Malignant peripheral nerve sheath tumor: Transformation in a patient with neurofibromatosis type 2

Neurofibromatosis to neoplasia transition: a rare case report of spindle cell malignant peripheral nerve sheath tumor with literature review

Introduction and importance

Malignant peripheral nerve sheath tumor (MPNST) is a rare and aggressive soft tissue malignant tumor. MPNST in the spinal canal is rarely seen except in cases of neurofibromatosis type 1. However, a long-segment extradural spinal malignant spindle cell neoplasm has not been reported in the current literature.

Case presentation

We present the first reported case of spinal malignant spindle cell neoplasm extended along the spine. The detected lesion is responsible for compressing various segments of the spinal cord, causing thinning of the cord and secondary stenosis of the spinal canal, leading to a condition known as multisegment compression myelopathy.

Clinical discussion

MPNSTs are typically detected late due to nonspecific symptoms, with a higher incidence in extremities and a notable occurrence in unusual locations. Diagnosis relies on MRI and histopathology, with S_100 positivity as a neural marker. MPNSTs can arise from neurofibromas or Schwann cells, with a significant portion resulting from TP53 mutations or secondary to radiation exposure.

Conclusion

This case stands out due to its unique presentation, characterized by a predominantly spindle cell morphology with certain epithelioid features. It is imperative to recognize this condition for an accurate diagnosis, emphasizing the spindle cell-type MPNST and highlighting its exceptionally poor prognosis.

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.

Metabolic landscapes in sarcomas

Metabolic rewiring offers novel therapeutic opportunities in cancer. Until recently, there was scant information regarding soft tissue sarcomas, due to their heterogeneous tissue origin, histological definition and underlying genetic history. Novel large-scale genomic and metabolomics approaches are now helping stratify their physiopathology. In this review, we show how various genetic alterations skew activation pathways and orient metabolic rewiring in sarcomas. We provide an update on the contribution of newly described mechanisms of metabolic regulation. We underscore mechanisms that are relevant to sarcomagenesis or shared with other cancers. We then discuss how diverse metabolic landscapes condition the tumor microenvironment, anti-sarcoma immune responses and prognosis. Finally, we review current attempts to control sarcoma growth using metabolite-targeting drugs.

Neurofibromatosis type 2 and related disorders

PURPOSE OF REVIEW

Neurofibromatosis type 2 (NF2) is a schwannoma predisposition syndrome, alongside schwannomatosis related to germline LZTR1 and SMARCB1 pathogenic variants. This review highlights their overlapping phenotypes, new insight into NF2 phenotype and treatment outcomes.

RECENT FINDINGS

Mosaic NF2 is more prevalent than previously thought. Use of next-generation sequencing and tumour testing is needed to differentiate mosaic NF2 and schwannomatosis. Developing NF2 phenotypic insights include vasculopathy with brainstem infarction and vessel stenosis; focal cortical dysplasia in severe phenotypes; swallowing/speech difficulties and continued debate into malignancy in NF2. Proposed are: use of visual evoked potentials to monitor optic nerve sheath meningioma; potential routine magnetic resonance angiogram in adolescence and a genetic score to cohort patients with similar pathogenic_variants, for natural history/treatment outcome studies. Cohort studies found survival analysis to hearing loss and unilateral visual loss in severe mutation groups was 32 and 38 years; active management gave better outcomes than surveillance in spinal ependymoma; gamma knife, bevacizumab and hearing preservation surgery maintained or improved short-term hearing in selected patients, and gamma knife had a good long-term tumour control in mild patients with small tumours.

SUMMARY

Further long-term outcome studies are needed comparing similar severity patients to allow informed decision making.