Can histopathologists reliably assess dysplasia in chronic inflammatory bowel disease?

Pathologist Experience and Concordance in the Diagnosis of Dysplasia in Long-standing Inflammatory Bowel Disease

Surveillance colonoscopies focused to detect dysplasia are recommended to prevent colorectal cancer in patients with long-standing colonic inflammatory bowel disease (IBD). To date, histologic diagnosis and gradation of IBD-related dysplasia has been challenged by a high variability among pathologists. We aimed to analyze the observer characteristics that are correlated with concordance deviations in this diagnosis. Eight pathologists evaluated a set of 125 endoscopic biopsy samples with a representative distribution of nondysplastic and dysplastic lesions from long-standing IBD patients. Two rounds of diagnosis were carried out during a period of 18 months. The κ test was applied to analyze concordance. Pathologists were grouped on the basis of their experience. A subanalysis was performed by eliminating the highly prevalent nondysplastic samples, as well as an analysis after observers' grouping. Overall interobserver agreement was good (κ=0.73), with an even higher pairwise value (κ=0.86) as well as the intraobserver agreement values (best κ=0.85). After eliminating the highly prevalent nondysplastic samples, the interobserver agreement was still moderate to good (best overall κ=0.50; best paired κ=0.72). Notable differences were seen between the pathologists with a high-volume and low-volume practice (best overall κ=0.61 and 0.41, respectively). The agreement in the diagnosis of dysplasia in IBD endoscopic biopsies may have been undervalued over time. This is the first study evaluating pathologists' diagnostic robustness in this field. The results suggest that examining a large volume of samples is the key factor to increase the consistency in the diagnosis and gradation of IBD-related dysplasia.

Combining aneuploidy and dysplasia for colitis' cancer risk assessment outperforms current surveillance efficiency: a meta-analysis

PURPOSE

Cancer risk assessment for ulcerative colitis patients by evaluating histological changes through colonoscopy surveillance is still challenging. Thus, additional parameters of high prognostic impact for the development of colitis-associated carcinoma are necessary. This meta-analysis was conducted to clarify the value of aneuploidy as predictor for individual cancer risk compared with current surveillance parameters.

METHODS

A systematic web-based search identified studies published in English that addressed the relevance of the ploidy status for individual cancer risk during surveillance in comparison to neoplastic mucosal changes. The resulting data were included into a meta-analysis, and odds ratios (OR) were calculated for aneuploidy or dysplasia or aneuploidy plus dysplasia.

RESULTS

Twelve studies addressing the relevance of aneuploidy compared to dyplasia were comprehensively evaluated and further used for meta-analysis. The meta-analysis revealed that aneuploidy (OR 5.31 [95 % CI 2.03, 13.93]) is an equally effective parameter for cancer risk assessment in ulcerative colitis patients as dysplasia (OR 4.93 [1.61, 15.11]). Strikingly, the combined assessment of dysplasia and aneuploidy is superior compared to applying each parameter alone (OR 8.99 [3.08, 26.26]).

CONCLUSIONS

This meta-analysis reveals that aneuploidy is an equally effective parameter for individual cancer risk assessment in ulcerative colitis as the detection of dysplasia. More important, the combined assessment of dysplasia and aneuploidy outperforms the use of each parameter alone. We suggest image cytometry for ploidy assessment to become an additional feature of consensus criteria to individually assess cancer risk in UC.

Colorectal neoplasia in IBD--a single-center analysis of patients undergoing proctocolectomy

PURPOSE

The risk, prevention, and treatment of colorectal neoplasia in inflammatory bowel disease (IBD) are still a matter of debate. The aim of this study was to analyze the occurrence of colorectal neoplasia in IBD patients who underwent proctocolectomy.

METHODS

The study population comprised of 123 IBD patients who underwent proctocolectomy because of neoplasia, therapy refractivity, or complications between January 2000 and July 2011.

