Myocarditis associated with Hashimoto's disease: a case report

We report on a sudden cardiac death case involving a 40-year-old man with no known medical history. Forensic autopsy showed lymphocytic myocarditis associated with lymphocytic thyroiditis. In both the heart and the thyroid gland, the inflammatory foci often had a nodular pattern with a germinal centre. Virological and toxicological analyses were negative. Postmortem biochemistry showed a slight increase in TSH in combination with normal T3 and T4 blood levels suggesting hypothyroidism. High titres of antiperoxidase and antithyroglobulin antibodies with normal levels of TSH receptor antibodies, in addition to biological hypothyroidism and lymphocytic inflammation were consistent with the diagnosis of Hashimoto's thyroiditis. Immunohistochemical studies excluded a lymphoma and showed no evidence of viral myocarditis. In contrast to Grave's disease, Hashimoto's thyroiditis has never been reported in association with myocarditis as a cause of sudden death. We conclude that the cardiac immunological and histological pattern, similar to that found in the thyroid gland suggests an autoimmune myocarditis.