Colon Cancer With Metastatic Involvement of the Thyroid Incidentally Found at Excision of Parathyroid Adenoma.

Metastatic disease from primary colon cancer in the thyroid is rare. The authors have submitted such a case. What makes this case particularly unusual is that it was in a man. 80% of such cases are in women. It has been speculated that there may be a humoral component. What is even more unique in this case is that it was found during the workup of a symptomatic parathyroid adenoma. The diagnosis was confirmed with immunochemistry using markers Cytokeratin 20 (CK20), Cytokeratin 7 (CK7), and Thyroid Transcription Factor 1 (TTF-1) .