Clinical presentation: A 31-year-old woman was referred for evaluation of a recurrent hyperthyroidism. At the time of the investigation, she was at the 5th gestational week. Her complaints have recurred for two weeks. She was treated for hyperthyroidism two years ago.

Palpation: Both lobes were enlarged. There were no palpable nodules.

Laboratory investigations: TSH 0.001 mIU/L, FT4 71.9 pM/L, TSAb 11.8 U/L (normal value < 1.5).

Ultrasonography. The thyroid was moderately hypoechogenic and presented numerous more hypoechogenic areas. None of them corresponded to a nodule in pathological sense. The vascularization was moderately increased.

Summary of follow-up. The patient was treated with propylthiouracil, her thyroid functions were checked every 4 weeks until the 23rd gestational week. The elevated FT4 levels have normalized 8 weeks after the initiation of thyrostatic therapy. At the 23rd week of pregnancy, the thyrostatic therapy was stopped. The patient remained euthyroid in the subsequent 6 months when her hyperthyroidism relapsed again. After restoration of elevated thyroid hormones, the patient underwent surgery. (Considering the precautions after a radioiodine therapy she decided to undergo total thyroidectomy.)

Histopathology: Diffuse goiter. Chronic lymphocytic thyroiditis.