Bulky malignant peripheral nerve sheath tumour of the left thigh in a pregnant woman presenting with a pathological fracture of the proximal femur.

Malignant peripheral nerve sheath tumour (MPNST) is an aggressive soft tissue sarcoma with a poor prognosis, affecting most commonly the extremities. The lungs constitute the most frequent location for distant metastases. Half of all MPNSTs arise in patients with neurofibromatosis type 1, while approximately 10% are radiation induced and the rest are sporadic.The authors present a pregnant woman in her 40s with a sporadic MPNST of the lower limb and with lung metastases at diagnosis. Treatment consisted of interilioabdominal amputation, followed by adjuvant chemotherapy. Partial response and disease stabilisation were achieved with chemotherapy.Surgical resection with negative margins is the only potentially curative therapy, while radiation therapy and chemotherapy might be useful in the neoadjuvant or adjuvant setting, but their advantage in survival is not demonstrated. In the reported case, chemotherapy permitted the achievement of partial response and stabilisation of the disease.

Asymmetry of thalamic hypometabolism on FDG-PET/CT in neurofibromatosis type 1: Association with peripheral tumor burden.

BACKGROUND AND PURPOSE: Thalamic hypometabolism is a consistent finding in brain PET with F-18 fluorodeoxyglucose (FDG) in patients with neurofibromatosis type 1 (NF1). However, the pathophysiology of this metabolic alteration is unknown. We hypothesized that it might be secondary to disturbance of peripheral input to the thalamus by NF1-characteristic peripheral nerve sheath tumors (PNSTs). To test this hypothesis, we investigated the relationship between thalamic FDG uptake and the number, volume, and localization of PNSTs. METHODS: This retrospective study included 22 adult NF1 patients (41% women, 36.2 ± 13.0 years) referred to whole-body FDG-PET/contrast-enhanced CT for suspected malignant transformation of PNSTs and 22 sex- and age-matched controls. Brain FDG uptake was scaled voxelwise to the individual median uptake in cerebellar gray matter. Bilateral mean and left-right asymmetry of thalamic FDG uptake were determined using a left-right symmetric anatomical thalamus mask. PNSTs were manually segmented in contrast-enhanced CT. RESULTS: Thalamic FDG uptake was reduced in NF1 patients by 2.0 standard deviations (p < .0005) compared to controls. Left-right asymmetry was increased by 1.3 standard deviations (p = .013). Thalamic hypometabolism was higher in NF1 patients with ≥3 PNSTs than in patients with ≤2 PNSTs (2.6 vs. 1.6 standard deviations, p = .032). The impact of the occurrence of paraspinal/paravertebral PNSTs and of the mean PNST volume on thalamic FDG uptake did not reach statistical significance (p = .098 and p = .189). Left-right asymmetry of thalamic FDG uptake was not associated with left-right asymmetry of PNST burden (p = .658). CONCLUSIONS: This study provides first evidence of left-right asymmetry of thalamic hypometabolism in NF1 and that it might be mediated by NF1-associated peripheral tumors.

A case report of giant malignant schwannoma of the sciatic nerve associated with neurofibromatosis-1: A CARE-compliant article.

RATIONALE: Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous syndrome that causes multiple central and peripheral nerve sheath tumors. People with NF1 have a 10% chance of developing malignant peripheral nerve sheath tumors (MPNSTs). Here we report a unique instance of a malignant schwannoma that has remained free of metastasis since its initial removal a decade ago. The malign schwannoma has been infrequently documented in the literature, and remarkably, no instances of such an extensive postoperative time without metastases have ever been described. PATIENT CONCERNS: A 46-year-old male patient with NF had multiple neurofibromas in different parts of his body, underwent surgery about 10 years ago (2013), and was diagnosed histopathologically as MPNST. DIAGNOSES: He was admitted to our institution with a recurrent mass in the posterior third of the proximal thigh and severe pain radiating to the left lower extremity, which presented as sciatic pain (2021). A magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography examination revealed that the tumor was likely malignant. INTERVENTIONS: Surgical excision was performed. OUTCOME: A 10-year follow-up revealed no metastases or neurologic impairment. LESSONS: When articles about benign schwannomas are placed in a separate category, little is written about NF-1-related malignant schwannomas of the sciatic nerve. MPNSTs are high-grade, aggressive sarcomas with a high risk of local recurrence (40%-65%) and metastasis to other body parts. Therefore, among the various benign peripheral nerve sheath tumors in NF-1 patients, the diagnosis of MPNST is crucial.Orthopedic surgeons should be aware that neurofibromas in NF-1 have a significant risk of developing MPNSTs. This study reports the successful treatment of a giant malignant sciatic nerve schwannoma with a long follow-up period without metastasis.

