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Intraosseous schwannoma is a rare benign nerve sheath tumor comprising < 1% of bone tumors. Relatively common locations for this tumor include the skull and mandible, and, to a lesser degree, the spine and sacrum. Intraosseous schwannoma involving the appendicular skeleton is exceedingly rare. The clinical and imaging presentation, as in this case, is nonspecific and includes pain in the setting of a lytic bone lesion. The first step in management is bone biopsy that often produces greater than expected pain. Definitive management is surgical. [ABSTRACT FROM AUTHOR]

Schwannomatosis is a rare neurocutaneous syndrome characterized by the presence of multiple schwannomas along the peripheral nerves, distinctly excluding the vestibular nerves. It is recognized as the third principal form of neurofibromatosis, alongside neurofibromatosis types 1 and 2. In this report, we discuss the case of a 45-year-old woman who initially sought medical attention for low back pain and swelling in her left axilla. Her magnetic resonance imaging revealed multiple enhancing intradural extramedullary lesions, along with a mass in the right upper thoracic region and another in the left axilla, raising suspicions of metastasis. However, a comprehensive analysis that aligned imaging results with histopathological findings confirmed the diagnosis of schwannomatosis. This case highlights the importance of differentiating between various conditions that can cause multiple intradural extramedullary masses, such as nerve sheath tumors, meningiomas, and metastasis. The presence of multiple schwannomas suggests a diagnosis of either neurofibromatosis type 2 or schwannomatosis, making the distinction between these two conditions critical for appropriate management.

Dendritic cell neurofibroma with pseudorosette (DCNP) is a novel entity of neurofibroma with sparse literature. Neurofibroma is a benign peripheral nerve sheath tumor having many known histological variants including localized, diffuse, plexiform, solitary, cellular, and atypical forms, all of which lead an indolent course. Like other forms of neurofibroma, DCNP usually is located in the dermis or deeper soft tissue or within the nerve trunk. It reveals a characteristic histomorphology of distinct multiple nodules comprising two types of cells: the outer lymphocyte like dark Type I cells (Schwann cell-like) forming pseudorosettes surrounding the inner scattered lighter and larger Type II cells (ganglion/dendritic cell-like). Although histogenesis of these two type of cells is debatable, immunopositivity for S100 suggests the neuronal origin and the fibrous pseudocapsule covering tumor nodules being immunopositive to epithelial membrane antigen (EMA) suggests perineurium. Here, we report two such cases of DCNP at two different yet unusual sites of cervical and perianal regions. Neither patient nor their family members had any features of neurofibromatosis(NF 1). Both the cases were adults, presented with firm nontender subcutaneous nodules of long duration causing pressure symptoms. Those were resected and evaluated for microscopy. Histomorphology aided by immunohistochemistry positivity for S100 and EMA confirmed DCNP. Follow up study after half an year of surgery was uneventful and Patients were found to be relieved of all symptoms. We present this unusual new variant that poses challenge for it’s close histological mimickers like cellular/epithelioid schwannoma and plexiform neuroma and yet want to emphasize the innocuous behavior of tumor that can be cured by surgical resection.

To evaluate the efficacy and safety of minimally invasive tubular removal of spinal schwannoma and neurofibroma. In this single-centre study, we retrospectively analysed 49 consecutive patients who underwent minimally invasive removal of a total of 51 benign spinal nerve sheath tumors using a non-expandable (n = 18) or expandable tubular retractor (n = 33) retractor system between June 2007 and December 2019. The extent of resection, surgical complications, neurological outcome, operative time, and estimated blood loss were recorded. Histopathology revealed 41 schwannomas and 10 neurofibromas. After a mean follow-up of 30.8 months, postoperative MRI showed gross total resection in 93.7%, and subtotal resection in 6.3% of the tumors. Three patients were lost to follow up. Of the subtotal resections, one was a schwannoma (2.4% subtotal resections in schwannomas) and two were neurofibromas (20.0% subtotal resections in neurofibromas). Intraspinal and paraspinal tumor localizations were equally accessible by minimally invasive tubular surgery. Conversion to open surgery was not required in any case. The mean operative time was 167 ± 68 min, and estimated blood loss was 138 ± 145 ml. We observed no major surgical complications. Spinal schwannoma and neurofibroma can be removed effectively and safely using a minimally invasive tubular approach, with satisfying extent of tumor resection comparable to the conventional open surgical technique and no increased risk for neurological deterioration. [ABSTRACT FROM AUTHOR]

Malignant peripheral nerve sheath tumors (MPNST) are rare heterogeneous group of soft tissue neoplasms. In most cases, they originate within the pre-existing neurofibromatosis. The emergence of glandular structures in MPNST is curious and enigmatic. We report a case of recurrent MPNST with glandular differentiation arising in the background of neurofibroma in a 20-year-old lady. By immunohistochemistry, MPNST showed focal positive staining for S100 and negative staining for SOX10 while adjacent neurofibroma showed diffuse positivity for S100 and SOX10. The glandular tumor cells showed positive staining for CDX2, Cam5.2, CK19, and CK7 (focal), while negative for SOX10 and S100. MPNST with glandular differentiation is quite rare which may pose a diagnostic challenge. The glandular differentiation in MPNST should be excluded from the metastasis from second primary with the aid of clinical and radiological correlation. [ABSTRACT FROM AUTHOR]

