observer variation anddiscriminatory of biopsyfeatures in ...'possible' in 63%. however,...

Gut 1994; 35: 961-968

Observer variation and discriminatory value ofbiopsy features in inflammatory bowel disease

A Theodossi, D J Spiegelhalter, J Jass, J Firth, M Dixon, M Leader, D A Levison,R Lindley, I Filipe, A Price, N A Shepherd, S Thomas, H Thompson

Departments ofGastroenterology andPathology, MaydayUniversity Hospital,CroydonA TheodossiS Thomas

MRC BiostatisticsUnit, Institute ofPublic Health,CambridgeD J Spiegelhalter

Departments ofPathology, St MarksHospital, LondonJJassN A Shepherd

Westminster Hospital,LondonJ FirthM LeaderR Lindley

University of LeedsM Dixon

St Bartholomew'sHospital, LondonD A Levison

UMDS, Guys Hospital,LondonI Filipe

Northwick ParkHospital, HarrowA Price

General Hospital,BirminghamH Thompson

Correspondence to:Dr A Theodossi, MaydayUniversity Hospital, MaydayRoad, Thornton Heath,Surrey CR4 7YE.

Accepted for publication28 October 1993

AbstractIf skilled histopathologists disagree overthe same biopsy specimen, at least onemust have an incorrect interpretation.Thus, disagreement is associated with,although not the cause of, diagnosticerror. The present study aimed todetermine the magnitude of variationamong 10 observers with a special interestin gastrointestinal histopathology. Theyindependently interpreted the samebiopsy specimens for morphologicalfeatures which may discriminate betweenpatients with Crohn's disease and ulcera-tive colitis and normal subjects. Thirty of41 features had agreement measuressignificantly better than expected bychance (p<005). The range of agreementin the 45 observer pairs over the finaldiagnosis was 65-76%. There was goodagreement in discriminating betweennormal slides and those showing con-firmed inflammatory bowel disease. Fornormal slides, however, the term non-specific inflammation was often appliedand without any consistency. In addition,true Crohn's disease slides were often andconsistently thought to be ulcerativecolitis. Having identified 11 importantdiscriminatory morphological features,two multiple regression analyses werethen carried out to produce a scoringsystem for inflammatory bowel disease.These results suggest there is considerableroom for improvement in the reliability ofcolonic biopsy specimen interpretationand that this could probably be achievedusing more exact definitions of morpho-logical features and diseases.(Gut 1994; 35: 961-968)

Clinicians are using colonoscopic mucosalbiopsy specimens more frequently to identifypatients suspected of having inflammatorybowel disease, to determine disease extentand severity, and to differentiate ulcerativecolitis from Crohn's disease.1 2 Histologicaldetection and classification of non-infectivechronic inflammatory bowel disease depend onaccurate interpretation of carefully preparedbiopsy material,3 but skilled histopathologistsobtaining information from the same biopsytissue may disagree about the findings.4 5

Giard et al 5 found poor reproducibility ofmorphological features and final diagnoses innormal subjects and those with inflammatorybowel disease. Cook and Dixon4 assessedobserver variation in the examination of

macroscopic and biopsy material taken frompatients with inflammatory bowel disease.They reported the percentage agreement, butdid not take into account the proportion ofobserved agreement due to chance alone.Surawicz and Belic6 and Allison et al 7 con-sidered the value of features in discriminatingacute self limited colitis from idiopathicinflammatory bowel disease, and reported bothdefinitions and simple percentage agreementon selected features.We believe that histopathology provides an

important contribution to the diagnosis ofinflammatory bowel disease. The aim of thepresent study therefore was to determine thereliability of the information obtained fromcolorectal mucosal biopsy specimens byassessing the magnitude of variation among 10histopathologists with a special interest ingastrointestinal histopathology who indepen-dently interpreted the same 76 biopsyspecimens. We set out to determine theobserver variation associated with the morpho-logical features and the final diagnoses. Ascoring system was then developed foridentifying patients with inflammatory boweldisease. In addition, at a video recordedmeeting we evaluated the question of whatleads to disagreement over important dis-criminatory features which were subsequentlyredefined.

MethodsSeven consultant histopathologists and threetrainees, all with a special interest in gastro-intestinal histopathology, were asked to reviewand independently code the same 76 biopsyspecimens. Thirty four specimens came frompatients with ulcerative colitis, 24 frompatients with Crohn's disease, and 18 fromnormal subjects. Many of these apparentlynormal subjects were eventually classified ashaving the irritable bowel syndrome or otherfunctional bowel disorder. In each instance thefinal diagnosis had been established byprolonged clinical follow up, radiological andmorphological assessments, and, whereappropriate, laparotomy or autopsy findings.Two slides taken from different levels of thebiopsy material were provided for all the 76patients. All of the slides were stained withhaematoxylin and eosin. The biopsy specimenstaken by sigmoidoscopy or colonoscopy werefrom patients who had been referred to theWestminster Hospital, London, for furtherevaluation of symptoms suggestive of inflam-matory bowel disease.

Variation between the pathologists was

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examined by providing a form on whichthey recorded their coding of morphologicalfeatures, as well as their histopathologydiagnoses. The coding form comprised 39different histological features. By design, noattempt was made to provide a strict definitionfor each of the features which were all ones inregular use. Each pathologist was asked toclassify each feature into one of four possiblegrades: 'absent', 'indefinite', 'little', or'marked'. Each of the four histologicalcategories of ulcerative colitis, Crohn's disease,normal, and mild non-specific inflammationhad to be graded as 'unlikely', 'possibly', or'likely' to be present.