RESULTS

One hundred fourteen (92.7%) patients were pre-operatively diagnosed with ulcerative colitis, 5 (4.1%) with colitis indeterminata, and 4 (3.3%) with colonic Crohn's disease. Colectomy was indicated in 39 (31.7%) patients because of a neoplasia, in 68 (55.3%) because of a refractory course of the disease, and in 16 (13.0%) because of complications. Neoplasia was found in 36 patients on a histopathologic evaluation of the colectomy specimens. Ten (8.1%) patients post-operatively showed a pre-operatively not described advanced neoplasia. In three (2.4%) of these patients, the detection of advanced neoplasia (two high-grade intraepithelial neoplasias (IENs), one carcinoma) was a complete de novo finding. Carcinoma had not been diagnosed pre-operatively in six (4.9%) patients. A multifocal distribution of neoplasia was seen in 66.7% of patients with neoplasia. The median duration of disease was 15.5 years in case of neoplasia opposed to 6.0 years in those without neoplasia detection.

CONCLUSION

Our data demonstrate a high rate of pre-operatively undetected high-grade IENs and carcinoma and a frequent multifocal occurrence in IBD patients with long-standing inflammation of the colon. This should be kept in mind for treatment decisions particularly in patients with a chronic refractory course of the disease.

Inter-observer and intra-observer variability in the diagnosis of dysplasia in patients with inflammatory bowel disease: correlation of pathological and endoscopic findings

AIM

Colonic epithelial dysplasia is deemed the precursor lesion of cancer arising in inflammatory bowel disease (IBD). It has been suggested that many dysplastic lesions could be endoscopically detected to obtain target biopsies, leading to better yield. However, the clinical impact of a diagnosis of dysplasia may be hampered by a significant degree of histological and endoscopic intra-observer and inter-observer variability. This study aimed to evaluate intra-observer and inter-observer variability in the microscopic diagnosis of dysplasia in IBD and correlate endoscopic and histological findings.

METHOD

In total, 158 cases of ulcerative colitis and 14 of Crohn's disease with dysplasia were selected from a pathology database. Slides were blindly reviewed twice by two expert gastrointestinal pathologists. Results of endoscopic examinations were extracted from the reports. The degree of intra-observer and inter-observer variability was determined by kappa statistics.

RESULTS

Overall, there was an excellent degree of histopathological inter-observer agreement (κ = 0.786). The lowest level of agreement in the dysplasia group was for indefinite dysplasia (κ = 0.251). Negative and high grade dysplasia diagnosis reached the highest level of agreement with κ values of 0.822 [95% confidence interval (CI) 0.673-0.971] and 1.00 (95% CI 0.850-1.149), respectively. Intra-observer agreement was good and increased during the latter period of the study (κ = 0.734, 95% CI 0.642-0.826). Endoscopic-histological correlation was poor among the negative endoscopies, as up to 43% of cases were diagnosed with at least focal high grade dysplasia. The endoscopic-histological correlation improved when evaluating suspicious endoscopic lesions.

CONCLUSION

Dysplasia is reliably diagnosed by expert gastrointestinal pathologists but has poor correlation with an endoscopic diagnosis of dysplasia.

Colorectal dysplasia in chronic inflammatory bowel disease: pathology, clinical implications, and pathogenesis

CONTEXT

Colorectal cancer, the most lethal long-term complication of chronic inflammatory bowel disease (IBD), is the culmination of a complex sequence of molecular and histologic derangements of the intestinal epithelium that are initiated and at least partially sustained by chronic inflammation. Dysplasia, the earliest histologic manifestation of this process, plays an important role in cancer prevention by providing the first clinical alert that this sequence is underway and serving as an endpoint in colonoscopic surveillance of patients at high risk for colorectal cancer.

OBJECTIVE

To review the histology, nomenclature, clinical implications, and molecular pathogenesis of dysplasia in IBD.

DATA SOURCE

Literature review and illustrations from case material.

CONCLUSIONS

The diagnosis and grading of dysplasia in endoscopic surveillance biopsies play a decisive role in the management of patients with IBD. Although interpathologist variation, endoscopic sampling problems, and incomplete information regarding the natural history of dysplastic lesions are important limiting factors, indirect evidence that surveillance may be an effective means of reducing cancer-related mortality in the population with IBD has helped validate the histologic criteria, nomenclature, and clinical recommendations that are the basis of current practice among pathologists and clinicians. Emerging technologic advances in endoscopy may permit more effective surveillance, but ultimately the greatest promise for cancer prevention in IBD lies in expanding our thus far limited understanding of the molecular pathogenetic relationships between neoplasia and chronic inflammation.

