Management of metastatic tumors invading the peripheral nervous system

Surgical treatment of rare peripheral nerve lesions: long-term outcomes and quality of life

Introduction

Rare peripheral nerve lesions comprise a histologically diverse group of neoplastic and non-neoplastic entities, characterized by infrequent occurrence and variable clinical presentations, presenting significant diagnostic and therapeutic challenges. This study presents eight cases of surgically treated rare peripheral nerve lesions with previously unreported long-term outcomes involving quality of life (QOL) assessment.

Methods

A retrospective analysis was conducted on medical records from 2012 to 2022 to identify surgically treated cases of rare peripheral nerve lesions, selecting eight cases based on determined inclusion and exclusion criteria. Long-term outcomes and QOL were assessed 12 months post-surgery by patient examination, control imaging and self-reporting questionnaires.

Results

The study included 4 benign (hemangioblastoma, angiomatoid fibrous histiocytoma, endometriosis (n=2)) and 4 malignant lesions (NTRK-rearranged spindle cell neoplasm, lymphoma, metastatic breast carcinoma (n=2)). Even though benign lesions generally presented with better outcomes, this was more closely related with level of nerve invasion and postoperative sequele, rather than presence of malignancy.

Discussion

Because of a global lack of experience in handling such cases, this study aimed to present the cases we encountered in detail to serve as a basis for future literature reviews. The findings highlight the importance of individualized treatment strategies and long-term follow-up to optimize functional recovery and patient well-being.

STING activation reprograms the microenvironment to sensitize NF1-related malignant peripheral nerve sheath tumors for immunotherapy

Neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene that encodes neurofibromin, a RAS GTPase-activating protein. Inactivating NF1 mutations cause hyperactivation of RAS-mediated signaling, resulting in the development of multiple neoplasms, including malignant peripheral nerve sheath tumors (MPNSTs). MPNSTs are an aggressive tumor and the main cause of mortality in patients with NF1. MPNSTs are difficult to resect and refractory to chemo- and radiotherapy, and no molecular therapies currently exist. Immune checkpoint blockade (ICB) is an approach to treat inoperable, undruggable cancers like MPNST, but successful outcomes require an immune cell-rich tumor microenvironment. While MPNSTs are noninflamed "cold" tumors, here, we converted MPNSTs into T cell-inflamed "hot" tumors by activating stimulator of IFN genes (STING) signaling. Mouse genetic and human xenograft MPNST models treated with a STING agonist plus ICB exhibited growth delay via increased apoptotic cell death. This strategy offers a potential treatment regimen for MPNSTs.

Melanoma metastasis to the femoral nerve: a novel case of melanoma masquerading as mononeuropathy. Illustrative case

BACKGROUND

Metastatic cancer may involve the central and peripheral nervous system, usually in the late stages of disease. At this point, most patients have been diagnosed and treated for widespread systemic disease. Rarely is the involvement of the peripheral nervous system the presenting manifestation of malignancy. One reason for this is a proposed "blood-nerve barrier" that renders the nerve sheath a relatively privileged site for metastases.

OBSERVATIONS

The authors presented a novel case of metastatic melanoma presenting as intractable leg pain and numbness. Further workup revealed concurrent disease in the brain and breast, prompting urgent treatment with radiation and targeted immunotherapy.

LESSONS

This case highlights the rare presentation of metastatic melanoma as a mononeuropathy. Although neurological complications of metastases tend to occur in later stages of disease after initial diagnosis and treatment, one must remember to consider malignancy in the initial differential diagnosis of mononeuropathy.

Metastatic Complications of Cancer Involving the Central and Peripheral Nervous Systems

Neurologic complications of cancer may involve both the central nervous system and peripheral nervous system manifesting as brain, leptomeningeal, intramedullary, intradural, epidural, plexus, and skull base metastases. Excluding brain involvement, neurologic complications affecting these other sites are relatively infrequent, but collectively they affect more than 25% of patients with metastatic cancer causing significant morbidity and mortality. Early diagnosis and intervention optimize quality of life and improve survival.

Spindle cell type malignant peripheral nerve sheath tumor arising in benign schwannoma with multiple intraosseous spinal metastasis: A case report

BACKGROUND

Malignant peripheral nerve sheath tumor (MPNST) arising in benign schwannoma with multiple intraosseous spinal metastasis is extremely rare, having a highly aggressive progression and poor prognosis. In such cases, the malignant cells of MPNST usually have an epithelioid morphology. Here, the authors present a very rare case of spindle cell type MPNST arising in benign schwannoma.

CASE

A 47-year-old woman had a history of wide marginal excision of right buttock spindle cell sarcoma previously. However, metastatic lesions to C7, L1 body, and the right lung were detected during follow-up. Total spondylectomy and stabilization of the C7 and L1 tumors were performed within an interval of 5 months. However, the patient expired 6 months after the last surgery. From analysis and study of three tumor specimens (right buttock, cervical and lumbar spine), the pathological diagnosis based on histomorphologic and immunohistochemical studies was spindle cell sarcoma, high grade, most consistent with MPNST arising in schwannoma.

RESULTS

It is important that pathologists and surgeons recognize that spindle cell type MPNST may arise in benign schwannoma, as this recognition aids in assessment of patients with schwannoma and contributes to the pathologist making a more precise diagnosis, and the surgeon better determining the appropriate therapeutic options and surgical methods.

Favorable outcome after radical resection and subsequent local irradiation of malignant peripheral nerve sheath tumor in the cervical spine

A 25-year-old man presented with malignant transformation to malignant peripheral nerve sheath tumor (MPNST) in the cervical spine associated with neurofibromatosis type 1. He presented with a 3-week history of rapidly increasing weakness and numbness in all four extremities. Magnetic resonance (MR) imaging of the cervical spine demonstrated a dumbbell-shaped tumor, which compressed the spinal cord at the C2-3 level. The tumor was excised, mainly within the spinal canal to decompress the spinal cord. The histological diagnosis was benign neurofibroma. Three months after surgery, he rapidly developed progressive tetraparesis and MR imaging revealed marked regrowth of an extradural mass into the spinal canal. At reoperation, the regrown mass in the spinal canal was totally excised. The histological diagnosis revealed MPNST. He underwent radiation therapy, with a total dose of 32 Gy, for approximately 3 weeks after the second surgery, but MR imaging showed tumor regrowth within the spinal canal, and his condition deteriorated. The decision was made to remove the tumor radically, including the involved facet and extradural lesion. Posterior fusion using a pedicle screw was performed one month later. He manifested no additional neurological deficits. He has been free of relapse for 46 months. Radical resection remains the most effective treatment for MPNST, although complete removal with a clear tumor margin is often impossible in practice.