Advanced endoscopy technologies to improve the detection and characterisation of colorrectal polyps

Colorectal cancer is a major health problem. An improvement to its survival has been demonstrated by performing colonoscopy screenings and removing its precursor lesions: polyps. However, colonoscopy is not infallible and multiple strategies have been proposed aimed at improving the quality thereof. This report describes the endoscopic systems available to improve the detection and characterization of polyps, the different classifications for histological prediction and the current indications of advanced endoscopic diagnostic techniques.

Serrated polyps of the large intestine

Serrated polyps of the large intestine comprise a family of lesions bearing some histological similarities, including an overall serrated configuration caused at least in part by inhibition of apoptosis by mutations in one of two genes. Over the past decade, it has become apparent that these lesions can be subdivided by histological criteria into lesions with differing degrees of relationship to the development of carcinoma, including sporadic microsatellite instable (MSI) carcinomas and probably carcinomas demonstrating the CpG island methylator phenotype (CIMP), which includes both MSI and microsatellite stable tumors. These differing histological subtypes can in part predict some of the molecular features of these lesions, and the combination of histological and molecular features is beginning to give us better insight into the potential natural history and therefore management of these lesions. This review will present the histological classification of these lesions, relate that histological classification to molecular aspects of the lesions, and present recommendations for management.

Molecular classification of patients with unexplained hamartomatous and hyperplastic polyposis

CONTEXT

Significant proportions of patients with hamartomatous polyposis or with hyperplastic/mixed polyposis remain without specific clinical and molecular diagnosis or present atypically. Assigning a syndromic diagnosis is important because it guides management, especially surveillance and prophylactic surgery.

OBJECTIVE

To systematically classify patients with unexplained hamartomatous or hyperplastic/mixed polyposis by extensive molecular analysis in the context of central rereview of histopathology results.

DESIGN, SETTING, AND PATIENTS

Prospective, referral-based study of 49 unrelated patients from outside institutions (n = 28) and at a comprehensive cancer center (n = 21), conducted from May 2, 2002, until December 15, 2004. Germline analysis of PTEN, BMPR1A, STK11 (sequence, deletion), SMAD4, and ENG (sequence), specific exon screening of BRAF, MYH, and BHD, and rereview of polyp histology results were performed.

MAIN OUTCOME MEASURES

Molecular, clinical, and histopathological findings in patients with unexplained polyposis.

RESULTS

Of the 49 patients, 11 (22%) had germline mutations. Of 14 patients with juvenile polyposis, 2 with early-onset disease had mutations in ENG, encoding endoglin, previously only associated with hereditary hemorrhagic telangiectasia; 1 had hemizygous deletion encompassing PTEN and BMPR1A; and 1 had an SMAD4 mutation. One individual previously classified with Peutz-Jeghers syndrome had a PTEN deletion. Among 9 individuals with an unknown hamartomatous polyposis, 4 had mutations in STK11 (1), BMPR1A (2), and SMAD4 (1). Of the 23 patients with hyperplastic/mixed polyposis, 2 had PTEN mutations. Substantial discrepancies in histopathology results were seen.

CONCLUSIONS

Systematic molecular classification of 49 patients with unexplained hamartomatous or hyperplastic polyposis uncovered a potential novel susceptibility gene, ENG, for juvenile polyposis. Importantly, given the substantial proportion of patients found to have germline mutations, more extensive analysis of the known susceptibility genes is indicated. Rereview of histology results by a dedicated gastrointestinal pathologist should be considered routinely, as organ-specific surveillance rests on defining syndromic diagnosis.

Hyperplastic polyps and colorectal cancer: is there a link?

Most colorectal cancers (CRCs) are thought to arise in preexisting polyps called adenomas. A second type of colorectal polyp known as a hyperplastic polyp has been regarded as harmless for decades. Patients with hyperplastic polyps are therefore not thought to be at any increased risk of CRC, and best-practice guidelines indicate that these polyps do not require surveillance colonoscopy. Recently, it has become clear that CRC is not a single disease. One type of CRC (30%) shows a chemical alteration in DNA known as methylation, and a proportion of these also show genetic instability at the level of DNA. There is now strong evidence that the hyperplastic polyp is not harmless, but it might serve as the precursor of CRC with DNA methylation and deficient DNA mismatch repair. This novel pathway applies particularly to the subset of hyperplastic polyps that occurs in the proximal colon. If this premise is correct, it would be unsafe to ignore these polyps. There is now a need to define the genetic steps that explain the evolution of CRCs that develop within hyperplastic polyps. At the clinical level, it will be necessary to identify biomarkers for hyperplastic polyps that are especially prone to malignant conversion. Screening can then be targeted more selectively toward patients who are at significantly increased risk of malignant transformation of hyperplastic polyps.