Neoplastic precursor lesions related to the development of cancer in inflammatory bowel disease

Dysplasia is an intermediate stage in the progression from inflammation to cancer in patients with inflammatory bowel disease. Clinically, dysplasia is used to define appropriate endpoints for colectomy in high-risk patients undergoing endoscopic surveillance. Surveillance is currently the only credible alternative to prophylactic colectomy for high-risk patients. The success of surveillance can be maximized by adherence of gastroenterologists to recommended procedural guidelines, adherence of pathologists to standardized histological criteria and nomenclature, and a joint commitment to close clinical-pathological communication. Technical enhancements to conventional endoscopy hold promise of improved efficiency and accuracy. Molecular-based testing may have a future role for risk stratification and early detection of neoplasia in inflammatory bowel disease.

Intestinal low-grade tubuloglandular adenocarcinoma in inflammatory bowel disease

Chronic idiopathic inflammatory bowel disease (IBD) with extensive colonic involvement predisposes to the development of colorectal adenocarcinoma. Among the types of cancer occurring in this setting is an unusually well-differentiated low-grade tubuloglandular adenocarcinoma (LGTGA) that has not been studied systematically thus far. A review of 149 IBD-associated cancer resections performed at our institution yielded 17 patients (11%) with 21 tumors classified as LGTGA based on the following histologic characteristics: very well-differentiated small to medium diameter glands with round or tubular profiles, low-grade cytologic characteristics and absence or paucity of desmoplastic reaction. Twelve patients had ulcerative colitis, 4 Crohn disease, and 1 indeterminate colitis. Their median age was 41.5 years (range, 28 to 58 y). Five patients had separate synchronous cancers of conventional types. LGTGAs ranged from 0.4 to 10 cm in size and varied in gross appearance. They included 5 flat lesions that were not identified visually but were detected either by palpation of the unfixed surgical specimen (1 case) or histologically in random sections (4 cases). The invasive glands usually bore a close histologic resemblance to overlying low-grade or indefinite dysplastic crypts. Twelve carcinomas (57%) with well-defined superficial regions of LGTGA progressed histologically to conventional adenocarcinoma in deeper regions. These tumors were significantly more advanced than 9 carcinomas that maintained low-grade histology throughout. Follow-up of 13 patients (76%) for a mean 4.0 years (range, 0.75 to 9.0 y) disclosed 10 (77%) with favorable outcomes and 3 (23%) with adverse outcomes. Two adverse outcomes were attributable to synchronous advanced-stage conventional cancers and the third to progression from LGTGA to poorly differentiated adenocarcinoma. The mucosa overlying and surrounding LGTGA showed low-grade dysplasia (LGD) in 18 cases (86%), indefinite dysplasia with focal LGD in 1 case (5%), and LGD with focal high-grade dysplasia (HGD) in 2 cases (10%). Immunohistochemical studies disclosed expression of MUC2 in 72%, MUC6 in 0%, CK7 in 69%, and CK20 in 100%. Coexpression of CK7 and CK20 was conserved in regions of conventional adenocarcinoma derived from LGTGA. Silencing of immunohistochemical expression of hMLH1 occurred in 6 of 11 tumors tested (55%), implicating defective DNA replication error repair in their pathogenesis. We conclude that LGTGA is a distinct clinicopathologic entity characterized by direct derivation from LGD mucosa of IBD, very well-differentiated morphology, frequent coexpression of CK7 and CK20, and frequent silencing of hMLH1. Histologic progression from LGTGA to conventional types of adenocarcinoma parallels clinical progression to more aggressive neoplasia. The potential of LGD to give rise directly to LGTGA, and by way of LGTGA to more aggressive cancers, reinforces recommendations in favor of aggressive management of IBD patients diagnosed with LGD.

Pathology of dysplasia and cancer in inflammatory bowel disease

Morphologic identification of dysplasia in mucosal biopsies is the best and most reliable marker of an increased risk for malignancy in patients who have inflammatory bowel disease, and it forms the basis of the recommended endoscopic surveillance strategies that are in practice for patients who have this illness. In ulcerative colitis (UC) and Crohn's disease (CD), dysplasia is defined as unequivocal neoplastic epithelium that is confined to the basement membrane, without invasion into the lamina propria. Unfortunately, unlike in UC, only a few studies have evaluated the pathologic features and biologic characteristics of dysplasia and carcinoma in CD specifically. As a result, this article focuses mainly on the pathologic features, adjunctive diagnostic methods, and differential diagnosis of dysplasia in UC.

