Intracranial Metastasis From Medullary Thyroid Carcinoma Mimicking As Invasive Meningioma: A Case Series

Abstract

Objective: To describe the clinical presentation, radiological findings, and surgical management of intracranial metastasis from medullary thyroid carcinoma, an exceedingly rare occurrence not previously reported in Pakistan.

Method: This case series describes three patients who presented to the neurosurgery outpatient clinic at Dow University Hospital, Karachi, in November 2024, June 2025, and January 2026 respectively, with scalp swellings and persistent headaches unresponsive to analgesics. Two patients also had seizures. Contrast-enhanced MRI in each case demonstrated an enhancing lesion extending from the intracranial compartment through the skull into the scalp, initially raising suspicion of an aggressive or invasive meningioma. All three underwent craniectomy with gross excision of the lesion, duraplasty, and cranioplasty, with tissue sent for histopathological analysis. Results: Histopathology in all three cases confirmed metastatic medullary thyroid carcinoma rather than meningioma. Postoperative recovery was uneventful, with resolution of headaches and seizures. On follow-up, patients remained clinically stable with no recurrence of symptoms.

Conclusion: Medullary thyroid carcinoma can metastasize to the brain and mimic primary CNS tumours such as meningioma on imaging, despite this being rare. A high index of suspicion and thorough metastatic workup are warranted whenever an intracranial lesion is encountered, and whole-body screening should be considered whenever a primary malignancy is identified, regardless of how uncommon its metastatic spread may be.