Anterior Skull Base Metastasis From Papillary Thyroid Carcinoma: A Case Report.

Distant metastasis occurs in 1% to 4% of patients with papillary thyroid carcinoma (PTC) and most commonly involves the lungs and bones, with skull base involvement being exceedingly rare. We present a case of a 58-year-old male patient who experienced skull-base metastasis of tall-cell variant PTC 4 years after multimodal treatment of aggressive disease. The patient presented to the otolaryngology clinic with left-sided postnasal drip, anosmia, ptosis, and proptosis. Magnetic resonance imaging of head showed a 1.9 × 2.7 × 4.4 cm mass with extensive invasion of the sinonasal cavities, cribriform plate, and left orbit, complicated by a postobstructive mucocele. In-office biopsy was consistent with metastatic PTC. He underwent endoscopic surgical debulking followed by postoperative radiation therapy. This case demonstrates how PTC with aggressive features can develop anterior skull base metastases years after initial treatment. Management required recognition of this diagnostic challenge and combined endoscopic resection and stereotactic radiotherapy, achieving local control while preserving neurologic function. The patient has remained stable at 7-month follow-up.