Localized amyloid in thyroid: are we missing it?

When present in thyroid, amyloid is an attribute almost always restricted to medullary thyroid carcinoma. Scant studies in the literature have demonstrated this finding in other thyroid pathologies as papillary thyroid carcinoma, amyloid goiter, and other benign entities. From our experience in thyroid pathology, we analyzed cases on which the stroma contained deposits of amorphous, acellular, and eosinophilic material characteristic of amyloid. Congo red stain on suspicious cases was performed; clinicopathologic investigation was done when results were positive. Seven patients with amyloid infiltration in the thyroid, in association with papillary thyroid carcinoma, and in 4 cases of benign pathologies were found in our own review. The association of amyloid and thyroid is discussed herein, including cases of systemic amyloidosis, malignancies, benign diseases, and thyroid goiter, from our practice and from the available literature.