[Thyroid papillary hyperplasia mistaken for papillary carcinoma in fine needle aspiration cytology and frozen section examination].

In a 40-year-old woman with a swelling in the left lobe of the thyroid gland, fine needle aspiration cytology led to the suspicion of papillary thyroid carcinoma. Hemithyroidectomy with a frozen section examination followed. The frozen section was also suggestive of papillary carcinoma and total thyroidectomy with cervicocentral lymph node dissection was performed. However, the final histological examination revealed papillary hyperplasia and not a malignancy. Thyroid papillary hyperplasia presenting as a single thyroid nodule is rare. Nevertheless, the possibility of thyroid papillary hyperplasia should be considered when the features of fine needle aspiration cytology are suggestive, but not fully evident for papillary carcinoma. In these cases it is important to wait for the final histology and abandon frozen section examination.