Malignant nerve-sheath neoplasms in neurofibromatosis: distinction from benign tumors by using imaging techniques

Neurofibroma of bladder: A case report and literature review

To improve the understanding and treatment level of urogenital nerve fibroma by sharing the clinical manifestations, imaging features, and pathological characteristics of a case of urogenital nerve fibroma.The patient was a middle-aged male with initial symptoms of painless gross hematuria, bladder irritation, and pelvic mass. Imaging examination showed a bladder mass, and transurethral bladder tumor resection was performed to reduce the tumor. Pathology was confirmed to be bladder neurofibroma. After 6 months of surgery, follow-up examination showed a significant reduction in tumor volume and no recurrence. The successful diagnostic and therapeutic experience of this case can be referenced for clinical practice.

Image-Based Differentiation of Benign and Malignant Peripheral Nerve Sheath Tumors in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a dominant hereditary disease characterized by the mutation of the NF1 gene, affecting 1/3000 individuals worldwide. Most NF1 patients are predisposed to benign peripheral nerve sheath tumors (PNSTs), including cutaneous neurofibromas (CNFs) and plexiform neurofibromas (PNFs). However, 5%-10% of PNFs will ultimately develop into malignant peripheral nerve sheath tumors (MPNSTs), which have a poor prognosis. Early and reliable differentiation of benign and malignant tumors in NF1 patients is of great necessity. Pathological evaluation is the “gold standard” for a definite diagnosis, but the invasive nature of the biopsy procedure restricts it from applying as a screening tool during the decades-long follow-up of these patients. Non-invasive image-based diagnostic methods such as CT and MRI are often considered essential screening tools for multiple types of tumors. For NF1 patients’ lifelong regular follow-ups, these radiological methods are currently used for tumor evaluation. However, no consensus was established on screening the malignant transformation of benign PNSTs. Moreover, novel technologies like radiogenomics and PET-MRI have not been well evaluated and fully adopted for NF1 patients. This review summarizes current studies of different imaging methods for differentiating benign and malignant tumors in NF1. Meanwhile, we discussed the prospects of the usage of new tools such as radiogenomics and PET-MRI to distinguish MPNST from benign PNSTs more precisely. Summarizing these findings will help clarify the directions of future studies in this area and ultimately contribute to the radiology images-based clinical screening of MPNST in NF1 patients and finally improve the overall survival rates of these patients.

MPNST without muscle weakness at presentation: an analysis of an underappreciated combination

INTRODUCTION

Malignant peripheral nerve sheath tumors (MPNSTs) of major motor nerves typically present with muscle weakness and pain. We aim to analyze and characterize patients with MPNST at major motor nerves but without muscle weakness at initial presentation.

METHODS

A retrospective search involving MPNSTs in a major nerve evaluated and/or treated at our institution from 1994 to 2019 was performed. Patients with no muscle weakness and available MRI were analyzed. Clinical materials, MR images and PET scans were reviewed for features of malignancy. This group of patients was compared to patients who presented with MPNSTs and muscle weakness.

RESULTS

Twenty-six patients were included in the no muscle weakness group. Of them, twenty-one (81%) patients had a positive family history for malignancy. Only 16 (62%) MR images were highly suspicious for malignancy. All 7 available PET-scans were highly suspicious for malignancy. Patients who presented with muscle weakness (n = 36), were more likely to have paresthesias and a history of NF-1 or radiation to the MPNST location (p-value < 0.05).

CONCLUSION

MPNSTs of major motor nerves without muscle weakness represent an underappreciated subset of cases which has potential treatment and outcome implications. These patients presented with fewer symptoms and had fewer risk factors than patients with muscle weakness. PET-scans should be considered as an extra method of trying to anticipate the diagnosis of an MPNST.

Diffusion-Weighted Magnetic Resonance Imaging Improves the Accuracy of Differentiation of Benign from Malignant Peripheral Nerve Sheath Tumors

OBJECTIVE

In patients with neurofibromatosis type 1 (NF1), it is important to accurately determine when plexiform neurofibroma (pNF) transforms to a malignant peripheral nerve sheath tumor (MPNST). The purpose of this study is to investigate the usefulness of diffusion-weighted imaging (DWI) in differentiating pNF and MPNST in NF1 patients.

METHODS

Among the NF1 patients who were referred to our hospital between 1985 and 2015, 10 cases of MPNST and 19 cases of pNF were included. We evaluated features of standard magnetic resonance imaging according to the differentiation criteria of malignancy from benignancy as previously reported, apparent diffusion coefficient (ADC) value based on the DWI and the correlation between ADC value and benignancy/malignancy. ROC analysis was performed to determine the appropriate cutoff value of ADC.

RESULTS

There were significant differences between MPNST and pNF in the size of the tumor (P = 0.009), peripheral enhancement pattern (P = 0.002), perilesional edema-like zone (P = 0.0008), and intratumoral cystic change (P = 0.02). The mean and minimum values of ADC were significantly lower in MPNST than those in pNF (P = 0.03 and P = 0.003, respectively). When we set a cutoff value of mean ADC as 1.85 × 10^-3 mm²/s, the sensitivity and specificity were 80% and 74%, respectively. The area under the curve value improved by adding the Wasa score to the mean ADC evaluation.

CONCLUSIONS

ADC values determined by DWI are useful in differentiating MPNST from pNF and adding ADC evaluation to standard MRI evaluation improved the diagnostic accuracy.

