Diagnosis and treatment options for nerve sheath tumors

O-arm guided minimally invasive resection of intrathoracic epidural schwannoma: how I do it

BACKGROUND

Schwannomas are the most common intrathoracic neurogenic tumors. In the past, they were often treated by traditional open surgery. Video-assisted thoracic surgery (VATS) has also been used for some large tumors. Recently, minimally invasive posterior neurosurgical technique provides a new option for some of these tumors.

METHOD

Here, we describe the specific steps involved in the O-arm guided minimally invasive removal of intrathoracic epidural schwannoma, as well as its advantages and limitations.

CONCLUSION

O-arm guided minimally invasive resection of intrathoracic epidural schwannoma is safe and effective and causes little damage.

Management of neurofibromatosis type 1-associated plexiform neurofibromas

Plexiform Neurofibromas (PN) are a common manifestation of the genetic disorder neurofibromatosis type 1 (NF1). These benign nerve sheath tumors often cause significant morbidity, with treatment options limited historically to surgery. There have been tremendous advances over the past two decades in our understanding of PN, and the recent regulatory approvals of the MEK inhibitor selumetinib are reshaping the landscape for PN management. At present, there is no agreed upon PN definition, diagnostic evaluation, surveillance strategy, or clear indications for when to initiate treatment and selection of treatment modality. In this review, we address these questions via consensus recommendations from a panel of multidisciplinary NF1 experts.

Magnetic resonance neurography appearance and diagnostic evaluation of peripheral nerve sheath tumors

Imaging appearances of peripheral nerve sheath tumors by MRI are difficult distinguish from soft-tissue tumors. The objective of this study was to evaluate the feasibility and imaging appearance of high-resolution 3-T magnetic resonance neurography (MRN) of the diagnosis of peripheral nerve sheath tumors (PNSTs) using sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) sequences. We retrospectively evaluated the MRI and 3D Short tau inversion recovery sampling perfection with application-optimized contrasts using varying flip-angle evolutions (3D-STIR SPACE) sequences of 30 patients with PNSTs diagnosed by surgery and pathology. The contrast-enhanced 3D-STIR SPACE images were retrospectively analyzed and evaluated for the visualization of PNSTs. The tumors were evaluated by their number, location, morphology, size, signal intensity and enhancement characteristics. The imaging findings and characteristic signs of conventional MRI scanning and contrast-enhanced 3D-STIR SPACE sequences were compared. In these cases, conventional MRI images display the location, number, shape, size and signal characteristics of the lesions. These tumors were mostly solitary and had a well-defined boundary. Compared to conventional MRI images, imaging appearances including neurogenic origin, length of the peripheral nerves and relation to the nerve of PNSTs on 3D-STIR SPACE images were more accuracy (P < 0.05). Compared to 3D-STIR SPACE images, contrast-enhanced images can more clearly display background suppression of the peripheral nerves. The “split fat” sign and “target” sign were seen in some patients. 3D STIR SPACE sequences demonstrate its significant capacity to diagnostic evaluate and location of PNSTs. This article comprehensively reviews radiologic findings and illustrates the MRN features of PNSTs. 3D-STIR SPACE sequences be used for preoperative evaluation of PNSTs.

Linear Accelerator-Based Stereotactic Radiosurgery for Cranial Intraparenchymal Metastasis of a Malignant Peripheral Nerve Sheath Tumor: Case Report and Review of the Literature

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are rare, aggressive soft tissue sarcomas. MPNST intracranial metastasis is exceedingly rare with only 22 documented cases in the literature and, to our knowledge, only 1 case with intraparenchymal brain metastasis. Most have been managed surgically; however, 2 documented cases were treated with Gamma Knife radiosurgery. Excluding this case report, there are no other documented cases of linear accelerator-based stereotactic radiosurgery (SRS) to treat MPNST brain metastasis.

CASE DESCRIPTION

A 41-year-old man with MPNST of the lung initially underwent tumor resection. He developed multiple systemic metastases that were managed with directed radiation therapy. A parietal brain metastasis was treated with linear accelerator-based SRS. Following SRS therapy, the patient was treated with a tropomyosin receptor kinase inhibitor. Complete resolution of brain metastasis was seen on brain magnetic resonance imaging 5 months after treatment with SRS. At 11 months after SRS, there was no evidence of recurrence or progression of the intraparenchymal disease. The patient continued to have stable extracranial disease on his ninth cycle of systemic treatment.