After the data had been analysed, theimportant findings were discussed at ameeting in the presence of all 10 histo-pathologists. At the beginning of themeeting, the histopathologists independentlyre-examined two of the biopsy specimens. Theslides associated with the highest observervariation were then jointly reviewed in order todetermine the source of disagreement. Themeeting was recorded on a video tape, fromwhich data were subsequently analysed andsummarised (see results). In order to improveagreement on 10 important morphologicalfeatures, three observers JRJ, NAS, DAL)redefined the features using six slides, threeshowing high and three low agreements foreach feature. At a second meeting, the 10 newdefinitions, together with the appropriateslides, were reviewed and criticised by theother authors, to improve the definitionsfurther (see Appendix). At this meeting, itwas decided that two groups of features, whichhad been individually graded on the form,would best be defined as composite features.Thus, the results contain a feature 'cryptarchitectural abnormality', which is calculatedas the most severe grade recorded for anyone of 'crypt branching', 'crypt distortion',and 'crypt atrophy'. A second compositefeature, 'neutrophil infiltration', is the mostsevere grade given to 'neutrophilic infiltration

Observers'True diagnostic

diagnosis category

uc

uc CDUC Normal

Non-specific

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CDNormal

Non-specific

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Normal CDNormal

Non-specificuc

All CDslides Normal

Non-specific

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M Likely E Possible = Unlikely

Figure 1: Observer's diagnosis in relation to true diagnosis in biopsy materialfrom patientswith Crohn's disease (CD) and ulcerative colitis (UC) and normal subjects.

of crypt epithelium' and 'neutrophils in laminapropria'.

STATISTICAL METHODSAn overall proportion of agreement wascalculated, and then corrected for chanceagreement. This kappa coefficient8 is providedtogether with its level of statistical significancein relation to a null value of 0 - just chanceagreement. We also reclassified each featureinto 'present' ('little' or 'marked') or 'absent'('absent' or 'indefinite'), and provided pro-portions of agreement on this scale. Thesecalculations were repeated for the opinionconcerning disease.To determine the value of each feature in

discriminating between normal subjects andthose with inflammatory bowel disease, andbetween Crohn's and ulcerative colitis, webegan by calculating the frequency of eachfeature graded 'little' or 'marked' for colitis,Crohn's, and normal subjects. We thencalculated the rank correlations between theobservers' reported grades of features and thetrue presence or absence of inflammatorybowel disease. We then repeated the analysisusing only the slides of Crohn's and ulcerativecolitis tissue and calculated rank correlationsfor the true presence/absence of ulcerativecolitis and Crohn's.

Eleven important discriminatory featureswere identified, based on their respectivefrequencies in the three classes of subjects andthe extent of agreement between the observerson the reporting of the features. These werethen reduced to 10 after carrying out twomultiple regression analyses which providedscores firstly, for differentiating 'normals' frompatients with inflammatory bowel disease andsecondly, for distinguishing Crohn's fromulcerative colitis in patients with confirmedinflammatory bowel disease.

ResultsFigure 1 shows that there was considerabledisagreement in providing a diagnosis,particularly in the assessment of the likelihoodof 'Crohn's disease and 'non-specificinflammation'. True ulcerative colitis is welldiagnosed, with 'ulcerative colitis' considered'possible' or 'likely' in 930/o of cases, although'Crohn's colitis' was also considered at least'possible' in 63%.However, for observations on slides that

were truly Crohn's disease, only 68%thought 'Crohn's' at least 'possible', whereas'ulcerative colitis' was thought at least'possible' in 69%. In 41% of times when anobserver saw a true Crohn's slide, 'ulcerativecolitis' was thought 'likely'. Thus, Crohn'sdisease was frequently and consistentlymistaken for 'ulcerative colitis', although wenote that true Crohn's or ulcerative colitisslides were only very rarely thought 'likely' tobe 'normal' or 'non-specific inflammation'.

Similarly, true normal slides were rarelythought 'likely' to be 'ulcerative colitis'; andnever thought 'likely' to be 'Crohn's disease'.

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Observer variation and discriminatory value of biopsy features in inflammatory bowel disease

TABLE I Incidence and interobserver variation on features, ranked by overaU kappa statistic and correlation with presenceof inflammatory bowel disease v normal, and ukerative colitis (UC) v Crohn 's disease (CD)

Rank correlationbetween grading of

% Gradings reported feature and'litde'or 'marked'

