Magnetic resonance appearance of peripheral nerve sheath tumors

Brachial plexus peripheral nerve sheath tumors (PNSTs): clinical and surgical management in the pediatric population

PURPOSE

Peripheral nerve sheath tumors (PNSTs) are rare in pediatric patients, especially in the brachial plexus. Research on PNSTs is lacking. This article presents a retrospective cohort study of pediatric patients diagnosed and treated with PNSTs, specifically brachial plexus tumors.

METHODS

All pediatric patients intervened in a single center between 2007 and 2023 with brachial plexus tumors were systemically analyzed.

RESULTS

Eleven pediatric patients with 14 brachial plexus PNSTs were studied. The gender distribution was 64% female and 36% male, with an average age of 10.7 years. Ninety-one percent had a previous NF-1 diagnosis. Right brachial plexus presented a higher prevalence (64%). Pain, Tinel's sign, and stiffness masses were common during diagnosis. Motor deficits were noted in 43% of the patients. Surgery was indicated for symptoms, particularly pain and rapid growth, increasing malignancy risk. Due to suspected malignancy, an en bloc resection with safety margins was performed. Among the patients, 57% received a histopathological diagnosis of MPNST (malignant peripheral nerve sheath tumor). Treatment included radiotherapy and chemotherapy. Clinical follow-up was conducted for all cases, involving clinical and oncological evaluations for all MPNSTs.

CONCLUSIONS

This article present a series of pediatric brachial plexus tumors, especially in NF-1, and emphasizes the importance of thorough evaluation for this group. Swift diagnosis is crucial in pediatrics, enabling successful surgery for small lesions with limited neurological symptoms, improving long-term outcomes. Prompt referral to specialized services is urged for suspected masses, irrespective of neurological symptoms. Benign tumor postsurgical progression shows better outcomes than MPNSTs, with complete resection as the primary goal. Needle-guided biopsy is not recommended.

MRI features of benign peripheral nerve sheath tumors: how do sporadic and syndromic tumors differ?

OBJECTIVES

To compare MRI features of sporadic and neurofibromatosis syndrome-related localized schwannomas and neurofibromas.

METHODS

In this retrospective study, our pathology database was searched for "neurofibroma" or "schwannoma" from 2014 to 2019. Exclusion criteria were lack of available MRI and intradural or plexiform tumors. Qualitative and quantitative anatomic (location, size, relationship to nerve, signal, muscle denervation) and functional (arterial enhancement, apparent diffusion-weighted coefficient) MRI features of sporadic and syndrome-related tumors were compared. Statistical significance was assumed for p < 0.05.

RESULTS

A total of 80 patients with 64 schwannomas (sporadic: 42 (65.6%) v. syndrome-related: 22 (34.4%)) and 19 neurofibromas (sporadic: 7 (36.8%) v. syndrome-related: 12 (41.7%)) were included. Only signal heterogeneity (T2W p=0.001, post-contrast p=0.03) and a diffused-weighted imaging target sign (p=0.04) were more frequent with schwannomas than neurofibromas. Sporadic schwannomas were similar in size to syndrome-related schwannomas (2.9±1.2cm vs. 3.7±3.2 cm, p = 0.6), but with greater heterogeneity (T2W p = 0.02, post-contrast p = 0.01). Sporadic neurofibromas were larger (4.6±1.5cm vs. 3.4±2.4 cm, p = 0.03) than syndrome-related neurofibromas, also with greater heterogeneity (T2W p=0.03, post-contrast p=0.04). Additional tumors along an affected nerve were only observed with syndrome-related tumors). There was no difference in apparent diffusion coefficient values or presence of early perfusion between sporadic and syndrome-related tumors (p > 0.05).

CONCLUSIONS

Although syndrome-related and sporadic schwannomas and neurofibromas overlap in their anatomic, diffusion and perfusion features, signal heterogeneity and presence of multiple lesions along a nerve are differentiating characteristics of syndrome-related tumors.

Imaging Features of Intraosseous Schwannoma: A Case Series and Review of the Literature

To characterize the imaging features of patients with pathologically confirmed intraosseous schwannoma (IOS), institutional pathology and imaging databases were searched for IOS cases over a period of 17 years. A musculoskeletal radiologist evaluated all imaging studies. Additionally, a literature search was performed to identify IOS cases that had imaging findings of at least two modalities. Six patients (one female, five males, mean age of 50 ± 14 years) with IOS were identified, with all lesions localized to the lumbosacral region. Radiographic imaging was available in four patients, while all patients underwent CT and MR imaging. Radiographs depicted lytic lesions, and CT depicted heterogeneous expansile lesions with centrally hypodense areas and peripheral sclerosis. All cases involved extra-osseous extension, producing a mass effect on adjacent soft tissues and nerve roots. On MRI, the neoplasms displayed iso- to- slightly- low signal intensity on T1-weighted images and hyperintense signal intensity on T2-weighted images with heterogeneous enhancement. The literature review resulted in 102 IOS cases, which to the best of our knowledge, is the largest review on IOS, and the imaging findings of the previously published cases were the same as our cases. IOSs are rare benign neoplasms that should be considered in the differential diagnosis of well-defined expansile lytic lesions with sclerotic borders. This is particularly important in middle-aged adults with mandibular, sacral, or vertebral body mass.

