[Thymoma and autoimmune thyroiditis. A case report].

We report an association between a thymus tumor and autoimmune thyroiditis. This association is probably related to loss of immune control secondary to loss of thymus integrity. A 48-year-old woman was hospitalized for thoracic pain. Her past history included thyroiditis treated by L-thyroxin for two years. The chest x-ray demonstrated a mediastinal opacity which was confirmed by computed tomography. Surgical resection was performed and histological analysis of the surgical specimen confirmed the diagnosis of lympho-epithelial thymoma. Thyroid immunity tests demonstrated the presence of anti-peroxidase antibodies confirming the diagnosis of Hashimoto's thyroiditis. Chest x-ray and CT-scan are indicated in patients with autoimmune thyroiditis to search for a thymic mass. Conversely, search for autoimmune thyroiditis is warranted in patients with an identified thymic mass.