Overall when disease is Trueagreement Significance presence True

Feature (%O) Kappa* p value UC CD Normal ofIBD UC

1 Crypt neutrophilia 69 (82)t 0-47 (0 62)t <0-001 53 56 2 0-46§ -0-062 Neutrophilic (1 or 5) infiltration 60 (82) 0-41 (0-63) <0-001 66 67 6 0-53§ 0-043 Epitheloid granulomas 88 )95) 0-41 (0-60) <0-001 0 21 0 0-18 -0-41§4 Langhan's type giant cells 94 (97) 0-40 (0-59) <0-001 1 11 0 0-13 -0-28§5 Neutrophils in lamina propria 60 (79) 0-40 (0-57) <0-001 61 61 6 0-51§ -0-026 Crypt distortion 57 (80) 0-38 (0-60) <0-001 78 51 4 0-53§ 0-34S7 Crypt abscesses distensive 79 (84) 0-37 (0-46) <0-001 18 32 1 0-27 -0-178 Ulceration of surface epithelium 71 (85) 0-36 (0-56) <0-001 31 24 0 0-33 0-079 Crypt architecture (6 or 16 or 21) 54 (79) 0-36 (0-56) <0-001 86 65 11 0-57§ 0-35§10 Mucin depletion 54 (79) 0-34 (0-57) <0-001 69 57 17 0-41§ 0-1511 Lymphoid follicles in lamina propria 63 (74) 0-33 (0-44) <0-001 36 40 32 0-09 -0-0412 Submucosal inflammation 79 (86) 0 33 (0-44) <0-001 18 20 1 0-21 -0-0113 Eosinophils 53 (77) 0-32 (0-51) <0-001 87 62 16 0-54§ 0-31§14 Crypt abscesses disruptive 81 (86) 0-31 (0-42) <0-001 14 26 0 0-24 -0-1615 Submucosal lymphoid aggregates 80 (84) 0-31 (0-39) <0-001 15 17 11 0-06 -0-0516 Crypt branching 55 (74) 0-30 (0-47) <0-001 63 39 5 0-44§ 0-30S17 Paneth cell metaplasia 84 (87) 0-29 (0-36) <0-001 19 4 6 0-09 0-23§18 Diffuse inflammation 50 (74) 0-27 (0-34) <0-001 84 77 41 0-41§ 0-0519 Plasma cells 52 (77) 0-27 (0-25) <0-001 87 89 57 0-38 0-0720 Villous mucosal configuration 70 (81) 0-26 (0-37) <0-001 30 12 6 0-23 0-29S21 Crypt atrophy 57 (71) 0-24 (0-27) <0-001 44 23 5 0-34 0-28§22 Crypt dilatation 55 (67) 0-23 (0-31) <0-001 57 42 8 0-39§ 0 1723 Inflammatory polyps 90 (96) 0-22 (0 24) <0-05 3 4 0 0-15 0-0124 Submucosal fibrosis 93 (95) 0-20 (0-26) <0-11 6 3 0 0-13 0-0425 Thickened muscularia mucosa 58 (79) 0-17 (0-30) <0-001 25 20 6 0-17 0-0826 Regenerative changes 48 (67) 0-17 (0-30) 0-01 51 44 11 0-32 0-0927 Crypt hyperplasia 52 (68) 0-15 (0-24) 41 29 11 0-26 0-1528 Oedema of lamina propria 50 (61) 0-15 (0-18) <0-001 44 41 30 0-11 0-0329 Neuronal hyperplasia 96 (97) 0-14 (0-22) 0-27 4 4 0 0-07 0-0730 Submucosal oedema 85 (90) 0-10 (0-13) 0-19 5 9 5 0 -0-1131 Superficial apthoid ulcer 92 (94) 0-10 (0-10) 0-27 5 4 0 0-13 0-0532 Vascularity 49 (59) 0-10 (0-14) <0-001 46 43 17 0-24 0-0233 Lymphocytes 42 (67) 0-08 (0-15) <0-001 79 85 49 0-36 0-0434 Fissuring 97 (99) 0-08 (0-02) 0-39 1 1 0 0-07 0-0235 Foreign body type giant cells 94 (96) 0-05 (0-02) 0-39 3 3 0 0-07 -0-0836 Focal inflammation 67 (78) 0-05 (0-09 0-20 10 26 7 0-06 -0-18§37 Histiocytes 34 (54) 0-05 (0-07) <0-001 45 55 27 0-25 -0-0838 Fat in lamina propria 97 (98) 0-01 (0) 0-50 2 0 0 0-07 0-0639 Submucosal lymphangiectasia 96 (98) 0 (-0-02) 0-50 1 2 0 0-08 -0-0240 Vasculitis 99 (99) -0-01 (-0-01) 0-50 0-3 0-4 0 0-04 -0-0441 Muciphages in lamina propria 82 (90) -0-02 (-0-02) 0-50 5 3 7 0 0-02

*Kappa= 1 - (100-overall agreement (%))/(100-expected agreement by chance (%)).#4The overall agreement and kappa values in brackets are the results obtained when the gradings were reclassified into a present-absent scale.§Top 10 features.

They were frequently thought 'possible' or'likely' 'non-specific inflammation', althoughthere was no agreement on this, and the gradewas as if given at random.

Table I displays 41 features ranked in orderof the observer agreement as measured by akappa statistic. The overall proportion of eachgrading is based on 10X 76=760 observations.The figures for overall agreement vary with therarity of the feature: 'fat in lamina propria'(#38) has overall agreement of 97% but this isonly because it was so often recorded as absent- on the rare occasions it was seen by anindividual, it was never recorded by one of hiscolleagues. The kappa statistic corrects for thischance agreement, although for more frequentfindings the standard error of the kappastatistic decreases and hence increases thestatistical significance of the improvement overagreement by chance alone. This can be seenby comparing features 'superficial aphthoidulcer' (#31) and 'vascularity' (#32): both havepoor agreement (kappa=0- 10), but the latterfeature is more common and hence its kappavalue is significantly different from zero.Separate 'pairwise' analysis comparing eachobserver with every other showed no individualstanding out as being distinct in their opinions,with overall agreement varying between 65%and 75%.