Mnemonics and Metaphorical Videos for Detecting/Diagnosing Musculoskeletal Sonopathologies

ABSTRACT

Musculoskeletal ultrasound identifies a broad range of pathologies. Typical sonographic images of certain pathological/abnormal conditions can be rendered and "highlighted" for the daily practice/language of musculoskeletal sonographers. The following text and accompanying figures/videos represent a collection of findings pertaining to commonplace pathological conditions. This article is the second part of a series-after the characteristic/metaphoric descriptions of normal musculoskeletal structures.

Diagnostic and Therapeutic Pathways of Intramuscular Myxoma

Intramuscular myxomas (IMMs) are benign tumors. Evidence regarding diagnostic and therapeutic pathways is rare, and guidelines do not exist due to their low incidence. The aim of this study was a retrospective analysis at a university cancer center and the interdisciplinary re-evaluation of the individual diagnostic and therapeutic procedures. Overall, 38 patients were included in the study. IMMs occurred mostly in middle-aged women. At the time of first consultation, 57.9% had few symptoms or were asymptomatic. In 92.1% of the cases, the tumor was localized in the extremities. The lower extremity was affected in 73.7%. The average size of IMMs was 5.0 cm. The proximally located tumors in the gluteus, thighs, and upper arms were significantly larger (p = 0.02) than the distally-located tumors in the forearms and lower legs. An MRI was performed in 97.4%. Based on imaging, an IMM was suspected in 5.6% by radiologists and in 54.1% by musculoskeletal surgeons. An incision biopsy was performed in 68.4% and led in 100.0% to the right histopathological diagnosis. In total, 89.5% of IMMs were resected. Postoperative complications requiring revision occurred in 8.8%. Recurrences or degenerations of IMMs were not reported in any of these cases.

Sciatic foramen anatomy and common pathologies: a pictorial review

This article reviews the relevant anatomy, imaging features on computed tomography, magnetic resonance imaging, and management of common processes involving the sciatic foramen. The anatomy of the sciatic foramen is complex and provides an important conduit between the pelvis, gluteus, and lower extremity. This paper reviewed the anatomy, common pathologies, and imaging features of this region including trauma, infection, nerve entrapment, tumor spread, hernia, and vascular anomaly.

Parosteal lipoma of the forearm: A case report and a literature review

RATIONALE

Parosteal lipomas are rare neoplasms comprising mature adipocytes situated in a proximity to bone. Although these tumors follow a benign course, the reactive osseous changes that may occur with such lesions might raise the suspicion of malignancy.

PATIENT CONCERNS

Here we present a case of a 33-year-old male patient complaining of pain and swelling in the right anterior forearm without history of trauma.

DIAGNOSIS

An magnetic resonance imaging of the region revealed a lobulated intramuscular fat intensity mass within the supinator muscle. Bony projection inseparable from the anterolateral radial diaphyseal cortex and periosteum was also seen. The radiological features suggested the diagnosis of parosteal lipoma.

INTERVENTION

After the radiological diagnosis of a parosteal lipoma, the patient was offered a total surgical excision of the mass.

OUTCOMES

The mass was removed successfully. Histopathology showed mature benign adipose tissue bordered by thin fibrous septa confirming the diagnosis of parosteal lipoma. Follow-up magnetic resonance imaging after 6 months did not reveal any signs of complications or recurrence.

LESSONS

Distinction of the features of parosteal lipomas is needed to establish the accurate diagnosis, discriminate it from malignant lesions, predict potential neurovascular compromises, and follow up until a curative action is planned.

A Large Intraoral Sublingual Schwannoma in a Pediatric Patient: A Case Report

INTRODUCTION

Schwannoma is a benign neoplasm that arises from Schwannoma cells found in the peripheral nerve sheath. It's a frequent neoplasm in the head and neck area, but it's exceedingly unusual to find it in the mouth. It's a rare occurrence in the oral cavity of the pediatric age group.

CASE REPORT

We present a 12-year-old kid who has had a smooth, firm, and non-tender mass in the sublingual region for the past year. The mass was removed completely using a transoral technique. The diagnosis of sublingual schwannoma was confirmed by histopathological and immunohistochemical testing.

CONCLUSION

Schwannomas are typically benign and have a good prognosis with a low risk of malignant change. It should be used as a differential diagnostic for sublingual diseases such as ranula and salivary gland lesions. In the case of lingual schwannoma, surgical removal of the tumor is the preferred therapy. The transoral method is the most popular treatment option for sublingual schwannoma.

Intraosseous schwannoma of the proximal humerus with pathologic fracture

BACKGROUND

Intraosseous schwannomas are extremely rare in the humerus, and less than five cases have been reported previously in the literature. This is the first report of its origin in the proximal humerus with pathologic fracture. We herein present this case to discuss the reason for its rarity and share our experience of management.

CASE PRESENTATION

A 55-year-old female patient presented with pain in the right shoulder, which was caused by tripping and falling over a board. Radiographs, computed tomography (CT) and magnetic resonance imaging (MRI) showed considerable tumor in proximal humerus, which connected with a fracture. For this suspected tumor, we performed two operations. Pathological examination demonstrated typical picture of a schwannoma, showing whorls and interlacing fascicles of schwannoma spindle cells. Immunohistochemistry, the tumor cells were diffusely positive for S-100 protein, SOX-10 and CD68, while they were completely negative for desmin, DOG-1, AE1/AE3 and P63. The Ki-67 index was about 10%. No mitoses or features of malignancy were identified. The final diagnosis of intraosseous schwannoma was made. The treatment for intraosseous schwannoma with pathologic fracture includes excisional biopsy, curettage, bone allograft, and fracture fixation. The patient recovered well. After the surgery, the patient gradually regained mobility and the pain subsided. There was no recurrence after 6 months of follow-up by X-ray.