A rare cause of cervical swelling: Solitary plexiform neurofibroma

INTRODUCTION

Plexiform cervical neurofibromas are benign neoplasm, extremely rare, difficult to diagnose and to manage. Only some cases have been reported in the literature.

CASE PRESENTATION

We report the case of a 60-year-old man admitted for a lateral neck mass, for which the surgical indication was the increase in volume of this mass, as well as the aesthetical impairment, the surgical exploration found the tumor attached to the cervical plexus. The excision of the mass was performed without damaging nerve. The pathological study was in favor of a plexiform neurofibroma.

DISCUSSION

Even though Plexiform cervical neurofibroma are extremely rare, and their diagnosis are not often primary evoked in front of any growing mass of this region, the surgeon must keep in mind the existence of these neoplasms as a differential diagnosis of a neck tumor.

CONCLUSION

Surgery remains the gold standard in the treatment of these locally invasive tumors. It is essential that the surgeon keep in mind the possibility of these tumors as a differential diagnosis of a neck tumor.

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

OBJECTIVES

To evaluate potential of conventional MRI and diffusion-weighted imaging (DWI) for differentiating malignant from benign peripheral nerve sheath tumors (PNSTs).

METHODS

Eighty-seven cases of malignant or benign PNSTs in the trunk or extremities that underwent conventional MRI with contrast enhancement, DWI, and pathologic confirmation between Sep. 2014 and Dec. 2017 were identified. Of these, 55 tumors of uncertain nature on MRI were included. Tumor size, signal, and morphology were reviewed on conventional MRI, and apparent diffusion coefficient (ADC) values of solid enhancing portions were measured from DWI. Patient demographics, MRI features, and ADC values were compared between benign and malignant tumors, and robust imaging findings for malignant peripheral nerve sheath tumors (MPNSTs) were identified using multivariable models.

RESULTS

A total of 55 uncertain tumors consisted of 18 malignant and 37 benign PNSTs. On MRI, tumor size, margin, perilesional edema, and presence of split fat, fascicular, and target signs were significantly different between groups (p < 0.05), as were mean and minimum ADC values (p = 0.002, p < 0.0001). Most inter-reader agreement was moderate to excellent (κ value, 0.45-1.0). The mean ADC value and absence of a split fat sign were identified as being associated with MPNSTs (odds ratios = 13.19 and 25.67 for reader 1; 49.05 and 117.91 for reader 2, respectively). The C-indices obtained by combining these two findings were 0.90 and 0.95, respectively.

CONCLUSIONS

Benign and malignant PNSTs showed different features on MRI and DWI. A combination of mean ADC value and absence of split fat was excellent for discriminating malignant from benign PNSTs.

KEY POINTS

• It is important to distinguish between malignant peripheral nerve sheath tumors (MPNSTs) and benign peripheral nerve sheath tumors (BPNSTs) to ensure an appropriate treatment plan. • On conventional MRI and diffusion-weighted imaging (DWI), MPNSTs and BPNSTs showed significant differences in tumor size, margin, presence of perilesional edema, and absence of split fat, fascicular, and target signs. • Absence of a split fat sign and mean apparent diffusion coefficient (ADC) values were robust imaging findings distinguishing MPNSTs from BPNSTs, with a C-index of > 0.9.

Laparoscopic resection of retroperitoneal intra-psoas muscle schwannoma: A case report and extensive literature review

INTRODUCTION

Soft tissue tumors of Schwann cells in either the peripheral or cranial nerves are known as schwannomas or also as neurilemmomas. Limited data exists regarding psoas muscle schwannoma in the literature. Therefore, we have done an extensive literature review and found a total number of 46 cases of intra-psoas schwannoma including our case, which are summarized in this article along with reporting our new case.

PRESENTATION OF CASE

We report a very rare case of primary left intra-psoas muscle schwannoma in a 39-year-old Saudi gentleman, smoker with an unremarkable medical and surgical history. The patient presented to the emergency department with exacerbated chronic lower abdominal pain since almost 2 years. After conforming the diagnosis, the patient was admitted electively and underwent uneventful laparoscopic hand-assisted resection.

DISCUSSION

Schwannomas are neurogenic tumors which known to be solitary, benign, well circumscribed, encapsulated, and slow-growing tumors. Multiple imaging modalities are used to detect such a tumor. Although there is no consensus on the best surgical approach, endoscopic mini-laparotomy, laparoscopy (anterior [as in our case] or lateral), and robotic resection were reported with good outcomes.

CONCLUSION

Retroperitoneal schwannoma and intra-psoas muscle variant are a rare entity, with slow growing rate and risk of malignant transformation. Therefore, high index of suspicion, good follow-up, and large-cohort studies are encouraged.

