BACKGROUND: The authors present the only known case of a World Health Organization grade II ectopic meningioma occurring in the infraclavicular brachial plexus, causing pain within the axilla not associated with a primary malignant meningioma of the central nervous system. Peripheral nerve sheath tumors are rare entities, the majority of which are schwannomas or neurofibromas. Ectopic meningiomas only represent 1%-2% of all meningiomas. To date, there is one other published case specifically of a primary ectopic meningioma located in the brachial plexus.
METHODS: Following the dissection of the left axilla, a dominant rubbery tumor involving the median nerve was encountered. The tumor capsule contained areas of hemorrhage and a soft core with nerve fascicles coursing through, which were not compromised during internal tumor debulking. The tumor lacked a clear pseudocapsule that is characteristically seen in schwannomas. Histopathological studies confirmed an atypical epithelioid neoplasm with elevated numbers of mitotic figures and BAP1 gene deletion.
CONCLUSIONS: Primary meningiomas arising outside the central nervous system are exceedingly rare. For this unusual higher-grade primary ectopic meningioma located in the distal brachial plexus, surgery with the goal of gross-total resection, adjuvant radiation, additional imaging, and genetics screening were recommended. Close follow-up is warranted. https://thejns.org/doi/10.3171/CASE24226.

Nerve sheath myxoma (NSM) is a rare benign peripheral nerve sheath tumor that affects young adults. NSMs are asymptomatic, slow-growing swellings located in the upper extremities, more rarely in the lower extremities. Given the high risk of recurrence, it is recommended to perform a complete exeresis. To our knowledge, the evolution and management of NMS during pregnancy have not been described yet. We report the first case of recurrent pretibial NSM in a pregnant girl and its follow-up and outcome during and after pregnancy. NSM is difficult to diagnose clinically or using imaging. The final diagnosis remains histopathological. It is known how various types of benign and malignant skin tumors can develop or change during pregnancy. With our case, however, we documented that pregnancy does not affect the growth and evolution of NSM. Given the benign nature of the lesions and their tendency to grow slowly, during pregnancy, follow-up of NSMs can be conducted through ultrasonography and surgical treatment postponed after delivery. Our case highlights the importance of careful monitoring and individualized decision making, especially in rare scenarios such as NSM, where data on the progression of benign lesions are limited. Our case highlights the importance of a careful monitoring and a tailored treatment in rare scenarios such as NSM, where data on the progression of benign lesions are limited. Considering the benign nature of the lesions and their tendency to grow slowly, follow-up of NSMs during pregnancy can be conducted through ultrasonography, and surgical treatment can be postponed after delivery.

BACKGROUND: Enucleation is a surgical technique to resect peripheral nerve schwannomas. The procedure has a low risk for postoperative deficit, but a small chance for recurrence, because tumor cells may remain inside the pseudocapsule that is left after resection. Magnetic resonance imaging (MRI) scans are frequently performed after surgery to investigate potential residual tumor, but currently there is little information in the literature on the value of follow-up with MRI.
METHODS: All patients who underwent enucleation of a peripheral nerve schwannoma between October 2013 and June 2022 were included. Postoperative MRI scans (gadolinium-enhanced) made at different time points after the surgery were re-examined for residual enhancement. Patients with residual enhancement were contacted to inform whether symptoms had recurred.
RESULTS: A total of 75 schwannoma enucleations in 74 patients were included. The first postoperative MRI scan, performed 3 months after the surgery, showed no residual enhancement in 50 patients. In the remaining 24 patients, another MRI scan was made 1 year after the surgery, which still showed a possible remnant in 11 patients. On the third MRI scan, performed 2 years after enucleation, there were 7 suspected cases (9%). None of these patients had clinical symptoms at a mean postoperative follow-up of 5 years.
CONCLUSIONS: Our data show that the value of postoperative MRI scans after enucleation of peripheral nerve schwannomas is limited, because residual enhancement in the beginning can be non-specific and the small percentage of patients, that persistently had a potential remnant, were all asymptomatic.

