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Colonic polyps commonly occur in all age groups and are of varied significance depending on the type of polyp and the symptoms manifested. There is some debate in the medical literature regarding the appropriate clinical management of polyps and the follow-up of patients after polypectomy. This discussion addresses the significance of colon polyps, including their etiology, histology, complications, detection, and management.
Currently known information about the development and progression of colon polyps and cancer is summarized and organized into a mathematical computer simulation model that successfully predicts the natural history of colon polyp and cancer development for an average patient with (1) familial polyposis coli (2) genetic susceptibility as measured by a positive family history, and (3) negative family history with a high fat diet. The mathematical model uses four distinct types of cells (normal, transformed, polypoid, and cancerous) and two kinetic processes (mutation and promotion). Arachidonic acid metabolites play a role in the model in the promotion of cancer from polyps, and account for that promotion through: (1) their effect on encouraging more polypoid cells in mitosis to move toward cancer; and (2) their immunosuppressive effect over time. The model also shows that one defect in allowing more cells to mutate to the transformed state is sufficient to account for the chain of events leading to the clinical sequelae of familial polyposis coli. A second genetic effect at another point in the process is unnecessary. The mechanism of action of Sulindac on colon polyps is explained by the model through inhibition of production of arachidonic acid metabolites, most notably prostaglandin E.
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A solitary hamartomatous polyp of the colon in a four year old boy was diagnosed by colonic sonography while barium enema and colonoscopy were non-diagnostic. Colonic sonography provides an additional simple, relatively non-invasive modality for evaluation of the colon.
A juvenile colon polyp was demonstrated by inferior mesenteric arteriography in a 21-year old man with recurrent, massive, unexplained gastrointestinal bleeding. The arteriogram demonstrated a mucosal blush at the tip of the polyp along with a solitary prominent draining vein in the stalk and a nest of draining veins at the base of the stalk.
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The concept of inevitable premalignancy in all adenomatous polyps of the colon was challenged as early as 1958, and since that time much debate has centered about the malignant potential of adenomatous polyps of the colon. Current thinking indicates that the majority of colonic polyps fall into one of four categories: hyperplastic, villous adenoma, adenomatous, and villoglandular. Analysis of the present series of 387 colonic polyps removed endoscopically indicates that the villoglandular group has a notable malignant potential, and that the pure adenomatous polyp probably carries a minimal malignant threat. The present series does not challenge the accepted concept that hyperplastic polyps are of no malignant potential, and that villous adenomas are quite frequently malignant at the time of diagnosis.
The distribution patterns of epithelial blood group AB antigens (BG) in colon polyps of varying degrees of differentiation were studied by the mixed cell agglutination reaction. BG appeared in colon polyps if a certain degree of dedifferentiation was present. Two different distribution patterns were recognized: 1) association of BG with the secretory part of goblet cells with slight-to-moderate atypia and 2) association of BG with the whole cells in cases of pronounced dedifferentiation and loss of secretory activity. The second type resembled the distribution pattern of BG found previously in colon carcinomas. With respect to BG, the mucosa of colon polyps behaved similarly to embryonal colon mucosa. The detection of BG represents a useful method to assess objectively the degree of dedifferentiation in most colon polyps.
Malignant colonic polyps on substantial stalks were seen in 3 patients. In each case the base of the pedicle was free of tumor. The author suggests that these were initially benign adenomatous polyps but subsequently became malignant. These findings suggest that initially benign colonic polyps can become malignant over a period of time and that the presence of a substantial stalk may not always be pathognomonic of benignity.
Although the hot biopsy technique is widely used to treat diminutive colon polyps, there is concern over its efficacy and safety. Our study involved 39 patients undergoing routine colonoscopy in whom 62 diminutive polyps were found in the rectosigmoid. These lesions were treated with hot biopsy forceps in the standard manner. Flexible sigmoidoscopy was repeated 1 and 2 weeks later with the original treatment sites being identified. Eleven of the 62 sites (17%) revealed persistent viable polyp remnants, indicating incomplete treatment. In terms of safety, there were no clinical complications in this small study and most post-biopsy ulcers were healed by 2 weeks. This study shows that the hot biopsy technique may be unreliable in eradicating diminutive colon polyps.
A patient who had metastasis from a focus of invasive carcinoma confined to the head of an otherwise benign pedunculated adenomatous polyp of the sigmoid colon is described. That only 20 such cases have been reported previously attests to the rarity of this phenomenon. Because the morbidity and mortality of radical surgery far outweigh the liklihood of metastasis from such foci of invasive carcinoma in pedunculated adenomatous colonic polyps, local removal is recommended.
