Papillary endothelial hyperplasia in the thyroid following fine-needle aspiration. A 74-year-old woman was found to have exuberant papillary endothelial hyperplasia within her thyroid gland subsequent to multiple fine-needle aspiration biopsies of a Hurthle cell neoplasm. To our knowledge, this histologic alteration in the thyroid has not been previously reported. We describe this unusual complication following fine-needle aspiration, and we delineate the clinicopathologic and differential diagnostic features. 