5% of soft tissue neoplasms and are responsible for a wide spectrum of morbidities ranging from localized neuropathy to fulminant metastatic spread and death. MR imaging represents the gold standard for identification of these neoplasms, however, current anatomic MR imaging markers do not reliably detect or differentiate benign and malignant lesions, and therefore, biopsy or excision is required for definitive diagnosis. Diffusion-weighted MR imaging (DWI) serves as a useful tool in the evaluation and management of PNSTs by providing functional information regarding the degree of diffusion, while diffusion tensor imaging (DTI) aids in determining the directional information of predominant diffusion and has been shown to be particularly useful for pre-operative planning of these tumors by delineating healthy and pathologic fascicles. The article focuses on these important neurogenic lesions, highlighting the current utility of diffusion MR imaging and future directions including computerized radiomic analysis. KEY POINTS: • Anatomic MRI is moderately accurate in differentiating benign from malignant PNST. • Diffusion tensor imaging facilitates pre-operative planning of PNSTs by depicting neuropathy and tractography. • Radiomics will likely augment current observer-based diagnostic criteria for PNSTs.

The implications of intradural extension in paraspinal malignant peripheral nerve sheath tumors: effects on central nervous system metastases and overall survival

OBJECTIVEIn this study, the authors sought to compare tumors with intradural extension to those remaining in the epidural or paraspinal space with the hypothesis that intradural extension may be a mechanism for seeding of the CSF with malignant cells, thereby resulting in higher rates of CNS metastases and shorter overall survival.METHODSThe authors searched the medical record for cases of malignant peripheral nerve sheath tumors (MPNSTs) identified from 1994 to 2017. The charts of the identified patients were then reviewed for tumor location to identify patients with paraspinal malignancy. All patients included in the study had tumor specimens that were reviewed in the surgical pathology department. Paraspinal tumors with intradural extension were identified in the lumbar, sacral, and spinal accessory nerves, and attempts were made to match this cohort to another cohort of patients who had paraspinal tumors of the cranial nerves and lumbar and sacral spinal regions without intradural extension. Further information was collected on all patients with and without intradural extension, including date of diagnosis by pathology specimen review; nerve or nerves of tumor origin; presence, location, and diagnostic date of any CNS metastases; and either the date of death or date of last follow-up.RESULTSThe authors identified 6 of 179 (3.4%) patients who had intradural tumor extension and compared these patients with 12 patients who harbored paraspinal tumors that did not have intradural extension. All tumors were diagnosed as high-grade MPNSTs according to the surgical pathology findings. Four of 6 (66.7%) patients with intradural extension had documented CNS metastases. The presence of CNS metastases was significantly higher in the intradural group than in the paraspinal group (intradural, 66.7% vs paraspinal, 0%; p < 0.01). Time from diagnosis until death was 11.2 months in the intradural group and approximately 72 months in the paraspinal, extradural cohort.CONCLUSIONSIn patients with intradural extension of paraspinal MPNSTs, significantly higher rates of CNS metastases are seen with a reduced interval of time from diagnosis to metastatic lesion detection. Intradural tumor extension is also a poor prognostic factor for survival, with these patients showing a reduced mean time from diagnosis to death.

Malignant peripheral nerve sheath tumours and neurofibromatosis 1: A case series and recommendations for care

Background: The incidence of malignant peripheral nerve sheath tumours (MPNST) in patients with neurofibromatosis 1 (NF1) is significantly higher than that of the general population. NF1-associated MPNST occur at a younger age and carry a worse prognosis than sporadic MPNST.Aim: This case series describes four cases of MPNST in patients with NF1.Setting: The study was performed in a public academic hospital in the Western Cape province of South Africa.Method: Demographics, disease status, histopathology, treatment and outcome data were collected retrospectively from medical charts and through review of histological slides.Results: The median age was 36.5 years. All tumours were > 5 cm at presentation and located on the trunk. One patient presented with metastatic disease. There was a mean delay of 3.5 months from presentation to initiation of treatment. Three patients underwent wide excision, with one receiving adjuvant chemotherapy and radiotherapy. At a median follow-up of 20 months from histological diagnosis only one patient was alive in clinical remission. Two patients had succumbed to progressive disease at 8 and 16 months from diagnosis and one patient with terminal metastatic disease was lost to follow-up.Conclusion: In this series the patients presented with advanced, often unresectable lesions for which single modality therapy was not curative. An adult NF1 health surveillance guideline for resource-constrained environments could lead to early diagnosis and treatment of MPNST and other complications in NF1 patients.