CONCLUSIONS

Although very rare, intraosseous schwannoma should be taken under consideration in the differential diagnosis of benign-appearing osseous tumor in the proximal humerus with pathologic fracture.

Histopathological explanation of the MRI target sign in extra-axial schwannomas

BACKGROUND

To better understand the nature of magnetic resonance imaging (MRI) findings in schwannomas, especially in the "target sign" of these findings, the histopathological investigation was performed.

METHODS

The MRI findings were correlated with histopathological features in 22 samples of schwannomas, which were mostly resected from the extremities. The histopathological analyses included alcian blue staining and immunohistochemical staining for S-100 protein, proliferating cell nuclear antigen (PCNA) and epithelial membrane antigen (EMA).

RESULTS

Seven of the 22 samples of schwannomas of the extremities exhibited target signs including a peripheral zone of homogeneously high signal intensity and a central zone of heterogeneous signal intensity in T2-weighted images. Gadolinium-enhanced T1-weighted images demonstrated a central heterogeneous enhancement and a peripheral ring of homogeneously low signal intensity. Histopathologically, S-100 and PCNA were positive only in the central heterogeneous signal area. In contrast, EMA was only stained on the degenerative epi/perineurium in the peripheral zone.

CONCLUSION

In schwannomas of the extremities showing target sign in T2-weighted images, histopathologically, the peripheral areas were suggested to be mucinous degeneration of the epineurium or perineurium, while the central areas were composed of truly neoplastic cells.

Diagnostic Accuracy of MRI for the Detection of Malignant Peripheral Nerve Sheath Tumors: A Systematic Review and Meta-Analysis

OBJECTIVE. This systematic review and meta-analysis evaluates the diagnostic accuracy of MRI for differentiating malignant (MPNSTs) from benign peripheral nerve sheath tumors (BPNSTs). MATERIALS AND METHODS. A systematic review of MEDLINE, Embase, Scopus, the Cochrane Library, and the gray literature from inception to December 2019 was performed. Original articles that involved at least 10 patients and that evaluated the accuracy of MRI for detecting MPNSTs were included. Two reviewers independently extracted clinical and radiologic data from included articles to calculate sensitivity, specificity, PPV, NPV, and accuracy. A meta-analysis was performed using a bivariate mixed-effects regression model. Risk of bias was evaluated using QUADAS-2. RESULTS. Fifteen studies involving 798 lesions (252 MPNSTs and 546 BPNSTs) were included in the analysis. Pooled and weighted sensitivity, specificity, and AUC values for MRI in detecting MPNSTs were 68% (95% CI, 52-80%), 93% (95% CI, 85-97%), and 0.89 (95% CI, 0.86-0.92) when using feature combination and 88% (95% CI, 74-95%), 94% (95% CI, 89-96%), and 0.97 (95% CI, 0.95-0.98) using diffusion restriction with or without feature combination. Subgroup analysis, such as patients with neurofibromatosis type 1 (NF1) versus those without NF1, could not be performed because of insufficient data. Risk of bias was predominantly high or unclear for patient selection, mixed for index test, low for reference standard, and unclear for flow and timing. CONCLUSION. Combining features such as diffusion restriction optimizes the diagnostic accuracy of MRI for detecting MPNSTs. However, limitations in the literature, including variability and risk of bias, necessitate additional methodologically rigorous studies to allow subgroup analysis and further evaluate the combination of clinical and MRI features for MPNST diagnosis.

Nerve Sheath Myxoma in the Lower Extremity: A Rare Case with Description of Magnetic Resonance Imaging and Sonographic Findings

BACKGROUND This report is of a nerve sheath myxoma presenting as a slow-growing mass in the back of the left ankle of a 36-year-old man that was investigated by ultrasound and magnetic resonance imaging (MRI) before the diagnosis was confirmed by histopathology. CASE REPORT We report a nerve sheath myxoma of the ankle in a 36-year-old man. The palpable abnormality was falsely assumed to be a ganglion cyst prior to advanced imaging. Magnetic resonance imaging demonstrated a lobular mass with high T2 and intermediate T1 signal as well as moderate enhancement. T2 sequences also demonstrated distinctive internal septae. These internal septae were also noted on sonographic evaluation prior to biopsy. The patient was treated with surgical excision, and pathologic analysis showed myxoid nodules with loose arrangements of spindled cells separated by fibrous septae. S-100 protein and glial fibrillary acidic protein positivity by immunohistochemistry staining was demonstrated. Follow-up imaging at 12 months showed no evidence of tumor recurrence. CONCLUSIONS This case highlights that while nerve sheath myxomas are rare tumors, they should be considered in cases of cutaneous soft-tissue masses with myxoid imaging features. Ultrasound and magnetic resonance imaging features of thin internal septae may be present and correspond well with the unique histopathological characteristics of these lesions. This report shows the importance of imaging of peripheral soft-tissue masses, including ultrasound and MRI, which can identify localized and benign features and the solid, cystic, and myxoid areas, which were characteristic in this case of benign nerve sheath myxoma.