Schwannoma is a tumor that develops from the nerve sheath. The authors report an unusual case of schwannoma of the median nerve (MN) that presented with a swelling over the left elbow with symptoms of median neuropathy for a period of 2 years. The diagnosis was based on the location of the tumor, associated clinical symptoms, and signs coupled with magnetic resonance imaging and fine needle aspiration cytology results. Schwannomas are indolent tumors that can go undiagnosed for extended periods of time owing to their slow-growing nature and low propensity for malignancy. Schwannomas are most commonly observed in the MN, the commonest location being the carpal tunnel. [ABSTRACT FROM AUTHOR]

Laryngeal schwannoma is a rare benign nerve sheath tumor that is slow growing. The diagnosis is made from a combination of clinical, radiological, and histopathological findings, and the main method of treatment is resection. We report a case of a 69-year-old presenting with a neck mass causing stridor, dysphagia, and orthopnea. CT of the neck showed an enhancing mass measuring 6.3 cm and extending superior to the larynx. Emergent tracheostomy and mass resection were performed, and histopathology and immunohistochemical findings were obtained from the specimen supporting schwannoma. In conclusion, while rare, schwannoma should always be considered as a differential diagnosis for a laryngeal mass. More studies are needed to assess the size and prognosis of the tumor. [ABSTRACT FROM AUTHOR]

Palisaded encapsulated neuroma (PEN) is a benign circumscribed nerve sheath tumor usually seen as a solitary painless papule on the face in middle‐aged adults. We report a 22‐year‐old male with multiple adolescent‐onset PENs distributed extensively, including the oral cavity and palms, contrary to the typical presentations. The lesions formed cobblestoned plaques and were confirmed through a skin biopsy, showing characteristic nodules of wavy spindle cells forming interlacing fascicles with interspersed clefts, and positive staining for specific markers, including markers for axons and perineurium. Notably, this case deviates from the usual presentation, shedding light on atypical manifestations of PEN in a young individual without any features suggestive of a neurocutaneous syndrome or multiple endocrine neoplasia syndrome. [ABSTRACT FROM AUTHOR]

An epidural hemangioma is a rare lesion, representing only 4% of epidural lesions, cavernous subtype being the most common. The lesion is located in the posterior region of the spine in up to 93% of cases and the dorsal spine is affected in 80% of cases. Spinal nerve sheath tumors are the most common intradural extramedullary masses. In this case report we discuss an unusual imaging presentation of epidural hemangioma which initially was reported as nerve sheath tumor but proven on biopsy as hemangioma. It is important to throw light on the fact that an epidural hemangioma can mimic nerve sheath tumor on imaging as its consideration in our reports will help the surgeon intraoperatively to be careful about the bleeding resulting from the manipulation of the former. [ABSTRACT FROM AUTHOR]

Tumors of the skin and subcutaneous tissues are uncommon in marmosets. In this report, we describe the gross, histopathology, and immunohistochemical findings of a nerve sheath tumor that arose in the left forearm of an adult female marmoset (Callthrix jacchus). [ABSTRACT FROM AUTHOR]

Schwannoma is a benign nerve sheath tumor that arises from Schwann cells of the peripheral nerve sheath with uncertain etiology. It is well-encapsulated and a slow-growing tumor. Approximately 25-48% of cases are seen in the head and neck region. Schwannoma of the oral cavity has an approximate incidence of 1%. Tongue base Schwannoma is a rare entity. It can affect all age groups and typically presents as a painless lump. However, when it grows larger than 3 cm, it may produce dysphagia, pain, or discomfort and change in the quality of voice. Hence, Schwannoma should be considered as one of the differential diagnoses of exophytic mass of the tongue. We report a rare case of Schwannoma of the base of the tongue in a 26-year-old male who presented with a complaint of lump, along with a review of the literature published in the last 64 years. [ABSTRACT FROM AUTHOR]

Neurofibromatosis type 1 (NF1) is an autosomal dominant cancer predisposition syndrome caused by germline alterations of the NF1 gene. Patients with NF1 are at increased risk for developing benign and malignant tumors, such as optic pathway glioma and peripheral nerve sheath neoplasms. The number of effective therapies for neurofibromatosis-related tumors has been historically limited. However, there have been recent advances in understanding and developing targeted therapies for these tumors, such as mitogen-activated kinase inhibitors and multiple tyrosine kinase inhibitors. Herein, we review the most prevalent tumors occurring in patients with NF1, updated management guidelines, and explore the approach to therapy in resource-limited settings.

Purpose: Malignant peripheral nerve sheath tumors (MPNSTs) are malignant tumors that arise from peripheral nerves and are the leading cause of mortality in Neurofibromatosis Type 1 (NF1). In this study, we characterized whether transcriptomic signatures of T-cell dysfunction (TCD) and exclusion (TCE) that inversely correlate with response to immune checkpoint blockade (ICB) immunotherapy exist in MPNSTs. Methods: MPNST transcriptomes were pooled from Gene Expression Omnibus (GEO). For each sample, a tumor immune dysfunction and exclusion (TIDE) score, TCD and TCE subscores, and cytotoxic T-cell(CTL) level were calculated. In the TIDE predictive algorithm, tumors are predicted to have an ICB response if they are either immunologically hot (CTL-high) without TCD or immunologically cold (CTL-low) without TCE. TIDE scores greater than zero correspond with ICB nonresponse. Results: 73 MPNST samples met inclusion criteria, including 50 NF1-associated MPNSTs (68.5%). The average TIDE score was + 0.41 (SD = 1.16) with 22 (30.1%) predicted ICB responders. 11 samples were CTL-high (15.1%) with an average TCD score of + 0.99 (SD = 0.63). Among 62 CTL-low tumors, 21 were predicted to have ICB response with an average TCE score of + 0.31(SD = 1.20). Age(p = 0.18), sex(p = 0.41), NF1 diagnosis (p = 0.17), and PRC2 loss(p = 0.29) were not associated with ICB responder status. Conclusions: Transcriptomic analysis of TCD and TCE signatures in MPNST samples reveals that a select subset of patients with MPNSTs may benefit from ICB immunotherapy. [ABSTRACT FROM AUTHOR]

