“Giant” Solid Cell Rest of the Thyroid: A Hyperplastic Change?

Abstract

We describe the case of a 50-year-old male who underwent total thyroidectomy bec ause of clinical suspicion of medullary thyroid carcinoma, due to persistent elevation of the serum calcitonin level (up to 23 pg/mL). Grossly, the thyroid had a multinodular appearance consistent with nodular hyperplasia (adenomatoid goiter). Microscopically, the sections taken from the isthmus showed a multinodular structure composed of well-defined epithelial nests with peripheral palisading resembling transitional epithelium (urothelium). Most of the nests were solid, but there were also cystic formations containing mucin. These epithelial nests were interspersed between the thyroid follicles and sometimes merged with them. Immunohistochemically, the nests displayed strong nuclear positivity for p63 and cell membrane staining for cytokeratin 5/6, International Journal of Surgical Pathology olume 17 Number 3 June 2009 268-269 © 2009 The Author(s) 10.1177/1066896909333747 http://ijsp.sagepub.com “Giant” Solid Cell Rest of the Thyroid: A Hyperplastic Change?