Imaging of Soft Tissue Tumors

Differentiation of malignant from benign soft tissue tumors is challenging with imaging alone, including that by magnetic resonance imaging and computed tomography. However, the accuracy of this differentiation has increased owing to the development of novel imaging technology. Detailed patient history and physical examination remain essential for differentiation between benign and malignant soft tissue tumors. Moreover, measurement only of tumor size based on Response Evaluation Criteria In Solid Tumors criteria is insufficient for the evaluation of response to chemotherapy or radiotherapy. Change in metabolic activity measured by ¹⁸F-fluorodeoxyglucose positron emission tomography or dynamic contrast enhanced-derived quantitative endpoints can more accurately evaluate treatment response compared to change in tumor size. Magnetic resonance imaging can accurately evaluate essential factors in surgical planning such as vascular or bone invasion and "tail sign". Thus, imaging plays a critical role in the diagnosis and treatment of soft tissue tumors.

Primary Site Identification of Soft-Tissue Mass: Things to Know in MRI Assessment

The spectrum of soft-tissue mass is varied, including neoplastic and nonneoplastic/inflammatory lesions. However, soft-tissue tumors have similar imaging findings and, therefore, the diagnosis of soft-tissue mass is challenging. Although careful assessment of the internal characteristics on imaging can often narrow the differential diagnoses, the differential diagnosis may be out of the question if identification of the soft-tissue mass origin is missed. The purpose of this article is to review the imaging findings and the essential anatomy to identify the primary site of the soft-tissue mass, and discuss the associated potential pitfalls. In order not to fall into a pitfall, recognition of characteristic imaging findings indicating the origin of the soft-tissue mass and anatomical knowledge of the normal tissue distribution are necessary. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

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

PURPOSE

To analyze the prevalence of classic magnetic resonance imaging (MRI) findings of intramuscular peripheral nerve sheath tumors (PNSTs), including schwannoma, ancient schwannoma, and neurofibroma.

METHOD

Thirty pathologically confirmed benign intramuscular PNSTs (24 schwannomas, 3 ancient schwannomas, and 3 neurofibromas) were retrospectively reviewed. Classic MRI findings of PNSTs including split fat sign, fascicular sign, target sign, entering and exiting nerve, and thin hyperintense rim were assessed for each intramuscular PNST. Denervation change of the affected muscle was also assessed. In ancient schwannoma and neurofibroma, the signal intensity (SI) and enhancement pattern were analyzed.

RESULTS

All intramuscular schwannomas revealed two more classic MRI findings. Eight of the 24 intramuscular schwannomas revealed affected muscle denervation change. All intramuscular ancient schwannomas showed only split fat sign. All intramuscular ancient schwannomas showed denervation change of the associated muscle. All intramuscular neurofibroma showed split fat sign and one case with target sign was detected. Ancient schwannomas were isointense SI on T1-weighted image (T1WI) and one case had hyperintense foci. They showed heterogeneously hyperintense SI on T2-weighted image (T2WI) with heterogeneous enhancement. Neurofibromas were isointense SI (2/3) and slight hyperintense SI (1/3) on T1WI and heterogeneously hyperintense SI on T2WI with heterogeneous enhancement. One ancient schwannoma showed conglomerated calcifications.

CONCLUSIONS

Intramuscular schwannomas were easily diagnosed based on MRI. In the case of intramuscular ancient schwannoma and neurofibroma with only split fat sign among the classic MRI findings, they might be distinguished from other intramuscular soft tissue tumors based on muscle denervation change or typical crescent split fat sign.

Solitary intramuscular myofibroma in an adult: Case report and MR imaging findings

Myofibroma is a benign, soft tissue neoplasm that predominantly affects infants and young children. Most occur in the skin or subcutaneous tissues, with a predilection for the head and neck regions. We describe the magnetic resonance (MR) imaging and histophathologic findings of a rare case of intramuscular myofibroma of the right deltoid in a healthy 30-year-old male. MR imaging revealed a well-circumscribed intramuscular mass, with isointense signal on T1-weighted images, hyperintense signal on T2-weighed images, and a "target-sign" with peripheral rim enhancement after gadolinium administration. The lesion was surgically excised with no complications, and the histopathologic analysis revealed the typical morphologic and histochemical markers of a myofibroma. We conclude that, although rare, myofibroma can be considered in the differential diagnosis of adults with lesions the above signal characteristics.

Lumbosacral plexiform neurofibroma: a rare case in an adult without neurofibromatosis type I

Plexiform neurofibromas are an uncommon variant of neurofibromas that are described as being essentially pathognomonic of neurofibromatosis type 1 (NF1). Plexiform neurofibromas in the absence of NF1 are extremely rare. We present the case of a 38-year-old woman with a large multilobulated lumbosacral mass extending into the pelvis and proximal thigh. Histopathology of a CT-guided biopsy of the mass revealed it to be a neurofibroma. The imaging findings were consistent with a plexiform subtype. Further imaging and clinical workup showed that the patient had no other identifiable neurofibromas and did not meet criteria for the diagnosis of NF1.

Soft-Tissue Tumors of the Hand-Imaging Features

Imaging studies of the hands and fingers are common, and radiologists are generally comfortable with traumatic and degenerative conditions which arise frequently in daily practice. However, a variety of common and uncommon soft-tissue tumors also occur in the hand, the appropriate diagnosis of which can be a source of confusion for both clinicians and radiologists. These lesions often have overlapping imaging characteristics; however, a structured approach can help provide a focused differential diagnosis and impact further workup and management. We discuss several such tumors, categorizing them as cystic-appearing, noncystic masses along tendons and aponeuroses, adipocytic tumors, vascular lesions, and miscellaneous lesions with imaging features that can aid diagnosis.

