Reparative change with extensive squamous metaplasia: A potential diagnostic pitfall on thyroid aspiration

Squamous metaplasia and cystic change can appear in the thyroid and mimic a variety of lesions. In this report, a patient with two dominant left thyroid nodules underwent fine needle aspiration (FNA) biopsy for each nodule. One of the nodules was diagnosed as consistent with papillary carcinoma and the other as suspicious for papillary carcinoma. Subsequent near total thyroidectomy revealed both lesions to be part of a goiter with extensive squamous metaplasia. This article discusses a potential pitfall in the interpretation of fine needle aspirates of squamous metaplastic cells in the thyroid.