Interobserver variability in the diagnosis of ulcerative colitis-associated dysplasia by telepathology

Telepathology (TP) is the practice of remote diagnostic consultation of electronically transmitted, static, digitalized images. The diagnostic efficacy of TP-based consultation services has not been widely tested. Dysplasia that arises in association with chronic ulcerative colitis (CUC) is, at present, the most important marker of an increased risk of malignancy in patients with this disease. Unfortunately, dysplasia is difficult to diagnose histologically and, as a result, suffers from a significant degree of intra- and interobserver variability. Furthermore, it is often necessary to obtain expert consultation of potential CUC-associated dysplasia cases before treatment. Therefore, the aim of this study was to evaluate the utility and interobserver variability of diagnosing dysplasia in CUC with the use of TP. Static, electronically transmitted, digitalized images of 38 CUC cases with areas considered negative, indefinite, or positive for dysplasia (low or high grade) were evaluated independently by four gastrointestinal pathologists. All cases were then graded by each of the pathologists by light-microscopic examination of the hematoxylin and eosin-stained glass slides. The degree of interobserver variability was determined by kappa statistics. Overall, there was a fair degree of agreement (kappa = 0.4) among the four reviewing pathologists after analysis of the digitalized images. The poorest level of agreement was in the indefinite and low-grade dysplasia categories. Grouping together several diagnostic categories (for instance, indefinite and low-grade dysplasia, or low-grade dysplasia and high-grade dysplasia) had no effect on the overall level of agreement. The degree of variability in interpretation of glass slides was slightly better (kappa = 0.43) but still remained fair. After reviewing all cases by glass slide analysis, the diagnosis was changed in 38% of the slides; in the majority of these, the grade of dysplasia was increased. Use of TP for consultation in CUC-associated dysplasia has a moderate level of interobserver agreement. Because of a variety of technical reasons, diagnoses rendered by evaluation of digitalized images tended to be of a lower grade than that observed after a review of the glass slides.

Dysplasia in barrett's esophagus. New techniques and markers

In this article, the authors describe the histologic features and classification of dysplasia in Barrett's esophagus. The histologic problems in the diagnosis and grading of dysplasia are discussed. Techniques that can serve as aids to the histologic diagnosis of dysplasia, such as flow cytometry and molecular markers, are reviewed.

Inter-observer variation between general and specialist gastrointestinal pathologists when grading dysplasia in ulcerative colitis

Histological dysplasia is the cornerstone of colorectal cancer surveillance in ulcerative colitis (UC). Recently, pathologists have received unfavourable media attention concerning other cancer screening programmes. The aim of this study was to determine whether colonic biopsy specimens should be examined by gastrointestinal pathologists as opposed to generalists, by examining inter-observer variation between the two groups. Fifty-one coded slides showing varying degrees of dysplasia were mailed to seven gastrointestinal and six general histopathologists. Pathologists allocated each biopsy into one of four categories without the benefit of a clinical history or an opportunity to use the 'indefinite' category that is included in the Riddell classification. The responses were analysed using kappa statistics. The overall kappa statistic for gastrointestinal pathologists was 0.30 [95% confidence interval (CI)=0.26-0.34] and for general pathologists 0.28 (95% CI=0.23-0.32). Agreement was best for high-grade dysplasia (kappa of 0.54 and 0.61 for GI and general pathologists, respectively). There was total concordance of the 13 pathologists in only four of the 51 slides (7.8%) (95% CI=0.4-15.2%). It is concluded from these results that gastrointestinal pathologists are no better than generalists when grading dysplasia in UC and that agreement is poor in both groups. There is therefore no evidence that there would be any benefit in having specialist histopathology centres concentrating specifically on the interpretation of all surveillance colonoscopy biopsies from around the UK. It must be made clear to the public that surveillance and screening programmes carry a significant rate of histological error and that perfection cannot be expected or achieved with present methods.