Diagnostic colonoscopy: performance measurement study

This is the fifth of a series of best practices studies undertaken by the Performance Measurement Initiative (PMI), the centerpiece of the Institute for Quality Improvement (IQI), a not-for-profit quality improvement subsidiary of the Accreditation Association for Ambulatory Health Care (AAAHC) (Performance Measurement Initiative, 1999a, 1999b, 2000a, 2000b). The IQI was created to offer clinical performance measurement and improvement opportunities to ambulatory health care organizations and others interested in quality patient care. The purpose of the study was to provide opportunities to initiate clinical performance measurement on key processes and outcomes for this procedure and use this information for clinical quality improvement. This article provides performance measurement information on how organizations that have demonstrated and validated differences in clinical practice can have similar outcomes, but at a dramatically lower cost. The intent of the article is to provide organizations with alternatives in practice to provide a better value to their patients.

What is a juvenile polyp? An analysis based on 21 patients with solitary and multiple polyps

BACKGROUND

Juvenile polyps, the most common pediatric gastrointestinal polyp, have been typically characterized as either hamartomatous overgrowths or reactive inflammatory proliferations. Recent observations of excessive colonic and gastric carcinoma and dysplasia in juvenile polyposis have prompted reclassification of this entity as a premalignant condition. The relationship between solitary or multiple juvenile polyps and malignancy is less clear.

PATIENTS AND METHODS

To further investigate the frequency and significance of dysplasia in juvenile polyps, we analyzed 28 polyps from 21 patients histologically and immunohistochemically for substances previously associated with neoplastic transformation in the colorectal adenomacarcinoma sequence.

RESULTS

Fifteen patients had a solitary polyp, two had 2 to 9 polyps, and four had polyposis with 10 or more polyps. Most polyps exhibited inflammatory or regenerative atypia. Foci of dysplasia were noted in polyps from 11 patients, and immunoreactivity for p53 and human chorionic gonadotropin was present in 12 of the 28 polyps each. These findings were all more frequent in the polyposis specimens than in solitary polyps.

CONCLUSIONS

These observations, in combination with reports of an increased risk of carcinoma in juvenile polyposis, suggest that juvenile polyps are lesions with a potential for neoplastic and malignant transformation, although they share features of an inflammatory reactive process. The implications for clinical management of patients and pathologic evaluation of juvenile polyps warrant further investigation.

Applications of gastrointestinal endoscopy in infants and children

Gastrointestinal endoscopy has become an integral part of defining and treating gastrointestinal disease in children. Premalignant conditions that have been identified by endoscopy with histologic evaluation include Barrett's esophagus, juvenile polyposis coli, generalized juvenile polyposis, familial polyposis, Gardner's syndrome, and Turcot's syndrome. Advances in endoscopic instrumentation has allowed successful endoscopic retrograde cholangiopancreatography (ERCP) to be performed in infants and children. Therapeutic ERCP has been performed to remove stones, ligate strictures, and place stents. This review focuses on selected advances in gastrointestinal endoscopy and related diseases.

Small rectosigmoid polyps as markers of proximal neoplasms

PURPOSE

The aim of this study was to determine the spatial distribution and histotype of small colorectal polyps and to determine the validity of distal-small colorectal polyps as markers of proximal neoplasms.

METHODS

In 366 patients who underwent total colonoscopy and removal of all polyps, the presence and features of polyps were recorded. The relationship between proximal neoplasms and distal polyps was investigated in 216 of 366 subjects who had no personal or familial history of colorectal neoplasia.

RESULTS

Of 366 patients, 96 were free from polyps. A total of 733 small colorectal neoplasms was removed from the remainder: 79.9 percent neoplastic and 20.1 percent hyperplastic, inflammatory, or hamartomatous. High-grade dysplasia was noted in 2.7 percent of the neoplastic polyps. One adenoma containing invasive carcinoma was observed. In the subset of 216 patients, proximal neoplasms were found in 11.4 percent of those with no distal polyps, 33.8 percent of those with distal-small colorectal polyps only (P < 0.01), and 58.8 percent of those with at least one polyp > 5 mm in diameter (P = 0.001). The proximal neoplasm percentage was the same in patients with at least one adenomatous-small polyp and those with only hyperplastic-small polyps.

CONCLUSIONS

A distal-small colorectal polyp, whether adenomatous or hyperplastic, may be a proximal neoplasm marker. Total colonoscopy is thus justified in all patients with distal polyps, regardless of their size and histotype.

