Yangming Cao M.D.               St. Luke’s Medical Center
Initial suspicion of familial adenomatous polyposis (FAP) led to the identification of hereditary nonpolyposis colorectal cancer: a family case report
         
 

This is to study a family who we initially suspected had familial adenomatous polyposis (FAP). The 62 year old proband presented with duodenal adenocarcinoma with 3 gastric adenomas. His personal history of subtotal colectomy for colon cancer at 45 years old, the rarity of duodenal adenocarcinoma in general population and his family history of colorectal cancer made us suspect that he might have familial adenomatous polyposis (FAP). With informed consent obtained, we started to investigate this family by obtaining medical records and gene tests. The proband had only about 10 colon polyps when he had subtotal colectomy for the cancer, based on which classic FAP was excluded. Three months after we started to investigate this family, the proband’s 32-year-old son developed rectal cancer. His family fulfilled the Amsterdam criteria for HNPCC, but we needed to exclude attenuated familial adenomatous polyposis (AFAP). The proband was negative for APC gene germline mutation, which made AFAP highly unlikely. On the other hand, he had high microsatellite instability (MDI) in the adenomas and cancer tissues. The fulfillment of Amsterdam criteria, the exclusion of AFAP, and the high MSI established the diagnosis of HNPCC in this family. The family members should be followed by the screening procedures recommended for HNPCC. In addition, only 17 cases of duodenal cancer associated with HNPCC can be identified in the literature, with our proband’s being the 18^th such case.