The pathology of epithelial pre-malignancy of the gastrointestinal tract

This chapter deals with pre-malignant epithelial lesions of the gastrointestinal tract that have the potential to become cancers. Pre-malignant lesions are divided into two types: those characterized by dysplastic mucosa and those without dysplasia. Examples of the two types are present in the oesophagus, stomach and intestine. In the oesophagus, dysplasia of the squamous epithelium is a precursor to squamous carcinoma. There are differences in interpretation between Western and Japanese pathologists in the diagnosis of oesophageal squamous lesions. Dysplasia in Barrett's oesophagus is regarded as a precursor of adenocarcinoma. The goal of endoscopic surveillance in Barrett's mucosa is the detection of high-grade dysplasia. There are several problems with our current knowledge of high-grade dysplasia and controversies regarding its management. There are differences in the interpretation of biopsies of gastric epithelial dysplasia between Japanese and Western pathologists. In the colon, pre-malignant lesions include dysplasia seen in inflammatory bowel disease and colonic adenomas. The most significant predictor of the risk of malignancy in patients with inflammatory bowel disease is the presence of dysplasia in colonic biopsies. Because of the similarity of neoplasia throughout the gastrointestinal tract, there have been attempts to unify its classification, terminology and diagnostic criteria internationally, the most recently proposed modified classification of gastrointestinal neoplasia being the Vienna classification. Dysplasia of the columnar mucosa has a similar appearance in Barrett's oesophagus, the stomach and the colon. Criteria for its histological diagnosis and grading are reviewed, with an emphasis on areas of diagnostic difficulty such as interobserver variation, and discrepancies between Western and Japanese pathologists. Implication of the presence of dysplasia that are specific to each organ site are discussed, highlighting weaknesses and controversies in current knowledge.

Two types of colorectal carcinoma in Crohn's disease

Fourteen examples of carcinoma developing in the colon or rectum were encountered in a series of 1008 patients with Crohn's disease treated in Aberdeen during the 34-year period, 1955-1988. Seven patients were under 55 years of age at the time of onset of Crohn's disease, and had a long history of the disease before carcinoma supervened. Older patients had short histories and a better prognosis. One squamous carcinoma may have arisen in relationship to a fistula in ano.

Distribution of aneuploid cell populations in ulcerative colitis with dysplasia or cancer

Flow cytometry was used to detect the presence and assess the distribution of aneuploid cell populations in eight proctocolectomy specimens from patients with ulcerative colitis. Mucosal samples were taken according to a systematic protocol for flow cytometry, the surrounding tissue was examined histologically, and the distributions of flow cytometric and histologic abnormalities were "mapped" within each resected colon. Two resection specimens that were negative for dysplasia lacked aneuploid cell populations. Four resection specimens with final case diagnoses of dysplasia or Dukes' stage A carcinoma had 1-5 regions of aneuploidy or increased 4N (G2/tetraploid) cell populations located in discrete areas of the colon. Two specimens with dysplasia or Dukes' stage C carcinoma each had 14-15 different, often overlapping, regions of aneuploidy or increased 4N (G2/tetraploid) cell populations involving large portions of the colonic mucosa. Analysis of the DNA content of the invasive portion of the tumor from the specimen with a Dukes' stage C carcinoma showed a single aneuploid cell population. The results show that single or multiple aneuploid cell populations are often present in colons resected for ulcerative colitis with dysplasia or early cancer. The distribution of these aneuploid cell populations suggests that each represents a clone of cells that has expanded to occupy a discrete region of colonic mucosa. Additional genetic errors may result in multiple aneuploid cell populations that may be associated with an increased risk of developing cancer. These data, therefore, are consistent with the hypothesis that genomic instability and clonal evolution are associated with the progression to dysplasia and carcinoma in ulcerative colitis. Because flow cytometry can measure aneuploid cell populations in colonoscopic mucosal biopsies, it may prove to be complementary to histology for detecting patients with ulcerative colitis who are at risk for neoplastic progression.

Understanding differential diagnostic disagreement in pathology

The Diagnostic Encyclopedia Workstation (DEW) was developed to support pathologists in diagnosing ovarian tumors. In this evaluation study, we had pathologists at several levels of experience diagnose a number of cases using either books or the DEW. In the context of this study, we needed a standard by which to measure performance of these pathologists. We, therefore, had experts enumerate for each test case the diagnoses they considered morphologically similar. To our surprise, the resulting lists of the experts varied considerably. The differential diagnosis of a disease based on its morphological characteristics, however, constitutes important reference knowledge in solving diagnostic problems. The question rose why the experts differed so much in their differential diagnostic knowledge. The ontogeny of a pathologist's personal knowledge is discussed and used to derive a model that can explain the limited consensus in differential diagnosis. The model helps to identify factors that may cause pathologists to diverge and others that may cause them to converge with respect to their knowledge. Strategies are proposed that are useful in achieving a better (differential) diagnostic consensus.

