726 J Clin Pathol 1991;44:726-733 Pathological mimics of chronic inflammatory bowel disease J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from
N A Shepherd
Introduction Iatrogenic inflammatory bowel disease Ulcerative colitis, Crohn's disease, and their Various therapeutic manoeuvres, both sur- intermediate forms collectively referred to as gical and medical, may directly cause inflam- idiopathic chronic inflammatory bowel disease, matory pathology in the intestines. Certain show a spectrum of pathological changes. surgical procedures can result in mor- Essentially their pathological diagnosis is one phological changes which simulate chronic of exclusion of the many causes of inflam- inflammatory bowel disease: these changes are mation in the intestines. The ultimate diag- largely independent of the original indication nosis may require corroboration with clinical, for surgery and represent a tissue response to microbiological, and radiological data. With an altered environment. Drugs can cause the advent of fibreoptic endoscopy, patho- inflammation of the intestinal mucosa. In the logists are more often confronted with small bowel enteric coated preparations and mucosal biopsy specimens of the gastro- non-steroidal anti-inflammatory drugs are intestinal tract, and the success of newer sur- common causes of inflammation, while in the gical techniques has meant that pathologists large intestine mucosal inflammatory changes are increasingly pressured to make un- are seen particularly with anti-neoplastic equivocal diagnoses of ulcerative colitis and agents and after enemas and suppositories. Crohn's disease. For instance, many would now consider restorative proctocolectomy DIVERSION COLITIS AND THE DEFUNCTIONED with ileal reservoir to be the operation of RECTUM choice in ulcerative colitis when medication When part of the colon or rectum is excluded has failed to control the disease,' and yet from the faecal stream for any reason, the Crohn's disease is an absolute contraindica- colorectal mucosa may become inflamed. The tion for this operation.2 It is essential, pathogenesis of this diversion colitis probably therefore, that the correct diagnosis is made relates to the lack of essential short-chain fatty before surgery is contemplated. acids, particularly butyrates, normally The importance of macroscopic examina- produced by anaerobic bacteria, which main- tion of surgical specimens to differentiate tain the healthy colonic mucosa.78 Such diver- ulcerative colitis and Crohn's disease has been sion colitis or proctitis occurs in the defunc- http://jcp.bmj.com/ emphasised, but the pathologist more often tioned large intestine in patients with func- has to make important diagnostic decisions, tional disorders, diverticular disease, and which will directly affect patient management, colorectal cancer.910 Macroscopically, the con- on biopsy specimens. Although both ulcer- dition is said to resemble ulcerative colitis." 12 ative colitis and Crohn's disease show charac- Histologically, diversion colitis shows diffuse teristic histological features in their classic chronic inflammation of the lamina propria form, none of the morphological changes seen and crypt abscesses may be present: in general on September 26, 2021 by guest. Protected copyright. in either condition is entirely specific. Patho- the lack of gross crypt architectural distortion logists generally rely on a combination of and goblet cell depletion militates against a morphological features to make the appro- diagnosis of ulcerative colitis (fig 1)." In priate diagnosis. This is especially so in severe cases, however, diversion colitis may Crohn's disease in which pathological features closely simulate ulcerative colitis micros- vary greatly from case to case. The two most copically.9"' Furthermore, the presence of characteristic features, fissuring ulceration and mucosal granulomas, together with the inflam- granulomas, can be seen in many other condi- matory pathology, may create a histological tions. Transmural inflammation is a little more appearance reminiscent of Crohn's disease.'415 specific but this feature is also seen in several The picture is further complicated by the fact other conditions. In about 10% of cases, par- that ulcerative colitis and Crohn's disease are ticularly in acute fulminant colitis, it may be both common indications for faecal stream impossible to differentiate the conditions and diversion. In ulcerative