Malignant Peripheral Nerve Sheath Tumors: From Epigenome to Bedside

Malignant peripheral nerve sheath tumors (MPNST) are aggressive sarcomas typically developing in the context of neurofibromatosis type 1 (NF-1). With the exception of surgical resection, these tumors are resistant to all current therapies, and unresectable, recurrent, or metastatic tumors are considered incurable. Preclinical studies have identified several novel candidate molecular targets for therapeutic intervention, but, to date, targeted therapies have proven ineffective. Recent studies have identified recurrent mutations in polycomb repressive complex 2 (PRC2) core components, embryonic ectoderm development protein (EED) and suppressor of zeste 12 homolog (SUZ12), in MPNST. These mutations result in global loss of the histone H3 lysine 27 trimethylation epigenetic mark, normally deposited by PRC2, and subsequent gain in acetylation at this residue. This altered chromatin state has been shown to promote MPNST malignancy; however, acetylation at this residue sensitizes MPNSTs to BRD4 and bromodomain and extra-terminal domain inhibition. Interestingly, the catalytic component of PRC2, enhancer of zeste homolog 2 (EZH2), is not mutated in MPNST, hinting that a noncanonical, PRC2-independent function of EZH2 may play a role in this cancer. This review examines the pathobiology of MPNST, the contribution of PRC2 subunits to this process, and the prospects for PRC2-related therapies for this cancer. IMPLICATIONS: Identification of mutations in the PRC2 components EED and SUZ12 in the majority of MPNSTs may imply noncanonical oncogenic activities of the intact component, EZH2, and provide new opportunities for therapeutic intervention.

MR Imaging of Primary Chest Wall Neoplasms

Primary chest wall neoplasms are uncommon and comprise a heterogeneous group of lesions that may be challenging to classify and diagnose. These tumors may be primary or secondary, malignant or benign, and arise from cartilaginous/osseous structures or soft tissues. The role of magnetic resonance (MR) imaging in the evaluation of chest wall tumors continues to expand given its superior soft tissue contrast relative to computed tomography. MR imaging can facilitate differentiation of neoplasms from normal chest wall structures and other disease processes due to infection and inflammation, and can fully characterize abnormalities by demonstrating the various internal components of complex lesions. It is important that radiologists be able to identify key features of primary chest wall neoplasms on MR imaging to provide focused differential diagnoses and guide patient management.

Soft-Tissue Sarcomas of the Abdomen and Pelvis: Radiologic-Pathologic Features, Part 2-Uncommon Sarcomas

Soft-tissue sarcomas occurring in the abdomen and pelvis are an uncommon but important group of malignancies. Recent changes to the World Health Organization classification of soft-tissue tumors include the movement of gastrointestinal stromal tumors (GISTs) into the soft-tissue tumor classification. GIST is the most common intraperitoneal sarcoma. Liposarcoma is the most common retroperitoneal sarcoma, and leiomyosarcoma is the second most common. GIST, liposarcoma, and leiomyosarcoma account for the majority of sarcomas encountered in the abdomen and pelvis and are discussed in part 1 of this article. Undifferentiated pleomorphic sarcoma (previously called malignant fibrous histiocytoma), dermatofibrosarcoma protuberans, solitary fibrous tumor, malignant peripheral nerve sheath tumor, rhabdomyosarcoma, extraskeletal chondro-osseous sarcomas, vascular sarcomas, and sarcomas of uncertain differentiation uncommonly arise in the abdomen and pelvis and the abdominal wall. Although these lesions are rare sarcomas and their imaging features overlap, familiarity with the locations where they occur and their imaging features is important so they can be diagnosed accurately. The anatomic location and clinical history are important factors in the differential diagnosis of these lesions because metastasis, more-common sarcomas, borderline fibroblastic proliferations (such as desmoid tumors), and endometriosis have imaging findings that overlap with those of these uncommon sarcomas. In this article, the clinical, pathologic, and imaging findings of uncommon soft-tissue sarcomas of the abdomen and pelvis and the abdominal wall are reviewed, with an emphasis on their differential diagnosis.

CT, MRI, and 18F-FDG PET/CT findings of malignant peripheral nerve sheath tumor of the head and neck

Background Malignant peripheral nerve sheath tumor (MPNST) is a highly malignant tumor and rarely occurs in the head and neck. Purpose To describe the imaging features of MPNST of the head and neck. Material and Methods We retrospectively analyzed computed tomography (CT; n = 14), magnetic resonance imaging (MRI; n = 16), and ¹⁸F-FDG PET/CT (n = 5) imaging features of 18 MPNSTs of the head and neck in 17 patients. Special attention was paid to determine the nerve of origin from which the tumor might have arisen. Results All lesions were well-defined (n = 3) or ill-defined (n = 15) masses (mean, 6.1 cm). Lesions were at various locations but most commonly the neck (n = 8), followed by the intracranial cavity (n = 3), paranasal sinus (n = 2), and orbit (n = 2). The nerve of origin was inferred for 11 lesions: seven in the neck, two in the orbit, one in the cerebellopontine angle, and one on the parietal scalp. Attenuation, signal intensity, and enhancement pattern of the lesions on CT and MRI were non-specific. Necrosis/hemorrhage/cystic change within the lesion was considered to be present on images in 13 and bone change in nine. On ¹⁸F-FDG PET/CT images, all five lesions demonstrated various hypermetabolic foci with maximum standard uptake value (SUV_max) from 3.2 to 14.6 (mean, 7.16 ± 4.57). Conclusion MPNSTs can arise from various locations in the head and neck. Though non-specific, a mass with an ill-defined margin along the presumed course of the cranial nerves may aid the diagnosis of MPSNT in the head and neck.

