Image-guided percutaneous biopsy of peripheral nerve tumors of indeterminate nature: risks and benefits

Benign peripheral nerve sheath tumors: an interdisciplinary diagnostic and therapeutic challenge

A benign peripheral nerve sheath tumor (bPNST) is a rare lesion associated with peripheral nerval structures. Symptoms may be heterogeneous, complicating diagnosis finding. Additionally, management concepts of bPNST may vary. In some cases, initial misdiagnosis leads to mistreatment resulting in severe functional deficits and chronic pain syndromes. Therefore, we analyzed patients treated for bPNST in our specialized institution with a primary focus on prior misdiagnosis and possible mistreatment. Patients with bPNSTs (schwannomas, neurofibromas, hybrid nerve sheath tumors, and perineuriomas) treated at the Neurosurgical Department between January 1, 2015, and July 31, 2021, were included. Assessment of demographics, tumor entity, tumor location, symptoms, the interval between the onset of symptoms and surgery, involved medical specialties, and outpatients' treatment, with particular focus on initial misdiagnosis and inappropriate medical treatment, was performed. Eighty-five patients were included in the final analysis with schwannoma being the most prevalent histopathological diagnosis (schwannoma (75.3%, n=64), neurofibroma (12.9%, n=11), hybrid nerve sheath tumor (5.9%, n=5), and perineurioma (5.9%, n=5)). An incorrect primary diagnosis was detected in 44.7% (n=38), leading to suboptimal or insufficient treatment in these cases. Of those, 28.9% (n=11/38) were treated suboptimal, while 18.5% (n=7/38) underwent unnecessary invasive diagnostics. Inappropriate surgery based on prior misdiagnosis, which led to severe neurological deficits in all these cases, was reported in 26.3% (n=10/38). For the first time, our data shows the quantity and impact of incorrect initial diagnosis in bPNST causing a delay in causative treatment or resulting in unnecessary or potentially harmful treatment.

Diagnosis and Treatment of Peripheral and Cranial Nerve Tumors with Expert Recommendations: An EUropean Network for RAre CANcers (EURACAN) Initiative

The 2021 WHO classification of the CNS Tumors identifies as "Peripheral nerve sheath tumors" (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly. Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry. Molecular analysis is not essential to establish the histological nature of these tumors, although genetic analyses on DNA extracted from PNST (neurofibromas/schwannomas) is required to diagnose mosaic forms of NF1 and SPS. MRI is the gold-standard to delineate the extension with respect to adjacent structures. Gross-total resection is the first choice, and can be curative in benign lesions; however, the extent of resection must be balanced with preservation of nerve functioning. Radiotherapy can be omitted in benign tumors after complete resection and in NF-related tumors, due to the theoretic risk of secondary malignancies in a tumor-suppressor syndrome. Systemic therapy should be considered in incomplete resected plexiform neurofibromas/MPNSTs. MEK inhibitor selumetinib can be used in NF1 children ≥2 years with inoperable/symptomatic plexiform neurofibromas, while anthracycline-based treatment is the first choice for unresectable/locally advanced/metastatic MPNST. Clinical trials on other MEK1-2 inhibitors alone or in combination with mTOR inhibitors are under investigation in plexiform neurofibromas and MPNST, respectively.

Cervical Paraspinal Chordoma: A Literature Review with a Novel Case Report

Chordomas are rare malignant neoplasms, accounting for 1–4% of all primary bone tumors. Most spinal chordomas occur in the sacrococcygeal region and the base of the skull; however, 6% of chordomas are observed in the cervical spine. In these cases, the lesion is mainly located in the midline. These tumors slowly grow before becoming symptomatic and encase the surrounding vascular and nerve structures. Patients with advanced chordoma have a poor prognosis due to local recurrence with infiltration and destruction of adjacent bone and tissues. Systemic chemotherapy options have not been fully effective in these tumors, especially for recurrent chordomas. Thus, new combinations of currently available targeted molecular and biological therapies with radiotherapy have been proposed as potential treatment modalities. Here, the present paper describes the case of a 41-year-old male with a C2–C4 chordoma located paravertebrally, who underwent surgical resection with a debulking procedure for a cervical chordoma. Computed tomography angiography revealed a paraspinal mass with bone remodeling and the MRI showed a paravertebral mass penetrating to the spinal canal with a widening of the intervertebral C2–C3 foramen. Initially, the tumor was diagnosed as schwannoma based on its localization and imaging features; however, the histopathology specimen confirmed the diagnosis of chordoma. This case study highlights the effectivity of radical surgical resection as a mainstay treatment for chordomas, discusses neuroimaging, diagnosis, and the use of currently available targeted therapies and forthcoming treatment strategies, as alternative treatment options for chordoma.