CONCLUSIONS

This report provides important insights into efficacy of linear accelerator-based SRS to treat MPNST brain metastases.

Tumor targeted delivery of doxorubicin in malignant peripheral nerve sheath tumors

Peripheral nerve sheath tumors are benign tumors that have the potential to transform into malignant peripheral nerve sheath tumors (MPNSTs). Interleukin-13 receptor alpha 2 (IL13Rα2) is a cancer associated receptor expressed in glioblastoma and other invasive cancers. We analyzed IL13Rα2 expression in several MPNST cell lines including the STS26T cell line, as well as in several peripheral nerve sheath tumors to utilize the IL13Rα2 receptor as a target for therapy. In our studies, we demonstrated the selective expression of IL13Rα2 in several peripheral nerve sheath tumors by immunohistochemistry (IHC) and immunoblots. We established a sciatic nerve MPNST mouse model in NIH III nude mice using a luciferase transfected STS26T MPNST cell line. Similarly, analysis of the mouse sciatic nerves after tumor induction revealed significant expression of IL13Rα2 by IHC when compared to a normal sciatic nerve. IL13 conjugated liposomal doxorubicin was formulated and shown to bind and internalized in the MPNST cell culture model demonstrating cytotoxic effect. Our subsequent in vivo investigation in the STS26T MPNST sciatic nerve tumor model indicated that IL13 conjugated liposomal doxorubicin (IL13LIPDXR) was more effective in inhibiting tumor progression compared to unconjugated liposomal doxorubicin (LIPDXR). This further supports that IL13 receptor targeted nanoliposomes is a potential approach for treating MPNSTs.

Malignant peripheral nerve sheath tumor in the paraspinal region mimicking a benign peripheral nerve sheath tumor: a case report

PURPOSE

Malignant peripheral nerve sheath tumors are extremely rare in the general population and display a predilection for metastasis to the lungs. Here, we present a rare case of a malignant peripheral nerve sheath tumor located in the paraspinal region and highlight the importance of preoperative biopsy in diagnosis of spinal epidural peripheral nerve sheath tumors.

METHODS

We describe the clinical course of the patient as well as the radiological and pathological findings of the tumor.

RESULTS

A 14-year-old girl presented with a six-month history of sacral pain. Occasionally she experienced left leg pain and abnormal gait. General physical examination revealed sensorial loss in the L5-S1 regions. T1-weighted sagittal MRI showed a hypointense oval mass and the contrast-enhanced T1-weighted axial MRI image showed heterogeneous enhancement of the tumor. On CT imaging, this tumor characteristically appears as a dumbbell-like mass with punctate calcification and widening L5-S1 intervertebral foramen. Complete resection was performed using an anterior approach. Intraoperative pathological examination revealed evidence of malignancy and subsequent immunohistochemical analysis of the tumor confirmed the diagnosis of MPNST. The postoperative course was uneventful and the patient has had significant improvement in her symptoms 1 month postoperatively.

CONCLUSIONS

Preoperative biopsy should be routinely performed for pathological differential diagnosis of spinal epidural PNSTs as well as surgical decision-making. Furthermore a combination of clinical manifestation, radiological findings and biopsy should also be pursued for diagnosing these tumors.

Accuracy and complications of CT-guided core needle biopsy of peripheral nerve sheath tumours

OBJECTIVE

This single-centre study retrospectively reviews the complications in patients that have occurred following peripheral nerve sheath tumour biopsy, and assesses whether there is an association with biopsy technique or underlying lesion characteristics.

MATERIALS AND METHODS

41 consecutive core needle biopsies of proven peripheral nerve sheath tumours over a 2-year period in a tertiary teaching hospital were reviewed. Patient demographics and symptoms, tumour characteristics and radiological appearances were recorded. Biopsy and surgical histology were correlated, and post-biopsy and surgical complications analyzed.

RESULTS

41 biopsies were performed in 38 patients. 68% schwannomas, 24% neurofibromas and 7% malignant peripheral nerve sheath tumours. Biopsy histology correlated with surgery in all cases. 71% of lesions were surgically excised. 60% of patients reported pain related to their lesion. Following the biopsy, 12% reported increased pain, which resolved in all cases. Pain exacerbation was noted in tumours smaller in size, more superficial and in closer proximity of the biopsy needle tip to the traversing nerve. Number of biopsy needle passes was not associated with an increased incidence of procedure-related pain.