Mr Imaging of Benign Peripheral Nerve Sheath Tumors

In a retrospective, nonblind review of MR imaging of 15 benign peripheral nerve neoplasms in 13 patients, the signal pattern of the tumors (including contrast-enhanced images) and stage were assessed. One lesion was subcutaneous, 9 intramuscular, 2 intermuscular and 3 extracompartmental. One lesion was located to the trunk, 5 to the upper extremity and 9 to the lower. The signal on T1-weighted spin-echo images was homogeneous isointense compared to adjacent muscle in 11 lesions and in 2 slightly hyper- and in 2 slightly hypointense. T2-weighted spin-echo images, acquired in all but one examination, showed a hyperintense signal, homogeneous in 8 and centrally inhomogeneous in 6 lesions. Postcontrast T1-weighted images of 11 lesions showed a strong signal, with an inhomogeneous enhancement in the center of the lesion similar to that obtained in T2-weighted images. In 2 cases there were signal characteristics indicating bleeding in the tumor. In one lesion both the nonenhanced and contrast-enhanced T1-weighted images showed a hypointense signal in the tumor center suggestive of intramuscular myxoma. All lesions were well delineated without reactive edema. In all cases, anatomic tumor location was correctly assessed. Although the findings were not pathognomonic for neurinoma, MR imaging provided valuable information confirming the clinical and cytologic assessments.

Imaging Evaluation of Malignant Chest Wall Neoplasms

Neoplasms of the chest wall are uncommon lesions that represent approximately 5% of all thoracic malignancies. These tumors comprise a heterogeneous group of neoplasms that may arise from osseous structures or soft tissues, and they may be malignant or benign. More than 50% of chest wall neoplasms are malignancies and include tumors that may arise as primary malignancies or secondarily involve the chest wall by way of direct invasion or metastasis from intrathoracic or extrathoracic neoplasms. Although 20% of chest wall tumors may be detected at chest radiography, chest wall malignancies are best evaluated with cross-sectional imaging, principally multidetector computed tomography (CT) and magnetic resonance (MR) imaging, each of which has distinct strengths and limitations. Multidetector CT is optimal for depicting bone, muscle, and vascular structures, whereas MR imaging renders superior soft-tissue contrast and spatial resolution and is better for delineating the full extent of disease. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT is not routinely performed to evaluate chest wall malignancies. The primary functions of PET/CT in this setting include staging of disease, evaluation of treatment response, and detection of recurrent disease. Ultrasonography has a limited role in the evaluation and characterization of superficial chest wall lesions; however, it can be used to guide biopsy and has been shown to depict chest wall invasion by lung cancer more accurately than CT. It is important that radiologists be able to identify the key multidetector CT and MR imaging features that can be used to differentiate malignant from benign chest lesions, suggest specific histologic tumor types, and ultimately guide patient treatment. (©)RSNA, 2016.

A rare case study of a retropharyngeal neurofibroma and a brief literature review

INTRODUCTION

Space occupying lesions in the retropharyngeal space are rare.

CASE REPORT

Here, we present a rare case of a retropharyngeal neurofibroma treated surgically through an open cervical approach without any complication.

DISCUSSION

Neurofibromas are benign, slowly growing neoplasms that could be associated or not with neurofibromatosis. They are derived from peripheral nerves. Diagnostic work-up should include CT-scan and MRI as well as a biopsy to confirm the diagnosis. Treatment of localized and diffuse neurofibromas is often surgical resection, which may require sacrifice of the nerve. Malignant transformation of these lesions, without association to NF-1, is rare and exceptionally documented in the literature.

CONCLUSION

We presented a rare case of solitary neurofibroma of the retropharyngeal space. Complete resection of the lesion was performed without any complication. We also presented a brief review of the literature about neurofibromas.

Malignant Peripheral Nerve Sheath Tumour of Small Intestine Presenting as Ileo-Ileal Intussusception - A Rare Tumour with Unusual Complication

Malignant Peripheral Nerve Sheath Tumours (MPNST) arises from a peripheral nerve or exhibit nerve sheath differentiation on histology. Proximal portions of the upper and lower extremities and the trunk are the most common sites of occurrence. Around 50% are associated with Neurofibromatosis Type 1 (NF1) with incidence of two to five per cent in patients with NF1. The estimated incidence in general population without NF1 is 0.0001% of which gastrointestinal MPNST are extremely rare. A 45-year-old lady without pathological antecedent for NF1 was admitted with pain in right lower abdomen and multiple episodes of vomiting for 3 months. Preoperatively intussusception was diagnosed in the small bowel with USG and CECT abdomen showing characteristic target sign. On laparotomy Ileo-ileal intussusception (proximal ileum telescoping into distal ileum) was found 2 feet proximal to ileo-caecal junction with surrounding inflammed mesentery and presence of intraluminal tumour as lead point. Resection of involved segment of ileum along with its mesentery was done followed by ileo-ileal anastomosis. Histopathology was suggestive of high grade MPNST. Postoperative course and follow up for last 10 month is uneventful. This case is unique in terms of a rare tumour presenting with unusual complication and only one case had been reported so far in western literature.

[The bladder involvement in Von Recklinghausen's disease]

La neurofibromatose de type 1 ou maladie de Von Recklinghausen est une maladie génétique autosomique dominante en rapport avec des mutations dans le gène suppresseur de tumeur NF1. L'atteinte uro-génitale au cours de cette maladie est rare et moins de 80 cas ont été rapportés à ce jour dans la littérature mondiale. Les auteurs rapportent un nouveau cas d'atteinte vésicale découverte fortuitement au cours du suivi d'une patiente atteinte de la maladie de Von Recklinghausen. A travers cette observation et une revue de la littérature les auteurs discutent également les difficultés diagnostiques, thérapeutiques ainsi que les modalités de suivi dans cette maladie.

