Treatment of malignant peripheral nerve sheath tumors in pediatric NF1 disease

Malignant Peripheral Nerve Sheath Tumor (MPNST) of the Uterine Cervix - A Systematic Literature Review and New Case Report with Possible New Therapeutic Approaches

Malignant schwannomas of the visceral organs are extremely rare. To date, 19 cases of cervical schwannoma have been reported in the literature worldwide. A single case prompted a review of the literature. The differential diagnosis between melanoma and schwannoma is made using the marker HMB-45, which is positive for melanoma and negative for schwannoma. This differentiation allowed us to identify two of the 20 cases that were probably not schwannomas. The prognosis of malignant cervical schwannoma is poor. Approximately half of the cases develop local recurrence or distant metastases within a short time, despite resection in healthy tissue. In one case, gene sequencing revealed a potential treatment approach with the mTOR inhibitor everolimus and trastuzumab. Unfortunately, the potential efficacy of these treatment options could not be tested because the patient was being treated at another hospital at the time of relapse, and they did not use a drug that matched the NGS profile.

Pediatric soft tissue tumors

The initial approach to soft tissue tumors in children and teenagers is everyone's responsibility. While the vast majority is benign, all practitioners dread missing a malignant lesion. The first step involves taking the patient's history and performing a clinical examination. Useful information can be gained from radiographs, ultrasound imaging and MRI. If there is no diagnosis at this stage, a biopsy (preferably percutaneous) is essential because unplanned excision can have serious consequences in terms of morbidity and even mortality. This should only be undertaken at a specialized facility after careful planning by the surgeon and interventional radiologist. Once the diagnosis has been made, the case should be discussed at a tumor board meeting to benefit from multidisciplinary expertise and input. Surgery is an essential component of the treatment and must be done at the appropriate time, after potential systemic (chemotherapy, targeted therapy) or local treatment (radiation therapy). LEVEL OF EVIDENCE: Expert opinion.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

An algorithmic approach to the management of peripheral nerve tumours

This article reviews the pathology and management of peripheral nerve tumours, including a framework for investigation and decision-making. Most tumours are benign, including schwannomas and neurofibromas, but malignant peripheral nerve sheath tumours can occur. The risk of malignant change is remote for schwannomas but higher for neurofibromas, particularly in neurofibromatosis type 1. Magnetic resonance imaging is useful for defining the relationship of a swelling with adjacent nerves but is not definitive for tissue diagnosis. Increasing size, pain and neurological deficit suggest malignant change and TruCut needle biopsy is indicated, although there is a risk of sampling error. Excision biopsy preserving nerve function may be carried out for benign tumours to relieve symptoms. Malignant tumours require a multidisciplinary approach. Complete surgical excision with clear margins is the only curative treatment and may be supplemented with radiotherapy and chemotherapy. However, prognosis remains poor, particularly for patients with neurofibromatosis.

Case Report of a Patient With Malignant Peripheral Nerve Sheath Tumor Treated With Wide Resection

Malignant peripheral nerve sheath tumors are soft tissue sarcomas originating from peripheral nerves. They are more frequently diagnosed in individuals with neurofibromatosis and tend to affect young men more often than women. The most common sites for these tumors within the peripheral nerve sheath are in the pelvis and the distal femur. Although chemotherapy and radiotherapy are not frequently used, it should be noted that in some cases, postoperative radiotherapy and chemotherapy may be beneficial. The primary treatment approach typically involves the complete surgical removal of the tumor. Here, we discuss the case of our patient whom we successfully treated with extensive resection and followed up with postoperative radiotherapy at our clinic.

Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces for Prophylactic Pain Control in Neurofibromatosis Type 1 Amputees

Neurofibromatosis type 1 (NF1) is an inherited multisystem disorder that affects one in 2500 to one in 5000 people. Neurofibromas are the second-most common benign peripheral nerve sheath tumors arising from Schwann cells and are associated with neurofibromatosis. Chronic pain and opioid use is elevated in patients with NF1 when neurofibromas are associated with sensory nerves. Surgical excision is the primary treatment of neurofibromas when they become large, malignant, or painful, but they are associated with high rates of recurrence. Targeted muscle reinnervation and regenerative peripheral nerve interfaces are two prophylactic surgical techniques that are used to prevent neuroma-associated residual limb and phantom pain in amputees. Both techniques stimulate physiologic regeneration of the nerve via trophic stimulus from denervated muscle. This case report describes two patients with NF1 who underwent targeted muscle reinnervation and/or regenerative peripheral nerve interfaces at the time of amputation. Despite the abnormality of the peripheral nerves involved, both patients had excellent postoperative outcomes with minimal pain. This experience advocates for the use of prophylactic nerve management techniques in neurofibromatosis patients despite baseline nerve pathology.

A chance to cut is a chance to cure: complete resection of an atypical neurofibroma prevents further progression to malignancy

Plexiform neurofibromas are the hallmark of neurofibromatosis type 1 (NF1) and significantly contribute to the overall burden of disease. While surgical excision has long been the only available therapy, the MEK inhibitor (MEKi) selumetinib has been approved as a non-surgical treatment option for these tumors in 2020 (USA) and 2021 (Europe), respectively. However, selumetinib will result in tumor shrinkage only after several months of therapy and might not prevent malignant transformation of a plexiform neurofibroma that occurs with a frequency of 10-15%. Here, we demonstrate that surgical excision might be the therapy of choice in some plexiform neurofibromas despite the availability of MEKi therapy.

The therapeutic potential of neurofibromin signaling pathways and binding partners

Neurofibromin controls many cell processes, such as growth, learning, and memory. If neurofibromin is not working properly, it can lead to health problems, including issues with the nervous, skeletal, and cardiovascular systems and cancer. This review examines neurofibromin's binding partners, signaling pathways and potential therapeutic targets. In addition, it summarizes the different post-translational modifications that can affect neurofibromin's interactions with other molecules. It is essential to investigate the molecular mechanisms that underlie neurofibromin variants in order to provide with functional connections between neurofibromin and its associated proteins for possible therapeutic targets based on its biological function.

Malignant peripheral nerve sheath tumor on a patient with a maternally inherited novel NF1 gene pathogenic germline variant: Case report

INTRODUCTION

Neurofibromatosis type 1 (NF1) is an autosomal dominant cancer predisposition syndrome caused by pathogenic variants in NF1, which negatively regulates the RAS pathway. Knowledge of the genotype-phenotype correlation in this disease is an important tool for prognostic evaluation and early detection of malignant peripheral nerve sheath tumors (MPNST), present in approximately 10% of these patients. We present the case of a teenager with a left jaw MPNST and a previously unreported germline pathogenic variant on NF1.

CASE PRESENTATION

An 11-year-old female with a NF1 clinical diagnosis was referred to our hospital with a MPNST in an advanced state. A previously unreported NF1 pathogenic variant was obtained (GRCh37: NM_182493.2 c.3299C>G, p.Ser1100*). Despite great efforts from the surgical and medical teams, the tumor progression couldn't be halted, resulting in the patient's death.

DISCUSSION

As MPNSTs are refractory to current treatment regimens, early diagnosis, and development of new therapies, such as MEK inhibitors, is necessary for reducing morbidity and mortality within NF1 patients. This increases the importance of a more widespread genetic testing strategy.

CONCLUSION

The report of a novel NF1 pathogenic variant in a patient with maternally inherited neurofibromatosis type 1 and a MPNST increases the knowledge of the genotype-phenotype correlation in the disease.

