TY - JOUR T1 - Microsatellite unstable colorectal cancer JF - Journal of Clinical Pathology JO - J Clin Pathol SP - 573 LP - 574 DO - 10.1136/jcp.54.7.573-b VL - 54 IS - 7 AU - J R Jass Y1 - 2001/07/01 UR - http://jcp.bmj.com/content/54/7/573.3.abstract N2 - The paper by Shitoh et al on the pathogenesis of non-familial colorectal carcinomas with high microsatellite instability (MSI) indicates little clinicopathological distinction from microsatellite stable cancers and a similar distribution of mutation in the adenomatous polyposis coli (APC) and TP53 genes, and loss of heterozygosity (LOH) at 17p.1 The authors claim that their data fit with some earlier studies, but several of the pioneering studies do not distinguish clearly between MSI low (MSI-L) and MSI high (MSI-H) cancers. Their findings are very different from multiple studies that adequately distinguish between sporadic MSI-H and MSI-L cancers.By way of explanation, the authors suggest that other studies may include hereditary non-polyposis colorectal carcinoma (HNPCC) cases. It is more likely that their own series includes HNPCC cases, because a lack of a family history does not exclude this diagnosis. Given that somatic mutations of hMSH2 and hMLH1 are described in six of their MSI-H cases, these could be examples of HNPCC because methylation of the promoter region of hMLH1 is regarded as the usual pathogenetic basis for non-familial examples of MSI-H colorectal cancer. Again, the failure to identify a germline mutation in these … ER -