Role of ultrasonography in detection of renal artery pseudoaneurysm caused by retroperitoneal malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1

Malignant peripheral nerve sheath tumors (MPNSTs) are extremely uncommon neoplasms, predominantly seen within the deep soft tissues of the extremities, in close proximity to the nerve trunks. Retroperitoneal MPNSTs are exceedingly rare, usually seen in association with neurofibromatosis type 1 (NF-1), and often result from malignant degeneration of a plexiform neurofibroma. These tumors are highly malignant and the prognosis is worsened if they occur in association with NF-1. Metastasis is not uncommon, but local invasion by these tumors is rarely reported. Renal artery pseudoaneurysms are mostly iatrogenic and rarely result from invasion by retroperitoneal neoplasms. Ultrasonography is a valuable tool in early diagnosis of these neoplasms and vascular complications, particularly in emergency cases requiring immediate operative intervention. To the best of our knowledge, no case of renal artery pseudoaneurysm caused by retroperitoneal MPNST has been reported to date. We present a case of a middle-aged female with Von Recklinghausen disease, complaining of sudden onset of severe abdominal pain, where ultrasound accurately diagnosed renal artery pseudoaneurysm caused by a large retroperitoneal MPNST, and who was later treated by radical excision of the tumor and nephrectomy.

Neurofibromatosis type 1 with bladder involvement

Neurofibromatosis type 1 is an autosomal dominant transmitted disease with various clinical manifestations. The bladder is the most commonly affected organ in the genitourinary system. The malignant transformation of the disease is rare, and unlike malign tumors, the treatment option for benign disease is usually conservative. The size and localization of the mass determine the symptoms, most of which are usually not specific. In this paper, we aim to present a 15-year-old patient with neurofibromatosis type 1 with bladder involvement. The clinical presentation and treatment options of this disease are discussed in the light of the literature.

Peripheral tumor and tumor-like neurogenic lesions

Neoplasms of neurogenic origin account for about 12% of all benign and 8% of all malignant soft tissue neoplasms. Traumatic neuroma, Morton neuroma, lipomatosis of a nerve, nerve sheath ganglion, perineurioma, benign and malignant peripheral nerve sheath tumors (PNST) are included in this group of pathologies. Clinical and radiologic evaluation of patients with neurogenic tumors and pseudotumors often reveals distinctive features. In this context, advanced imaging techniques, especially ultrasound (US) and magnetic resonance (MR) play an important role in the characterization of these lesions. Imaging findings such as location of a soft tissue mass in the region of a major nerve, nerve entering or exiting the mass, fusiform shape, abnormalities of the muscle supplied by the nerve, split-fat sign, target sign and fascicular appearance should always evoke a peripheric nerve sheath neoplasm. Although no single imaging finding or combination of findings allows definitive differentiation between benign from malign peripheric neurogenic tumors, both US and MR imaging may show useful features that can lead us to a correct diagnosis and improve patient treatment. Traumatic neuromas and Morton neuromas are commonly associated to an amputation stump or are located in the intermetatarsal space. Lipomatosis of a nerve usually appears as a nerve enlargement, with thickened nerve fascicles, embedded in evenly distributed fat. Nerve sheath ganglion has a cystic appearance and commonly occurs at the level of the knee. Intraneural perineuroma usually affects young people and manifests as a focal and fusiform nerve enlargement. In this article, we review clinical characteristics and radiologic appearances of these neurogenic lesions, observing pathologic correlation, when possible.

MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas

OBJECTIVE

The objective of this study was to identify the MRI criteria that best differentiate malignant peripheral nerve sheath tumors from benign neurofibromas.

MATERIALS AND METHODS

We retrospectively analyzed MR images obtained for 41 histologically diagnosed cases of malignant peripheral nerve sheath tumor and 20 cases of neurofibroma that had been treated at four tertiary institutions. Twenty of the patients with malignant peripheral nerve sheath tumors and 14 patients with neurofibromas developed the disease in association with neurofibromatosis 1. The MR images were evaluated with regard to tumor size, signal intensity, heterogeneity of T1- and T2-weighted MR images, enhancement pattern, definition of margins, presence of perilesional edemalike zone, and presence of intratumoral cystic lesions.

RESULTS

Significant differences between malignant peripheral nerve sheath tumors and neurofibromas were noted for the largest dimension of the mass, peripheral enhancement pattern, perilesional edemalike zone, and intratumoral cystic lesion. In cases associated with neurofibromatosis 1, heterogenicity on T1-weighted images was also significant in differentiating neurofibroma from malignant peripheral nerve sheath tumor. The presence of two or more of the four features suggestive of malignancy indicated malignant peripheral nerve sheath tumor with a sensitivity of 61% and a specificity of 90%.

CONCLUSION

The MR features described in this study are useful for distinguishing malignant peripheral nerve sheath tumors from neurofibromas. If a tumor has two or more of the four statistically significant features, it can be considered to be highly suspicious of malignancy and should be subjected to a biopsy for early diagnosis.

