Follicular adenoma with papillary architecture: a lesion mimicking papillary thyroid carcinoma

Abstract

The papillary structures in the study cases are unlikely to represent degenerative changes due to their proliferative activity. In view of (i) the encapsulation and the uniformity of the constituent cells, (ii) the varying degrees of immunoreactivity for CK19 and HBME and negative immunoreactivity for Ret oncogene protein, and (iii) the absence or insufficiency of nuclear criteria for the diagnosis of PTC and the absence of lymph node metastasis in all study cases, we believe that these lesions represent the papillary variant of follicular adenoma. Recognition of this pathological entity is important to avoid an over-diagnosis of PTC.