Unusual Etiology of Chronic Posterior Leg Pain in a Running Athlete: Could It Be a Schwannoma? A Case Report and Review of the Literature

Schwannomas represent only 5% of all soft tissue tumors. As a variant of this tumor, the plexiform schwannoma is rare accounting for less than 5% of all schwannomas. Herein, we report a rare case of a 49-year-old athlete who suffered from a pain in the posterior aspect of the right leg one year before his presentation. Initially, a radiograph of his right leg showed no abnormality, and so, the emergency physician discharged him on analgesics and anti-inflammatory medications, and rest was advised. The persistent pain obliged the patient to consult our orthopedic department. On examination, we found a firm mass in the proximal medial aspect of his right leg. The neurovascular exam was normal. Sonography of the leg was not conclusive. Therefore, magnetic resonance imaging was performed, and a hemangioma or schwannoma was suspected. The patient underwent surgery in which the entire tumor mass was shelled out in one piece with no damage. The histopathological finding was concomitant with a plexiform schwannoma. Follow-up evaluation, sixteen months later, showed no evidence of recurrence, and the patient has regained his previous level of sportive activities. So, given the case described here, despite the rarity of the schwannoma, it should be taken into consideration as a possible diagnosis in such situation to promote early diagnosis and appropriate treatment.

Malignant peripheral nerve sheath tumor of nasal cavity and paranasal sinus with 13 years of follow-up-A case report and review of literature

Although extremely rare, sarcomas including malignant peripheral nerve sheath tumors should be considered in the differential diagnosis of sino-nasal tract lesions. Long-term cure is possible through definitive operative management followed by adjuvant therapy.

Mechanisms, Treatment, and Patient Outcome of Iatrogenic Injury to the Brachial Plexus-A Retrospective Single-Center Study

BACKGROUND

Injury to the brachial plexus is a devastating condition, with severe impairment of upper extremity function resulting in distinct disability. There are no systematic reports on epidemiology, causative mechanisms, treatment strategies. or outcomes of iatrogenic brachial plexus injury (iBPI).

METHODS

We screened all cases of iatrogenic nerve injuries recorded between 2007 and 2017 at a single specialized institution. Mechanism of iBPI, type of previous causative intervention, location and type of the lesion as well as the type of revision surgery and functional patient outcome were analyzed.

RESULTS

We identified 14 cases of iBPI, which all presented with significant impairment of upper extremity motor function (at least 1 muscle Medical Research Council grade 0). Neuropathic pain was present in most patients (11/14). Orthopedic shoulder procedures such as rotator cuff fixation, arthroplasty, and repositioning of a clavicle fracture accounted for iBPI in 7 of 14 patients. Other reasons for iBPI were resection or biopsy of a peripheral nerve sheath tumor in 3 patients or lymph node situated at the cervicomediastinal area in 2 patients. Mechanisms also included transaxillary rib resection in one and sternotomy in another patient. The treatment of iBPI was conducted according to each individual's needs and included neurolysis in 4, nerve grafting in 9, and nerve transfers in 1 patient. We found improved symptoms after treatment in most patients (11/14).

CONCLUSIONS

Most common causes for iBPI were shoulder surgery and resection or biopsy of peripheral nerve sheath tumor and lymph nodes. Early referral to specialized peripheral nerve centers may help to improve functional patient outcome.

Fatty rind of intramuscular soft-tissue tumors of the extremity: is it different from the split fat sign?

OBJECTIVE

To analyze intramuscular soft-tissue tumors with fatty rind, and to evaluate the difference between fatty rind and split fat sign on magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We retrospectively analyzed 50 pathologically confirmed intramuscular masses on MRI. We evaluated the distribution and shape of fatty rind and muscle atrophy.

RESULTS

Fatty rind was found more frequently in benign lesions (80% [36 out of 45]) compared with malignant lesions (25% [1 out of 5]; P = 0.013). Thirty-six benign lesions were peripheral nerve sheath tumors (PNSTs; n = 19), hemangiomas (n = 11), myxomas (n = 2), ganglion cysts (n = 2), giant cell tumor (n = 1), and leiomyoma (n = 1). One malignant lesion was a low-grade fibromyxoid sarcoma. In all masses with fatty rind, fat was confined to the proximal and the distal ends. In 12 cases, complete or partial circumferential fatty rind was also noted. Fatty rinds at both ends showed crescent, triangular, or combined shape. The prevalence of crescent-shaped fatty rind was significantly higher in benign PNST (17 out of 38) compared with the other tumors (1 out of 32; P < 0.001). Complete circumferential fat was noted only in hemangioma (n = 5). Triangular fatty rind was related to peripheral location of the mass or muscle atrophy.

CONCLUSION

Most intramuscular tumors with fatty rinds were benign, and PNST was the most common tumor type. Fatty rind could be caused by displaced neurovascular bundle fat, fatty atrophy of the muscle involved, or intermuscular or perimysial fat. Crescent-shaped fatty rind was noted more frequently in benign PNSTs.

Sonographic Features and Diagnosis of Peripheral Schwannomas

BACKGROUND

To determine the sonographic features of peripheral schwannomas.

METHODS

This retrospective study included 54 cases of schwannoma in 51 patients. Ultrasonography (US) and MRI were performed in all patients. The US features of each tumor were analyzed and compared with pathologic findings. The US target sign was compared with the MRI findings.

