Determining the origin of poorly differentiated adenocarcinomas remains a challenge for the pathologist. This manuscript reports the use of a panel of specific immunohistochemical stains to determine the primary site of a tumor in the colon. A 45-year-old man had a right hemicolectomy for adenocarcinoma. Immunohistochemical staining documented that the lesion was a metastasis from a primary pancreatic adenocarcinoma-an unusual pattern of spread. The case emphasizes the important use of immunohistochemistry in identifying the primary source of lesions, allowing for appropriate treatment and staging.
Key Points
* Immunohistochemistry is a valuable tool in identifying the primary source of adenocarcinoma allowing for appropriate treatment and staging.
* To our knowledge, this is the first report of a case of pancreatic adenocarcinoma that presented initially as a symptomatic colon lesion.
* The mechanism of this unusual pattern of dissemination to the colon from a pancreatic primary is not well described.