[Solitary brain metastasis of thyroid papillary carcinoma mimicking a cavernous angioma by MRI].

We report a case of a brain metastasis of thyroid papillary carcinoma. A 50-year-old man suffered generalized convulsion. MRI showed a mixed intensity mass with a perifocal low intensity rim in T2WI, mimicking cavernous angioma. The patient underwent craniotomy and total removal of the mass. The resected specimen revealed thyroid papillary carcinoma. Further examination showed a mass in his thyroid gland. Other distant metastases were not revealed. This is a case of a solitary brain metastasis of thyroid papillary carcinoma and the patient's initial symptom was caused by brain metastasis. Such cases are extremely rare. The mass was presurgically diagnosed as a cavernous angioma but was actually a case of brain metastasis. If we had not performed mass removal, we would not have been able to diagnose it as brain metastasis from thyroid papillary carcinoma and would have not taken appropriate steps toward further examinations and treatment. We must manage carefully a mass resembling cavemous angioma in MRI in consideration of the possibility of its being another diseases such as a metastatic tumor.