Introduction:Skull base metastasis from follicular thyroid carcinoma (FTC) is uncommon, with an incidence of 2.5%. Presented here is a case of a 63-year-old female presenting with a 2-year history of progressive left eye proptosis, with a previous history of thyroid surgery for non-toxic goiter. Imaging findings were uncharacteristic of any common skull base tumor. Biopsy revealed follicular thyroid carcinoma. The authors used this case as basis and performed an analysis on available literature for FTC skull base metastasis to help guide management of future cases.

Methods:Using PRISMA guidelines, a systematic search across PubMed, Google Scholar, and Cochrane Library using MeSH keywords “Skull base,” “Metastasis,” and “Follicular Thyroid Carcinoma,” identified 18 records. After screening, 15 articles assessed for eligibility, with 8 studies meeting inclusion criteria for qualitative analysis.

Results:Studies showcased a consistent age range (43 to 69 years) among patients diagnosed with FTC. Presentation varied depending on tumor location, with symptoms such as dysphagia, proptosis, epistaxis, facial dysesthesia, and visual impairment. Tumor size ranged from 3cm x 3cm x 2cm to 6.8cm x 3.9cm x 5.3cm, influencing management strategies ranging from simple biopsy to sub-temporal complete excision. Adjuvant therapies included combinations of intensity-modulated radiation therapy (IMRT) with immunotherapy, multiple courses of I-131 therapy, oral radioiodine ablation, and radiotherapy, with outcomes showing improvement in most cases. Follow-up duration varied from 12 to 60 months.

Conclusion:FTC skull base metastasis remains to be an uncommon entity in neurosurgery. Its rarity creates a lack of established guidelines and treatment algorithms. A high index of suspicion as well as good history and physical examination skills are necessary to achieve an adequate diagnosis. Multidisciplinary teams form the cornerstone of a patient-tailored approach to its management.