A 3-year-old intact male African pygmy hedgehog was presented at theTeaching Hospital of the Faculty of Veterinary Medicine, University of Belgrade, with a growth on the left side of its abdomen. After clinical examination, the mass was surgically removed, and histopathological findings indicated a nerve sheath tumor. The hedgehog fully recovered after surgery and was euthanized eight months later due to the appearance of multicentric changes in the internal organs. Further necropsy and macroscopic, cytologic, histopathologic, and immunohistochemical findings revealed that the tumor was a multicentric high-grade T-cell lymphoma. This is an unusual case of an African pygmy hedgehog with two different neoplasms-a nerve sheath tumor followed by lymphoma. [ABSTRACT FROM AUTHOR]

Simple Summary: Surgery for retroperitoneal benign nerve sheath tumors (PNST) is often conducted without microsurgical techniques, as evident from the literature. However, this is associated with a risk of permanent postoperative neurological deficits when lesions arise from relevant retroperitoneal nerve trunks. Among the papers describing micro/neurosurgical approaches to such tumors, only a few report more than five patients. Here, we present our interdisciplinary approach to retroperitoneal PNST in a series of 15 benign retroperitoneal tumors arising from major lumbosacral nerve trunks. The combination of expertise from both neurosurgeons and abdominal surgeons led to good neurological and oncological outcomes. Our data provide further confirmation that such an interdisciplinary approach is the optimal strategy to manage benign retroperitoneal nerve sheet tumors. Peripheral nerve sheath tumors (PNST) of the retroperitoneum are rare and are often treated by general surgeons dealing with retroperitoneal cancers. However, resection without the correct microsurgical technique can cause permanent neurological deficits and pain. Here, we discuss our interdisciplinary approach based on the integration of expertise from neurosurgery and abdominal surgery, allowing for both safe exposure and nerve-sparing microsurgical resection of these lesions. We present a series of 15 patients who underwent resection of benign retroperitoneal or pelvic PNST at our institution. The mean age of patients was 48.4 years; 67% were female. Tumors were 14 schwannomas and 1 neurofibroma. Eight patients (53%) reported neurologic symptoms preoperatively. The rate of complete resection was 87% (n = 13); all symptomatic patients showed improvement of their preoperative symptoms. There were no postoperative motor deficits; one patient (7%) developed a permanent sensory deficit. At a mean postoperative follow-up of 31 months, we observed no recurrences. To our best knowledge, this is the second-largest series of benign retroperitoneal PNST consistently managed with microsurgical techniques. Our experience confirms that interdisciplinary management allows for safe treatment of these tumors with good neurological and oncological outcomes. [ABSTRACT FROM AUTHOR]

Simple Summary: The diagnosis of retroperitoneal sarcoma may be challenging for the radiologist. Current guidelines report postsurgical margin as the strongest predictive factor for disease-specific survival and recurrence, as well as histologic subtype and grade. The role of the radiologist is indeed important in RPS diagnosis, management, and follow-up, as the ability to promptly recognize local progression, invasion of nearby structures, and complications has a direct impact on patients' survival. A practical guide is provided to radiologists with an overview of the current knowledge regarding cross-sectional CT/MRI imaging features of patients with retroperitoneal sarcomas, presenting tips and tricks to improve imaging diagnosis of RPS. Primary retroperitoneal sarcomas (RPS) represent around 10–16% of all sarcomas, with liposarcomas and leiomyosarcomas being the most common subtypes. RPS have some peculiar characteristics, imaging appearances, worse prognosis, and complications compared to other locations of sarcoma. Commonly, RPS primarily present as large masses, progressively encasing adjacent structures, causing mass effect, and complications. RPS diagnosis is often challenging, and these tumors may be overlooked; however, failure to recognize RPS characteristics leads to a worse prognosis for the patients. Surgery is the only recognized curative treatment, but the anatomical constraints of the retroperitoneum limit the ability to achieve wide resection margins; therefore, these tumors have a high rate of recurrence, and require long-term follow-up. The radiologist has an important role in the diagnosis of RPS, the definition of their extent, and their follow-up. Specific knowledge of the main imaging findings is required to reach an early diagnosis, and, ultimately, to guarantee the best patient management. This article provides an overview of the current knowledge regarding cross-sectional imaging features of patients with retroperitoneal sarcomas, presenting tips and tricks to improve imaging diagnosis of RPS. [ABSTRACT FROM AUTHOR]