Pictorial essay: imaging of peripheral nerve sheath tumours

Peripheral nerve sheath tumours (PNST) may be benign or malignant. Benign PNSTs include neurofibroma and schwannoma. Neurogenic tumours share certain characteristic imaging features, suggested by a fusiform-shaped mass with tapered ends, the "split-fat" sign, atrophy of the muscles supplied by the involved nerve, the "fascicular sign," and the "target sign"; these imaging features are best demonstrated on magnetic resonance imaging. This pictorial essay emphasizes the characteristic signs and distinguishing features of PNSTs on imaging.

The Surgical Management of Symptomatic Peripheral Nerve Sheath Tumors

OBJECTIVE

To determine the clinical presentation and morbidity of the surgical management of peripheral nerve sheath tumors (PNSTs).

METHODS

We performed a retrospective chart review of surgically treated PNSTs at the University of Miami between 1991 and 2008.

RESULTS

There were a total of 140 cases, including 87 schwannomas, 34 neurofibromas, and 19 malignant peripheral nerve sheath tumors (MPNSTs). The average age of the total study group was 49.0 years; it was significantly lower for patients with neurofibroma. There was a high correlation between neurofibroma tumors and neurofibromatosis-1. Most patients with benign tumors presented with a painful mass, paresthesias, or numbness without significant weakness. Patients who had previously undergone attempted resections and preoperative biopsy had a significantly increased risk (41%) for developing postoperative neurologic deficits when compared with patients who presented with de novo tumors (15%). Intraoperative monitoring appeared to reduce the risk of postoperative motor deficit, particularly in neurofibromas. Most MPNSTs (&gt;80%) were diagnosed at stage IIB or higher and had a combined mortality rate of 31.6% at 78 months. Tumor size was the best predictor of adverse outcome, as all MPNST mortalities occurred in patients with a tumor size of more than 7 cm.

CONCLUSION

PNSTs are a heterogeneous group of lesions. Benign tumors respond well to marginal excision, whereas MPNSTs are aggressive sarcomas that require multimodal management. There was a significantly increased risk of postoperative neurologic deficits in patients who had undergone a previous biopsy, and thus tertiary referral without biopsy is recommended when a PNST is suspected.

Pancreatic schwannoma: literature review

Pancreatic schwannoma is a rare neoplasm. Accurate preoperative diagnosis remains difficult, but computed tomography (CT) scanning and magnetic resonance imaging (MRI) help to establish the diagnosis, and definitive diagnosis requires immunohistochemical examination. Cystic pancreatic schwannomas should be considered in the differential diagnosis of cystic neoplasms and pseudocysts. Simple enucleation may be adequate for pancreatic schwannoma. In this report, we examine a case of benign pancreatic schwannoma in a 56-year-old woman. She was being evaluated for an ovarian teratoma, and an 8-cm cystic mass was incidentally found in the head of the pancreas. She underwent a pylorus preserving Whipple procedure with bilateral oopherectomy. Only 37 cases have been reported in the English literature. We present a thorough review with an emphasis on the clinical presentation, diagnostic modalities, and treatment options in the management of this rare clinical entity.

Diffusion-weighted imaging of retroperitoneal malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1

We present the diffusion-weighted imaging (DWI) findings for a malignant peripheral nerve sheath tumor arising in a retroperitoneal plexiform neurofibroma in a patient with neurofibromatosis type 1. Signal intensity of the malignant area was high on DWI and low on the apparent diffusion coefficient map and differed from findings for the benign area. DWI enabled clear differentiation between malignant and benign areas of the tumor.

Varying degrees of FDG uptake in multiple benign neurofibromas on PET/CT

We report fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) findings of three neurofibromas in the mediastinum and neck in a 26-year-old woman with neurofibromatosis type 1. PET/CT scans demonstrated varying degrees of FDG uptake with maximum standard uptake values (SUV(max)) of 5.3, 1.8 and 3.2 for left lower neck, left paratracheal and right paravertebral masses, respectively. Surgical resections were carried out and histopathology confirmed three benign neurofibromas with various tissue components and cellularities.

Extramedullary Intradural Spinal Tumors: A Pictorial Review

Defining the location of tumors and mass lesions of the spine in relation to the spinal cord and the dura is of the utmost importance as certain types of lesions tend to occur in certain locations. The differential diagnostic considerations will vary according to location of the mass lesion as will the treatment and prognosis of these various lesions. The category of extramedullary intradural masses includes a variety of lesions from meningiomas and nerve sheath tumors (neurofibromas, schwannomas) to less common tumors (hemangiopericytoma), metastases, benign tumors (lipoma, dermoid, epidermoid), inflammatory disorders (arachnoid adhesions, sarcoidosis), vascular lesions (spinal-dural arteriovenous fistula), and cystic lesions (perineural or Tarlov cysts). Characteristic magnetic resonance imaging findings are helpful for localization and characterization of these lesions before treatment, as well as for follow-up after treatment. We present a pictorial review of the various extramedullary intradural lesions of the spine, with pathologic correlation. We discuss imaging features that are typical for the various entities and describe various therapeutic options that are important considerations for surgical treatment of these lesions.

