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Malignant peripheral nerve sheath tumor in a 34-year-old man with neurofibromatosis type 1. (a) Coronal three-dimensional short tau inversion recovery image from a whole-body MRI scan reveals multiple ovoid homogeneously T2 hyperintense lesions (arrows) in the neck that are compatible with neurofibromas. (b) Postcontrast T1 mDixon image from the same examination demonstrates a right paraspinal lesion (arrow) that features cystic components, and another lesion in the ipsilateral thigh (arrowhead) that shows targetoid enhancement. On diffusionweighted imaging, the lesions exhibited apparent diffusion coefficient values of 0.7 and 2.4 Â 10 À3 mm 2 /second, respectively. On biopsy, the paraspinal lesion proved to be a high-grade malignant peripheral nerve sheath tumor. On axial T2 Dixon images at baseline (c) and after 3-month follow-up (d), the malignant lesion (asterisk) exhibits considerable growth in size.
Source publication
Peripheral nerve sheath tumors (PNSTs) are neoplasms derived from neoplastic Schwann cells or their precursors. Whereas benign PNSTs are relatively common and considered curable lesions, their malignant counterparts are rare but highly aggressive and require early diagnosis and treatment. MR imaging has been the modality of choice for noninvasive e...
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Rare epithelial structures in benign nerve sheath tumors are almost always glandular in appearance. We describe a case of intraoral plexiform schwannoma with concurrent squamous epithelial hyperplasia. The lesion occurred as a pigmented nodule on the gingiva of a 35-year-old woman with no systemic involvement. Histologically, unencapsulated, plexif...
Malignant triton tumors (MTTs) are rare and aggressive sarcomas categorized as a subgroup of malignant peripheral nerve sheath tumors (MPNSTs). MTTs arise from Schwann cells of peripheral nerves or existing neurofibromas and have elements of rhabdomyoblastic differentiation. We report the occurrence of MTTs in two sisters. The first patient is a 36...
Schwannoma is a benign nerve sheath tumor composed of Schwann cells, which normally produce the insulating myelin sheath covering peripheral nerves. Here, we report a rare unsuspected case of 6 year old female child with schwannoma on the right side of the middle third of the dorsum of the tongue. This case highlights the clinicopathological featur...
Citations
... MRI can non-invasively suggest the neurogenic origin of a soft tissue mass and may help to distinguish between benign and malignant variants. However, MRI is limited in the distinction between schwannoma and neurofibroma [105], as well as between schwannoma and MPNST [106,107]. The MR-imaging-based Neuropathy Score Reporting and Data System (NS-RADS) is a recently developed framework to standardize MRI reporting in peripheral neuropathy [108,109]. ...
... MRI features of a neurogenic tumor. The direct continuity between a nerve and a lesion, resembling a tail coming off the lesion, is called a tail sign [106,107]. This feature is almost pathognomonic of a PNST, particularly when seen along the long axis of a lesion and when a large nerve is involved. ...
... A fusiform or round shape is also suggestive of a neurogenic tumor. Muscle denervation changes, including edematous changes, fatty infiltration, and/or atrophy of the innervated muscle, also strongly suggest the diagnosis [107,108]. ...
BACKGROUND
The 2021 WHO classification of the CNS Tumors identifies as “Peripheral nerve sheath tumors” (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness.
MATERIAL AND METHODS
The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly.
RESULTS
Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry. Molecular analysis is not essential to establish the histological nature of these tumors, although genetic analyses on DNA extracted from PNST (neurofibromas/schwannomas) is required to diagnose mosaic forms of NF1 and SPS. MRI is the gold-standard to delineate the extension with respect to adjacent structures. Gross-total resection is the first choice, and can be curative in benign lesions; however, the extent of resection must be balanced with preservation of nerve functioning. Radiotherapy can be omitted in benign tumors after complete resection and in NF-related tumors, due to the theoretic risk of secondary malignancies in a tumor-suppressor syndrome. Systemic therapy should be considered in incomplete resected plexiform neurofibromas/MPNSTs. MEK inhibitor selumetinib can be used in NF1 children ≥2 years with inoperable/symptomatic plexiform neurofibromas, while anthracycline-based treatment is the first choice for unresectable/locally advanced/metastatic MPNST. Clinical trials on other MEK1-2 inhibitors alone or in combination with mTOR inhibitors are under investigation in plexiform neurofibromas and MPNST, respectively.