CONCLUSION

Core biopsy of a suspected peripheral nerve sheath tumour may be performed safely before excisional surgery to confirm lesion histology and assist prognosis. There is excellent correlation between core biopsy and excised surgical specimen histology. The most common complication of pain exacerbation is seen in a minority and is temporary, and more likely with smaller, more superficial lesions and a closer needle-tip to traversing nerve distance during biopsy.

Malignant Peripheral Nerve Sheath Tumor of the Lower Eyelid: Case Presentation and Literature Review

Solitary benign neurogenic tumors are common in the orbit, but only rarely arise from peripheral nerves in the eyelids. In contrast, malignant tumors of neural or nerve sheath elements are exceedingly rare in the orbit and, to date, have never been reported in the lower eyelid. The authors report a 55-year-old man with multiple recurrent lower eyelid masses initially treated as chalazia then misdiagnosed as neurotropic malignant melanoma on pathology. Diagnosis of malignant peripheral nerve sheath tumor was ultimately confirmed histopathologically after surgical resection. The patient has since undergone multiple resections and adjuvant radiotherapy. Twenty-two months since the last procedure, the patient remains disease-free.

Estrogen receptor beta in breast cancer

Estrogen is essential for growth and development of the mammary glands and has been associated with the promotion and growth of breast cancer and in line with this, most human breast cancers are initially estrogen-dependent and undergo regression when deprived of their supporting hormone. Estrogen exerts many of its effects via two nuclear estrogen receptors (ERs), ERα and ERβ. The discovery of a second ER, ERβ, demanded a full re-evaluation of estrogen action in all target tissues and different estrogen associated diseases, including human breast cancer. However, despite over 15 years of research, the exact role, if any, of ERβ in human breast cancer remains elusive. The main challenges now are to develop highly selective anti-ERβ antibodies that are applied to large well characterized human breast cancer samples to validate their diagnostic potential and to explore ERβ-selective agonists in animal models of breast cancer to validate their therapeutic potential.

Pediatric and adult malignant peripheral nerve sheath tumors: an analysis of data from the surveillance, epidemiology, and end results program

Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue sarcomas that arise predominantly from Schwann cells. Despite the fact that MPNSTs have high local recurrence rates and are generally associated with poor prognosis, little is known about prognostic factors or effective clinical management for this tumor type. The purpose of this study was to describe the distributions of patient and tumor characteristics and to identify predictors of cause-specific survival among MPNST cases reported to SEER between 1973 and 2008. Patient and tumor characteristics were compared between pediatric and adult MPNST cases. Cox regression and tree-based survival analysis were used to examine factors associated with MPNST-related mortality separately among adults and children. A total of 1,315 MPNST cases were isolated from the 1973-2008 SEER dataset. Among pediatric cases, sex, race, and radiation therapy predicted MPNST survival, whereas among adults, tumor site, tumor grade, number of primary tumors, and tumor size were significant predictors. As tumor size at diagnosis/resection may be the only somewhat "modifiable" prognostic factor, future studies should aim to identify biological and social attributes associated with tumor size at diagnosis, separately among individuals with and without NF-1, in order to help identify earlier opportunities for clinical intervention.

A bilateral cervical swelling and it is not a malignancy

BACKGROUND

This case report is about a patient with 2 synchronous bilateral cervical schwannomas.

PATIENTS AND METHODS

A 59-year-old white man presented a 6-month history of painless bilateral cervical swelling. Magnetic resonance imaging revealed 2 tumors in the carotid sheath. Both tumors, which derived from the cervical sympathetic chain, were surgically removed.

RESULTS

Histopathologically, both tumors were diagnosed as schwannomas.

CONCLUSIONS

Commonly, a bilateral cervical swelling is not caused by 2 schwannomas. It is unusual for 2 schwannomas to appear in a patient synchronously without any evidence of neurofibromatosis or schwannomatosis. Differential diagnosis of a bilateral cervical swelling includes malignancy, carotid body tumor, and chronic infection.

Solitary plexiform neurofibroma, a pitfall in diagnosis of lipoma

Plexiform neurofibromatosis is almost invariably associated with neurofibromatosis type I. A case of an isolated back plexiform neurofibroma, initially thought to be a lipoma, is presented, with emphasis on the importance of eliciting family history in reaching a diagnosis of neurofibromatosis. Currently, surgical resection is still the treatment of choice though a management plan is not well defined. Patients need appropriate regular follow-up to detect malignancy or early recurrence.

