[A case of primary malignant lymphoma in the thyroid gland arising from pre-existing Hashimoto's disease].

Primary malignant lymphoma in the thyroid gland is relatively rare. It has been reported that primary malignant lymphomas comprise 0.8-8% of all thyroid malignancies. The relation to Hashimoto's disease is controversial. A 63-year-old woman with a 9-year history of diffuse goiter visited our hospital. A clinical diagnosis of Hashimoto's disease had previously been made. After 15 months, she noted the rapid growth of the goiter and enlargement of cervical lymph nodes . A cervical lymph node was biopsied, histologic examination lymphoma (large lymphoid-diffuse type). This suggests that malignant lymphoma in the thyroid gland may arise from pre-existing Hashimoto's disease.