Case Study of an Unusual Intracranial Mesenchymal Neoplasm.

Background and importance: A 51-year-old woman with multiple sclerosis (MS) presented for MS management and follow-up, including repeat MRIs. On imaging, a slowly growing enhancing lesion was noted in the left posterior insula. Histopathology reported this tumor as a low-grade mesenchymal neoplasm, not elsewhere classified. The case reported here will add to the library of central nervous system tumors, which may help identify other previously unclassifiable tumors.

Clinical presentation: The lesion was inconsistent with MS plaques, and MRI and computed tomography angiography showed no signs of aneurysm. After evaluation, we recommended surgery to remove the lesion. Surgical excision posed a challenge as the dominant hemisphere posterior insula can be difficult to access. We used a trans-sylvian approach, sparing vasculature within the sylvian fissure with clean excisional margins. The trans-sylvian approach enabled minimal manipulation of brain tissue surrounding the lesion, including the receptive speech center. The patient recovered without complications. Postsurgical follow-up revealed no new neurological symptoms or deficits and no sign of tumor recurrence.

Conclusion: The trans-sylvian approach we used to excise the tumor resulted in a favorable outcome for the patient. This case supports that the trans-sylvian approach, while technically more demanding, is feasible and potentially beneficial.