Biopsy study of polyps in the duodenal bulb

To clarify the clinical and histological features of polyps in the duodenal bulb (DB), we studied, clinicopathologically, a total of 263 patients (179 male, 84 female) with polyps in the DB. The patients were 13-86 yr of age (average age, 57.1 yr). On endoscopy, a semipedunculated or pedunculated polyp with a relatively large size was seen in 33 patients, and small polyps, either single or multiple, were incidentally discovered in 230 patients. Histological examination of the biopsied specimens from polyps revealed gastric tissue in 182 cases (69.2%), cyst formation in 51 (19.4%), and other miscellaneous lesions (tubular adenoma, Brunner's gland hyperplasia, etc.) in 30 (11.4%). With regard to the gastric tissue, a "full-thickness" or "incomplete" body-type mucosa was identified in 27 cases of polyps, and hyperplastic surface epithelium was recognized in 155. Forty cases of hyperplastic surface epithelium-type polyps were subclassified as "pyloric"-type mucosa, because pyloric gland-like components seen under the surface epithelium were identical to those of the gastric antrum. It was reconfirmed that small polyps with little or no clinical significance could be produced by various histological features.

[Classification of colorectal adenomas based on the histological picture in patients without symptoms]

During screening of colorectal carcinoma by the test of occult haemorrhage in 1985 to 1989 in the Bruntál district during coloscopic examination of positive subjects a total of 277 adenomatous polyps of the large intestine were revealed. Adenomatous polyps were detected in 227 patients where by in 180 solitary polyps were involved and in 47 cases synchronous polyps. 222 adenomatous polyps were in the rectum and left half of the colon (80.1%). Histological examination revealed: tubular adenoma 153 cases (55.23%), tubovillous adenoma 92 cases (33.21%), villous adenoma 13 cases (4.69%), adenoma with intramucous carcinoma 12 cases (4.43%) and adenoma with invasive carcinoma 7 cases (2.53%).

[Proposal for a radiological classification of multiple adenomatosis of the colon]

The double contrast enemas of 47 patients with multiple adenomatosis of the colon and rectum were analyzed. According to the density and the distribution of polyps on the mucosal surface, the radiological patterns were classified into three different groups: sporadic, dense and confluent adenomas. Radiographic patterns of each patient were related to the clinical and pathological data collected during the diagnosis and the follow-up. The clinical and pathological features and the evolution of the disease appear to be different in each group of patients (identified by the radiological classification). The occurrence of cancer at the time of the diagnosis of polyposis is closely correlated either to the number of polyps or to their size and the age of patients. The occurrence of metachronous cancer is correlated only to the number of polyps, not to their size, nor to the surgical treatment of the polyposis. If these data are confirmed on a wider number of patients, the role of radiological survey might become a more prominent one, not only in diagnosing, but also in therapy planning, as well as in the prognostic evaluation of multiple adenomatosis of colon.

Epithelial polyps of the large intestine. A classification based on biologic behavior

Classifications of colonic polypoid lesions are often based on their pathogenesis. Little attention is paid to the biologic behavior (or predicted behavior, based on experience) of these lesions. Classification based on biologic behavior separates these lesions, regardless of histogenesis, according to possible malignant potential. This helps the clinician to explain the implications of the histopathologic diagnosis to the patient and to understand when aggressive or prophylactic therapy should be pursued.

[Results of coloscopic polypectomy in respect of the dignity (author's transl)]

The commonest type of polyps in the large intestine in our series of 506 polypectomies in 262 patients were adenomas (64%) especially tubular adenomas. Severe epithelial atypia being present in 11% of all adenomas and it was three times more discovered in villous adenomas than in tubular forms and with increasing adenomas size. Because severe epithelial atypia could be observed in polyps with diameters less than 5 mm it should be demanded to remove each polyp for an exact histological examination independent of his size. Single forceps biopsies of polyps do not allow the estimation of their further development in view of malignancy.

[Value and results of coloscopic polypectomy]

From August 1976 till the end of February 1979 158 polyp in 83 patients (48 male and 35 female) were removed by means of the rectocoloscopic polypectomy with the high frequency diathermy loop. 66% of the polypi had a diameter of less than 1 cm. Most the polypi were with about 70% in the sigma and in the rectum. With 60.7% the adenomas appeared most frequently, followed by the hyperplastic polypi in 20% and by the inflammatory ones in 13.3% of the cases. With the increase of size of the polypi the proportion of the adenomas clearly increased in comparison to the other kinds of polypi. Severe epithelial atypias (altogether 23.1%) were more frequently in adenomas larger than 2 cm than in smaller ones. An invasive carcinoma was found in no polypus. Thus the endoscopic polypectomy in every case meant a curative therapy with great economic use. In patients a haemorrhage appeared as a complication of the coloscopic polypectomy. Only the removal of the polypi in toto allows an exact histological classification and the answer of the decisive question, whether in one adenoma only severe epithelial atypias are present and thus the polypectomy is therapeutically sufficient or whether there exists an adenocarcinoma, for the removal of which an operation according to the principles of the carcinoma surgery must be carried out. The endoscopic ablation of the adenomas thus means a genuine prophylaxis of cancer.