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UNASSIGNED: Peripheral nerve sheath tumors are the most common tumor of the peripheral nerves. In general, surgery has a favorable outcome and is the treatment of choice. However, postoperative neurologic deficits are not uncommon, and predictors of outcome are poorly defined.
UNASSIGNED: To evaluate clinical outcomes after surgical treatment of benign peripheral nerve sheath tumors and identify outcome predictors that may affect preoperative decision making and improve surgical outcomes.
UNASSIGNED: In this single center retrospective study, all patients surgically treated for a benign peripheral nerve sheath tumor between 2005 and 2020 were eligible for inclusion. Medical records and imaging data were reviewed. Studied outcomes were changes in neurological symptoms, pain, and tumor recurrence. Logistic regression was performed to identify possible outcome predictors.
UNASSIGNED: In total, 81 patients undergoing 85 separate surgeries for benign peripheral nerve sheath tumors were included. The most common preoperative symptoms were local pain (90%) followed by a noticeable mass (78%), radiating pain (72%), sensory deficit (18%), and motor deficit (16%). A postoperative improvement of symptoms was seen in 94% of those with pain, 48% of those with sensory deficits and 78% of those with motor deficits. However, 35% and 9% developed new postoperative sensory and motor deficits, respectively. Multivariable analysis showed complete tumor removal as a predictor of reduced pain (p = 0.033), and younger age and larger tumors were risk factors for persistent or increased sensory deficits (p = 0.002 and p = 0.005, respectively). There were no significant predictors of motor deficits. Neurocutaneous syndromes were associated with increased odds of tumor recurrence on univariable analysis (p = 0.008).
UNASSIGNED: Surgery of benign peripheral nerve sheath tumors is a safe procedure with a favorable outcome in most cases. Younger age and larger tumors were risk factors for persistent or increased sensory deficits, while complete tumor removal was associated with reduced pain. Patients with neurocutaneous syndromes had a higher rate of tumor recurrence. To further evaluate outcome predictors, we recommend future studies to focus on longer follow-up periods to assess the natural course of postoperative neurological deficits.

Soft tissue tumors/sarcomas (STSs) in felines, encompassing a variety of mesenchymal tumors with similar histomorphological features, present diagnostic challenges due to their diverse cellular origins and the overlap with other tumor types such as feline sarcoid. This study aimed to delineate the clinical, histomorphological, and immunohistochemical characteristics of 34 feline facial spindle cell tumors affecting 29 cats, including testing for bovine papillomavirus type 14 (BPV14), the virus causing feline sarcoids. Only five out of 12 tumors previously diagnosed as feline sarcoids based on histomorphology were confirmed by PCR for BPV14, underscoring the importance of comprehensive diagnostic approaches to accurately distinguish between STSs and feline sarcoids. This study shows that most facial spindle cell tumors were compatible with peripheral nerve sheath tumors (PNSTs) based on positive immunohistochemical staining for Sox10 and other immunohistochemical markers such as GFAP, NSE, and S100. Some of these tumors displayed as multiple independent masses on the face or as erosive and ulcerative lesions without obvious mass formation, an atypical presentation and an important highlight for general practitioners, dermatologists, and oncologists. This study also describes periadnexal whorling of neoplastic cells as a novel histomorphologic finding in feline facial PNSTs and emphasizes Sox10 as a useful complementary immunohistochemical marker for the diagnosis of facial PNST in cats, providing valuable insights for veterinary pathologists.

Schwannoma is a type of peripheral nerve sheath tumor that is often found in the head and neck. Schwannomas in the digestive system, particularly the colon and rectum, are exceptionally rare, and they are mostly non-malignant and asymptomatic although sometimes patients can present with symptoms similar to those observed in patients with other gastrointestinal tumors like abdominal pain, fullness, nausea, vomiting, and change in bowel habits. For diagnosis and treatment, surgical resection along with biopsy is the gold standard. In this paper, we describe a rare case of sigmoid schwannoma that was successfully treated in our department by surgical resection.

BACKGROUND: Epithelioid malignant peripheral nerve sheath tumor (EMPNST) of the bladder is a rare entity with devastating features. These tumors are thought to originate from malignant transformation of pre-existing schwannomas of pelvic autonomic nerve plexuses, and unlike the conventional malignant peripheral nerve sheath tumor (MPNST), are not associated with neurofibromatosis. The tumor has distinctive morphological, immunohistochemical and molecular features. Additionally, it tends to be more aggressive and have a higher mortality. This is the first case that presents with a synchronous urothelial carcinoma of the bladder and the epithelioid variant of MPNST in the literature. It\'s also the second reported case of EMPNST originating from the bladder wall.
METHODS: In this case report, we present the detailed clinical course of a 71-year-old patient with EMPNST of the bladder alongside a literature review.
CONCLUSIONS: During the management of EMPNST cases, offering aggressive treatment modalities to the patient, such as radical cystectomy, is appropriate for the best chance to contain the disease, regardless of the tumor stage and the extent of local disease at initial diagnosis.

