A case of mixed connective tissue disease complicated with thymic carcinoma and Hashimoto's thyroiditis.

We report the case of a 63-year-old woman who suffered from mixed connective tissue disease (MCTD) complicated with thymic carcinoma and Hashimoto's thyroiditis. Although many systemic syndromes associated with thymoma and thymic carcinoma, i.e., myasthenia gravis, pure red cell aplasia, hypogammaglobulinemia, and Hashimoto's thyroiditis, are known, this is the first report of MCTD complicated with thymic carcinoma. It was suggested that MCTD may be a paraneoplastic syndrome associated with thymic carcinoma.