Introduction: Benign peripheral nerve tumors (BPNTs) are a heterogenous group of soft tissue tumors that include a variety of nerve sheath tumors, granular cell tumor (GCT), and ganglioneuroma. Only a few large studies exist on cytopathology and diagnostic accuracy using fine‐needle aspiration (FNA) biopsy for this set of neoplasms. Materials and methods: Both surgical and cytopathology files were searched for cases of BPNT. FNA biopsy was performed using standard techniques. Results: Eighty‐nine cases from 88 patients (male:female = 1:1; age range: 16–85 years, mean age, 51 years) met inclusion criteria. FNA sites included extremities (58, 65%), head/neck (14, 16%), deep (9, 10%), and trunk (8, 10%). Aspirates were from primary neoplasms in all but one instance. There were 65 schwannomas, seven neurofibromas, seven perineuriomas, seven GCTs, and three ganglioneuromas/neuromas. Aspirates of schwannoma, GCT, neurofibroma (NF), and perineurioma (PN) were correctly diagnosed in 86%, 100%, 29%, and 0% of cases, respectively. Five tumors (6%) were interpreted as either a specific sarcoma or suspicious for sarcoma. Remaining aspirates were classified as spindle cell neoplasm, salivary gland neoplasm, and nondiagnostic. Cytologic features for schwannoma, NF, PN, and ganglioneuroma showed spindle cell–dominant smears arranged mainly in syncytial clusters. GCT aspirates contained a population of epithelioid cells harboring coarsely granular cytoplasm and bare nuclei. Immunohistochemical (IHC) staining in 55 (62%) cases showed S‐100 expression in 95%. Conclusion: FNA biopsy coupled with IHC is reliable in correctly classifying schwannoma and GCT, but less so for NF. Perineurioma can be mistaken for sarcoma. When combined with ancillary immunohistochemical staining, FNA cytopathology is capable of accurately diagnosing most benign peripheral nerve neoplasms. Isolated cellular pleomorphism is not uncommon in this tumor category, and should not be mistaken for malignancy. [ABSTRACT FROM AUTHOR]

Combined ganglioneuroma-schwannoma is an exceedingly rare tumor that has only been described in isolated case reports. We document a 64-year-old man with an incidentally discovered combined ganglioneuroma-schwannoma of the retroperitoneum that was intimately associated with sympathetic ganglia. We highlight the morphological and immunohistochemical findings of this rare tumor, and show evidence of its origin from sympathetic ganglia. [ABSTRACT FROM AUTHOR]

Background: Brachial plexus region tumors are rare. In this study, we reviewed our experience with resection of tumors involving or adjacent to the brachial plexus to identify patterns in presentation and outcome. Methods: We report a retrospective case series of brachial plexus tumors operated on by a single surgeon at a single institution over 15 years. Outcome data were recorded from the most recent follow-up office visit. Findings were compared to a prior internal series and comparable series in the literature. Results: From 2001 to 2016, 103 consecutive brachial plexus tumors in 98 patients met inclusion criteria. Ninety percent of patients presented with a palpable mass, and 81% had deficits in sensation, motor function, or both. Mean follow-up time was 10 months. Serious complications were infrequent. For patients with a preoperative motor deficit, the rate of postoperative motor decline was 10%. For patients without a preoperative motor deficit, the rate of postoperative motor decline was 35%, which decreased to 27% at 6 months. There were no differences in motor outcome based on extent of resection, tumor pathology, or age. Conclusion: We present one of the largest recent series of tumors of the brachial plexus region. Although the rate of worsened postoperative motor function was higher in those without preoperative weakness, the motor deficit improves over time and is no worse than antigravity strength in the majority of cases. Our findings help guide patient counseling in regard to postoperative motor function. [ABSTRACT FROM AUTHOR]

Background: Chondromas, benign cartilaginous primary bone tumors, seldom occur in the spine. Most spinal chondromas arise from the cartilaginous parts of the vertebra. Chondromas originating from the intervertebral disc are extraordinarily rare. Case Description: A 65-year-old female experienced recurrence of low back pain and left-sided lumbar radiculopathy after microdiscectomy and microdecompression. A mass continuous with the intervertebral disc was found to be compressing the left L3 nerve root and was resected. Histologic examination revealed a benign chondroma. Conclusion: Chondromas developing from the intervertebral disc are extremely rare; we could find only 37 reported cases. Identification of these chondromas is difficult because until surgical resection they are almost indistinguishable from herniated intervertebral discs. Here, we describe a patient with residual/recurrent lumbar radiculopathy caused by a chondroma originating from the L3-4 intervertebral disc. When a patient has recurrence of spinal nerve root compression after discectomy, a chondroma arising from the intervertebral disc is an uncommon but possible etiology. [ABSTRACT FROM AUTHOR]

• Dumbbell schwannomas with intrathoracic extension are difficult to cure surgically. • Ventral/ventrolateral approaches to the thoracic spine confer increased morbidity. • Unstaged, posterior-only approach to schwannomas with ventral extension is feasible. Dumbbell schwannomas of the thoracic spine are challenging to cure surgically. Surgeons are familiar with posterolateral approaches to the spine, however, these may provide inadequate exposure for large tumors extending to ventral extraspinal compartments. Ventrolateral transpleural approaches offer direct access to the ventral thoracic spine and intrathoracic cavity, though are associated with increased morbidity and pulmonary complications, and may necessitate a staged procedure in order to address concomitant dorsal pathology. Herein we describe our experience with single-stage, posterior approach to dumbbell schwannomas with large ventral extraspinal components, and review the literature regarding surgical approaches for these tumors. Retrospective review of patients who underwent a single-stage, posterior spinal surgery for thoracic dumbbell schwannomas from 2008 to 2018. Inclusion criteria were age > 18 years and ventral thoracic tumor component. Three patients underwent a simultaneous retropleural thoracotomy and posterior spinal approach, through a single incision, for the resection of dumbbell (intradural and extradural) schwannomas. Mean age was 49.7 years and 2 patients were female. All patients were neurologically intact at baseline. Lesions were 4–8.2 cm in the largest dimension (mean 6.1 cm). GTR was achieved in all patients. One pleural rent occurred intraoperatively; there were no other intraoperative or perioperative complications. At a mean follow-up of 14.1 months all patients remained motor and sensory intact and there was no evidence of recurrence. The combined retropleural thoracotomy-posterior spinal approach provides safe and sufficient access for resection of large dumbbell schwannomas of the thoracic spine. [ABSTRACT FROM AUTHOR]