Surgical Management of Peripheral Nerve Pathology in Patients With Neurofibromatosis Type 2.

BACKGROUND: Neurofibromatosis type 2 (NF2) is rare genetic disorder mainly characterized by the development of central nervous system lesions, but peripheral nerve pathology may also cause high morbidity including pain, motor, and sensory loss. OBJECTIVE: To describe the tumor burden of patients with peripheral nerve pathology in NF2 including peripheral neuropathies and schwannomas and the results of surgery in the latter group. METHODS: We conducted a retrospective chart review of all patients with NF2 followed up at our NF2 Reference Center to include all patients suffering from peripheral nerve pathology. Tumor detection relied on focal MRIs based on symptoms. RESULTS: Thirty-four patients harboring 105 peripheral nerve schwannomas and 1 perineurioma were included. Schwannomas were mainly located in major nerves (n = 74, 71%) compared with subcutaneous (n = 23, 22%) and intramuscular (n = 8, 7%) cases. Most schwannomas (81/90-90%) were classical discrete tumors while multinodular cases represented only 9 cases (10%). During follow-up, 63 (60%) tumors were operated in 24 patients, including 39 schwannomas of major nerves. A complete resection was achieved in most of the cases (52/63, 83%) with a complete relief of preoperative pain in most patients (57/60, 95%). Persistent motor deficits (5/39, 13%) were mostly encountered in patients operated from multinodular schwannomas (4/5, 80%). Six patients had an associated peripheral neuropathy with 5 cases of pseudo-Charcot-Marie-Tooth-associated amyotrophy. CONCLUSION: Surgery remains a safe and effective method of treating peripheral nerve schwannoma-associated pain in NF2, with the exception of rare multinodular tumors. Special attention should be drawn to patients harboring severely debilitating neuropathies and perineuriomas.

Malignant Peripheral Nerve Sheath Tumors Without Muscle Weakness at Presentation: An Analysis of an Underappreciated Combination.

OBJECTIVE: Patients with malignant peripheral nerve sheath tumors (MPNSTs) of major motor nerves typically present with muscle weakness and pain. We aimed to analyze and characterize patients with MPNSTs of major motor nerves but without muscle weakness at initial presentation. METHODS: We performed a retrospective search of MPNSTs in a major nerve evaluated and/or treated at our institution from 1994 to 2019. Patients with no muscle weakness and available magnetic resonance imaging were analyzed. Clinical materials and magnetic resonance imaging and positron emission tomography scans were reviewed for features of malignancy. This group of patients was compared with patients who presented with MPNSTs and muscle weakness. RESULTS: Of 26 patients with MPNSTs who presented with no muscle weakness, 21 (81%) had a positive family history for malignancy. Only 16 (62%) magnetic resonance imaging scans were highly suspicious for malignancy. All 7 available positron emission tomography scans were highly suspicious for malignancy. Patients who presented with muscle weakness (n = 36) were more likely to have paresthesias and a history of neurofibromatosis 1 or radiation to the MPNST location (P < 0.05). CONCLUSIONS: MPNSTs of major motor nerves without muscle weakness represent an underappreciated subset of cases that have potential treatment and outcome implications. These patients presented with fewer symptoms and had fewer risk factors than patients with muscle weakness. Positron emission tomography should be considered as an additional method to try to anticipate the diagnosis of an MPNST.

Malignant nerve sheath tumor of oculomotor nerve in a pediatric patient.

Malignant nerve sheath tumors are extremely rare pathologies. They tend to occur within peripheral nerves and have close association of neurofibromatosis disease. Here, we present the second case of MNST of oculomotor nerve in literature. The patient was a 2-year-old girl with left sided oculomotor nerve palsy. After resection, the patient immediately had chemotherapy and radiotherapy. One year after surgery disease progressed with extensive intracranial seedings, and she passed away.