OBJECTIVE: To determine the inter-reader reliability and diagnostic performance of classification and severity scales of Neuropathy Score Reporting And Data System (NS-RADS) among readers of differing experience levels after limited teaching of the scoring system.
METHODS: This is a multi-institutional, cross-sectional, retrospective study of MRI cases of proven peripheral neuropathy (PN) conditions. Thirty-two radiology readers with varying experience levels were recruited from different institutions. Each reader attended and received a structured presentation that described the NS-RADS classification system containing examples and reviewed published articles on this subject. The readers were then asked to perform NS-RADS scoring with recording of category, subcategory, and most likely diagnosis. Inter-reader agreements were evaluated by Conger\'s kappa and diagnostic accuracy was calculated for each reader as percent correct diagnosis. A linear mixed model was used to estimate and compare accuracy between trainees and attendings.
RESULTS: Across all readers, agreement was good for NS-RADS category and moderate for subcategory. Inter-reader agreement of trainees was comparable to attendings (0.65 vs 0.65). Reader accuracy for attendings was 75% (95% CI 73%, 77%), slightly higher than for trainees (71% (69%, 72%), p = 0.0006) for nerves and comparable for muscles (attendings, 87.5% (95% CI 86.1-88.8%) and trainees, 86.6% (95% CI 85.2-87.9%), p = 0.4). NS-RADS accuracy was also higher than average accuracy for the most plausible diagnosis for attending radiologists at 67% (95% CI 63%, 71%) and for trainees at 65% (95% CI 60%, 69%) (p = 0.036).
CONCLUSIONS: Non-expert radiologists interpreted PN conditions with good accuracy and moderate-to-good inter-reader reliability using the NS-RADS scoring system.
CONCLUSIONS: The Neuropathy Score Reporting And Data System (NS-RADS) is an accurate and reliable MRI-based image scoring system for practical use for the diagnosis and grading of severity of peripheral neuromuscular disorders by both experienced and general radiologists.
CONCLUSIONS: • The Neuropathy Score Reporting And Data System (NS-RADS) can be used effectively by non-expert radiologists to categorize peripheral neuropathy. • Across 32 different experience-level readers, the agreement was good for NS-RADS category and moderate for NS-RADS subcategory. • NS-RADS accuracy was higher than the average accuracy for the most plausible diagnosis for both attending radiologists and trainees (at 75%, 71% and 65%, 65%, respectively).

The understanding of schwannoma tumorigenesis has been reshaped by the recent identification of SH3PXD2A::HTRA1 fusion in 10% of intracranial/spinal schwannomas. Nonetheless, pathologic features of schwannomas harboring this fusion, as well as its prevalence outside intracranial/spinal locations, have not been characterized. We screened 215 consecutive schwannomas for their clinicopathologic characteristics and fusion status using reverse-transcriptase polymerase chain reaction (RT-PCR). Among 29 (13.5%) fusion-positive schwannomas, the most prevalent location was peripheral somatic tissue (30.7%, 19/62), followed by spinal/paraspinal (18.4%, 7/38), body cavity/deep structures (10%, 2/20), intracranial (1.3%, 1/75), and viscera (0/13). All 8 cellular, 4 microcystic/reticular, and 3 epithelioid schwannomas were fusion-negative, as were 41/42 nonschwannomatous peripheral nerve sheath tumors. Remarkably, a distinct \'serpentine\' palisading pattern, comprising ovoid/plump cells shorter than usual schwannian cells in a hyalinized stroma, was identified in most fusion-positive cases and the schwannomatous component of the only fusion-positive malignant peripheral nerve sheath tumor. To validate this finding, 60 additional cases were collected, including 36 with (≥10% arbitrarily) and 24 without appreciable serpentine histology, of which 29 (80.6%) and 2 (8.3%) harbored the fusion, respectively. With percentages of \'serpentine\' areas scored, 10% was determined as the optimal practical cut-off to predict the fusion status (sensitivity, 0.950; specificity, 0.943). Fusion positivity was significantly associated with serpentine histology, smaller tumors, younger patients, and peripheral somatic tissue, while multivariate logistic linear regression analysis only identified serpentine histology and location as independent fusion-predicting factors. RNA in situ hybridization successfully detected the fusion junction, highly concordant with RT-PCR results. Gene expression profiling on 18 schwannomas demonstrated segregation largely consistent with fusion status. Fusion-positive cases expressed significantly higher HTRA1 mRNA abundance, perhaps exploitable as a biomarker. In summary, we systematically characterize a series of 60 SH3PXD2A::HTRA1 fusion-positive schwannomas, showing their distinctive morphology and location-specific prevalence for the first time.