colitis the rectum is the term "indeterminate colitis" is used.3 For often defunctioned as a mucus fistula after the purposes of this review it is not intended total colectomy, and severe colonic Crohn's to concentrate on the pathological differenti- disease may be ameliorated by faecal stream Department of ation of ulcerative colitis and Crohn's disease diversion.'6 17 The defunctioned rectum in Histopathology, as this has been the of standard texts patients with ulcerative colitis may show Gloucestershire Royal subject Hospital, Great and reviews.' This review is primarily con- transmural inflammation, fissures, and gran- Western Road, cerned with recently described conditions and ulomas: an erroneous diagnosis of Crohn's Gloucester GL1 3NN newly recognised situations where the micro- disease may result.'8 It should be emphasised Correspondence to: scopic features may inappropriately suggest that the pathological examination of a defunc- Dr N A Shepherd a of chronic inflammatory bowel tioned segment of bowel may be very mislead- Accepted for publication diagnosis 20 February 1991 disease. ing: the diagnosis of chronic inflammatory Pathological mimics ofchronic inflammatory bowel disease 727
ar bowel disease should be restricted to the f,,<:', ' .' *", <@. ~,. t^*.*;streamdiversion.'8. J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from THE ILEAL RESERVOIR Restorative proctocolectomy with ileal alofreservoir is now one of the more favoured '- surgical alteratives among both surgeons and patients, for patients with ulcerative colitis -.'.'r^^s. of surgical manipulation and reservoir con- http://jcp.bmj.com/ struction.26 As in many other sites in the gut, ~~)~~~ ~ '~~i~ granulomas are a major source of diagnostic -~E~~~ - ~:- -, confusion. They are occasionally seen, par- -~ticularly~~~~~ in lymphoid follicles, in the reservoir mucosa of patients with an indisputable diag- ~~. - ~. nosis of ulcerative colitis (fig 2B).26 Such gran- ,~~~.~~*.~~~~ ~ ~ ulomas probably represent a reaction of the on September 26, 2021 by guest. Protected copyright. $~; the W.. ~ ileal mucosa, particularly lymphoid tissue, :'~ ~ to an altered intraluminal environment or to *141f.aAS~ ~ ~extraneous material. Grohn's disease remains f~~~ ~ ~ ~ ~ ~~' an absolute contraindication for pelvic ~~~~~~reservoir~~~21 surgery2: pathological changes ~~I~~IJ-J .~~~~~* ~~within/ the reservoir may closely resemble those seen in Crohn's disease but such a 'I;114 ~~~~~~~~~diagnosis should not be made solely on the - ~~~~~~~pathological changes seen in the reservoir. DRUGS ~~~Small.<~~~~~~~~~~~~ bowel ulceration may be caused by any number of conditions, although drugs seem to be a- common cause.27 Enteric coated potas- -'1W~~~~ - / ~~~~ sium supplements cause small bowel ulcera- - , -~ ... tion,s probably by an ischaemic effect due to C';Ad ~~~~~~~~~~~~~~vascularconstriction induced by high concen- -4;~trations of potassium ions: the histological -~~~-.- ~~~ ~ ~ ~ ~~ ~ ~~ changes affect only the mucosa and submucosa Figure 2 Mucosal biopsy specimens from pelvic ileal reservoirs. (A) There is subtotal and are unlikely to be confused with active villous atrophy, diffuse chronic in.jammation, andgross crypt distortion. (B) A well Crohn's disease.' Now accepted as one of the circumscribed epithelioidgranuloma in the characteristic position within a lymphoid commonest causes of clinically important ileal follicle in a rather distorted mucosal biopsy specimen. In the absence of other stigmata of Crohn's disease such granulomas probably represent a tissue reaction to persorbed ulceration are non-steroidal anti-inflammatory intraluminal material (haematoxylin and eosin). drugs (NSAIDs).29 These also cause mucosal 728 Shepherd redundancy is a characteristic feature of the condition, and inflammation, with histological features ofmucosal prolapse, is sometimes seen J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from in the sigmoid colon."'3 This syndrome was originally described as segmental colitis, al- though it has become clear that inflammatory pathology restricted to the segment affected by diverticular disease shows a wide spectrum of microscopic disease, from non-specific inflam- matory changes through to florid active inflam- matory change associated with crypt architec- tural distortion simulating ulcerative colitis (fig 3).4142 In a small proportion of cases it has been suggested that such segmental or crescentic