Herniated discs in the lumbar spine are common, however, extraforaminal disc herniations are less frequently encountered. Occasionally, rare disc herniations can mimic other pathologies such as nerve tumor. We present such case and a review of similar cases in the scientific literature. A 71-year-old male who presented with back pain and right-side sciatic pain. Magnetic resonance imaging revealed a fusiform enhancing 3 cm × 2 cm lesion that was concerning for a nerve sheath tumor. A minimally invasive lateral trans-psoas approach was performed for a biopsy that revealed disc fragments and a full resection was performed. The patient's symptoms improved at follow-up. Although uncommon, extraforaminal disc herniations can be mistaken for peripheral nerve tumors on imaging. The spine surgeon should remain vigilant about these entities and plan the surgical treatment accordingly.

Spinal schwannomas (SSs) are usually benign tumors with a good prognosis when treated by surgical excision. However, complete resection can be complicated by factors such as the tumor location and configuration. In the present study, we sought to identify the factors associated with incomplete surgical resection (residual) and the factors associated with tumor recurrence. We performed a retrospective review of 113 cases of SSs treated surgically from 2008 to 2021. Of the 113 SSs, 102 were benign and 2 were malignant nerve sheath tumors. Of the 102 benign SSs, gross total resection (GTR) was performed for 87, with 8 displaying residual and 7, recurrent tumor. We found a significantly higher ratio of cervical and sacral tumors (P = 0.008 and P = 0.004, respectively), dumbbell and foraminal configurations (P < 0.0001 and P = 0.0006, respectively), and larger tumor volumes (P = 0.003) in the residual and recurrent cohorts compared with the GTR cohort. A second operation was performed for 2 patients in the residual and 4 patients in the recurrent cohorts. The total complication rate was 6%. We found that most benign SSs will be amenable to GTR (85% of cases), with an excellent prognosis. The patients with residual or recurrent tumor were more likely to have had a cervical or sacral location, a dumbbell or foraminal configuration, and a larger tumor volume. Except for 1 new SS and 1 recurrent tumor that had necessitated a lateral approach, the remainder had been treated using a posterior approach. At surgery, ultrasonography of the canal is advisable to ensure that the intra- and extraspinal components of dumbbell lesions have both been entirely removed. [ABSTRACT FROM AUTHOR]

Familial melanoma-astrocytoma syndrome is a tumor predisposition syndrome caused by inactivating germline alteration of the CDKN2A tumor suppressor gene on chromosome 9p21. While some families with germline CDKN2A mutations are prone to development of just melanomas, other families develop both melanomas, astrocytomas, and occasionally other nervous-system neoplasms including peripheral nerve sheath tumors and meningiomas. The histologic spectrum of the astrocytomas that arise as part of this syndrome is not well described, nor are the additional genetic alterations that drive these astrocytomas apart from the germline CDKN2A inactivation. Herein, we report the case of a young man with synchronous development of a pleomorphic xanthoastrocytoma, diffuse astrocytoma, and paraspinal mass radiographically consistent with a peripheral nerve sheath tumor. His paternal family history is significant for melanoma, glioblastoma, and oral squamous cell carcinoma. Genomic profiling revealed that he harbors a heterozygous deletion in the germline of chromosome 9p21.3 encompassing the CDKN2A and CDKN2B tumor suppressor genes. Both the pleomorphic xanthoastrocytoma and diffuse astrocytoma were found to have homozygous deletion of CDKN2A/B due to somatic loss of the other copy of chromosome 9p containing the remaining intact alleles. Additional somatic alterations included BRAF p.V600E mutation in the pleomorphic xanthoastrocytoma and PTPN11, ATRX, and NF1 mutations in the diffuse astrocytoma. The presence of germline CDKN2A/B inactivation together with the presence of multiple anatomically, histologically, and genetically distinct astrocytic neoplasms, both with accompanying somatic loss of heterozygosity for the CDKN2A/B deletion, led to a diagnosis of familial melanoma-astrocytoma syndrome. This remarkable case illustrates the histologic and genetic diversity that astrocytomas arising as part of this rare glioma predisposition syndrome can demonstrate.
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Schwannoma is a slow-growing benign tumor that originates from the nerve sheath consisting of the Schwann cells. It is an encapsulated nerve sheath tumor of neuroectodermal origin. This is an encapsulated and well-circumscribed lesion composed of different cellular patterns. Schwannoma usually originates from the superior vestibular nerve in the internal auditory canal. These tumors are rarely found in the external ear. Schwannoma is an extremely rare tumor on the pinna. The most common clinical presentation of the schwannoma on the pinna is painless progressive swelling. The diagnosis of schwannoma is confirmed by histopathological study and immunohistochemistry. Here, we report a case of schwannoma that was found on the external ear which is very uncommon in routine clinical practice. [ABSTRACT FROM AUTHOR]

