Histopathological and clinical evaluation of serrated adenomas of the colon and rectum.

We evaluated the diagnostic utility of the histological characteristics ascribed in the literature to serrated adenomas and developed a practical working model to allow their reliable identification. We also documented the frequency and location of serrated adenomas identified in an unselected series of individuals undergoing colonoscopic evaluation, as well as the clinical characteristics of those individuals. One hundred forty consecutive individuals (prospective polyp data set; 97 male, 43 female; age mean: 63.3 y; age range: 29-98 y) with 255 polyps were identified from 919 individuals undergoing colonoscopy. Further polyps previously removed from these individuals were added for the purpose of histological assessment (extended polyp data set, n = 380). All polyps were assessed by two independent examiners for eight selected architectural and cytological features of serrated adenomas. In the prospective polyp data set, 56 patients had 72 hyperplastic polyps, 7 had 9 serrated adenomas, 3 had 4 admixed polyps, and 98 had 170 conventional adenomas. There was no difference in the age, sex, or cancer association of the seven patients with serrated adenomas when compared with the case of other individuals with polyps. The prevalence of serrated adenomas was 9/919 (1%) in our population, with an average size of 5.8 mm. When assessing serrated adenomas histologically, the combination of nuclear dysplasia and serration of >/=20% of crypts provided the most accurate model for detection of these lesions (sensitivity 100%, specificity 97%). Other criteria provided supportive evidence but did not increase the diagnostic yield. The optimum model for the histological identification of the serrated adenoma includes the presence of a serrated architecture in >/=20% of crypts in association with surface epithelial dysplasia.

The relationship between hypomethylation and CpG island methylation in colorectal neoplasia.

Tumors are often characterized by an imbalance in cytosine methylation as manifested both by hypermethylation of CpG islands and by genome hypomethylation. These epigenetic changes were assessed in colorectal neoplasia to determine whether they arose through a common mechanism or indeed were distinct and unrelated phenomena. Fresh representative samples of adenomas, hyperplastic polyps, colorectal cancers, and normal mucosa were used in this study. Global methylation levels were measured by analyzing the methyl-accepting capacity of DNA. Methylation of p16, hMLH1, and MINT 1, 2, 12, and 31 were assessed by bisulfite polymerase chain reaction. Microsatellite status was determined by polymerase chain reaction using six markers and hMLH1 and proliferating cell nuclear antigen expression was assessed by immunohistochemistry. Normal colonic mucosa had a higher endogenous 5-methyl cytosine content than all proliferative lesions of the colon (P < 0.001). The extent of demethylation in hyperplastic polyps and adenomas was significantly related to its proliferative rate. Right-sided hyperplastic polyps were more likely to be methylated than adenomas (odds ratio, 2.3; confidence interval, 1.1 to 4.6). There was no relationship between the level of global hypomethylation and hypermethylation. Some hyperplastic colorectal polyps have a propensity to develop dense CpG island methylation. Hypermethylation and hypomethylation contribute separately to the process of carcinogenesis.

Early studies on the safety and efficacy of thalidomide for symptomatic inflammatory bowel disease.

BACKGROUND AND AIM: Thalidomide is clinically effective in the treatment of graft versus host disease in bone marrow transplantation and aphthous ulceration in HIV infection. It appears to exert a selective effect on tumor necrosis factor-alpha (TNF-alpha) production. Tumor necrosis factor-alpha is implicated in the pathogenesis of inflammatory bowel disease (IBD). The aim of this study was to assess the efficacy and safety of thalidomide in symptomatic IBD. METHODS: Eleven patients (nine males, mean age 33 years, range 20-77 years) with chronic inflammatory bowel disease (six Crohn's disease (CD), four ulcerative colitis (UC), one indeterminate colitis (IC)) who were symptomatic despite standard medical therapy were administered a daily dose of thalidomide for 12 weeks in an open-labeled protocol. Their response was assessed by using clinical, colonoscopic, histological, and immunological methods. RESULTS: Two patients withdrew at 3 weeks because of mood disturbances. Of the remaining nine patients, eight (five CD, two UC and one IC) had a marked clinical response, while one patient with CD had no response. The mean stool frequency decreased from 4.3 to 2.3 per day (P = 0.0012), and the stool consistency increased from 2.1 to 1.2 (P = 0.02). The mean Crohn's Disease Activity Index decreased from 117 to 48 (P = 0.0008). Endoscopic inflammatory and histological grade, C-reactive protein and erythrocyte sedimentation rate (ESR) all decreased significantly (P = 0.011, P = 0.03, P = 0.023 and P = 0.044, respectively). However, the serum TNF-alpha levels did not change. Side-effects included mild sedation, xerostomia and skin dryness in all, constipation in three, and minor abnormalities in nerve conduction in one patient. CONCLUSION: These data strongly suggest that thalidomide is an effective short-term treatment for symptomatic IBD.

The serrated neoplasia pathway.

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.