Papillary Thyroid Carcinoma With Prominent Hobnail Features: A New Aggressive Variant of Moderately Differentiated Papillary Carcinoma. A Clinicopathologic, Immunohistochemical, and Molecular Study of 8 Cases

In Response: We would like to thank Profe- ssor Jorge Albores-Saavedra for the interesting comments that he made about our publication. 3 The 2 tumors of papillary thyroid carcinoma with hobnail features that he described appear to have characteristics in com- mon with some of the tumors descri- bed by Asioli et al. 3 Although hobnail cells in oncocytic neoplasms have been described, 1,4,5,7,8 showing that such tumors usually have a more aggres- sive biologic behavior is important to support the clinicopathologic findings described in our report. 3 Some other thyroid tumors such as tall-cell carci- nomas may have oncocytic features and behave more aggressively than typical papillary thyroid carcinomas, 7 whereas other tumors with oncocytic features such as Warthin-like papil- lary thyroid carcinomas behave more like typical papillary thyroid carcino- mas. 2 Thus, molecular changes such as p53 overexpression and BRAF mutations that we described may be important parameters to explain the more aggressive behavior of the tumors in our series. In addition, changes in cell orientation with loss of polarity and possibly alteration in specific gly- coproteins 6 may contribute to the higher propensity to metastasize to sites not usually encountered with typical papillary thyroid carcinomas