colitis, the latter named for the characteristic involvement of the mucosal folds in the sig- moid, may precede the development of distal Figure 3 Sigmoid colonic biopsy specimenfrom crescentic or diverticular colitis. There ulcerative colitis.4' This form of colitis, being is diffuse chronic inflammation with pronounced crypt distortion and crypt abscesses are predominantly an inflammation of the luminal present (right). There was no clinical or radiological evidence of ulcerative colitis and mucosa, is quite distinct from diverticulitis, a the rectal mucosa was histologically normal (haematoxylin and eosin). condition in which stasis, infection, and inflam- mation occur primarily in the diverticula them- inflammation and ulceration in the colorectal selves.43 mucosa.30 The picture is complicated by the The clinical and histological diagnosis of fact that NSAIDs may exacerbate chronic chronic inflammatory bowel disease restricted inflammatory bowel disease.3' 32 Attention has to the sigmoid colon can be very difficult when recently focused on the late stage pathology of diverticular disease is present. While segmental small intestinal disease induced by NSAIDs.29 or crescentic colitis, associated with diver- So-called diaphragm disease has highly ticular disease, can produce histological chan- characteristic macroscopic and microscopic ges that closely mimic ulcerative colitis, the appearances, which, once recognised, are three pathological hallmarks of Crohn's disease readily differentiated from Crohn's disease.29 -granulomas, transmural inflammation, and NSAIDs, methyldopa, gold, antineoplastic fissuring ulceration-may all be seen as a result agents and penicillins are the most widely of diverticular disease of the sigmoid colon.4' recognised drugs known to cause active An association between Crohn's disease and inflammation in the large intestinal mucosa. diverticular disease has been postulated, but is Methyldopa causes an acute colitis in a small probably no more common than would be proportion of cases33 and gold causes a charac- expected by the natural prevalence of the teristic eosinophilic infiltrate.34 5'fluoro-uracil conditions." 45 Ifall the pathological features of http://jcp.bmj.com/ has been the most widely studied of the ulcerative colitis and Crohn's disease can be chemotherapeutic agents to cause acute colitis. seen as a result of the inflammatory complica- In the acute phase epithelial necrosis is the tions ofdiverticular disease, can one make a firm predominant feature while in the resolving diagnosis of chronic inflammatory bowel dis- phase crypt regeneration and distortion ease in the sigmoid colon with diverticulosis? reminiscent of healed ulcerative colitis are Caution is needed, and other areas of the observed.35 intestines should be investigated and biopsied, on September 26, 2021 by guest. Protected copyright. particularly the rectum if ulcerative colitis is ENEMAS AND SUPPOSITORIES suspected. Radiological studies of the sigmoid Most enemas and suppositories cause little colon may be helpful in establishing a double mucosal pathology but hypertonic saline diagnosis.46 Isolated involvement of the sig- enemas and bisacodyl, in particular, produce moid colon in Crohn's disease is relatively crypt epithelial proliferation and degeneration unusual and doubt should be cast on any such with inflammatory change.637 In general the diagnosis in the presence ofdiverticular disease pathological changes due to enemas more and the absence of any other stigmata of closely resemble ischaemia or infective colitis Crohn's disease. and lack the chronic inflammatory component of chronic inflammatory bowel disease. Sup- positories, particularly those containing Infective enterocolitis NSAIDs, may also cause mucosal damage and Infectious (acute, self-limiting) colitis in gen- result in rectal bleeding.' The resulting histo- eral has rather characteristic histological logical changes are generally those of mild, features which are unlikely to be confused with non-specific chronic inflammation, but ulcerative colitis. The predominance of acute occasionally active inflammation is seen.38 over chronic inflammatory cells, the lack of crypt architectural abnormalities, and the presence of oedema and neutrophils within the Diverticular disease crypt epithelium rather than in the crypt lumen Although diverticular disease is essentially a are all helpful features in favour of infective functional