Müller et al describe a family with classic HNPCC of the Lynch syndrome type II. The 32-year-old proband had an early-onset carcinoma of the ovary, uterus, and colon. Microsatellite instability was evidenced in her colon cancer. The specific germline mutation (hMSH2, hMLH1, PMS1, PMS2) was not reported. In their description of HNPCC, the authors state that it may include, "many adenomatous polyps (typically up to 100) with a predilection for the proximal colon...." In fact, the number and location of polyps in the colon does not differ from general population estimates. Colonic adenocarcinomas are more poorly differentiated and have an excess of signet-ring cells. A special type called undifferentiated medullary (solid or cribriform) carcinoma, although rare in the general population, is reported in about 10% of HNPCC.
The authors state that the Amsterdam criteria need to be fulfilled for an HNPCC diagnosis. These criteria, however, were developed to aid researchers