[Identification of 2 families with hereditary nonpolyposis colonic cancer (HNPCC) and the Amsterdam criteria. Relevance of the genealogic tree and follow-up].

Hereditary nonpolyposis colorectal cancer (HNPCC) diagnosis is based either on the so-called "Amsterdam 1 criteria" or "Amsterdam 2 criteria", which includes extracolonic neoplasms associated with Lynch II syndrome. Many families are suspected of having a hereditary predisposition to cancer and may benefit from close surveillance. We describe a family (family 1) with suspected HNPCC at the beginning who fulfilled the Amsterdam 1 criteria over the course of its follow-up. We also describe an Amsterdam 2 family (family 2) with a very young affected individual. Both of them received genetic counseling and screening recommendations. A total colonoscopy was done to an asymptomatic member of family 1 and he was diagnosed with an early-stage colon cancer. He underwent subtotal colectomy because of the high risk of metachronous lesion. Screening recommendations must be the same in Amsterdam 2 families as in Amsterdam 1. Both families show the importance of considering the family history when hereditary criteria are suspected.