ガンマナイフ後に増大した甲状腺乳頭癌脳深部転移の1例

A Case of Tumor Progression after Gamma Knife Radiosurgery for Brain Metastasis of Thyroid Papillary Carcinoma in Deep Subcortical White Matter

Ⅰ．はじめに

　甲状腺乳頭癌（thyroid papillary carcinoma：TPC）は比較的予後のよい癌で，他臓器転移は少ない．転移する部位は，主に肺や骨が多く，脳への転移は，0.1～5％と少ない^3,6,7,13)．

　今回われわれは，大脳深部のTPC脳転移に対するガンマナイフ照射後，腫瘍が増大し，CTと駒井式フレームを用いて定位的手技を利用して腫瘍摘出術を行った1例を経験したため，文献的考察を加え報告する．

　We report a case of a brain metastasis of thyroid papillary carcinoma. A 67-year-old man had undergone a radical operation for thyroid papillary carcinoma 6 years before. He had no neurological deficit, but CT showed an enhanced lesion in the left frontal lobe. He underwent gamma knife radiosurgery. Four months later, the lesion with massive peritumoral edema was identified on magnetic resonance imaging (MRI). The edema was treated medically, however, recovery was seen neither on MRI nor clinically. Then left craniotomy was performed, with total resection of the tumor. During the operation Komai's stereotactic instruments were used for CT guided stereotactic surgery. Histopathological analysis of the surgical specimen confirmed mixed necrosis and papillary carcinoma of the thyroid gland. The patient was discharged without neurological deficit and is now kept under observation as an outpatient. Brain metastases from thyroid cancer are rare and we report a case of resection of brain metastasis of a thyroid papillary carcinoma after gamma knife radiosurgery.