CONCLUSION
Given the heterogeneity and rarity of these tumors, there is a paucity of well-powered clinical trials, thus it is not possible to generate evidence-based treatment recommendations for non-surgical modalities. However, some clinical trials have been reported on targeted therapies in plexiform neurofibromas of NF1 patients or in heterogenous cohorts of soft-tissue tumors, including MPNSTs, with initial data of efficacy that need to be further investigated.
... MRI can non-invasively suggest the neurogenic origin of a soft tissue mass and may help to distinguish between benign and malignant variants. However, MRI is limited in the distinction between schwannoma and neurofibroma [105], as well as between schwannoma and MPNST [106,107]. The MR-imaging-based Neuropathy Score Reporting and Data System (NS-RADS) is a recently developed framework to standardize MRI reporting in peripheral neuropathy [108,109]. ...
... MRI features of a neurogenic tumor. The direct continuity between a nerve and a lesion, resembling a tail coming off the lesion, is called a tail sign [106,107]. This feature is almost pathognomonic of a PNST, particularly when seen along the long axis of a lesion and when a large nerve is involved. ...
... A fusiform or round shape is also suggestive of a neurogenic tumor. Muscle denervation changes, including edematous changes, fatty infiltration, and/or atrophy of the innervated muscle, also strongly suggest the diagnosis [107,108]. ...
The 2021 WHO classification of the CNS Tumors identifies as “Peripheral nerve sheath tumors” (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly. Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry. Molecular analysis is not essential to establish the histological nature of these tumors, although genetic analyses on DNA extracted from PNST (neurofibromas/schwannomas) is required to diagnose mosaic forms of NF1 and SPS. MRI is the gold-standard to delineate the extension with respect to adjacent structures. Gross-total resection is the first choice, and can be curative in benign lesions; however, the extent of resection must be balanced with preservation of nerve functioning. Radiotherapy can be omitted in benign tumors after complete resection and in NF-related tumors, due to the theoretic risk of secondary malignancies in a tumor-suppressor syndrome. Systemic therapy should be considered in incomplete resected plexiform neurofibromas/MPNSTs. MEK inhibitor selumetinib can be used in NF1 children ≥2 years with inoperable/symptomatic plexiform neurofibromas, while anthracycline-based treatment is the first choice for unresectable/locally advanced/metastatic MPNST. Clinical trials on other MEK1-2 inhibitors alone or in combination with mTOR inhibitors are under investigation in plexiform neurofibromas and MPNST, respectively.
... This is sometimes referred to as the "tail sign," virtually pathognomonic of a peripheral nerve sheath tumor. However, benign and malignant nerve tumors may show this feature [20]. Occasionally, the characteristic "target sign" can be observed on T2-WI: hypointensity at the center of the mass, due to the fibrous component, and hyperintensity at the periphery, caused by the myxomatous component [21]. ...
IntroductionSchwannomas are benign neurogenic tumors arising from neural sheaths and rarely develop in the sublingual space. We report the case of an ancient sublingual schwannoma in an asymptomatic 12-year-old patient. Furthermore, we propose a review of the literature on non-vestibular schwannomas of the sublingual region.Materials and ResultsWe performed a complete excision of the lesion through a submandibular transcervical approach, sparing the left sublingual and submandibular glands, lingual nerve, and hypoglossal nerve. There was no need to perform a sural nerve graft to restore nerve function. The nerve of origin was identified intraoperatively as the mylohyoid nerve and was sacrificed during the en-block removal of the lesion. As of today, there are still multiple issues in the diagnosis and management of head and neck non-vestibular schwannomas. Preoperative evaluation through fine-needle aspiration cytology has an accuracy of only 20%. Identification of the nerve of origin is complex but critical to preserve nerve function after treatment.Conclusion
An accurate preoperative evaluation allows to make an informed decision whether to undergo surveillance or surgery, with potential nerve grafting after removal of the lesion. Definitive diagnosis is often possible only after surgery, with clinical observation and histopathological examination of the surgical specimen.
... It is also useful in predicting histology of nerve sheath tumours since schwannomas, as in our case, typically arise eccentrically from a nerve with displacement of its fascicles. 4 Furthermore, such techniques can be applied to other extracranial nerves 5 in the diagnosis of cranial neuropathies or in interventional planning for tumours in the head and neck region. Gradient echo-based DESS and CISS sequences partially overcome the problem of long acquisition time in conventional spin echo-based magnetic resonance neurogram; nonetheless images can be significantly compromised by susceptibility artefacts if adjacent implants are present. ...