Features which are rarely observed, usually(but not inevitably) have low kappa values. Forexample, muciphages (#41) were present in6% of the observations leading to a kappa of-0-02. Epithelioid granulomas (#3) were alsorarely observed (in 7% of observations) but theassociated kappa value was considerably higherat 0-41, indicating that when seen there wasmuch closer agreement on their presence. Bycontrast, common features such as lympho-cytes (#33) may have poor agreements.When the features are reclassified into just

'present' or 'absent' (table I - note tit), it isinevitable that agreement will improve.However, it can be seen there is little change inoverall ranking. Thus, a feature such as'lymphocytes (#33) does not have poor agree-ment simply because of minor disputes overwhether the abnormality should be called'little' or 'marked'; there is serious disagree-ment with one third of paired comparisons ofpathologists giving conflicting opinion over thepresence or absence of 'lymphocytes'.As a formal method of investigating the

relationship between features and the presenceof inflammatory bowel disease, we show therank correlation coefficient (Spearman's rho)between the grade given to the feature and thetrue presence/absence of disease. The 10features with the highest correlation with true

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TABLE II Details of two true-Crohn's disease (CD) slidesin which substantial dispute existed concerning thelikelihood of 'CD'

Grades Unlikely Possible Likely

(A) Slide no 11 (CD). Eight histopathologists' diagnosticopinion concerning 'CD':

Opinion concerning Absent 2'mucin depletion' Indefinite(#10) Little 1 1 2

Marked 2(Spearman rank correlation= 0-76, p<0 05)(B) Slide no 56 (true CD). Nine histopathologists' diagnosticopinion concerning 'CD':Opinion concerning Absent 2 1

'Epithelioid Indefinite 1 1granulomas' (#3) Little 1 2

Marked 1(Spearman rank correlation= -0-76, p<0 05)

Entries in the tables show the number of observers gradingeach combination of opinion about 'Crohn's' and a selectedfeature for each slide, eg, two observers thought'mucin depletion' was 'marked', and also stated an opinionthat Crohn's disease was 'unlikely' to be the true diagnosis.The observed relationship suggests that improvement inagreement on these and other features may improve diagnosticagreement.

inflammatory bowel disease are indicated byasterisks. There is a strong relationship betweengood agreement and discriminatory power - nofeature ranking below 23 in agreement is inthe top 10 for discrimination. The most usefulfeatures for distinguishing inflammatory boweldisease from normal were thus neutrophils(#1, #5, and their composite #2), crypt archi-tectural abnormality (#6, #16, and the com-posite measure #9), mucin depletion (# 10),eosinophils (#13), diffuse pattern of inflamma-tion (#18), and crypt dilatation (#22).We now consider features that are useful for

distinguishing Crohn's from ulcerative colitis,and hence the final column of Table I is basedsolely on the 58 inflammatory bowel diseaseslides. The rank correlations for features andtrue ulcerative colitis are calculated and the 10most powerful features identified: epithelioidgranulomas (#3), Langhan's type giant cells(#4), crypt architecture (#6, #16, #21, and #9),eosinophils (#13), Paneth cell metaplasia(#17), villous mucosal configuration (#20),and focal inflammation (#36). Again betteragreement is strongly related to discriminatoryvalue, although the importance of 'focalinflammation' persists in spite of poor agree-ment. This suggests that a firmer definitionmay lead to improved diagnostic power.To illustrate further the apparent relation-

ship between disagreements on specificfeatures and disagreements between claimed

TABLE III Ten selected important features and their contribution to indices fordiscriminating normalfrom inflammatory bowel disease (IBD) slides, and ulcerativecolitis (UC) from Crohn's disease (CD). (Ulceration of the surface epithelium (#8) wasincluded in the discriminant analyses but its rounded coefficient was zero in both indices.)Numbering offeatures corresponds to that in Table I

Feature IBD/normal score UC/CD

#2 Neutrophilic infiltration 1 -1#3 Epithelioid granulomas 1 -6#9 Crypt architectural abnormalities 3 1#10 Mucin depletion 1#13 Eosinophils 2 3# 17 Paneth cell metaplasia 2#18 Diffuse inflammation 1 -2#20 Villous mucosal configuration 1#22 Crypt dilatation 1#36 Focal inflammation 3 -2Range of score 0 to 12 (high favours - 1 1 to 8 (negative favours

IBD) CD, positive favours UC)

TABLE IV Suggested strategy showing the conclusion to bedrawn for any combination of the inflammatory boweldisease (IBD)/normal and ukerative colitis (UC)/Crohn'sdisease (CD) scores

UC/CD score

<-3 -2to2 >3:61 - 'Normal' -

IBDinormal score 2 to 4 'CD' 'Possible IBD' 'UC':>5 'CD' 'IBD' 'UC'

Note: the top right combination cannot be obtained from thescores given in Table III. The top left combination can only beobtained if 'epithelioid granulomas' is the only abnormalfeature recorded among the seven contributing to theIBD/normal score. This has not been observed in our series.

diagnoses, we consider two slides (#11 and#56) which were actually of Crohn's diseasebut which gave rise to substantial dispute.Table II shows the relationship betweenopinion concerning 'Crohn's disease' and theopinion given to two selected features. Theclear relationship, while not proving thatviewing a particular feature causes the claimeddiagnosis to be made, strongly supports theidea that reduced disagreement on specificinfluential features could give rise to betteragreement on claimed diagnosis, with accom-panying increase in accuracy.The scoring systems based on all 76 biopsy

specimens and derived from the discriminantanalyses are shown in Table III. Thus, abiopsy in which an observer reported diffuseinflammation, eosinophils, crypt architecturalabnormalities, and Paneth cell metaplasiawould receive an inflammatory boweldisease/normal score of 6 and a ulcerativecolitis/Crohn's disease score of 4. In Table IV,the two scoring systems are seen togetherforming a 'strategy' in which the inflammatorybowel disease/normal and ulcerativecolitis/Crohn's scores classify each slide intoone of the cells.