Brachial artery thrombosis in a dog causing monoparesis mimicking nerve sheath tumor.

There are few differential diagnoses for non-orthopedic thoracic limb lameness in adult dogs aside from nerve tumors and disk-associated nerve compression; this report introduces another etiology. A 9-year-old male castrated mixed dog presented with an episodic history of nonweight-bearing thoracic limb lameness. Additional clinical signs included an atrophied thoracic limb with cool paw pads and painful axillary region. Magnetic resonance imaging, computed tomography, ultrasound, and exploratory surgery confirmed a chronic thrombus of the right brachial artery. No underlying cause for the thrombus was identified. The dog has been successfully managed on long-term rivaroxaban and clopidogrel. Follow-up ultrasound of the thrombus suggested early remodeling.

Malignant peripheral nerve sheath tumors arising from schwannomas: case series and literature review.

A malignant peripheral nerve sheath tumor (MPNST) arising from a schwannoma is extremely rare, with limited literature on its clinicopathologic features. Here, we present a case series and literature review on patients with MPNSTs arising from schwannomas. We performed a retrospective review of patients from our institution's records to identify those with MPNSTs arising from schwannomas. We conducted a search for additional cases from the literature utilizing PubMed. 20 patients (including 2 at our institution and 18 from 16 prior publications) were identified. The patients aged 22-93 (mean 52) years, and 63% were females. Histologically, while most MPNSTs arising from schwannomas were of epithelioid-type, 7 tumors (including 2 at our institution) were of conventional spindle-cell type. All 20 patients underwent surgical excision, while a subset received additional radiotherapy and/or chemotherapy. In 17 patients with available follow-up, the overall survival was 2-72 (median 12) months. MPNSTs rarely arise from schwannomas and should be considered in patients with a clinical diagnosis of schwannoma, however, with atypical radiologic or clinical features. MPNSTs arising from schwannomas can show epithelioid or spindle-cell histology and harbor an aggressive course, even with surgical excision and adjuvant treatment.

Tarsal Tunnel Syndrome.

Tarsal tunnel syndrome is paresthesia and pain in the foot and ankle caused by entrapment and compression of the tibial nerve within the fibro-osseous tarsal tunnel beneath the flexor retinaculum. The most helpful diagnostic criteria are a positive Tinel sign at the ankle and objective sensory loss along the distribution of the tibial nerve. Treatment is designed to reduce the compression of the nerve, and surgical nerve release is indicated with failure of conservative options. It is important to identify the causative factor of the nerve compression and eliminate it to obtain excellent results.

Repetitive syncope caused by a rare massive sporadic malignant peripheral nerve sheath tumor involving carotid arteries: A case report.

RATIONALE: Malignant peripheral nerve sheath tumors (MPNSTs) are rare sarcomas arising from peripheral nerves. MPNSTs are uncommon in the head and neck, and various clinical manifestation often make the diagnosis challenging. PATIENT CONCERNS: A 67-year-old female was referred for evaluation of repetitive syncope with a massive mass in the neck. Preoperative evaluation revealed potential neuroendocrine activity of the mass and enhanced computed tomography showed carotid artery was involved. DIAGNOSIS: According to the preoperative imaging, intraoperative finding and postoperative pathological examination, the diagnosis of left neck MPNST involving left carotid arteries was made. INTERVENTIONS: Volume expansion therapy with phenoxybenzamine started one week before surgery. Complete surgical resection of the mass was performed and pathological analysis suggested the diagnosis of MPNST. The postoperative radiotherapy was not given due to her poor nutrition. OUTCOMES: This patient recovered well after surgery and no sign of recurrence was noted at 2-year follow-up. LESSONS: Though the involvement of carotid artery with neuroendocrine activity is rare in sporadic MPNST, preoperative scanning of blood and urine catecholamine is crucial for intraoperative hemodynamic stability, especially when carotid artery is involved.

Chromosome 8 gain is associated with high-grade transformation in MPNST.

