[Hereditary non polyposis colorectal cancer (HNPCC). A clinical and genetic entity].

The first description of hereditary non polyposis colorectal cancer goes back to Warthin's study in 1895. In 1966 two families with autosomal dominant predisposition to colon and endometrial cancer were found. This condition was defined initially as familial neoplasm syndrome, then Lynch syndrome, and at last hereditary non polyposis colorectal cancer (HNPCC). HNPCC is classically subdivided into Lynch syndrome I (characterized by predisposition to colorectal cancer with early age of onset, to cancer of the proximal colon, and excess of synchronous and metachronous cancer), and Lynch syndrome II (characterized by similar colic phenotype with augmented risk of extracolonic neoplasm). If all clinical characteristics are present, it is possible to suspect HNPCC: however, diagnosis is difficult. Histological and genetic features of colon cancer confirm the diagnosis of HNPCC. Surgical therapy of colic neoplasm is total colectomy. A careful screening of HNPCC family members is one of the cardinal point in prevention. Follow-up of these surgical patients is the same as for sporadic neoplasms.