Table V shows the consequences had thatstrategy been used by the observers inreviewing the slides. We can now compare theaccuracy of the observers' original diagnosisshown in Figure 1 with that of the scoringsystem strategy. For normal slides the scoringsystem makes more positive diagnosis of'normal' (66% v 52%) for a similar number ofconfident, but wrong, diagnoses of inflamma-tory bowel diseases (9% v 7%). For Crohn'sdisease, the scoring method makes fewercorrect positive diagnoses (28% v 37%), makesthe same number of false negative diagnoses of'normal' (10% v 8%), but makes substantiallyfewer false confident diagnoses of 'ulcerativecolitis' (11% v 41%), tending to be morecautious and classifying these slides as indeter-minate 'inflammatory bowel disease'. Forulcerative colitis slides, the scoring system isdefinitely more diffident in asserting 'ulcerativecolitis' (37% v 71%), makes similar falsenegative 'normal' diagnoses (3% v 4%), butmakes substantially fewer false diagnoses of'Crohn's' (6% v 10%).

Altogether 363 (52%) of slides would havebeen given a confident diagnoses, with 81%accuracy, while a further 213 (31%) wouldhave been classified as indeterminate inflam-matory bowel disease, with 99% accuracy.

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TABLE V Conclusions that would have been drawn hadthe observers used the strategy in Table IV on 689 readingsof slides, divided by disease category

True disease (%)

Conclusion Normal CD UC

'Normal' 108 (66) 22 (10) 10 (3)'CD' 4 (2) 59 (28) 2 (6)'UC' 9 (6) 23 (11) 126 (37)'IBD' 1 (1) 74 (35) 138 (44)'Unsure' 41 (25) 32 (15) 40 (13)

163 (100) 210 (100) 316 (100)

CD= Crohn's disease; UC=ulcerative colitis.

PANEL MEETING (INCLUDING REVIEW OF SLIDESSHOWING MARKED DISAGREEMENT)Two slides were selected for re-reading beforethe meeting. Table VI shows the considerabledisagreement that was observed. Differenthistopathologists use the term 'non-specificinflammation' in different ways. Somepathologists apply 'non-specific inflammation'to biopsy specimens where they are confidentthat inflammatory bowel disease or anothercondition such as irradiation colitis is present,but they cannot discriminate between theseconditions. Others restrict the term forbiopsies where they cannot discriminatebetween Crohn's and ulcerative colitis. Stillothers like to use the term when they believeCrohn's is likely to be present, but where thespecimen shows insufficient evidence to makea definite diagnosis of Crohn's. Somehistopathologists use the term to indicate thatmild non-specific inflammation is present butthere is no histological evidence of inflamma-tory bowel disease. The results from thepresent study indicated, however, that therewas very little agreement on 'non-specificinflammation'.

Focal inflammation was the only featurewith a low agreement measure that thepathologists considered to be important. Otherfeatures with low kappa values were thought tobe rare and unusual and therefore unimpor-tant. The terms 'absent', 'indefinite', 'little',and 'marked' were criticised. For example,how many granulomas should be present onthe slide before changing one's opinion from'little' to 'marked'? And if there were onlymicro-granulomas present, should they bedescribed as 'little' or 'marked'. Differentpathologists had different definitions for focalinflammation. One observer would describe an

isolated crypt abscess as focal inflammation.

Others used the term when they saw patchychronic inflammation on the slide. But howmany of these 'patches' must one see beforechanging one's opinion from 'little' to'marked'? A patch of chronic inflammatorycells that consisted only if lymphocytes couldbe the edge or part of a lymphoid follicle.Thus, some observers would call such a

patch focal inflammation only if they couldalso see polymorphs amongst the lymphocytes.Similarly, patchy areas of inflammation whichare regularly spaced on the slide should raiseone's suspicions that these might all be arisingfrom lymphoid follicles.One observer commented that a well known

feature such as mucin depletion should be easy

to detect by everybody. Yet slides were shownwhere the observers were divided on thepresence or absence of mucin depletion. Oneof the pathologists therefore concluded thatthere was probably general agreement on

mucin depletion but differences in opinionoccurred because of the different ways inwhich different histopathologists interpretedany one feature in the presence of all theothers. On reviewing the slide where on thefirst reading three observers had seen and fourhad not seen granulomas, and where on thesecond reading no one saw granulomas, it tooka long time to find a granuloma. Once one was

seen, all 10 pathologists agreed that granulo-mas, or rather micro-granulomas, were pre-sent. The relevance of micro-granulomas inthe diagnosis of Crohn's disease has beenemphasised by Rotterdam et al.10 This slidehighlighted the problem of observation of fea-tures. All 10 pathologists concluded thatimportant features can be missed because ofthe problem of observation even among experi-enced observers. In addition, this videorecorded meeting showed clearly that theobservers may have different working defini-tions for morphological features considered tobe well known and in routine use.

