[Difficulties in the diagnosis of painful Hashimoto's thyroiditis--case report].

Painful Hashimoto's thyroiditis is an atypical variant of Hashimoto's thyroiditis characterised by thyroid pain and fever. We report the case of a 40-year-old female whose clinical manifestation so closely mimicked subacute thyroiditis that she was initially diagnosed as having de Quervain's disease. Only finding a lymphocytic infiltration in fine needle biopsy specimens of the thyroid gland and positive antithyroid antibodies allowed us to correctly interpret the clinical manifestation of our patient leading to the diagnosis of painful Hashimoto's thyroiditis. No beneficial effect was produced by nonsteroidal antiinflammatory drugs while some improvement was observed after treatment with propranolol. The most effective drug was thiamazole that not only normalised thyroid hormone levels but also caused disappearance of fever and markedly reduced pain intensity. The discussed case shows difficulties in diagnosis of inflammatory processes in the thyroid gland and indicates that antithyroid drugs may be effective agents in hyperthyroid patients with painful Hashimoto's thyroiditis.