Endocrine Abstracts

Introduction: Riedel’s thyroiditis (RT) is a rare and chronic fibro-inflammatory disease firstly described by Riedel in 1896. It is characterized by a dense fibrosis that replaces normal thyroid parenchyma. The fibrotic process invades adjacent structures of the neck and extends beyond the thyroid capsule, which differentiates RT from other inflammatory or fibrotic disorders of the thyroid. The overall incidence in outpatients is 1.06 per 100 000. We presented here a case of Riedel’s thyroiditis, which is operated for a suspicion of thyroid malignancy.

Case report: A 48-year-old woman was admitted to the hospital with shortness of breath and swelling in the neck. Her thyroid was firm and multiple nodules were palpated. She was euthyroid. Anti-TPO and anti-Tg antibody levels were in normal ranges. In her thyroid ultrasonography, right lobe’s dimensions were increased. There were hypoechoic areas with irregular margins with dimensions of 9 mm at left upper pole, 23×15 mm at right middle pole and 9×9 mm at left lower pole, which were totally interpreted as thyroiditis. Multinodular hyperplasia with hypoactivity in the nodules of right lobe was obtained in the thyroid scintigraphy. In the fine-needle aspiration biopsy, there were no atypical cells. Surgery was performed to exclude malignancy and to relieve the patient’s complaints. On pathological examination, Riedel’s thyroiditis was diagnosed.

Conclusion: The main diagnostic modality in Riedel’ thyroiditis is pathological examination. The criteriae most commonly used to diagnose Riedel’s thyroiditis are gross description of visible fibroinflammatory process involving all or a portion of the thyroid gland, gross or histological evidence of extension into adjacent structures, absence of granulomatous reaction and neoplasm. It may occur in a multinodular goiter, mimicking thyroid cancer. So such a rare disorder may also be encountered in the investigation of thyroid malignancy.