DiscussionThis study, conducted by experiencedhistopathologists on colorectal biopsies frompatients with inflammatory bowel disease andpatients with functional diarrhoea, has shownserious disagreements both in the inter-pretation of morphological features and thefinal histopathological diagnoses. Experienced

TABLE VI Opinions of 10 observers reviewing two slides, before a video taped meeting; all observations taken on same twomicroscopes within a one hour period

Slide #11 (true CD) Slide #26 (true normal)

Absent Indefinite Little Marked Absent Indefinite Little Marked

21 Crypt atrophy 6 1 2 1 9 136 Focal inflammation 8 2 3 3 3 13 Epithelioid granulomas 10 9 14 Langhan's type giant cells 9 1 1010 Mucin depletion 1 7 2 108 Ulceration of surface eptihelium 3 4 2 1 10

Unlikely Possible Likely Unlikely Possible Likely

UC 3 2 5 9 1CD 3 6 1 7 2 1Normal 10 5 4 1Non-specific inflammation 10 2 4 4

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histopathologists can accurately discriminatebetween biopsy specimens from normal subjectsand those from inflammatory bowel disease, butthe differentiation of Crohn's from ulcerativecolitis is less reliable. In addition, patients withfunctional diarrhoea (our 'normal' group) wereoften found to show features of non-specificinflammation. Giard et al 5 also found betteragreement on ulcerative colitis than Crohn'sdisease and that agreement was poor for normalmucosa. Myren" noted that pathologists haddifficulty distinguishing ulcerative colitis fromnon- specific inflammation and normal biopsytissues from those with non-specific inflamma-tion. However, 'ordinary non-specific acute andchronic inflammation is the major form takenby colitis'.'2 Although the term cannot thereforebe discarded, it should be used cautiously toavoid mistaking normal individuals for thosewith inflammatory bowel disease.

Over the past two decades severalpapers'3-15 have addressed the problem ofdifferentiating Crohn's from ulcerative colitis,and idiopathic inflammatory bowel diseasefrom acute self limited colitis. 16 However, bothCrohn's and ulcerative colitis typically have along and variable course due to unpredictableremissions and relapses.'7 In addition, many ofthe diagnostic features occur with similarfrequency in the two conditions, and neitherdisease has a pathognomonic finding, 'presentin every case of the one and absent in everycase of the other'.'8 Thus, sometimes onlycolitis indeterminate'9 can be established.

Previously, the accuracy of biopsy diagnosisof ulcerative colitis and Crohn's disease wasfound to be 70% and 40% respectively in 126patients.17 In contrast to previous reports,12 13the present study suggests that mucindepletion does not distinguish Crohn's fromulcerative colitis. Its main value is to distin-guish normal biopsy tissues from specimensshowing inflammatory bowel disease. Cryptabscesses have been reported either withsimilar frequency in ulcerative colitis andCrohn's,12 13 20 or, more often, in ulcerativecolitis.3 Interestingly, we found crypt abscessesmore often in Crohn's disease.4 12Colonoscopic biopsy, however, only rarelyyields submucosal tissue, and, surprisingly, wefound submucosal fibrosis in 6% of ulcerativecolitis and in only 3% of Crohn's diseasetissues.

Although, in our material, submucosaloedema occurred more often in Crohn'scolitis, the difference was not significant (5% v9%) and as it is associated with a low agree-ment measure, we do not recommend using itin distinguishing Crohn's from ulcerativecolitis. It is widely accepted that Paneth cellmetaplasia does not discriminate betweenCrohn's disease and ulcerative colitis.3 2022Our study, however, suggests this is animportant marker for ulcerative colitis. We andothers20 have not confirmed either that adiffuse pattern of inflammation discriminatesbetween Crohn's and ulcerative colitis,3 orthat pseudopolyps are found more often inulcerative colitis,'2 but we can agree with Priceand Talbot3 that a villous mucosal configura-

tion occurs more often with ulcerative colitis.Since crypt distortion (4%), crypt branching

(5%), crypt atrophy (5%), and crypt architec-tural changes (11%) were seen in our normalgroup, we agree that minor degrees of fibrosisand crypt distortion probably do occur in thehealing phase of acute self limited colitis. 12 It islikely therefore that minor inflammatorychanges, together with minor crypt changes,are found in patients who after prolongedclinical follow up do not have inflammatorybowel disease. Clearly, patients with theseminor morphological changes will need carefulfollow up with repeat biopsies.The lamina propria in a normal colono-

scopic biopsy specimen contains the occasionaleosinophil.3 20 21 23 Others have suggestedthat mucosal eosinophilia is a marker of theseverity3 12 23 or chronicity2 4 of ulcerativecolitis, but we have found that mucosaleosinophilia is useful in that it distinguishesnormal subjects from those with inflammatorybowel disease and its presence favours thediagnosis of ulcerative colitis.25Lymphoid aggregates have been found to be

good discriminators in idiopathic inflamma-tory bowel disease.6 7 19 On average onelympho-glandular complex occurs approxi-mately every 2 cm in normal subjects, and oneevery 07 cm in patients with colitis.26 Wefound lymphoid follicles in similar frequency inCrohn's colitis, ulcerative colitis, and normalsubjects. Clearly the value of lymphoid tissueis controversial and we recommend lymphoidaggregates should not be used as a major dis-criminator for idiopathic inflammatory boweldisease.