Spinal neurofibromatosis (SNF) is a rare form of Neurofibromatosis in which neurofibromas exist bilaterally throughout all spinal roots. Despite previous attempts made to characterize and classify the disease as a separate clinical form of the disease, the low incidence rate of the disease and scarcity of previous reports calls for further studies and reports to elaborate this clinical entity. The patient in this report was a 36-year-old man presenting with lower limb weakness, unsteady gait, and paresthesia. The patient also presented with multiple cutaneous café-au-lait spots, cutaneous neurofibromas, and a large neurocutaneous neurofibroma of right facial nerve. Magnetic resonance imaging (MRI) of spine revealed bilateral spinal neurofibromas across all spinal cord roots. MRI study of head revealed no abnormalities in the brain and optic tract. The patient fulfilled both NIH criteria as well as revised criteria for NF1. Despite total spinal cord involvement, surgical intervention was withheld from the patient due to high propensity of recurrence as seen with previous attempts in removing peripheral neurofibromas, slowprogression of symptoms, and lack of significant pain and impairment. SNF is often described as a form of disease with infrequent presentation of classical NF1 symptoms other than spinal tumors. The case presented here however, presented with several cutaneous neurofibromas and café-au-lait spots. Considering the positive outcome of surgical intervention in a few other reports, the decision to surgically intervene should be left to the clinical judgement of the participating surgeon, patient preference and socioeconomic background in a case-by-case manner. [ABSTRACT FROM AUTHOR]

Cranial nerve schwannomas almost always arise from sensory or mixed nerves. Motor cranial nerves, such as the trochlear nerve, are rarely associated with schwannomas. No consensus has yet been made for surgical intervention because of the low number of reported cases of trochlear nerve schwannomas. This study comprises a systematic review of the literature and our experience for surgically treated trochlear nerve schwannomas. Three databases (Web of Science, PubMed, and Cochrane Library) were searched without date restrictions. Studies were included if they were published in the English literature and presented patients of any age who underwent surgical treatment for trochlear schwannoma. Data extracted from the included studies were combined with our experience. Forty-one studies, presenting 43 patients, met the inclusion criteria. The total number of patients was 45 after our experience was added. The most common symptoms were diplopia (62.2%), headache (46.7%), and motor weakness (37.8%). Mean age during the diagnosis was 45.1 years. Although the subtemporal transtentorial approach (n = 14) is the most preferred method, its application has decreased in recent years. In the last decade, the lateral suboccipital approach (n = 11) has gained popularity. Residual postoperative trochlear nerve deficit was detected in 81% of patients. The probability of neurologic deficit was not statistically associated with tumor volume (P = 0.914), location (P = 0.669), or resection rate (P = 0.554). Although trochlear schwannomas are rare and their treatment involves challenges, total resection with the proper approach provides the most desirable results. [ABSTRACT FROM AUTHOR]

Spinal neurofibromatosis (SNF) is a rare form of Neurofibromatosis in which neurofibromas exist bilaterally throughout all spinal roots. Despite previous attempts made to characterize and classify the disease as a separate clinical form of the disease, the low incidence rate of the disease and scarcity of previous reports calls for further studies and reports to elaborate this clinical entity. The patient in this report was a 36-year-old man presenting with lower limb weakness, unsteady gait, and paresthesia. The patient also presented with multiple cutaneous café-au-lait spots, cutaneous neurofibromas, and a large neurocutaneous neurofibroma of right facial nerve. Magnetic resonance imaging (MRI) of spine revealed bilateral spinal neurofibromas across all spinal cord roots. MRI study of head revealed no abnormalities in the brain and optic tract. The patient fulfilled both NIH criteria as well as revised criteria for NF1. Despite total spinal cord involvement, surgical intervention was withheld from the patient due to high propensity of recurrence as seen with previous attempts in removing peripheral neurofibromas, slow progression of symptoms, and lack of significant pain and impairment. SNF is often described as a form of disease with infrequent presentation of classical NF1 symptoms other than spinal tumors. The case presented here however, presented with several cutaneous neurofibromas and café-au-lait spots. Considering the positive outcome of surgical intervention in a few other reports, the decision to surgically intervene should be left to the clinical judgement of the participating surgeon, patient preference and socioeconomic background in a case-by-case manner.

Malignant melanotic nerve sheath tumor (MMNST) is a rare and potentially aggressive lesion defined in the 2021 WHO Classification of Tumors of the Central Nervous System. MMNST demonstrate overlapping histologic and clinical features of schwannoma and melanoma. MMNST often harbor PRKAR1A mutations, especially within the Carney Complex. We present a case of aggressive MMNST of the sacral region in a 48-year-old woman. The tumor contained PRKAR1A frameshift pR352Hfs*89, KMT2C splice site c.7443-1G>T and GNAQ p.R183L missense mutations, as well as BRAF and MYC gains. Genomic DNA methylation analysis using the Illumina 850K EpicBead chip revealed that the lesion did not match an established methylation class; however, uniform manifold approximation and projection (UMAP) placed the tumor very near, or with, schwannomas. The tumor expressed PD-L1, and the patient was treated with radiation and immune checkpoint inhibitors following en bloc resection. Although she had symptomatic improvement, she suffered early disease progression with local recurrence, and distant metastases, and died 18 months after resection. It has been suggested that the presence of GNAQ mutations can differentiate leptomeningeal melanocytic neoplasms and uveal melanoma from MMNST. This case and others demonstrate that GNAQ mutations may exist in malignant nerve sheath tumors; that GNAQ and PRKAR1A mutations are not always mutually exclusive and that neither can be used to differentiate MMNST or MPNST from all melanocytic lesions.