The risk of malignant degeneration of colonic polyps has traditionally rested on various roentgenographic criteria such as broad base, irregular surface and size larger than 1 cm. With the aim of facilitating the choice of treatment of colonic polyps, an appraisal is made of the morphology of 200 polyps removed from 154 patients. The results of barium enema and double contrast techniques are compared with those obtained at colonoscopy. Radiography is found to have considerable shortcomings in evaluation of the appearance of the polyp. As the correlation of the gross morphology of the polyp of histology is weak endoscopic polypectomy should be performed whenever possible.
A 3-layer immunoperoxidase technique was used to demonstrate carcinoembryonic antigen (CEA) in colonic polyps from patients with or without previous or concurrent malignancy. CEA was demonstrated in a higher percentage of the polyps received as fresh specimens that were rapidly frozen and fixed in ethanol, than in formalin-fixed, paraffin-embedded sections. Tissue CEA content of both colonic carcinomas and polyps was determined by radioimmunoassay, and it was found that benign colonic tumours had levels of tissue CEA comparable to colonic cancer, indicating that CEA concentration in a tumour does not reflect its grade of malignancy. In fact, in one case in which both colonic cancer and polyps were removed, the polyps had the higher quantities of tissue CEA. Further, tissue CEA concentration of a polyp was not dependent on its size or location. Studying the titres of circulating CEA in these patients revealed an elevation of plasma CEA in one-third of the patients with only colonic polyps, whilst the patients with cancer all had increased titres.
A unique family with a distinct syndrome of adenomatous colonic polyps and sebaceous cysts without osseous or soft tissue abnormalities is presented. One member had benign gastric polyps limited to the upper half of the stomach and another had a medulloblastoma of the cerebellum. A histologic feature in the colon of the propositus was the presence of atypical epithelium in flat mucosa as well as in the colonic polyps.
Ultraviolet laser-induced fluorescence was examined in vivo to determine whether the technique can reliably distinguish between hyperplastic and adenomatous polyps of the colon. Spectra from 86 normal colonic sites, 35 hyperplastic polyps, and 49 adenomatous polyps were recorded in vivo. Polyp type was independently determined by two senior pathologists who were unaware of the fluorescence measurement. A multivariate linear regression analysis was used to differentiate spectra from hyperplastic and adenomatous polyps and resulted in a sensitivity, specificity, predictive value positive, and predictive value negative for identifying adenomatous polyps of 86%, 80%, 86%, and 80%, respectively. These values were not significantly different from the accuracy of routine clinical pathology. Thus, ultraviolet laser-induced fluorescence appears to show promise as a means for distinguishing tissue types. However, further experience is needed before its routine clinical use can be recommended. Significant changes in the fluorescence spectra occurred postmortem, suggesting that future studies of laser-induced fluorescence of colonic tissue must use data acquired in vivo.
Many pathologists, gastroenterologists, and oncologists agree that villous (papillary) adenomas of the large bowel are at risk for the development of large bowel cancer. The role of adenomatous polyps (tubular adenomas) in the genesis of large bowel cancer is not a point of agreement. Future studies with molecular biologic techniques of colon polyps and adjacent mucosa and of the colonic mucosa of animals under treatment with colon carcinogens may clarify the role of colon polyps and other factors in the genesis of large bowel cancer. Polyps larger than 1.0 cm should be removed thrugh the proctosigmoidscope or the colonoscope.
A retrospective review of all colonoscopic polypectomies performed in a busy surgical endoscopy unit over a 6-month period was undertaken. All patients were included who presented with colonic polyps measuring less than 1 cm in diameter for which sufficient specimens were available for histopathologic examination. In all, 262 were polyps removed from 206 patients; of these, 158 (60%) were neoplastic. There was a statistically significant predilection for polyps in the right colon to be neoplastic. Worrisome histologic patterns (severe dysplasia, carcinoma in situ, or invasive carcinoma) were seen in 18 specimens (6.5%). In two patients, polypoid carcinoma could be identified; in one case it involved a lesion measuring 0.2 cm in diameter. Since these lesions exhibit no distinctive gross features, only their endoscopic removal and histologic study can ensure proper diagnosis and treatment.
A prospective study investigated the significance of solitary diminutive colonic polyps discovered during screening flexible sigmoidoscopy. Eighty-two patients with a solitary diminutive polyp (less than or equal to 5 mm) underwent colonoscopy after cold biopsy of the index polyp. Of the patients with adenomatous index polyps, 42.5 percent had proximal neoplastic polyps. Of the patients with hyperplastic index polyps, proximal neoplastic polyps were found in 38.9 percent. These data suggest that diminutive polyps identified during flexible sigmoidoscopy, whether adenomatous or hyperplastic, place the patient in the intermediate risk group for colorectal neoplasia. We recommend that any patient with polyps seen during screening sigmoidoscopy, regardless of histopathology, should undergo colonoscopy.