Features such as granulomas and focalinflammation can be regarded as helpfulpositive discriminators of Crohn's disease. Ourstudy suggests the finding of chronicinflammation in the absence of a villousmucosal configuration, crypt branching,Paneth cell metaplasia, and crypt atrophy arestrong pointers to possible Crohn's disease,and thus the latter features can be described asimportant negative features which tend tofavour Crohn's.The combination of 'little' and 'marked' as

'present' may lead to loss of some informationand thus, for example, may prevent ahistopathologist from using a 'marked' thick-ening of the muscularis mucosae in support ofa diagnosis of ulcerative colitis. But there is nogold standard whether the feature is 'little' or'marked' in a particular biopsy specimen. Thepresent study has shown poor agreement onthis feature, although when 'little' and'marked' were lumped together, agreementimproved (kappa value from 0-17 to 03).Better agreement may lead to less error, since iftwo observers agree on the presence or absenceof a finding they are both either correct orincorrect. By contrast, if they disagree thenat least one of them is incorrect. Thus, onlyagreement may be associated with fullaccuracy.The classification of inflammatory bowel

disease should be based on all availableevidence including clinical, radiological, and

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6rX histopathological data. In addition, sequentialinformation may be required over a period oftime.3 19 To ask for the final diagnosis on the

ii.f _ , .00 basis of two slides, taken out of the usual* -';,J>;. context of histopathology decision making,

may be considered unrealistic. We have foundconsiderable disagreement, however, betweenexperienced observers reviewing the sameslides. In addition, this disagreement existswhether the biopsy specimens are takenfrom the rectum or colon., either through thesigmoidoscope or the colonoscope, andwhether they are active or quiescent., anddisagreement is intimately related toinaccuracy since some of the reported observa-tions will be correct and others incorrect.Furthermore, deeper sections or additionalbiopsy specimens will not necessarilyguarantee better agreement.

Biopsy specimen showing crypt atrophy, crypt banding, crypt distortion, and a It is therefore our unshaken belief that oururface (haematoxylin and eosin, original magnification x40). study has shown considerable error in using

colorectal biopsy specimens for classifyingpatients. In addition, we have identifiedfeatures with such poor reproductivity that werecommend caution when using them fordecision making. The strategy in Table IV

M ~. $ - should be used as an aid., in conjunction with*-}-<*<tb- >IC&;t -bvisclinical judgment and the observer's intuition.

- Furthermore, in clinical decision making, therecommendation from the strategy should becarefully integrated with other objective data

]: Bi o psyspecimnlobtained from the clinical, laboratory and'mradiological evaluation of the patient.

~~ - 4 ~~~~TAppendix

DEFINITIONS

Crypt branching (see Fig 2)The presence of two or more branched crypts in an ade-quate sized biopsy specimens. Crypt branching needs to

~. ~ ~;j~* ~ ~2'~ be distinguished from the normal branching seen- between mucosal hillocks.

_1 _ -. ii Crypt distortion (see Fig 2)3: Biopsy specimen showing neutrophil infiltration (haematoxylin and eosin, Irregular shaped, non-parallel, variable diameter, cysticmagnification X 100). as opposed to the normal parallel, test tube shaped

crypts.

Crypt atrophy (see Fig 2)Refers to the increased gap (space) between the base ofthe crypt and muscularias mucosa, but not necessarilycrypt themselves. There are fewer crypts and thereis an increased ratio of lamina propria to cryptepithelium. Crypts may be reduced, normal orincreased in height.

It is worth mentioning that all of these definitions canonly really be applied if there is an adequate sizedbiopsy that has been appropriately orientated. In addi-

**tion, if there is crypt atrophy and crypt distortion., it is4. difficult to identify crypt branching.

We recommend that the three definitions, crypt* branching, crypt distortion, and crypt atrophy, be

grouped as 'architectural abnormalities' and that thisfeature is of major importance in discriminating

* opsbetween normal biopsies and those taken from chronic'~~~ ?'~~~~i~ ~ ~ ~ inflammatory bowel disease.

i~~~~~~~g~~ ~ ~ ~ ~ ~ ~ Nutohi nilrton(e Fg3The unequivocal presence of neutrophils infiltrating thelamina propria or the crypt epithelium, or both, as

. ~~~~~opposed to neutrophils found inside small blood ves-sels. The presence of even a few neutrophils is a relevantfinding. They may be present either in the epithelium,

4: Biopsy specimen showing discontinuous inflammation (haematoxylin and eosin, the lamina propria, or they may be found in relation to!magnification X 40). a ruptured crypt.