One of the most common malignancies affecting adults with Neurofibromatosis type 1 (NF1) is the malignant peripheral nerve sheath tumor (MPNST), an aggressive and often fatal sarcoma that commonly arises from benign plexiform neurofibromas. Despite advances in our understanding of MPNST pathobiology, there are few effective therapeutic options, and no investigational agents have proven successful in clinical trials. To further understand the genomic heterogeneity of MPNST, and to generate a preclinical platform that encompasses this heterogeneity, we developed a collection of NF1-MPNST patient-derived xenografts (PDX). These PDX were compared with the primary tumors from which they were derived using copy number analysis, whole exome sequencing, and RNA sequencing. We identified chromosome 8 gain as a recurrent genomic event in MPNST and validated its occurrence by FISH in the PDX and parental tumors, in a validation cohort, and by single-cell sequencing in the PDX. Finally, we show that chromosome 8 gain is associated with inferior overall survival in soft-tissue sarcomas. These data suggest that chromosome 8 gain is a critical event in MPNST pathogenesis and may account for the aggressive nature and poor outcomes in this sarcoma subtype.

Malignant Intracerebral Nerve Sheath Tumor Presenting With Intratumoral Hemorrhage.

BACKGROUND: Primary central nervous system sarcomas are rare primitive mesenchymal non-meningothelial tumors. Malignant peripheral nerve sheath tumor accounts for 5% of sarcomas, with an incidence of approximately 0.001% and a recognized association with neurofibromatosis type 1. Its intracranial subtype, the so-called malignant intracerebral nerve sheath tumor (MINST), is even more infrequent. Current knowledge about its clinical presentation and best therapeutic management is poor because of the limited number of cases reported in literature. Commonly, intratumoral hemorrhage occurs at the time of diagnosis and, notably, most patients had intracranial hemorrhage prior to definitive diagnosis. CASE DESCRIPTION: We report a case of MINST in a young boy affected by neurofibromatosis type 1 who presented a spontaneous intracranial hemorrhage, successfully treated with surgery and postoperative adjuvant therapy. The tumor relapsed 1 year after and was successfully retreated with a second surgery. CONCLUSIONS: Malignant intracerebral nerve sheath tumors are rare sarcomas that can be associated with intratumoral hemorrhage at the time of presentation, mostly in patients with neurofibromatosis type 1. Surgery promptly performed, associated with adjuvant therapy, can result in an encouraging survival rate.

Association of intraneural perineurioma with neurofibromatosis type 2.

BACKGROUND: Neurofibromatosis type 2 (NF2) is a genetic disorder characterized by mutations of the NF2 tumor suppressor gene that predisposes patients to develop multiple tumors in the peripheral and central nervous system. The most common neoplasms associated with the disease are schwannomas and meningiomas. Both have been shown to contain abnormalities in chromosome 22 and the NF2 gene, suggesting a genetic component to their pathogenesis. Perineuriomas are rare benign tumors arising from the perineural cells. They are commonly classified as intraneural and soft tissue perineuriomas. Several studies have reported mutations in genes on chromosome 22 in both types of perineuriomas, and there are reports of soft tissue perineuriomas associated with NF2 gene mutations. Despite this, perineuriomas are not considered as part of the NF2 constellation of tumors. METHOD: The electronic medical records were searched for patients with a radiologic or pathologic diagnosis of intraneural perineurioma. Patients with clinical signs and genetic testing consistent with a diagnosis of NF2 were further evaluated. RESULTS: Of 112 patients meeting inclusion criteria, there were two cases of intraneural perineurioma in patients with NF2 treated at our institution (1.8%). We include a third patient treated at another facility for whom we performed a virtual consultation. CONCLUSIONS: The rarity of both NF2 and perineuriomas could explain the rarity of perineuriomas in the setting of NF2. Furthermore, there is divergent intraneural and soft tissue perineurioma somatic mutation pathogenesis, and there may be cytogenetic overlap between perineuriomas and multiple tumor syndromes. Our observed occurrence of intraneural perineurioma in the setting of NF2 in several patients provides further evidence of a potential link between the NF2 gene and the development of intraneural perineurioma.

Limb Undergrowth in Intraneural Perineuriomas: An Under-Recognized Association.