RESULTS

On US, 53 of the 54 schwannomas had a regular shape and clear margins, and one had an irregular shape. Thirty-seven of the 54 schwannomas were categorized as solid, 16 as cystic and solid, and one as entirely cystic; distal sound enhancement was associated with 47 schwannomas. The target sign was seen in 24, the rat tail sign in 28, the vessel accompanying sign in 22, and the split fat sign in 5. The entering and exiting nerves were situated centrally in 9 and eccentrically in 19 schwannomas. Vascularity on color Doppler imaging using a 0 to III scale was graded 0 in 4 schwannomas, I in 10, II in 26, and III in 14. Twenty-four target signs were detected in 54 schwannomas by US, and 28 were detected by MRI. There was good agreement between the target signs noted on US and those seen on MRI (κ = 0.631, p < 0.001).

CONCLUSIONS

The sonographic diagnosis of peripheral schwannomas is feasible and reliable. The target sign is a prominent US feature in peripheral schwannomas, comparable to that observed with MRI. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:127-133, 2017.

Tongue base schwannoma: differential diagnosis and imaging features with a case presentation

Schwannomas are slow growing, encapsulated neoplasms that arise from the nerve sheath. A vast majority of these benign neoplasms occur in the head and neck region, most commonly involving the 8th cranial nerve. Schwannomas arising from the base of tongue are very rare and, thus, can easily escape the list of differential diagnosis for a posterior tongue mass. A systematic approach is recommended for diagnosis of a posterior tongue mass, with neoplastic, infectious, and congenital categories. We report a case of a 24-year-old female, who presented with pressure sensation in the throat. On imaging, she was found to have a mass in the right posterior tongue with follow-up biopsy results yielding a schwannoma. Characteristic imaging features for various possible etiologies of a posterior tongue mass are also discussed.

High-Resolution Ultrasound of Schwannomas of the Limbs: Analysis of 72 Cases

Schwannomas are common benign tumors that develop in peripheral nerves. High-resolution ultrasound (HRUS) is an effective imaging modality in clinics. The aim of this study was to define the value of HRUS in diagnosing schwannomas that originate from different nerves in limbs. We reviewed the ultrasound and surgical records of 72 pathologically confirmed schwannomas in the limbs of 60 patients. Results revealed that 44 (61.1%) of 72 cases, 44 (75.9%) of 58 cases and 0 (0%) of 14 cases received an overall correct pre-operative diagnosis, a correct pre-operative diagnosis in nerve trunks and a correct pre-operative diagnosis in small branches, respectively. Identification of the nerve of origin of schwannomas through HRUS likely increased confidence in diagnosing these benign tumors.

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.

Association between intraosseous schwannoma occurrence and the position of the intraosseous nutrient vessel: A case report

Intraosseous schwannoma is a rare benign bone tumor that originates from Schwann cells of the nerve sheath. The majority of intraosseous schwannomas arise in the mandible and sacrum, but an intraosseous schwannoma involving the ulna is described in the present case report. Radiologically, the current case presented as a well-defined lytic lesion, with a pathological fracture and no intralesional calcification, in the proximal metaphysis of the left ulna. Using magnetic resonance imaging, an intraosseous mass spreading out from the cortical defect was observed. The lesion appeared isointense to skeletal muscle on T1-weighted images, and hyperintense or heterogeneous on T2-weighted images. The differential diagnosis comprised benign bone tumors, including bone cyst, aneurysmal bone cyst, giant cell tumor and fibrous dysplasia. Based on the results of a needle biopsy, a schwannoma involving the ulnar bone was diagnosed, and tumor marginal resection followed by artificial bone grafting and fixation was performed. A total of one year subsequent to surgery, the patient exhibits no symptoms, and there is no evidence of disease recurrence.

Telltale signs of peripheral neurogenic tumors on magnetic resonance imaging

Peripheral nerve sheath tumors are categorized into benign and malignant forms, comprising of neurofibroma and schwannoma in the benign category and malignant peripheral nerve sheath tumors in the malignant category. Magnetic resonance imaging plays an important role in the diagnosis of these lesions. The various imaging features and signs that help to identify and characterize a nerve sheath tumor are, distribution of the tumor along a major nerve, an entering or exiting nerve sign, target sign, a fascicular sign and a split-fat sign.

Sonographic Differentiation Between Schwannomas and Neurofibromas in the Musculoskeletal System

OBJECTIVES

The purpose of this study was to determine key features and define a strategy for differentiation between schwannomas and neurofibromas using sonography.

METHODS

This retrospective study was approved by the Institutional Review Board at our hospital, and informed consent was waived. We reviewed sonograms of pathologically proven schwannomas and neurofibromas of the extremities and body wall. On grayscale images, tumors were evaluated on the basis of their size, maximum-to-minimum diameter ratio, shape, contour, margin, location, encapsulation, echogenicity, echo texture, cystic changes, presence of intratumoral calcifications, presence of a target sign, and presence of an entering or exiting nerve. If an entering or exiting nerve was identified, the nerve-tumor position and nerve-tumor transition were characterized. On color Doppler images, the presence and amount of vascularity were evaluated. Student t tests were used for analysis of continuous variables (size, maximum-to-minimum diameter ratio, and age); χ(2) and Fisher exact tests were used for analysis of categorical variables.

RESULTS

A total of 146 pathologically proven tumors, including 115 schwannomas and 31 neurofibromas of the extremities and body wall, were included. The maximum diameter, maximum-to-minimum diameter ratio, contour, cystic portion, nerve-tumor position, nerve-tumor transition, and vascularity were significantly different in schwannomas versus neurofibromas (P < .05), and a lobulated contour, fusiform shape, and hypovascularity of neurofibromas could be helpful for differentiation when a prediction model is considered. The nerve-tumor position, nerve-tumor transition, and maximum-to-minimum diameter ratio were also significantly different between groups (P < .05) and thus could be useful for differentiation of neurogenic tumors.

