A case of an isolated extracranial mass with brain extension in a 46 year old female with a history of follicular-variant of thyroid carcinoma

Background:

Follicular variant of papillary thyroid carcinoma (FVPTC) is a histologic subtype of papillary thyroid carcinoma (PTC) characterized by follicular architecture with the nuclear features of classical PTC. FVPTC is considered more aggressive than conventional PTC, often presenting with extrathyroidal extension and regional lymphadenopathy. Bone metastases occur in approximately 0.6–6.9% of PTC cases, but metastasis to the skull is exceedingly rare. This report underscores both the diagnostic and therapeutic challenges of such cases and highlights the role of radioactive iodine ablation (RAI) in disease management.

Case:

A 46-year-old female presented with a progressively enlarging right parieto-occipital soft tissue mass. She had undergone total thyroidectomy for FVPTC five years earlier, followed by RAI therapy. Current imaging revealed tumor recurrence with calvarial metastasis extending intracranially. The patient underwent post-ablative radioactive iodine therapy prior to planned surgical excision of the mass.

Conclusion:

Bone metastases from well-differentiated thyroid carcinomas are rare, and skull involvement is particularly uncommon. Comprehensive imaging and systemic evaluation are essential to determine disease extent and monitor treatment response. While reports of skull metastasis from FVPTC after total thyroidectomy are scarce, this case emphasizes the importance of including metastatic disease in the differential diagnosis of skull lesions, even in long-term postoperative patients. Multimodal treatment—combining surgery, RAI, and radiotherapy—remains critical for optimal management and local disease control.

Dr. Lorence Nepangue is an Internal Medicine resident at Chong Hua Hospital Cebu with interests in endocrine oncology, gastroenterology, neurology, and infectious diseases. A graduate of Cebu Institute of Medicine, he focuses on rare cancer presentations, especially atypical thyroid carcinoma metastases. He advocates for early stroke diagnosis in the young and improving HIV care. Beyond clinical work, he mentors trainees in research and internal medicine. His long-term goal is to pursue fellowship in either gastroenterology or infectious disease specialty and advance care for rare endocrine malignancies through research and clinical innovation.