BACKGROUND: Intraneural (IN) perineuriomas are a rare benign hypertrophic nerve tumor, most frequently occurring in young patients. Patients with IN perineurioma have been anecdotally found to have limb undergrowth; however, this has not been systematically evaluated. METHODS: Archived electronic records from 1990 to 2018 from a single institution were reviewed for pathology or radiology reports documenting a diagnosis of IN perineurioma. This identified 111 patients; 3 patients with IN perineurioma of cranial nerves were excluded. We further reviewed the 108 patients and identified those with a documented limb length discrepancy (LLD) or hand/foot size discrepancy (HFD) and tried to correlate findings with nerve-territory distribution. RESULTS: Twenty-seven (25.0%) patients had either LLD or HFD. Nine patients had only an LLD, 6 patients had only an HFD, and 12 patients had both. Patients with undergrowth were significantly younger at diagnosis than patients without (6.14 vs. 22.9 years, respectively). Although there was a trend toward a greater incidence of LLD in lower extremity IN perineuriomas, this was not statistically significant. Patients with proximal IN perineuriomas had a higher incidence of LLD or HFD than patients with distal IN perineuriomas. The difference between the 2 groups was statistically significant (P < 0.0001). All instances of undergrowth were explained by nerve-territory bone innervation. CONCLUSIONS: Limb undergrowth occurs in the affected nerve territory and is likely under-reported in patients with IN perineuriomas. Within our series, patients with documented LLD and HFD were likely to be significantly younger at diagnosis than patients without undergrowth.

New Frontiers in Therapy of Peripheral Nerve Sheath Tumors in Patients With Neurofibromatosis Type 1: Latest Evidence and Clinical Implications.

Almost all individuals with neurofibromatosis type 1 (NF1) develop peripheral nerve sheath tumors (PNSTs), mainly benign neurofibromas, however about 10% of PNSTs will undergo transformation to malignant peripheral nerve sheath tumors (MPNSTs). Surgical treatment of PNSTs has traditionally been regarded as a standard approach. The availability of new agents that target specific molecular pathways involved in the pathogenesis of PNST has led to a number of clinical trials, which resulted in increased chances for better survival and quality of life. This review presents the latest evidence and clinical implications for new therapies of PNSTs in patients with NF1 emphasizing the potential benefit from the use of Ras/MAPK pathway inhibitors, immunotherapy, chemotherapy or radiation therapy. We present evaluation of current knowledge on available treatment modalities.

Malignant peripheral nerve sheath tumor of the sciatic nerve presenting with leg pain in the setting of lumbar scoliosis and spinal stenosis.

STUDY DESIGN: Case report. OBJECTIVE: We present a case of malignant peripheral nerve sheath tumor (MPNST) presenting as neuropathic pain in the setting of lumbar scoliosis and spinal stenosis. Most peripheral nerve sheath tumors are benign, and malignant cases are more commonly associated with neurofibromatosis type 1 or prior radiation exposure. MPNST is a rare tumor with a poor prognosis. We report a case of MPNST that presented as neuropathic pain following lumbar decompression and fusion surgery. METHODS: A 60-year-old woman presented for management of lumbar scoliosis, stenosis, and left leg pain. After lumbar decompression and fusion surgery, the patient was readmitted to the hospital after falling 10 weeks post-op. She reported gradual recurrence of leg pain. Left foot drop was noted on exam. Imaging studies showed no spinal changes postoperatively or residual stenosis. Obesity limited electrodiagnostic studies. Hip MRI revealed a lobular soft tissue mass in the left sciatic notch. Surgical resection and pathology provided the diagnosis of MPNST. The patient declined wide resection and other interventions after seeking a second opinion. Palliative pain management was implemented. RESULTS: The patient expired 15 months after her index spinal surgery. CONCLUSIONS: MPNST is an extremely rare tumor that can present with symptoms similar to radiculitis. Clinical signs and symptoms of MPNST are vague and nonspecific due to compression of surrounding structures. Surgical wide resection is the first line of treatment for MPNST with chemotherapy and radiotherapy as adjuvant treatments. MPNST has a poor prognosis with reported 5-year survival ranging from 16 to 54%. This case demonstrates the need to pursue additional workup when diagnostic imaging and objective findings do not satisfactorily explain the clinical presentation. LEVEL OF EVIDENCE: IV.