Figure 2villous si

Figure :original

Figure aoriginal

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968 Theodossi, Spiegelhalter, _tass, Firth, Dixon, Leader, Levison, Lindley, Filipe, Irice, Shepherd, Thomas, Thompson

~~~~~~~ ~ ~ ~ ~~~~~~0 '

.:: J

Figure 5: Biopsy specimen showing mucin depletion (haematoxylin and eosin, originalmagnification X 100).

EosinophilsThese are present in small numbers in the normal lam-ina propria. There is no definition of the baseline ofnormality, but the subjective impression of increasedeosinophilia was reasonably consistent betweenobservers. Such factors as thickness of sections, stainingand degree of accompanying inflammation, will influ-ence subjective impression.

Focal inflammation has been re-named asdiscontinuous inflammation (Fig 4)This is defined as the presence of oedematous or nor-mal mucosa, as defined by the presence of a normalarchitecture and the absence of inflammation, togetherwith the presence of active inflammation in another partof the same biopsy.

Scattered lymphoid aggregates do not constitute reli-able evidence of active inflammation. Demonstration ofskip areas within a colonoscopic series would be indica-tive of discontinuous inflammation.

Epitheloid granuloma (see Fig 5)An aggregate of epitheloid histiocytes with or withoutmulti-nuclear giant cells. Caution should be exercised

Figure 6: Biopsy specimen showing granuloma (haematoxylin and eosin, original

manfctinx10.

when not well circumscribed, when related to cryptrupture, when small and superficial, and when relatedto foreign material.

Mucin depletion (see Fig 6)Impression of unequivocal reduction of goblet cellswithin crypt epithelium.

We wish to acknowledge Merck Sharp and Dohme; support forthe panel meeting and video preparation.

1 Durdey P, Weston PMT, Williams NS. Colonoscopy orbarium enema as initial investigation of colonic disease.Lancet 1987; ii: 549-5 1.

2 Lindsey DC, Freeman JG, Cobden I, Record CU. Shouldcolonoscopy be the first investigation for colonic disease?BM3 1988; 296: 167-9.

3 Talbot IC, Price AB. Biopsy pathology in colorectal disease.London: Chapman and Hall, 1987.

4 Cook MG, Dixon MF. Analysis of the reliability of detec-tion and diagnostic value of various pathological featuresin Crohn's disease and ulcerative colitis. Gut 1973; 14:255-62.

5 Giard RWM, Hermans J, Ruiter DJ, Hoedemaeker PJ.Variations in histopathological evaluation of non-neoplastic colonic mucosal abnormalities, assessment andclinical significance. Histopathology 1985; 9: 535-41.

6 Surawics CN, Belic L. Rectal biopsy helps to distinguishself-limited colitis from idiopathic inflammatory boweldisease. Gastroenterology 1987; 92: 318-28.

7 Allison MC, Hamilton-Dutoit SJ, Dhillon AP, Pounder RE.The value of rectal biopsy in distinguishing self-limited colitis from early inflammatory bowel disease.QJ7Med 1987; 65: 985-95.

8 Fleiss JL. Statistical methods for rates and proportions. 2nd Ed.New York: Wiley, 1981.

9 Armitage P, Berry G. Statistical methods in medical research.Blackwell. Oxford.

10 Rotterdam H, Korelitz BI, Sommers SC. Micro-granulomas in grossly normal rectal mucosa in Crohn'sdisease. Am J Clin Pathol 1977; 67: 550-4.

11 Myren J, Serck-Hanssen A, Solberg L. Routine and blindhistological diagnosis on colonoscopic biopsies comparedto clinical - colonoscopic observations in patients withand without colitis. Scand J Gastroenterol 1976; 11:135-40.

12 Yardley JH, Donowitz M. Colorectal biopsy in inflamma-tory bowel disease. In: Yardley JH, Morson BC, AbellMR, eds. The gastrointestinal tract. Baltimore: Williamsand Wilkins Co, 1977: 50-94.

13 Glotzer DJ, Gardner RC, Goldman H, Hinrichs HR, RosenH, Zetzel L. Comparative features and course of ulcera-tive colitis and granulomatous colitis. New Engl J7 Med1970; 282: 582-7.

14 Schachter H, Goldstein MJ, Rappaport H, Fennesy jJ,Kirsner JB. Ulcerative and granulomatory colitis - validityof differential diagnostic criteria. Ann Interni Med 1970;72: 841-51.

15 Clamp SE, Myren J, Bouchier RAD, Watkinson G, DeDombal FT. Diagnosis of inflammatory bowel disease: aninternational multi-centre scoring system. BMJ 1982;284: 91-5.

16 Anonymous. Which type of colitis? [Editorial]. Lancet 1988;i: 336.

17 Frei JV, Morson BC. Medical audit of rectal biopsydiagnosis of inflammatory bowel disease. Clin Pathol1982; 35: 341-4.

18 Hywell Jones J, Lennard-Jones JE, Morson BC, ChapmanM, Sackin MJ, Sneath PHA, Spicer CC, Card WI.Numerical taxonomy and discriminant analysis applied tonon-specific colitis. QJrMed 1973; 168: 715-32.

19 Price AB. Overlap in the spectrum of non-specific inflam-matory bowel disease 'colitis indeterminate'. J Clin Pathol1978; 31: 567-77.

20 Goldman H, Antonioli DA. Mucosal biopsy of the rectum,colon and distal ileum. Hum Pathol 1982; 13: 981-1012.

21 Whitehead R. Ulcerative colitis, Crohn's colitis, ischaemiccolitis, pseudomembranous and antibiotic-associatedcolitis. In: Mucosal biopsy of the gastrointestinal tract. 3rdEd. Whitehead R. London: WB Saunders Company,1985: 213-57.

22 Price AB, Morson EC. Surgical pathology of Crohn'sdisease and ulcerative colitis. Hun Pathol 1975; 6: 7-29.

23 Heatley RV, James PD. Eosinophils in the rectal mucosa.Gut 1978; 20: 787-91.

24 Willoughby CP, Piris J, Truelove SC. Tissue eosinophils inulcerative colitis. Scand J Gastroenterol 1979; 14: 395-9.

25 Anthonisen P, Riis T. Eosinophilic granulocytes inthe rectal mucosa in patients with ulcerative colitisand Crohn's disease of the ileum and colon. ScandJ Gastroenterol 1971; 6: 731-4.

26 O'Leary AD, Sweeney EC. Lymphoglandular complexes ofthe colon; structure and distribution. Histopathology 1986;10: 267-84.



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