CONCLUSIONS

Sonographic findings are helpful in differentiating between schwannomas and neurofibromas.

Tumor burden evaluation in NF1 patients with plexiform neurofibromas in daily clinical practice

BACKGROUND

Existing volumetric measurements of plexiform neurofibromas (PNs) are time consuming and error prone, as they require delineation of PN boundaries, a procedure that is not practical in the typical clinical setting. The aim of this study is to assess the Plexiform Neurofibroma Instant Segmentation Tool (PNist), a novel semi-automated segmentation program that we developed for PN delineation in a clinical context. PNist was designed to greatly simplify volumetric assessment of PNs through use of an intuitive user interface while providing objectively consistent results with minimal interobserver and intraobserver variabilities in reasonable time.

MATERIALS AND METHODS

PNs were measured in 30 magnetic resonance imaging (MRI) scans from 12 patients with neurofibromatosis 1. Volumetric measurements were performed using PNist and compared to a standard semi-automated volumetric method (Analyze 9.0).

RESULTS

High correlation was detected between PNist and the semi-automated method (R(2) = 0.996), with a mean volume overlap error of 9.54 % and low intraobserver and interobserver variabilities. The segmentation time required for PNist was 60 % of the time required for Analyze 9.0 (360 versus 900 s, respectively). PNist was also reliable when assessing changes in tumor size over time, compared to the existing commercial method.

CONCLUSIONS

Our study suggests that the new PNist method is accurate, intuitive, and less time consuming for PN segmentation compared to existing commercial volumetric methods. The workflow is simple and user-friendly, making it an important clinical tool to be used by radiologists, neurologists and neurosurgeons on a daily basis, helping them deal with the complex task of evaluating PN burden and progression.

Rare case of chest wall schwannoma with destruction of rib, masquerading as a breast mass

Schwannomas are slow growing, benign, nerve sheath tumours of Schwann cell origin. They predominantly involve head, neck and flexor surfaces of upper and lower extremities, while the chest wall is an uncommon location for schwannomas. Schwannomas may rarely cause erosion of adjacent bone. We are reporting a very rare case of a chest wall schwannoma with destruction of rib which occurred in a 35-year-old female patient, which initially presented as a breast mass and was radiologically misinterpreted as a malignant soft tissue tumour.

Lymphangiopathy in neurofibromatosis 1 manifesting with chylothorax, pericardial effusion, and leg edema

Background

This case report documents the affliction of the lymph vessels as a phenotypic feature of neurofibromatosis-1 (NF-1).

Methodology

Routine transthoracic echocardiography, computed tomography scan of the thorax, magnetic resonance angiography of the renal arteries, and conventional digital subtraction angiography were applied. Comprehensive NF-1 mutation analysis was carried out by fluorescence in situ hybridization analysis, long-range reverse transcriptase polymerase chain reaction, and multiple-ligation probe assay. All other investigations were performed using routine, well-established techniques.

Results

The subject is a 34-year-old, half-Chinese male; NF-1 was suspected at age 15 years for the first time. His medical history included preterm birth, mild facial dysmorphism, “café au lait” spots, subcutaneous and paravertebral fibromas, multifocal tachycardia, atrial fibrillation, and heart failure in early infancy. Noncalcified bone fibromas in the femur and tibia were detected at age 8 years. Surgical right leg lengthening was carried out at age 11 years. Bilateral renal artery stenosis, stenosis and aneurysm of the superior mesenteric artery, and an infrarenal aortic stenosis were detected at age 15 years. Leg edema and ectasia of the basilar artery were diagnosed at age 18 years. After an episode with an erysipela at age 34 years, he developed pericardial and pleural effusion during a 4-month period. Stenosis of the left subclavian vein at the level of thoracic duct insertion was detected. After repeated pleural punctures, pleural effusion was interpreted as chylothorax. Reduction of lymph fluid production by diet and injection of talcum into the pleural cavity had a long-term beneficial effect on the chylothorax. Leg edema and chylothorax were attributed to affliction of the lymph vessels by the NF-1.

Discussion

Lymphangiopathy resulting in impaired lymph fluid flow and sequestration of lymph fluid into the pleural sinus and the legs may be a rare phenotypic feature of NF-1.

Multiple schwannomas of the upper limb related exclusively to the ulnar nerve in a patient with segmental schwannomatosis

Schwannomas are benign encapsulated tumours arising from the sheaths of peripheral nerves. They present as slowly enlarging solitary lumps, which may cause neurological defects. Multiple lesions are rare, but occur in patients with neurofibromatosis type 2 or schwannomatosis. Positive outcomes have been reported for surgical excision in solitary schwannomas. However, the role of surgery in patients with multiple lesions is less clear. The risk of complications such as iatrogenic nerve injury and the high likelihood of disease recurrence mean that surgical intervention should be limited to the prevention of progressive neurological deficit. We report a case of a 45 year old male who presented with multiple enlarging masses in the upper limb and sensory deficit in the distribution of the ulnar nerve. The tumours were found to be related exclusively to the ulnar nerve during surgical exploration and excision, a rare phenomenon. The masses were diagnosed as schwannomas following histopathological analysis, allowing our patient to be diagnosed with the rare entity segmental schwannomatosis. One year post-operatively motor function was normal, but intermittent numbness still occurred. Two further asymptomatic schwannomas developed subsequently and were managed conservatively.

