An unusual form of Riedel's thyroiditis: a case report and review of the literature.

We report the case of a 36-year old woman with a history of long-term fever associated with a biologic inflammatory syndrome that was not corrected by several courses of corticosteroid treatment. The only remarkable result during previous investigations was the presence of a positive Epstein-Barr virus (EBV) serology. Clinical examination revealed an heterogenous thyroid with a nodule on the right lobe. Serum thyrotropin (TSH) concentration was normal. The levels of antiperoxidase antibodies and thyrocalcitonin were normal. Ultrasound examination of the neck showed a 3-cm hypoechogenous nodule in the right lobe of the thyroid. A total thyroidectomy was performed. Histopathologic findings led to the diagnosis of Riedel's thyroiditis. We observed a dramatic improvement after surgery with absence of fever and normalization of inflammatory parameters. The role of EBV infection in the process of this unusual form of Riedel's thyroiditis is discussed.