Abstract
Metastasis to the sella turcica and pituitary gland is rare and review of the literature revealed only 12 cases of metastatic thyroid carcinoma involving this site. A 49 year old woman presented with progressive visual impairment and headache. Past history includes 2 operations for benign multinodular goiter. Three months before presentation, she underwent subtotal thyroidectomy for large multinodular goiter that was confirmed to be follicular thyroid carcinoma .Brain MRI showed 5.5X4cm mixed intensity lobulated sellar and suprasellar mass lesion containing areas of necrosis and sub acute blood with some encasement of the cavernous part of both(internal carotid artery) ICAs. The patient underwent transsphenoidal removal of the lesion to alleviate visual impairment. The histopatholgical features of the pituitary tumor proved as metastatic follicular carcinoma of the thyroid gland. She received first dose of (Radioactive iodine) RAI131 ablation therapy 4 months later. Further debulking surgery of the pituitary lesion and to the thyroid recurrences were done. She is partially sighted due to rapidly enlarging pituitary metastasis with protruding eyes and lung metastasis. Fractionated ablative doses of RAI131 therapy and external beam irradiation were administered at early 2009 with steroid cover. The patient is still under close follow up with suppressive thyroxin therapy
We hereby present a rare case of follicular thyroid carcinoma metastasis to the pituitary gland with an aggressive behavior and brief review of literature.

Key words: Follicular carcinoma, metastasis, pituitary, RAI 131.