Tail-end troubles: imaging of soft-tissue buttock tumours

Primary soft-tissue buttock tumours are relatively common entities, although they are infrequently reported in the literature. The buttock can be a difficult anatomical site to treat soft-tissue tumours due to the proximity of the sciatic nerve and the propensity of tumours at this site to extend into the pelvis and perineum. Therefore, the radiologist plays an important role in the multidisciplinary assessment of these lesions. Cross-sectional imaging, principally magnetic resonance imaging, is used to determine the exact location and extension of the tumour. Furthermore, certain tumours have characteristic imaging appearances that can help to establish a suitably ordered differential diagnosis. From our prospectively maintained database at The Royal Marsden Hospital, including 225 cases that were treated at the Sarcoma Unit over a 30 year period, we present examples of benign and malignant primary soft-tissue buttock tumours and describe the pertinent imaging characteristics, with emphasis on computed tomography and magnetic resonance imaging findings.

Magnetic resonance neurography of the pelvis and lumbosacral plexus

Recent advances in magnetic resonance (MR) imaging have revolutionized peripheral nerve imaging and made high-resolution acquisitions a clinical reality. High-resolution dedicated MR neurography techniques can show pathologic changes within the peripheral nerves as well as elucidate the underlying disorder or cause. Neurogenic pain arising from the nerves of the pelvis and lumbosacral plexus poses a particular diagnostic challenge for the clinician and radiologist alike. This article reviews the advances in MR imaging that have allowed state-of-the-art high-resolution imaging to become a reality in clinical practice.

Detection of peripheral nerve pathology: comparison of ultrasound and MRI

OBJECTIVE

To compare accuracy of ultrasound and MRI for detecting focal peripheral nerve pathology, excluding idiopathic carpal or cubital tunnel syndromes.

METHODS

We performed a retrospective review of patients referred for neuromuscular ultrasound to identify patients who had ultrasound and MRI of the same limb for suspected brachial plexopathy or mononeuropathies, excluding carpal/cubital tunnel syndromes. Ultrasound and MRI results were compared to diagnoses determined by surgical or, if not performed, clinical/electrodiagnostic evaluation.

RESULTS

We identified 53 patients who had both ultrasound and MRI of whom 46 (87%) had nerve pathology diagnosed by surgical (n = 39) or clinical/electrodiagnostic (n = 14) evaluation. Ultrasound detected the diagnosed nerve pathology (true positive) more often than MRI (43/46 vs 31/46, p < 0.001). Nerve pathology was correctly excluded (true negative) with equal frequency by MRI and ultrasound (both 6/7). In 25% (13/53), ultrasound was accurate (true positive or true negative) when MRI was not. These pathologies were typically (10/13) long (>2 cm) and only occasionally (2/13) outside the MRI field of view. MRI missed multifocal pathology identified with ultrasound in 6 of 7 patients, often (5/7) because pathology was outside the MRI field of view.

CONCLUSIONS

Imaging frequently detects peripheral nerve pathology and contributes to the differential diagnosis in patients with mononeuropathies and brachial plexopathies. Ultrasound is more sensitive than MRI (93% vs 67%), has equivalent specificity (86%), and better identifies multifocal lesions than MRI. In sonographically accessible regions ultrasound is the preferred initial imaging modality for anatomic evaluation of suspected peripheral nervous system lesions.

Brachial plexus tumors in a consecutive series of twenty one patients

Objective

This is a retrospective review of 22 surgically treated benign and malignant tumors of brachial plexus region to describe clinical presentation, the characteristics of brachial plexus tumor and clinical outcomes with a literature review.

Methods

Twenty-one patients with consecutive 22 surgeries for primary brachial plexus tumors were enrolled between February 2002 and November 2011 were included in this study. The medical records of all patients were reviewed.

Results

Eleven male and 10 female patients were enrolled. Mean age was 39 years. Three patients had brachial plexus tumor associated with neurofibromatosis (13.6%). Presenting signs and symptoms included parenthesis and numbness (54.5%), radiating pain (22.7%), direct tenderness and pain (27.2%), palpable mass (77.3%). Twelve patients presented preoperative sensory deficit (54.5%) and 9 patients presented preoperative motor deficit (40.9%). Twenty tumors (90.9%) were benign and 2 tumors (9.1%) were malignant. Benign tumors included 15 schwannomas (68.2%), 4 neurofibromas (18.2%) and 1 granular cell tumor (4.5%). There were 1 malignant peripheral nerve sheath tumor (MPNST) and 1 malignant granular cell tumor. Gross total resection was achieved in 16 patients (72.7%), including all schwannomas, 1 neurofibroma. Subtotal resection was performed in 6 tumors (27.3%), including 3 neurofibromatosis associated with brachial plexus neurofibromas, 1 MPNST and 2 granular cell tumor in one patient.

Conclusion

Resection of tumor is the choice of tumor in the most of benign and malignant brachial plexus tumors. Postoperative outcomes are related to grade of resection at surgery and pathological features of tumor.

Peripheral and cranial nerve sheath tumors-a clinical spectrum

To analyze the incidence of nerve sheath tumors in a tertiary care hospital over a period of 5 years and review the literature. Medical case records from last 5 years were retrieved and histopathology and operative details were studied in a retrospective analysis. There is a slight male preponderance when it comes to nerve sheath tumors and acoustic schwannomas accounted for the largest fraction among schwannomas. Nerve sheath tumors include a wide spectrum of schwannomas, neurofibromas and malignant peripheral nerve sheath tumors. Hence combination of clinical, pathological and surgical expertise is needed to diagnose accurately.