Primary ectopic meningioma of the brachial plexus: A case report and literature review.

Background: Meningioma is the most common primary intracranial tumor. Less commonly, it may also arise extracranially in ectopic locations. Primary ectopic meningioma arising from the brachial plexus is extremely rare, with only two published cases. We present a case of primary brachial plexus meningioma, proven by histological analysis, and a review of the literature. Case Description: A 25-year-old man presented with swelling in the left supraclavicular region. Magnetic resonance imaging (MRI) demonstrated the presence of a mass arising from the brachial plexus. Initial pathological diagnosis and repeat biopsies were inconclusive and interpreted as a low-grade mesenchymal tumor with uncertain biologic potential. The proposed differential diagnosis included epithelioid schwannoma, atypical epithelioid neoplasm, or a low-grade malignancy. The fact that the differential diagnosis included both benign possibilities and low-grade malignancies raised complex questions about the preferred treatment plan. The surgical techniques necessary for each of these diagnoses vary. Typically, soft-tissue malignancies necessitate extensive resection, while in benign tumors, limited resection may suffice. Extensive resection within the brachial plexus carries substantial neurological and, therefore, functional morbidity. Finally, the patient underwent marginal resection of the tumor. The final pathological diagnosis was concluded as meningioma. The patient recovered completely, without neurological deficits, and repeated MRI demonstrated no residual or recurrence of the lesion. Conclusion: Although uncommon, we recommend considering the rare possibility of meningioma as a differential diagnosis for brachial plexus tumors, particularly in cases where the initial pathological examination is inconclusive for more prevalent tumors such as schwannoma and neurofibroma. Due to the rarity of this pathology, conclusive treatment recommendations cannot be made, especially regarding the decision to follow-up versus surgical resection. This debate is particularly pertinent in instances where the malignant potential of the pathology is uncertain and where surgical intervention carries a significant risk of functional impairment. We believe that maximal and safe surgical excision is the primary method of treatment, which potentially confers an excellent prognosis.