... 1e5 Almost 90% of the NFs occur sporadically, whilst 10% are associated with neurofibromatosis type-1 (NF-1). 1,3,5,6 The incidence rates of NFs located in the hand are 0.8% in the general population and between 10% and 15% within patients with NF-1. 4 The presence of a solitary NF of the ulnar nerve at the level of the hand is extremely uncommon; also, to our knowledge a solitary NF of the ulnar nerve with an extrafascicular location, outside of Guyon canal, has not been previously described in the literature. Also, to our knowledge there are no reports regarding a symptomatic, solitary NF of the ulnar nerve as an inaugural presentation of NF-1. ...
... 2,3,6 Almost 95% of solitary NFs occur sporadically, mostly in young to middle-aged patients, and are not associated with NF-1. 2,3,5,6 A wide range of PNSTs can occur in patients with NF-1, and these are mostly multiple solitary, cutaneous NFs. 1,2 The massive-sized or plexiform NF subtypes are highly specific and almost always associated with NF-1. ...
... 2,5,6 Additionally, larger and multiple solitary NFs, deeper in location, have been described in the setting of NF-1. 3,5 The emergence of PNSTs in the extremities is rarely reported in the literature. Also, differently from the presented case, the majority of solitary NFs occurring at the hand or wrist level are cutaneous and tend to arise from the flexor crests and cutaneous nerves in adults, without the presence of NF-1. 1 Solitary NFs may have a variable initial presentation, ranging from an asymptomatic, slow-growing tumor that is incidentally found to neurogenic dysfunction with progressive pain, weakness, hypoesthesia, and tingling due to the mass' effect upon adjacent nerves. ...
Available online xxx Key words: Neurofibromatosis NF-1 Peripheral nerve sheath tumor hand tumorSolitary neurofibroma Ulnar nerve neurofibroma We report the case of a 34-year-old woman with hypothenar pain due to a solitary neurofibroma (NF) of the ulnar nerve, with an extrafascicular location, outside Guyon canal, with no clinical evidence of associated neurologic impairment, who was successfully treated with surgical resection. The identification of this isolated tumor led to the diagnosis of a new genetic variant of neurofibromatosis type 1 after genome sequencing. At the 1-year follow-up, the patient remains asymptomatic without recurrence or other peripheral nerve sheath tumors. A solitary NF of a deep-seated nerve is extremely rare, especially in the context of neurofibromatosis type 1. To our knowledge, there are no reports of a NF of the ulnar nerve with an extraneural location. In the presence of a solitary NF related to a deep-seated peripheral nerve, neurofibromatosis type 1 should always be excluded.
... Malignant PN sheath tumors show lower ADC values (< 1.1 × 10 −3 mm 2 /s) than schwannomas or neurofibromas (> 1.3 × 10 −3 mm 2 /s) [41]. Thus, the hypercellular nature of PN tumors can be assessed without need for the administration of exogenous contrast; however, further studies are needed to determine if DTI will be able to achieve a greater level of histology characterization for PN tumors [42]. DTI allows the evaluation of the relation of the PN fascicle with the main types of tumors. ...
Purpose
To perform a review of the physical basis of DTI and DCE-MRI applied to Peripheral Nerves (PNs) evaluation with the aim of providing readers the main concepts and tools to acquire these types of sequences for PNs assessment. The potential added value of these advanced techniques for pre-and post-surgical PN assessment is also reviewed in diverse clinical scenarios. Finally, a brief introduction to the promising applications of Artificial Intelligence (AI) for PNs evaluation is presented.
Methods
We review the existing literature and analyze the latest evidence regarding DTI, DCE-MRI and AI for PNs assessment. This review is focused on a practical approach to these advanced sequences providing tips and tricks for implementing them into real clinical practice focused on imaging postprocessing and their current clinical applicability. A summary of the potential applications of AI algorithms for PNs assessment is also included.
Results
DTI, successfully used in central nervous system, can also be applied for PNs assessment. DCE-MRI can help evaluate PN's vascularization and integrity of Blood Nerve Barrier beyond the conventional gadolinium-enhanced MRI sequences approach. Both approaches have been tested for PN assessment including pre- and post-surgical evaluation of PNs and tumoral conditions. AI algorithms may help radiologists for PN detection, segmentation and characterization with promising initial results.