MPNST without muscle weakness at presentation: an analysis of an underappreciated combination

INTRODUCTION

Malignant peripheral nerve sheath tumors (MPNSTs) of major motor nerves typically present with muscle weakness and pain. We aim to analyze and characterize patients with MPNST at major motor nerves but without muscle weakness at initial presentation.

METHODS

A retrospective search involving MPNSTs in a major nerve evaluated and/or treated at our institution from 1994 to 2019 was performed. Patients with no muscle weakness and available MRI were analyzed. Clinical materials, MR images and PET scans were reviewed for features of malignancy. This group of patients was compared to patients who presented with MPNSTs and muscle weakness.

RESULTS

Twenty-six patients were included in the no muscle weakness group. Of them, twenty-one (81%) patients had a positive family history for malignancy. Only 16 (62%) MR images were highly suspicious for malignancy. All 7 available PET-scans were highly suspicious for malignancy. Patients who presented with muscle weakness (n = 36), were more likely to have paresthesias and a history of NF-1 or radiation to the MPNST location (p-value < 0.05).

CONCLUSION

MPNSTs of major motor nerves without muscle weakness represent an underappreciated subset of cases which has potential treatment and outcome implications. These patients presented with fewer symptoms and had fewer risk factors than patients with muscle weakness. PET-scans should be considered as an extra method of trying to anticipate the diagnosis of an MPNST.

Surgical Management of Symptomatic Lumbar, Sacral, and Lumbosacral Plexus Tumors: a Peripheral Nerve Unit Experience

OBJECTIVE

Data concerning the surgical treatment of lumbosacral plexus tumors (LSPTs) is scarce. This study aims to present our experience with a series of 19 patients surgically treated for symptomatic LSPTs at our institution.

METHODS

This is a retrospective study of 19 patients surgically treated for symptomatic LSPTs from 2011 to 2019. Clinical data were retrieved from medical records and consisted of age, gender, clinical presentation, location of the lesion, surgical approach, final histopathologic diagnosis, follow-up time, outcomes, and complications.

RESULTS

Nineteen surgical procedures were conducted. Thirteen patients were female and six, male. The median age of patients was 45 years (range 20 to 63 years). No patients harbored genetic syndromes. Surgical treatment appears to be correlated to the reduction of pain in patients with peripheral nerve sheath tumors (PNSTs), as assessed by visual analog scale (VAS). Sixteen patients did not present with new-onset deficits during follow-up (84.2%), two of whom recovered from their preoperative deficit. Four patients presented with postoperative weakness. The histopathological diagnoses were 11 schwannomas, four neurofibromas, three metastases, and one lymphoma.

CONCLUSIONS

LSPTs are rare. When surgical treatment is indicated, it usually requires multidisciplinary management. Surgery appears to be effective concerning the reduction of pain in PNSTs and may also recover neurological deficits. Iatrogenic neurological deficits are an evident risk, such that intraoperative multimodal monitoring should always be performed if available. In lesions involving the sacral plexus, we found it to be indispensable.

Percutaneous image-guided biopsy in malignant peripheral nerve sheath tumors

BACKGROUND

The decision to biopsy a peripheral nerve tumor is largely based on its presumed behavior and prognosis, determined by patient history, clinical exam, and radiologic characteristics. Percutaneous image-guided biopsy is not without risk in patients with malignant peripheral nerve sheath tumors (MPNSTs); in particular, there may be concern regarding worsening neurologic function, increasing neuropathic pain, and incorrect or absent diagnosis.

METHODS

Following approval by our institutional review board, we reviewed records from 1990 to 2019 at our institution's three main sites ("our institution"). Patients with pathology-proven MPNST were selected. Further inclusion criteria included image-guided percutaneous biopsy performed at our institution, pathology report available for review, and follow-up documentation to determine post-biopsy complications.

RESULTS

Three hundred thirty-one patients with MPNST were reviewed. In total, 73 patients undergoing image-guided percutaneous biopsies were included. Twenty-two (30.1%) had biopsy-related complications. This included ten patients with misdiagnosis (13.7%) and six patients with non-diagnostic biopsies (8.2%). Six patients had new or worsened pain that resolved with time and neuropathic pain medication (8.2%), and one patient had subjectively worsened proximal weakness (1.3%) which resolved.

CONCLUSION

We found nearly a third of patients undergoing biopsy had a biopsy-related complication. The single largest complication was the inability to obtain an accurate diagnosis (21.9%) with the first biopsy. This may lead to the need for repeat percutaneous or open biopsies, or a non-oncologic initial surgery with implications for disease-free and overall survival. Neurologic complications including exacerbation of pain or a deficit were rare and transient. It remains important that clinicians balance the potential risks and benefits based on individual patient characteristics when determining the necessity of an image-guided percutaneous biopsy.