Papillary thyroid cancer with unusual late onset pituitary and orbital choroidal metastases. Case report and literature review

Papillary thyroid cancer is the most common type of differentiated thyroid cancer (DTC) and in most cases, disease is localized to the neck and remission of disease is common. Though distant metastasis of DTC is unusual; involved sites are more often the lungs and bones, while less common sites include the liver and kidney. No case of metastasis to both intraocular choroid and the pituitary gland has previously been reported. We describe a case of a 58-year-old man who presented with multifocal papillary thyroid carcinoma (PTC) with cervical node metastasis. According to risk stratifications in DTC, the patient stratified as low risk of recurrence. Five years after initial presentation, he was found to have mediastinal lymph node metastasis. Fifteen years post diagnosis, his PTC metastasized to his liver, bone, lung, pituitary gland, orbital choroid and choroid plexus. Remarkably, the only symptom the patient developed as a result of this metastasis was alteration in his vision, which was treated with bevacizumab. Despite initial improvement, he developed ptosis and third nerve symptoms. His pituitary metastasis was treated with Cyber-Knife Surgery and his systemic metastasis was treated with the tyrosine kinase inhibitor (TKI) lenvantinib, resulting in new improvement of his vision. Lenvantinib treatment led to a very marked decrease in the size of his intraocular and choroid plexus lesions and stabilization of his pituitary mass size. The patient developed central hypoadrenalism that required treatment with glucocorticoid replacement.

A review of literature for the past 5 decades revealed that metastasis of DTC to the orbital choroid and the pituitary gland have been reported in 17 and 16 cases, respectively. This report is unique as it presents the first case of metastatic PTC to both the intraocular choroid and the pituitary gland. Furthermore, no prior study reported simultaneous DTC metastasis to intraocular choroid and the ventricular choroid. This case highlights that despite their rarity, intraocular and pituitary metastasis of DTC should be considered as potential causes of atypical symptoms such as visual changes or hypopituitarism. Finally, use of TKI therapy for DTC with metastasis to the intraocular choroid and pituitary gland can improve the disease course.