Conclusion
DTI, DCE-MRI are feasible tools for the assessment of PN lesions. This manuscript emphasizes the technical adjustments necessary to acquire and post-process these images. AI algorithms can also be considered as an alternative and promising choice for PN evaluation with promising results.
... Befunde nach Entitäten 1. Schwannom [67,68] Schwannome zeigen sich in der MRN als scharf begrenzte, bekapselte, fusiforme bis rundliche Läsionen mit einer exzentrischen Lokalisation. Sie weisen in der Signalgebung eine deutliche T2w-Hyperintensität auf; je größer der Befund ist, desto stärker tritt jedoch die inhomogene Binnenmatrix im Zentrum in den Vordergrund, so dass größere Schwannome oft eine makroskopisch zystische Degeneration aufwiesen. ...
... KM-Aussparungen. [67,68] Das solitäre Neurofibrom zeigt sich typischerweise als scharf begrenzte, fusiform bis rundliche Nervenläsion, welche eine zentrale Lokalisation zur Nervenhauptachse ohne Kapsel aufweist. Eine T2-w Hyperintensität ist eher variabel ausgeprägt und weniger typisch zu beobachten als bei einem Schwannom. ...
... unten). [67,68] In der MRN findet sich beim Perineurioum eine diffus der Längsachse des Nervs folgende Binnenraumforderung mit konzentrischer bis spindeliger Auftreibung. Wichtig ist auch eine variable, meist nur geringe bis moderate T2-w Hyperintensität, welche diesen Bildbefund oft von anderen "typischeren" Nerventumoren unterscheidet. ...
Die biologische Heterogenität und die in den letzten Jahren weiterentwickelten Möglichkeiten
in der Diagnostik (Neurosonographie, Kernspintomographie, Molekularpathologie und
genetische Diagnostik) und Therapie (intraoperatives Neuromonitoring, intraoperative
Neurosonographie) lässt eine große Variationsbreite in der Versorgungsqualität von PNT
erwarten.
Diese Leitlinie versucht, bekannte und neue Verfahren in Diagnostik und Therapie zu bewerten
und stützt sich auf die wissenschaftliche Literatur und die Expertise ausgewiesener
Spezialisten aus den verschiedenen, an der Behandlung der Tumoren beteiligten
Fachrichtungen. Ziel ist es, verlässliche und allgemein akzeptierte Definitionen des
Notwendigen und Angemessenen in Diagnostik und Therapie zu geben.
Die Diagnostik der peripheren Nerventumoren findet primär im ambulanten/ vertragsärzlichen
Bereich statt. Die Behandlung kann in Einzelfällen ambulant, muss jedoch bei einer Vielzahl
tiefsitzender und komplexer PNT stationär erfolgen. Den Leitlinienentwicklern ist bewusst,
dass die Versorgung durch Vertreter unterschiedlicher Fachdisziplinen erfolgt.
Diese Leitlinie soll Entscheidungen in der Diagnostik und medizinischen Versorgung von
Patienten mit PNT-verdächtigen Symptomen auf eine rationale Basis stellen und die Qualität
der Versorgung verbessern.
... 15 All the similarities make it very difficult to confidently distinguish both tumours on MRI; the only way to diagnose them is from histopathology examination. 6 Despite playing a key role in most neck mass workup, fineneedle aspiration provides less valuable information for PNSTs. 9 It is difficult to diagnose PNSTs from cytological smears due to Video 1 Endoscopic view of the larynx shows right vocal palsy at the paramedian position with right arytenoid prolapses anteromedially. ...
A 33-year-old woman was diagnosed with right recurrent laryngeal nerve (RLN) schwannoma. She presented with a long history of hoarseness, and only recently developed dysphagia. On physical examination, a mass was observed over the right cervical level IV. Endoscopic examination of the larynx showed that she had right unilateral vocal cord palsy. She successfully underwent transcervical resection of the tumour followed by injection laryngoplasty. This study discusses the presentation of the tumour, radiological findings, our working diagnosis and treatment options of RLN schwannoma.