Intraneural perineurioma of the median nerve: case report and literature review

Intraneural perineurioma is a benign peripheral nerve sheath tumor of perineurial cell origin. We present the case of an intraneural perineurioma of the median nerve in a 23-year-old woman which posed a diagnostic challenge. Ultrasonography was found to be a quick, easy, and effective screening tool for identifying the source of the deficit followed by MRI to further elucidate the lesion. We discuss surgical management options for optimizing functional outcomes when addressing such lesions.

Surgical strategies for managing foraminal nerve sheath tumors: the emerging role of CyberKnife ablation

Sixteen Stanford University Medical Center (SUMC) patients with foraminal nerve sheath tumors had charts reviewed. CyberKnife radiosurgery was innovative in management. Parameters were evaluated for 16 foraminal nerve sheath tumors undergoing surgery, some with CyberKnife. Three neurofibromas had associated neurofibromatosis type 1 (NF1). Eleven patients had one resection; others had CyberKnife after one (two) and two (three) operations. The malignant peripheral nerve sheath tumor (MPNST) had prior field-radiation and adds another case. Approaches included laminotomy and laminectomies with partial (three) or total (two) facetectomies/fusions. Two cases each had supraclavicular, lateral extracavitary, retroperitoneal and Wiltze and costotransversectomy/thoracotomy procedures. Two underwent a laminectomy/partial facetectomy, then CyberKnife. Pre-CyberKnife, one of two others had a laminectomy/partial facetectomy, then total facetectomy/fusion and the other, two supraclavicular approaches. The MPNST had a hemi-laminotomy then laminectomy/total facetectomy/fusion, followed by CyberKnife. Roots were preserved, except in two. Of 11 single-operation-peripheral nerve sheath tumors, the asymptomatic case remained stable, nine (92%) improved and one (9%) worsened. Examinations remained intact in three (27%) and improved in seven (64%). Two having a single operation then CyberKnife had improvement after both. Of two undergoing two operations, one had symptom resolution post-operatively, worsened 4 years post-CyberKnife then has remained unchanged after re-operation. The other such patient improved post-operatively, had no change after re-operation and improved post-CyberKnife. The MPNST had presentation improvement after the first operation, worsened and after the second surgery \and CyberKnife, the patient expired from tumor spread. In conclusion, surgery is beneficial for pain relief and function preservation in foraminal nerve sheath tumors. Open surgery with CyberKnife is an innovation in these tumors' management.

FORAMINAL NERVE SHEATH TUMORS

OBJECTIVE

To conduct a retrospective review of outcomes in 15 patients with 18 foraminal tumors, including 17 benign peripheral nerve sheath tumors and 1 malignant peripheral nerve sheath tumor, who underwent CyberKnife (Accuray, Inc., Sunnyvale, CA) radiosurgery at Stanford University Medical Center from 1999 to 2006.

METHODS

Symptoms and findings, neurofibromatosis (NF) association, previous radiation, imaging, dosimetry, tumor volume, central necrosis, and the relation of these factors to outcomes were evaluated.

RESULTS

Before treatment, 1 asymptomatic patient had radiculopathic findings, 3 patients experienced local pain with intact neurological examinations, and 7 patients had radiculopathic complaints with intact (1 patient), radiculopathic (4 patients), or radiculomyelopathic examinations (2 patients). Five patients had myelopathic complaints and findings. Three patients had NF1-associated neurofibromas, 1 patient with NF2 had a schwannoma, and 1 patient had a schwannomatosis-related lesion. Two likely radiation-induced lesions, a neurofibroma and a malignant peripheral nerve sheath tumor, were observed. Prescribed doses ranging from 16 to 24 Gy, delivered in 1 to 3 fractions of 6 to 20 Gy, resulted in maximum tumor doses ranging from 20.9 to 30 Gy. Target volumes ranged from 1.36 to 16.9 mL. After radiosurgery, the asymptomatic case remained asymptomatic, and neurological findings improved. Thirteen of 15 symptomatic patients with (12 patients) or without (3 patients) neurological findings improved (3 cases after resection) or remained stable, and 2 patients worsened. Symptoms and examinations remained stable or improved in 8 (80%) of 10 patients with schwannomas and 3 (60%) of 5 patients with neurofibromas. Tumor volumes decreased in 12 (67%) of 18 tumors and increased in 3 tumors. Tumor volumes decreased in 8 of 10 schwannomas and 3 of 7 neurofibromas. Central necrosis developed in 8 (44%) of 18 tumors.

