[De Quervain thyroiditis. Corner points of the diagnosis]

Inflammatory disorders of the thyroid gland are divided into three groups according to their duration (acute, subacute and chronic). De Quervain's thyroiditis (also termed giant cell or granulomatous thyroiditis) is a subacute inflammation of the thyroid, which accounts for 5% of thyroid disorders. The etiology is unknown, it usually appears two weeks after an upper viral respiratory infection. The clinical feature includes neck pain, which is aggravated during swallowing, and radiates to the ear. On palpation, the thyroid is exquisitely tender. The erythrocyte sedimentation rate is markedly elevated, the leukocyte count, C-reactive protein are normal or slightly elevated. The natural history of granulomatous thyroiditis involves four phases: the destructive inflammation results temporarily in hyperthyroidism followed by euthyroidism. After a transient hypothyroidism the disease becomes inactive and the thyroid function is normalised. Ultrasonographic findings are diffuse hypoechogenic structures, but nodules may also occur. The disease often remains unrecognised, or the first phase of the disease is diagnosed and treated as hyperthyroidism. The diagnosis can be confirmed by the presence of the thyroid autoantibodies, radioiodine uptake and fine needle aspiration cytology. There is no special treatment, non-steroid anti-inflammatory drugs or steroid should be given to relieve the pain. The aim of the authors is to shed light the key points of diagnosis and differential diagnosis by the presentation of four slightly different cases.