... Although several studies have assessed MRI features that may help differentiate benign peripheral nerve sheath tumours (BPNSTs) from malignant peripheral nerve sheath tumours (MPNSTs), there is none that specifically considers primary tumours of the brachial plexus. The reported morphological MRI features that are associated with MPNST include poorly defined margins [2], large size [3][4][5][6][7], a peripheral enhancement pattern [2,5], peri-lesional oedema-like signal intensity (SI) [8], intra-tumoural cystic change [5,9], an association with neurofibromatosis type 1 (NF-1) [4,5,9] and absence of a 'fascicular' [10,11] or 'target' sign [9,[11][12][13][14][15][16][17]. However, these described MRI features have only moderate sensitivity and specificity for differentiating BPNST from MPNST [18], which has led to research in advanced MRI techniques utilising diffusion-weighted imaging (DWI) [6,8,9,19,20], diffusion tensor imaging (DTI) and tractography [21,22] in an attempt to improve imaging differentiation. ...
... The reported morphological MRI features that are associated with MPNST include poorly defined margins [2], large size [3][4][5][6][7], a peripheral enhancement pattern [2,5], peri-lesional oedema-like signal intensity (SI) [8], intra-tumoural cystic change [5,9], an association with neurofibromatosis type 1 (NF-1) [4,5,9] and absence of a 'fascicular' [10,11] or 'target' sign [9,[11][12][13][14][15][16][17]. However, these described MRI features have only moderate sensitivity and specificity for differentiating BPNST from MPNST [18], which has led to research in advanced MRI techniques utilising diffusion-weighted imaging (DWI) [6,8,9,19,20], diffusion tensor imaging (DTI) and tractography [21,22] in an attempt to improve imaging differentiation. ...
Objective
To identify if morphology of the entering and exiting nerve involved by a nerve sheath tumour in the brachial plexus can help differentiate between benign (B) and malignant (M) peripheral nerve sheath tumours (PNSTs).Materials and methodsRetrospective review of 85 patients with histologically confirmed primary PNSTs of the brachial plexus over a 12.5-year period. Clinical data and all available MRI studies were independently evaluated by 2 consultant musculoskeletal radiologists blinded to the final histopathological diagnosis assessing for maximal lesion dimension, visibility and morphology of the entering and exiting nerve, and other well-documented features of PNSTs.ResultsThe study included 47 males and 38 females with mean age 46.7 years (range, 8–81 years). There were 73 BPNSTs and 12 MPNSTs. The entering nerve was not identified in 5 (7%), was normal in 17 (23%), was tapered in 38 (52%) and showed lobular enlargement in 13 (18%) BPNSTs compared with 0 (0%), 0 (0%), 2 (17%) and 10 (83%) MPNSTs respectively. The exiting nerve was not identified in 5 (7%), was normal in 20 (27%), was tapered in 42 (58%) and showed lobular enlargement in 6 (8%) BPNSTs compared with 4 (33%), 0 (0%), 2 (17%) and 6 (50%) MPNSTs respectively. Increasing tumour size, entering and exiting nerve morphology and suspected MRI diagnosis were statistically significant differentiators between BPNST and MPNST (p < 0.001). IOC for nerve status was poor to fair but improved to good if normal/tapered appearance were considered together with improved specificity of 81–91% for BPNST and sensitivity of 75–83%.Conclusions
Morphology of the adjacent nerve is a useful additional MRI feature for distinguishing BPNST from MPNST of the brachial plexus.
... It is isointense to muscle on T1-weighted images and heterogeneously hyperintense on T2-weighted images, typically with heterogeneous enhancement (Fig 9) (50,51). Some of the MRI features that may help differentiate this tumor from plexiform neurofibroma include its large size, disproportionate growth at follow-up examinations, peripheral enhancement pattern, perilesion edema-like zone, and intratumor necrosis (50)(51)(52). ...
Soft-tissue sarcomas in children comprise a heterogeneous group of entities with variable manifestation depending on the age of the patient and the location of the tumor. MRI is the modality of choice for evaluating musculoskeletal soft-tissue tumors and plays a paramount role in both initial diagnosis and assessment of tumor response during and after treatment. Conventional MRI sequences, such as T1- and T2-weighted imaging, offer morphologic information, which is important for localizing the lesion and describing anatomic relationships but not accurate for determining its malignant or benign nature and may be limited in differentiating tumor response from therapy-related changes. Advanced multiparametric MRI offers further functional information that can help with these tasks by using different imaging sequences and biomarkers. The authors present the role of MRI in rhabdomyosarcoma and other soft-tissue sarcomas in children, emphasizing a multiparametric approach with focus on the utility and potential added value of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI in characterization and staging, determination of pretreatment extent, and evaluation of tumor response and recurrence after treatment. ©RSNA, 2020.