Nerve sheath tumors (NSTs) are characterized by neoplastic proliferation of Schwann cells, perineurial cells, endoneurial and/or epineurial fibroblasts. Diagnosis of NST is often challenging, particularly in distinguishing malignant NST (MNST) from other soft tissue sarcomas, or sometimes between low-grade MNST and benign NST. Recent studies in human pathology have demonstrated loss of trimethylation at lysine 27 of histone 3 (H3K27me3) in a subset of MNSTs using immunohistochemistry. Loss of H3K27me3 expression is rare in other high-grade sarcomas and also appears to be useful in distinguishing benign and low-grade MNSTs from high-grade subsets. In our retrospective study, we performed H3K27me3 immunohistochemistry in 68 canine tumors previously diagnosed as NST. We detected loss of H3K27me3 expression in 25% (n = 17) of all canine NST, including one neurofibroma, whereas 49% (n = 33) of tumors had mosaic loss of expression and 26% (n = 18) retained expression. No statistically significant differences were found between H3K27me3 expression, histopathological features of tumors, and their immunoreactivity for Sox10, claudin-1, GFAP, and Ki67. Because the classification of canine NST is not yet fully established and its correlation with the prognosis and clinical course of the disease is lacking, prospective studies with possible genetic analyses are needed to assess the true diagnostic value of H3K27me3 loss in canine NST.

Nerve sheath tumors are a group of tumors originating from Schwann cells, fibroblasts, and perineurial cells. In veterinary pathology, the terminology for nerve sheath tumors remains inconsistent, and many pathologists follow the human classification of such tumors in practice. Immunohistochemistry plays an important role in the diagnosis of nerve sheath tumors, but specific immunohistochemical and molecular biomarkers are lacking. In our study, we histopathologically reevaluated 79 canine nerve sheath tumors and assessed their reactivity for the immunohistochemical markers Sox10, claudin-1, GFAP, CNPase, and Ki-67. Based on the results, we classified the tumors according to the most recent human classification. Twelve cases were diagnosed as benign nerve sheath tumors, including six neurofibromas, three nerve sheath myxomas, two hybrid nerve sheath tumors (perineurioma/neurofibroma and perineurioma/schwannoma), and one schwannoma. Sixty-seven tumors were malignant nerve sheath tumors, including fifty-six conventional, four perineural, one epithelioid malignant nerve sheath tumor, and six malignant nerve sheath tumors with divergent differentiation. We believe that with the application of the proposed panel, an updated classification of canine nerve sheath tumors could largely follow the recent human WHO classification of tumors of the cranial and paraspinal nerves, but prospective studies would be needed to assess its prognostic value. [ABSTRACT FROM AUTHOR]

Amaç: Schwannomlar, Schwann hücrelerinden köken alan benign periferik sinir kılıfı tümörleridir.Sıklıkla asemptomatik, yavaş büyüyen, gerçek kapsülle çevrili, kesit yüzü pembe, beyaz-sarı renkli, genellikle küçük tümörlerdir. Bu çalışmanın amacı schwannomların görülme yaşı, cinsiyet, boyut, yerleşim yeri gibi özelliklerini ortaya koymak ve bu özellikler arasındaki ilişkiyi araştırmaktır. Gereç ve Yöntem: Konya Eğitim ve Araştırma Hastanesi Patoloji Kliniği’nde 2008-2018 yılları arasında schwannom tanısı alan hastaların verileri retrospektif olarak incelendi. Bulgular: Olguların yaş ortalaması 41.25±18.4’dür. Schwannomlar ortalama 2.96±2.1 cm çapındadır. 101 olgunun 51’i erkek, 50’si kadındır. Olguların 76’sında %75.3 tümör dermal ve subkutan, 11’inde %10.9 mediastinal, 11’inde %10.9 intraabdominal, 3’ünde %2.9 intrakranial ve spinal yerleşimlidir. Dermal ve subkutan schwannomlar DSS ’ın 39’u %51.3 ekstremite, 22’si %29 baş-boyun bölgesi, 15’i %19.7 gövde yerleşimlidir. 97 olguda tümör soliter ve sporadiktir. İntraabdominal schwannomlar İAS ’ın9’u %81.8 kadın, 2’si %18.2 erkektir. Ortalama tümör çapı DSS’da 2.32±1.58 cm, intrakraniyal ve spinal schwannomlar İKSS da 3.40±0.79 cm, mediastinal schwannomlar MS ’da 5.26±2.28 cm, İAS’da 5.00±2.62 cm’dir. MS’lu bir olguda eksizyondan bir yıl sonra tümör nüks etmiştir. Sonuç: Schwannomlar en sık 5.dekatta, genellikle 5 cm’den küçük, sıklıkla dermal ve subkutan yerleşimli olarakekstremite ve baş-boyun bölgesinde, her iki cinsiyette eşit sıklıkta, büyük çoğunluğu soliter ve sporadik olarak izlendi. İAS kadınlarda daha sıktır. DSS,MS ve İAS’lardan daha küçüktür. Nüks nadirdir.

