Myasthenia gravis with thymoma associated with occult thyroid carcinoma.

We report herein a case of myasthenia gravis associated with thymoma and occult thyroid carcinoma with metastasis to a cervical lymph node, which was treated in two stages by a total thymectomy and radical dissection of the bilateral neck after a total thyroidectomy. A 48 year old woman was admitted with right blepharoptosis and hypodynamia of the proximal muscles. After various examinations, a diagnosis of myasthenia gravis was made. The association of thymoma was clarified upon CT scanning and a total thymectomy performed. However, after surgery, swelling of the cervical lymph nodes became apparent and a biopsy revealed metastasis of thyroid carcinoma in the lymph nodes. A diagnosis of occult thyroid carcinoma with metastasis to a cervical lymph node was subsequently made and a total thyroidectomy and radical dissection of the bilateral neck performed 37 days after the total thymectomy. The patient's postoperative course was uneventful and for the time being, no recurrence is expected. It is considered better to perform two-stage operations for easier and safer postoperative management when myasthenia gravis associated with occult thyroid carcinoma is treated, although it depends on the development of thyroid carcinoma being occult.