[Pathology and classification of colorectal polyps]

This survey deals with the principles of classifying colorectal polyps and with the fundamentals of anatomic pathology of these growths. In this connection, the epithelial neoplastic types, which are now known as adenomas, are of particular importance in so far as they are the potential precursors of carcinomas of the colon and rectum (""adenoma cancer sequence''). The polypectomy specimen alone enables definite histo-pathological diagnosis.

[Colorectal polyps. Pathologico-anatomical and statistical studies on 3037 polyps]

Report on 3037 colorectal polyps from the Deutsche Klinik für Diagnostik Wiesbaden that were observed within about 6 years and submitted to microscopic examination. The polyps were classified according to the WHO nomenclature, 1976. Adenomas and metaplastic (hyperplastic) polyps were the most frequenty types. The terms 'carcinoma in situ,' 'focal carcinoma,' 'adenoma with severe cellular atypia,' and 'malignant polyp' are explained and discussed in view of possible false interpretations by the surgeon. It is stressed that only the term 'adenoma with severe cellular atypia' (WHO classification) should be retained. In 286 cases, primary multiplicity of polyps was observed. There were recurrent polyp(s) in 154 cases (7%). Most frequently the recurrent polyp(s) corresponded to the type that had been found during the first examination. Finally, some remarks are made concerning the techniques of biopsy and of pathological examination.

[Colonorectal adenoma: relationships among histological structure, dimensions of the polyps, and age distribution]

Among 1258 polyps from the lower gastro-intestinal tract removed by rectoscopy or coloscopy and examined histologically there were 744 adenomas, 72% tubular, 27% papillary and 1% villous. 96.5% of all adenomas were extracted from patients aged over 40 years. Four fifths of the tumours were found in the rectum and sigmoid colon. Only 6% of the tubular adenomas were more than 15 mm in diameter, compared with 32% of papillary and 57% of villous adenomas. The special significance of the adenomas lies in their potential malignancy (adenoma-to-cancer sequence).

[Pathology of colonic polyps]

Recent developments in the field of polyps of the colon are discussed. The WHO classification represents a definite improvement. Apart from standardization, non-neoplastic polypoid changes of varying etiology and hamartomatous polyps are clearly distinguished from neoplastic, non-malignant adenomas. The various changes are outlined briefly in their essential characteristics. Clear-cut differentiation from early invasive cancer is of considerable importance for practical therapeutic purposes. Focal carcinoma within an adenoma is referred to only if invasion through the muscularis mucosae is established, while all other changes confined to the mucosa are termed adenomas with focal epithelial atypia. With regard to the relation between adenoma and cancer of the colon, recent results on topographical distribution of adenomas through the colon are of considerable significance. From serial studies of biopsy and autopsy specimens on the one hand, and from assessment of colon carcinoma incidence compared with mortality rates in carcinomas of different localizations on the other, it is evident that special attention should be given henceforward to adenomas, possible precursors, and carcinomas in the upper segments of the colon.

Genetics of gastrointestinal polyposis

This review deals with the types of gastrointestinal polyposis in which genetic factors play an essential part, namely, the hamartomatous lesions of Peutz-Jeghers syndrome and multiple juvenile polyposis and the neoplastic tumors of familial polyposis coli and multiple adenomas. The mode of inheritance, associated lesions, malignancy potential, and possible interrelationships between the various types of polyposis are discussed. The knowledge that the lesions are inherited should enable other family members to be investigated and treated at an early stage, a matter of considerable importance in the prevention of cancer when there is an associated risk of gastrointestinal carcinoma.

[Contribution of cases to the new classification of polyposis syndrome in the gastrointestinal tract]

In Schweizerische Medizinische Wochenschrift 106, 894-897 (1976) an article was published on a kinship with hereditary "minor adenomatous polyposis" of the colon with a higher than expected incidence of carcinoma of the stomach. Evidence for a genetic relationship between this family (Sch.) and another branch with an isolated case (Sch. E.) of familial polyposis of the gastrointestinal tract was found. The patient Sch. E. is presented here. The polyposis of this patient is phenotypically identical with that found in the classical familial polyposis of the colon, but also exhibits features of "minor adenomatous polyposis". A systematic clinical-endoscopic examination of ten members of the patient's family produced no further cases of gastrointestinal polyposis of carcinomata. In the case of Sch. E., therefore, a spontaneous mutation is postulated. A new classification of the various types of colonic polyposis is suggested.