Clear cell tumors of parotid gland encompass a wide spectrum of neoplasms, including benign and malignant epithelial neoplasms. Additionally, tumors from adjacent structures such as paraganglioma, and metastatic neoplasms may also show clear cells. Overlapping cytological features may cause difficulty in diagnosis. This 50-year-old female presented with inability to close the right eye for 4 years, and with an infra-auricular swelling. Fine-needle aspiration cytology (FNAC) done outside was submitted for review with a diagnosis of neuroendocrine tumor. Smears showed clusters of tumor cells with abundant vacuolated cytoplasm and uniform round to ovoid nuclei. Features were those of salivary gland neoplasm of uncertain malignant potential, that is Milan category IVB: cellular neoplasm with clear cell features, with differential diagnoses of myoepithelial cell neoplasms, acinic cell carcinoma and paraganglioma. FNAC repeated for better characterization showed similar polygonal cells, accompanied by few spindle-shaped cells with ovoid nuclei, suggestive of paraganglioma. However, DOTANOC uptake was absent. Patient underwent radical parotidectomy; intraoperative frozen section showed a spindle cell tumor. Final histopathology revealed an intraparotid facial nerve schwannoma. The tumor was multi-nodular, with some nodules being composed almost entirely of polygonal cells with clear cytoplasm, that is, Antoni B areas, and others showing typical Antoni A areas admixed with Antoni B areas. Parotid FNAC has high accuracy for diagnosis of epithelial lesions; however, mesenchymal tumors often pose a diagnostic difficulty. Intraparotid schwannoma is not uncommon and may be diagnosed easily on FNAC when morphology is classical. However, intra-tumoral heterogeneity and less common histological subtypes may present a pitfall in cytodiagnosis., (© 2024 Wiley Periodicals LLC.)

Consensus recommendation published in 2017 histologically defining atypical neurofibromatous neoplasm of uncertain biologic potential (ANNUBP) and malignant peripheral nerve sheath tumor (MPNST) were codified in the 2021 WHO Classification of Tumors of the Central Nervous System and the 2022 WHO Classification of Tumors of Soft Tissue and Bone. However, given the shift in diagnostic pathology toward the use of integrated histopathologic and genomic approaches, the incorporation of additional molecular strata in the classification of Neurofibromatosis Type 1 (NF1)-associated peripheral nerve sheath tumors should be formalized to aid in accurate diagnosis and early identification of malignant transformation to enable appropriate intervention for affected patients. To this end, we assembled a multi-institutional expert pathology working group as part of a "Symposium on Atypical Neurofibroma: State of the Science". Herein, we provide a suggested framework for adequate interventional radiology and surgical sampling, and recommend molecular profiling for clinically or radiologically worrisome non-cutaneous lesions in patients with NF1 to identify diagnostically-relevant molecular features, including CDKN2A/B inactivation for ANNUBP, as well as SUZ12, EED, or TP53 inactivating mutations, or significant aneuploidy for MPNST. We also propose renaming "low-grade MPNST" to "ANNUBP with increased proliferation" to avoid the use of the "malignant" term in this group of tumors with persistent unknown biologic potential. This refined integrated diagnostic approach for NF1-associated peripheral nerve sheath tumors should continue to evolve in concert with our understanding of these neoplasms., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Neuro-Oncology.)

Background: The authors report on a patient who presented with an extremely large presacral schwannoma and subsequent mass effect-induced hydronephrosis and kidney failure. To the authors' knowledge, this case represents the largest radiographically verified spinal schwannoma in the medical literature. The tumor presented here was more than three times as large as a typical giant schwannoma. While smaller presacral schwannomas are usually uncomplicated surgical cases, the supergiant schwannomas described here create significant surgical challenges., Observations: The extremely large size of this nerve sheath tumor introduced a level of surgical complexity not seen in most spinal schwannoma cases. The authors hope that this case informs surgeons regarding the approach to excision of giant spinal schwannomas., Lessons: The resection of giant spinal schwannomas is likely to involve one or more lengthy surgeries, and the resection volume can be limited by excessive bleeding. Physicians approaching these large, benign spinal tumors should be aware of the challenges of surgery duration and hemostasis before approaching a tumor of this kind. https://thejns.org/doi/10.3171/CASE24224.

Background: Granular cell tumors (GCTs) are uncommon peripheral nerve sheath tumors of Schwann cell origin that may occur throughout the body. However, they rarely occur in the spinal canal. Case Description: A 49-year-old male presented with burning sensation in the left knee. The MRI of the lumbar spine showed an L3-L4 intradural extramedullary tumor. Complete surgical resection was successfully performed and the L3 root burning improved. Histopathologically, the lesion proved to be a benign GCT. Conclusion: Spinal GCTs are rare benign tumors that may be found in an intradural extramedullary location in the spine. The preferred treatment is complete surgical resection as subtotal/partial resection may result in recurrence warranting radiation therapy. [ABSTRACT FROM AUTHOR]

Herniated discs in the lumbar spine are common, however, extraforaminal disc herniations are less frequently encountered. Occasionally, rare disc herniations can mimic other pathologies such as nerve tumor. We present such case and a review of similar cases in the scientific literature. A 71-year-old male who presented with back pain and right-side sciatic pain. Magnetic resonance imaging revealed a fusiform enhancing 3 cm × 2 cm lesion that was concerning for a nerve sheath tumor. A minimally invasive lateral trans-psoas approach was performed for a biopsy that revealed disc fragments and a full resection was performed. The patient's symptoms improved at follow-up. Although uncommon, extraforaminal disc herniations can be mistaken for peripheral nerve tumors on imaging. The spine surgeon should remain vigilant about these entities and plan the surgical treatment accordingly. [ABSTRACT FROM AUTHOR]

Benign tumors of brachial plexus (BP) are relatively rare. However, these tumors pose a surgical challenge due to their origin in an anatomically complex region containing neurovascular tissue nexus. We describe a case of giant BP schwannoma involving the right neck and supraclavicular fossa extending to the right pectoral region without any associated neurological deficit.