Papillary thyroid carcinoma with brain and lung metastases: a case report

Papillary thyroid carcinoma (PTC) usually has a favorable prognosis, the concurrent occurrence of brain and lung metastases is extremely rare, thus such cases have significant clinical reporting value. We report a case of a patient with multifocal PTC who presented with delayed multiple metastases.

In January 2025, a 61-year-old female suddenly developed speech impairment and right limb weakness without an obvious cause. Upon reviewing her medical history, it was found that she had undergone a total thyroidectomy six years earlier because of multiple papillary thyroid carcinomas. Upon admission, relevant examinations were performed: cranial MRI revealed a solitary mass in the left frontal lobe, and a chest CT revealed multiple nodules in both lungs. The postoperative pathological examination of the brain lesion and bronchoscopic biopsy of the mediastinal lymph nodes revealed metastatic thyroid cancer (Pax-8, Tg, and TTF-1 positive). Diagnostic ¹³¹I whole-body scan after high-dose radioactive iodine treatment (180 mCi) revealed no significant radioactive isotope uptake by the lung metastases, indicating a radioactive iodine-resistant disease. Subsequently, three cycles of systemic chemotherapy (albumin-bound paclitaxel combined with carboplatin) were tried, but they were discontinued because of extreme toxicity.

The patient underwent surgical resection of brain metastases, and then switched to the multi-kinase inhibitor anlotinib due to poor chemotherapy tolerance. After approximately 10 weeks of anlotinib treatment, the first CT assessment showed a partial response, with the lung metastases shrinking and partially resolving. The most recent follow-up CT (in March 2026) confirmed that the remission was ongoing.

This case indicates that PTC can result in uncommon, delayed, and numerous distant metastases even years after radical surgery. This highlights the importance of life-long surveillance, including chest and crinial imagings. The partial remission with anlotinib underscores its value as a therapeutic option in this setting.