Precancer and cancer in extensive ulcerative colitis: findings among 401 patients over 22 years

Patients with extensive ulcerative colitis who do not need early surgery have been offered regular examination with the aim of detecting precancerous change (dysplasia) or early colorectal carcinoma. Outpatient visits with clinical examination, sigmoidoscopy, and biopsy were supplemented by two-yearly colonoscopy after the disease course reached 10 years. During the 22 year period from the beginning of 1966 to the end of 1987, 401 patients entered the programme and together contributed 4048 patient-years of observation. Apart from nine patients who left the country, follow up is complete until 1986 or 1987. Colorectal carcinoma developed in 22 patients and, in a further 12, biopsy evidence of precancer, described as severe/high grade dysplasia, was confirmed in a colectomy specimen. The cumulative probability of developing carcinoma was 3% at 15 years, 5% at 20 years, and 9% at 25 years; corresponding figures for precancer or carcinoma, or both were 4%, 7%, and 13%. Five patients died of colorectal carcinoma, two while under regular observation and three after developing carcinoma four to six years after their last attendance. Among the 17 patients who developed carcinoma while under observation, the Dukes stage was A or B in 12. Patients with extensive colitis whose disability does not warrant early surgery have a clinically important cancer risk after the disease has been present for 10 years. Our results suggest that follow up in the manner described reduces the mortality from this complication. Further work is needed to define the optimum method of surveillance and show if it is cost effective.

Observer reproducibility in grading dysplasia in colorectal adenomas: comparison between two different grading systems

The two most well known and well defined grading systems for dysplasia in colorectal adenomas were compared with regard to reproducibility. The Konishi-Morson system (KMS) operates with several histological and cytological variables and grades of mild, moderate, and severe dysplasia. The Kozuka system is based on the extent of nuclear pseudostratification and also has three grades of dysplasia (III-V). As the group of severe dysplasia is very large in this system, it was extended with two higher grades, similarly based on individual histological criteria, known hereafter as the extended Kozuka system (EKS). Fifty six adenomas were graded by two observers, each observer grading twice according to the KMS criteria and twice according to EKS criteria. Intraobserver reproducibility was excellent for the KMS and moderate for the EKS, but this was not significant. The overall interobserver reproducibility was similar (moderate) for the KMS and for the EKS. Kappa values for interobserver reproducibility on individual categories were excellent for severe dysplasia according to the KMS, but low for all other categories in both systems. By simplifying both systems into two groups a high reproducibility can be obtained, but this implies that all the original grades (III-V) for the EKS must be grouped together. It is therefore recommended that a simplified KMS is used for further studies on the biological importance of dysplasia and for comparison between histological changes and other markers for colorectal neoplasia.

Gastric dysplasia: inter-observer variation, sulphomucin staining and nucleolar organizer region counting

Gastric dysplasia is regarded as a pre-neoplastic lesion and is generally believed to have higher potential for malignant transformation with increasing grade. To obtain consistency in diagnosis and management, reproducible diagnostic criteria are needed. We have used the classification system of the International Study Group on Gastric Cancer--ISGGC and investigated the interobserver variation in histological diagnosis. A Kappa statistic of 0.579, which reflects moderate agreement, was obtained for variation between two experienced pathologists. The prevalence of type III intestinal metaplasia was studied and found to occur in 55% of dysplastic areas, but in only 9% of hyperplastic areas (P less than 0.01). In addition, the correlation of mean nucleolar organizer region (AgNOR) counts with diagnostic categorization was investigated. A significant inter-observer variation was found between an experienced pathologist and a postgraduate student and only one of the observers obtained statistically significant separation of mean AgNOR counts between the categories of high-grade dysplasia, low-grade dysplasia, atypical hyperplasia, simple hyperplasia and normal.