Soft Tissue Tumors of the Hand. 2. Malignant

Soft tissue tumors of the hand arise from skin, subcutaneous tissue, tendons, nerve, and blood vessels. Many of these lesions occur on other parts of the body; however, the hand remains a unique site because these tumors have symptoms, appearances, treatments, and prognoses that may be quite different than when on other parts of the body. Their characteristics and the severity of symptoms vary markedly depending on the exact location, size, and type of tumor-and many of these tumors can have multiple forms of presentation. Two articles are intended to provide an overview of benign (previous article) and malignant tumors (this article) of the hand. The rarer and more deleterious tumors are discussed in detail while the common tumors and epidermal lesions with which practitioners are familiar are briefly overviewed. At the completion of these review articles, participants should be able to identify and diagnose various benign and malignant hand tumors as well as understand the accepted current treatment of these growths.

Nerve sheath tumor surgery: case-guided discussion of ambiguous findings, appropriateness of removal, repeated surgery, and nerve repairs

✓In this article the authors attempt to raise awareness of the pitfalls and controversial issues in nerve tumor surgery. In a case-guided format, examples of ambiguous findings, inappropriate tumor removal, repeated surgery, and nerve repairs are provided. The authors also discuss the need to establish a correct diagnosis preoperatively and to avoid the erroneous identification of malignant peripheral nerve sheath tumors (MPNSTs). They emphasize that not all of the principles of soft tissue sarcoma treatment protocols are applicable to MPNST. A situation of repeated surgery for supposedly malignant tumor is described, and an outline of the indications for, and an approach to, repair after lesion removal is given.

Imaging of peripheral nerve tumors

Recent advancements in the field of imaging, particularly magnetic resonance imaging, have improved the way peripheral nerve tumors are diagnosed, monitored, and treated both medically and surgically. When combined with the all-important clinical evaluation and electrodiagnostic studies, imaging permits a clinician to accomplish the following: identify the size, shape, location, and distribution of mass lesions; infer the risks in resecting a mass lesion by displaying its relationship to nearby nerve fascicles; determine growth rates when serial imaging studies are available; suggest the nature of the pathological entity; and visualize muscle denervation associated with nerve damage. The authors describe some of the commonly used imaging modalities and discuss their use in evaluating and treating peripheral nerve tumors and other mass lesions.

From the archives of the AFIP: abdominal neoplasms in patients with neurofibromatosis type 1: radiologic-pathologic correlation

Neurofibromatosis type 1 (NF1) is one of the most common genetic disorders. NF1 is a complex disease resulting from a spectrum of mutations that may occur at many locations along the large, complex NF1 gene, which is located on chromosome 17. Mutations of the NF1 gene lead to abnormal tumor suppression. Consequently, patients with NF1 have an increased prevalence of benign and malignant neoplasms throughout the body. There are five categories of NF1 tumors that occur in the abdomen: neurogenic, neuroendocrine, nonneurogenic gastrointestinal mesenchymal, embryonal, and miscellaneous. Many of these tumors are age related, occur at specific anatomic locations, and have unique imaging features. Notably, many patients have a variety of organs affected because there is a high prevalence of multiple tumors occurring in the same patient. Neurofibromas are the most common benign neoplasms and may occur in the retroperitoneum or visceral organs. Malignant peripheral nerve sheath tumor is an aggressive malignancy that is the most common malignant tumor of the abdomen in patients with NF1. Interpreting abdominal imaging studies in patients with NF1 can be challenging because of the wide spectrum and diverse nature of tumors that occur in this disease.

Neurofibromatose plexiforme retroperitoneal e pélvica: aspectos na tomografia computadorizada e ressonância magnética - relato de caso e revisão da literatura

Os autores apresentam um caso de neurofibromatose tipo I, caracterizado por múltiplos neurofibromas plexiformes no retroperitônio e pelve. A tomografia computadorizada mostrou lesões marcadamente hipoatenuantes, acometendo principalmente psoas e regiões paravertebrais, aspectos que mimetizavam outras doenças, como abscessos e linfonodomegalias. A ressonância magnética foi útil para a melhor caracterização da extensão dos neurofibromas, bem como de sua estrutura interna.

Giant nerve sheath tumour: report of six cases

Giant nerve sheath tumour is a rare tumour originating from the nerve sheath. It differs from the conventional nerve sheath tumour only by the size these tumours can reach. There are two main type of tumours that occur in the nerve sheath which include neurofibroma and schwannoma. The current views are that schwannomas arise from the progenitor of the schwann cell. Whereas the neurofibroma series probably arise from a mesenchymal origin closer to a fibroblast. We report on six cases of nerve sheath tumour that occur in the spinal and paraspinal region that presented to us over a 5 year period.

Malignant peripheral nerve sheath tumors

The rarity of MPNSTs and the lack of any singular diagnostic radiologic or pathologic signature lead to several management challenges. These tumors are best managed as part ofa multidisciplinary team so as to optimize patient care and facilitate research. Suspicion of an MPNST based on clinical or radiologic alteration of a soft tissue mass in proximity to a peripheral nerve, especially in the context of NF I, should lead to referral to such a tertiary center. Early diagnosis followed by oncologic surgery to obtain tumor-free margins provides the best chance for long-term cure. Psychologic support and occupational rehabilitation are vital components of the overall care of these relatively young patients faced with often disabling surgery. Current adjuvant therapy with radiation and chemotherapy is suboptimal. There have been major inroads toward the molecular biologic understanding of MPNSTs,with several biologic targets that are of potential therapeutic interest. Proper evaluation of these novel and promising management strategies requires a concerted effort to refer these patients to the tertiary centers through which multi-institutional clinical trials can be undertaken.