Case report: First case of undifferentiated embryonal sarcoma of the liver in a child with neurofibromatosis type 1, treated by hepatic chemoperfusion with transcatheter arterial chemoembolization

Introduction

In this report we firstly describe undifferentiated embryonal sarcoma of the liver (UESL) in a patient with neurofibromatosis type 1 (NF1), fatally complicated by synchronous malignant peripheral nerve sheath tumor (MPNST) with a highly aggressive metastatic course. The case also represents our first experience of chemoperfusion involving the transcatheter arterial chemoembolization (TACE) in a pediatric patient, applied as a treatment for UESL.

Case presentation

A 13-year-old girl was diagnosed with NF1 and presented with a liver tumor identified as UESL by histological assessment. The tumor was refractive to the conventional first-line chemotherapy. The patient received hepatic chemoperfusion with TACE, which was efficacious; however, the overall curative outcome was unsatisfactory due to synchronous unresectable retroperitoneal MPNST with mesenteric metastases and ultimate progression of the UESL.

Conclusion

This is the first reported case of UESL in a patient with NF1. The results demonstrate the efficacy of hepatic chemoperfusion with TACE in pediatric UESL.

The clinical course and role of surgery in pediatric malignant peripheral nerve sheath tumors: a database study

OBJECTIVE

Malignant peripheral nerve sheath tumors (MPNSTs) are rare tumors found throughout the body, with their clinical course in children still not completely understood. Correspondingly, this study aimed to determine survival outcomes and specific clinical predictors of survival in this population from a large national database.

METHODS

All patients with MPNSTs aged ≤ 18 years in the US National Cancer Database (NCDB) between 2005 and 2016 were retrospectively reviewed. Data were summarized, and overall survival was modeled using Kaplan-Meier and Cox regression analyses.

RESULTS

A total of 251 pediatric patients with MPNSTs (132 [53%] females and 119 [47%] males) were identified; the mean age at diagnosis was 13.1 years (range 1-18 years). There were 84 (33%) MPNSTs located in the extremities, 127 (51%) were smaller than 1 cm, and 22 (9%) had metastasis at the time of diagnosis. In terms of treatment, surgery was pursued in 187 patients (74%), chemotherapy in 116 patients (46%), and radiation therapy in 129 patients (61%). The 5-year overall survival rate was estimated at 52% (95% CI 45%-59%), with a median survival of 64 months (range 36-136 months). Multivariate regression revealed that older age (HR 1.10, p < 0.01), metastases at the time of diagnosis (HR 2.14, p = 0.01), and undergoing biopsy only (HR 2.98, p < 0.01) significantly and independently predicted a shorter overall survival. Chemotherapy and radiation therapy were not statistically significant.

CONCLUSIONS

In this study, the authors found that older patient age, tumor metastases at the time of diagnosis, and undergoing only biopsy significantly and independently predicted poorer outcomes. Only approximately half of patients survived to 5 years. These results have shown a clear survival benefit in pursuing maximal safe resection in pediatric patients with MPNSTs. As such, judicious workup with meticulous resection by an expert team should be considered the standard of care for these tumors in children.

Neurofibromatosis in the Era of Precision Medicine: Development of MEK Inhibitors and Recent Successes with Selumetinib

PURPOSE OF REVIEW

Patients with neurofibromatosis type 1 (NF1) are at increased risk for benign and malignant neoplasms. Recently, targeted therapy with the MEK inhibitor class has helped address these needs. We highlight recent successes with selumetinib while acknowledging ongoing challenges for NF1 patients and future directions.

RECENT FINDINGS

MEK inhibitors have demonstrated efficacy for NF1-related conditions, including plexiform neurofibromas and low-grade gliomas, two common causes of NF1-related morbidity. Active investigations for NF1-related neoplasms have benefited from advanced understanding of the genomic and cell signaling alterations in these conditions and development of sound preclinical animal models. Selumetinib has become the first FDA-approved targeted therapy for NF1 following its demonstrated efficacy for inoperable plexiform neurofibroma. Investigations of combination therapy and the development of a representative NF1 swine model hold promise for translating therapies for other NF1-associated pathology.