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The concept of a 'serrated neoplasia pathway' refers to a pattern of progression of neoplasms of the colon and rectum that involves hyperplastic polyps and serrated adenomas and which results in the development of carcinoma. The existence of this pathway was initially suggested on morphological grounds. Over the past few years, the increasing recognition of biological and genetic similarities in lesions of this pathway has served to reinforce this concept. The likely existence of such a distinct pathway of colorectal carcinogenesis has implications for the practice of surgical pathology. Most notably, it requires pathologists to recognise the entity of the serrated adenoma, and also to recognise those features of hyperplastic polyps that may be associated with a potential for neoplastic progression.

Background: GPIbalpha is the von Willebrand factor binding subunit of the GPIb/VI/IX receptor of platelets. We have recently demonstrated that GPIbalpha and the other receptor subunits of this platelet complex are aberrantly expressed on the surface of breast cancer cell lines in a functional form. The current study examines the clinicopathological correlates of GPIbalpha expression in human breast cancer., Materials and Methods: GPIbalpha expression was examined in a retrospective series of human breast cancers using immunohistochemistry., Results: We found that of 98 primary breast cancers, 61 (62.2%) expressed GPIbalpha. The presence of the receptor did not correlate with any known prognostic variables including age, tumour size, or number of involved lymph nodes. GPIbalpha expression was not related to overall survival when the group was considered as a whole. However, it was prognostically important when considered in relation to the menopausal status of patients., Conclusion: We conclude that GPIbalpha immunoreactivity does not appear to be of prognostic significance overall, but may be important in a subset of breast cancer patients.

About 10-15% of colorectal cancers show high-level microsatellite instability. The characteristics and very existence of low-level instability (MSI-L) are unclear, although some studies have found associations between MSI-L and molecular characteristics, notably more frequent K-ras mutations and a low level of allele loss near APC. We have attempted to define a MSI-L group of tumors by analyzing 107 sporadic colorectal carcinomas at 44 microsatellites. Ten (9.7%) MSI-H cancers were identified, but there was no evidence for a discrete MSI-L group. However, the 97 non-MSI-H cancers showed greater variation in the frequency of MSI than was expected by chance. Most cancers (68%) in the non-MSI-H group showed some MSI and could therefore be classed as nominally MSI-L. No association was found between MSI-L (or the level of MSI) and any clinicopathological or molecular variable, including K-ras mutation and loss of heterozygosity at APC. The causes of variation in level of the MSI in non-MSI-H colorectal cancers are unknown, but the differences are quantitative and probably reflect the evolutionary histories of the cancers rather than qualitatively different genetic pathways of tumorigenesis.