CONCLUSION

CyberKnife radiosurgery resulted in pain relief and functional preservation in selected foraminal peripheral nerve sheath tumors and a malignant peripheral nerve sheath tumor. Symptomatic and neurological improvements were more noticeable with schwannomas. Myelopathic symptoms may necessitate surgical debulking before radiosurgery.

Experimental therapeutic approaches to peripheral nerve tumors

✓Discovery that the Schwann cell is the primary cell type responsible for both the neurofibroma as well as the schwannoma has proven to represent a crucial milestone in understanding the pathogenesis of peripheral nerve tumor development. This information and related findings have served as a nidus for research aimed at more fully characterizing this family of conditions. Recent discoveries in the laboratory have clarified an understanding of the molecular mechanisms underlying the pathogenesis of benign peripheral nerve tumors. Similarly, the mechanisms whereby idiopathic and syndromic (NF1- andNF2-associated) nerve sheath tumors progress to malignancy are being elucidated. This detailed understanding of the molecular pathogenesis of peripheral nerve tumors provides the information necessary to create a new generation of therapies tailored specifically to the prevention, cessation, or reversal of pathological conditions at the fundamental level of dysfunction. The authors review the data that have helped to elucidate the molecular pathogenesis of this category of conditions, explore the current progress toward exploitation of these findings, and discuss potential therapeutic avenues for future research.

Immunoprofiles in malignant peripheral nerve sheath tumor: three case reports and literature review

Because there are no standardized radiologic and histologic criteria, the differential diagnosis of malignant peripheral nerve sheath tumors (MPNSTs) from other spindle cell neoplasms poses great challenges for pathologists. Because early diagnosis of MPNSTs arising from benign peripheral nerve sheath tumors (BPNSTs) means a better prognosis, many immunohistochemical and molecular studies have recently emerged. Nevertheless, no gold standard diagnostic criterion is to be found in the literature. For example, S-100 protein is widely used in the diagnosis of MPNST. Other promising ancillary markers are p53 and Ki-67; however, the staining patterns and possible mechanisms of these markers are seldom mentioned in the literature. These evoke our interest. Only six cases diagnosed as MPNST were retrieved from the archives of the Department of Pathology, Kaohsiung Medical University Chung-Ho Memorial Hospital between 1988 and September 2005. Clinical files were available for three of them, and we found nuances in the immunohistochemistry from these previous reports. Here, we present these rare sarcomas and review the literature.

Neurofibromatosis-associated nerve sheath tumors

In this paper the authors describe a patient with neurofibromatosis Type 1 (NF1) who presented with sequelae of this disease. They also review the current literature on NF1 and NF2 published between 2001 and 2005.

The method used to obtain information for the case report consisted of a family member interview and a review of the patient's chart. For the literature review the authors used the search engine Ovid Medline to identify papers published on the topic between 2001 and 2005. Neurofibromatosis Type 1 appears in approximately one in 2500 to 4000 births, is caused by a defect on 17q11.2, and results in neurofibromin inactivation. The authors reviewed the current literature with regard to the following aspects of this disease: 1) diagnostic criteria for NF1; 2) criteria for other NF1-associated manifestations; 3) malignant peripheral nerve sheath tumors (PNSTs); 4) the examination protocol for a patient with an NF1-related NST; 5) imaging findings in patients with NF1; 6) other diagnostic studies; 7) surgical and adjuvant treatment for NSTs and malignant PNSTs; and 8) hormone receptors in NF1-related tumors. Pertinent illustrations are included.

Neurofibromatosis Type 2 occurs much less frequently than NF1, that is, in one in 33,000 births. Mutations in NF2 occur on 22q12 and result in inactivation of the tumor suppressor merlin. The following data on this disease are presented: 1) diagnostic criteria for NF2; 2) criteria for other NF2 manifestations; 3) malignant PNSTs in patients with NF2; 4) examination protocol for the patient with NF2 who has an NST; and 5) imaging findings in patients with NF2. Relevant illustrations are included.

It is important that neurosurgeons be aware of the sequelae of NF1 and NF2, because they may be called on to treat these conditions.