MR imaging of brachial plexus

The brachial plexus is a complex anatomic component originating from ventral rami of the lower cervical nerve roots from C5 to C8 and upper thoracic spinal nerve roots from T1, providing sensory and motor innervation to the upper extremities. As it is inaccessible to palpation, clinical evaluation of the brachial plexus is very challenging and localizing lesions along its course is very difficult. The gamut of pathologic conditions involving the brachial plexus includes primary tumor, direct extension of adjacent tumor, metastasis, trauma, or an inflammatory condition. MR imaging provides superior diagnostic ability due to its ability of multiplanar imaging and greater soft tissue contrast. This article discusses MR imaging findings in a variety of pathologic conditions, with special emphasis on neoplastic process.

Positron emission tomography of schwannomas: emphasizing its potential in preoperative planning

OBJECTIVE

In this article, we describe FDG uptake in schwannoma as measured on positron emission tomography (PET). FDG uptake is compared with tumor cellularity, tumor size, and tumor proliferation rate (Ki-67 index).

CONCLUSION

Schwannomas generally have a high tumor-to-background ratio on FDG PET. Semiquantitative analysis with standardized uptake values (SUVs) reveals a wide variation in SUVs that can be explained by variations in the degree of cellularity. No correlation was found between FDG uptake and tumor size or tumor proliferation rate (Ki-67 index). Because these tumors often have a high level of FDG uptake, distinguishing schwannomas from malignant peripheral nerve sheath tumors before biopsy or surgery is not possible. Even in cases in which the maximum SUV or average SUV is greater than 6.0, schwannomas cannot be excluded. Therefore, schwannoma should be included in the differential diagnosis of peripheral nerve sheath tumors with low, intermediate, or high SUVs.

Chest wall tumors: radiologic findings and pathologic correlation: part 2. Malignant tumors

Malignant chest wall tumors are classified into eight main diagnostic categories: muscular, vascular, fibrous and fibrohistiocytic, peripheral nerve, osseous and cartilaginous, adipose, hematologic, and cutaneous. However, there are malignant tumors that arise in the chest wall and that do not fit well in any of these categories (eg, Ewing sarcoma and synovial sarcoma). Malignant chest wall tumors typically manifest as painful, rapidly growing, large palpable masses. Chest radiography, the technique most often used for initial evaluation, can be helpful for detecting cortical destruction. However, computed tomography is more sensitive than chest radiography for detecting calcified tumor matrix and cortical destruction. Magnetic resonance imaging often allows more accurate delineation and localization of the tumor and is helpful for determining the presence and extent of tumor invasion and for tissue characterization. Although the imaging features of many malignant chest wall tumors are nonspecific, knowledge of the typical radiologic manifestations of these tumors often enables their differentiation from benign chest wall tumors and occasionally allows a specific diagnosis to be suggested. The article reviews the clinical and imaging features of the most common malignant chest wall tumors and presents images collected at a single cancer referral center.

Pedunculated malignant peripheral nerve-sheath tumour of the diaphragm presenting as recurrent lung infection: ultrasound diagnosis

We report a rare case of malignant peripheral nerve-sheath tumour of the diaphragm in a 12-year-old boy with neurofibromatosis presented clinically and radiographically as recurrent lung infection. Ultrasound revealed a pedunculated diaphragmatic tumour invading the posterior chest wall. This case highlights that this unusual tumour may limit diaphragmatic excursion leading to, and even being masked by, superimposed lung infection. In patients with neurofibromatosis, ultrasound is recommended when chest radiography shows a basal lung opacity.

MR imaging of spinal tumors in children with neurofibromatosis 1

OBJECTIVE

The need for radiologic surveillance of spinal tumors in children with neurofibromatosis 1 is controversial and unresolved. We aimed to determine the incidence of spinal tumors in asymptomatic patients, describe the imaging findings, and evaluate the clinical usefulness of a prospective MR imaging surveillance program of the spine in children with neurofibromatosis 1.

SUBJECTS AND METHODS

Of 62 children consecutively seen in a neurofibromatosis 1 clinic, 53 (85.5%) were recruited for MR imaging of the whole spine. All children satisfied the clinical criteria for diagnosis of neurofibromatosis 1. Imaging findings, clinical signs and symptoms, and subsequent clinical management were reviewed.

RESULTS

The patients were 35 boys and 18 girls (age range, 11 months-18 years; mean age, 9.6 years), all of whom were asymptomatic, with no remarkable neurologic signs. Seven children (13.2%) had spinal neurofibromas: four had solitary neurofibromas (two dumbbell, one intradural, and one paraspinal tumor) and three had plexiform neurofibromas of the sacral plexus and thoracic and lumbar nerve sheaths. The incidences of scoliosis, localized cutaneous neurofibromas, and massive soft-tissue neurofibromas were 71.4%, 71.4%, and 28.6%, respectively, in the group with spinal neurofibromas (n = 7), and 30.4%, 39.1%, and 8.7%, respectively, in the group without spinal neurofibromas (n = 46). Patient clinical outcome was affected in only one patient (1.9%) in whom a solitary neurofibroma was resected. Follow-up imaging in 10 patients (mean period, 29 months) showed no evidence of tumor occurrence, progression, or recurrence.

CONCLUSION

Although benign spinal neurofibromas are not uncommon in asymptomatic children with neurofibromatosis 1, the clinical usefulness of spine surveillance with MR imaging is limited in these children, making its effectiveness questionable.