PATHOLOGICAL FEATURES OF HEREDITARY NONPOLYPOSIS COLORECTAL-CANCER

In hereditary non-polyposis colorectal cancer (HNPCC) patients, the ca ncer frequently arises in the proximal colon and is often multiple (sy nchronous or metachronous). Pathologic differences seem to exist betwe en hereditary and sporadic Barge bowel cancer, but the data are not un iform. Many authors reported that the following histologic features ar e often present in HNPCC: 1) mucinous histotype, 2) poorly differentia ted tumors, 3) presence of peritumoral lymphocytic infiltrate, with Cr ohn's-like lymphoid reaction. Such features have also been found in ap parently sporadic colorectal cancer with, but not in sporadic colorect al cancer without DNA replication errors. Many studies have suggested that adenoma plays a main role in HNPCC carcinogenesis, and that the ' 'adenoma-carcinoma sequence'' may be the pathway to cancer in HNPCC as in sporadic colorectal cancer. Moreover, HNPCC adenomas show an early onset, villous component, high-grade dysplasia, and positivity for DN A replication errors more frequently than sporadic adenomas. Such data suggest that the adenoma-carcinoma sequence is accelerated in HNPCC a nd that surveillance in these patients should therefore be strict to a void cancer development.