Observer study of the grading of dysplasia in ulcerative colitis: comparison with clinical outcome

Patients with extensive ulcerative colitis are entered into surveillance programs that aim to detect premalignant changes. Biopsy specimens have been collected in the St Mark's Hospital (London) surveillance program over a 22-year-period. Specimens from patients reported as having dysplasia were reexamined. A total of 207 biopsy specimens from 86 patients were graded by five experienced pathologists according to the severity of the dysplasia. The overall agreement between the pathologists grading the specimens was poor; each pair agreed on between 42% and 65% of the slides. The best agreement was for slides that were said to show no dysplasia. Comparison with clinical outcome indicated that the pathologists most likely to diagnose dysplasia in patients with carcinoma were also likely to diagnose dysplasia in patients who did not go on to develop carcinoma. Calculating an average grade of dysplasia did not significantly improve diagnostic accuracy. Despite the findings of this interobserver study, dysplasia has been a successful marker in clinical practice. Pathologists should ensure that they have access to previous slides from the same patient and adequate clinical information before reporting biopsies as positive for dysplasia. An additional biopsy should usually be undertaken before surgery is considered.

Observer variability in histopathological reporting of cervical biopsy specimens

Sections from 100 cervical biopsy specimens were studied by 12 consultant histopathologists to determine the robustness of the existing pathology terminology and classification. Analysis by kappa statistics showed good agreement in the diagnosis of CIN 3 and squamous carcinoma but an inability to distinguish accurately between the lesser grades of CIN. It is recommended that the classification be changed to low grade (present CIN 1 and 2) and high grade (present CIN 3) categories alone. There was very poor agreement in the identification of cellular changes associated with human papilloma virus (HPV) infection.

Observer variation in the assessment of dysplasia in ulcerative colitis

Six histopathologists allocated 100 sections from patients with long-standing ulcerative colitis into four diagnostic categories, regular hyperplasia, reactive atypia, low-grade and high-grade dysplasia. Their allocations were analysed using kappa statistics, including Fleiss's multiple kappa for groups of observers, and agreement on specific diagnoses was explored by constructing a conditional probability matrix. The nature of their disagreements was investigated using coefficients for systematic and haphazard errors. Over the four diagnostic categories there was a wide range of pairwise agreement from a low of 49% up to 72% and kappa values were only 'fair' or 'moderate'. As expected, agreement over the two categories 'dysplasia' vs 'no dysplasia' was better, ranging from 68% to 84%, and for 'atypia present' (reactive atypia, low- and high-grade dysplasia) vs "no atypia' two pairings achieved over 90% and 11 pairings over 80% agreement. In view of its clinical importance, conditional agreement on high-grade dysplasia, pairwise agreement on this diagnosis ranged from 100% down to as low as 33%. However, most of these disagreements fell into the low-grade dysplasia category so that closer follow-up and further biopsies would still have been indicated. It is a truism that the basis for safe management is careful co-operation between clinicians and pathologists who have all the relevant facts and who know and trust one another's judgement. Thus, several aspects of the ideal diagnostic process cannot be evaluated in inter-observer studies and the element of artificiality should be borne in mind when applying the findings to diagnostic practice. Nevertheless, the low level of agreement on the diagnosis of high-grade dysplasia achieved by certain pairings of specialist pathologists is a disturbing outcome of this study. Inaccuracies should be minimized by a concensus approach and we therefore recommend referral of putative cases of dysplasia to interested pathologists for further opinions. We would also advocate that pathologists faced with appearances which are indefinite between reactive atypia and dysplasia, would do better to describe them in terms of "atypia, significance uncertain', so that closer surveillance is undertaken, rather than force them into more precise diagnostic categories which may be incorrect.

Value of endoscopic surveillance in the detection of neoplastic change in Barrett's oesophagus

Fifty-six patients with Barrett's oesophagus diagnosed between 1977 and 1986 were prospectively studied by 6-monthly endoscopic surveillance and biopsy. During follow-up to-date, four patients have developed high-grade dysplasia and three have adenocarcinoma of the oesophagus. Two of the adenocarcinomas were preceded by progressively severe dysplastic changes but in the third no dysplasia had been previously detected. The incidence of adenocarcinoma was 1 per 56 patient-years of follow-up. Changes in symptomatology or gross endoscopic appearances were usually absent, even after adenocarcinoma had developed, indicating that biopsy is essential for early diagnosis. The high risk of malignant change makes endoscopic surveillance advisable in all patients with Barrett's oesophagus.