disorder of the colon, a wide variety colitis.4748 Occasionally, ulcerative colitis-like of inflammatory pathology may be associated changes may be seen in more chronic forms with the condition. For instance, mucosal of infectious colitis, particularly chronic Pathological mimics ofchronic inflammatory bowel disease 729 Figure 4 helpful histological variables are evidence of Microgranulomas inflammatory and architectural chronicity and (arrowheads) in resolving well formed epithelioid granu- phase of culture confirmed the presence of J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from salmonella enterocolitis lomas, these changes favouring a diagnosis of (haematoxylin and eosin). Crohn's disease. Pseudomembranous entero- colitis, due to Clostridium difficile toxin, is most likely to be mistaken for acute ischaemia rather than chronic inflammatory bowel disease, al- though early lesions show non-specific patchy inflammation with surface epithelial degenera- tion.54 Well formed granulomas are a feature of some infective colitides, chlamydial infection,55 yersiniosis,56 57 and tuberculosis being the most characteristic. Yersiniosis is perhaps the most likely infectious enterocolitis to produce- pathological confusion with Crohn's disease. The most helpful differentiating features are central necrosis within granulomas and the relative lack of transmural inflammation in yersiniosis.57 Examination of local lymph nodes, if available, is also helpful.58 If there is any doubt yersinia serology should be perfor- med. In cases of Crohn's disease associated with a florid sarcoid-like granulomatous re- sponse it may be impossible to rule out tuber- culosis on histological grounds alone. Tuber- culosis is favoured if there is florid coalescent shigellosis and amoebiasis.49 Acute chlamydial granulomatous inflammation, extensive caseous is seen in proctitis may resemble active ulcerative necrosis (some central necrosis colitis.50 These ulcerative colitis-like changes Crohn's granulomas, particularly in the anal in the absence of occur more often with the bacteria that cause region), and nodal granulomas are invasion of the mucous intramural granulomas.59 6' Acid fast bacilli inflammation by direct intestinal as opposed to those which elaborate only demonstrable in about 50% of membrane including a toxin such as Salmonella and Yersinia.5' It tuberculosis cases but clinical data, chest radiology and Mantoux testing, may be of may be difficult to differentiate infectious colitis, condi- particularly in a resolving phase, from Crohn's value.61 Other infective granulomatous disease in colonic biopsy specimens.6 Poorly tions, such as schistosomiasis, deep mycoses, microgranulomas are a feature and larval infestations are not often confused http://jcp.bmj.com/ circumscribed organisms of some infective colitides, particularly salmon- with Crohn's disease as the infecting ella52 (fig 4) and Campylobacter.53 Microbiology are usually readily identifiable. not helpful-in only about 40% of Viral infection, in particular by cyto- is always simplex virus cases is an infectious agent identified.' Most megalovirus (CMV) and herpes (HSV), may result in acute enterocolitis, especially in the immunosuppressed. Both produce characteristic histological appearances on September 26, 2021 by guest. Protected copyright. reminiscent ofchronic inflammatory bowel dis- ease (fig 5): the clinical history and the presence of inclusion bodies and multinucleate giant cells help to substantiate the diagnosis of viral enterocolitis. CMV colitis is a recognised com- plication of ulcerative colitis and may induce acute fulminant colitis with toxic dilatation.62 CMV, HSV, and cryptosporidiosis may pro- duce a florid active enterocolitis, masquerading as active ulcerative colitis, in patients with AIDS. The correct diagnosis relies on the demonstration of the organisms or their cyto- pathic effects. The enterocolitis of atypical myobacteriosis in AIDS is not usually con- fused with Crohn's disease as the histiocytic infiltrate diffusely involves the lamina propria and Ziehl-Neelsen stains show overwhelming numbers of bacteria. Non-specific (microscopic) colitis and lymphocytic colitis architectural Figure S CMV colitis. The inflammatory changes with crypt Microscopic colitis denotes a patient group abnormalities resemble ulcerative colitis. Inset: CMV inclusions are present (haematoxylin and eosin). with chronic watery diarrhoea and normal 730 Shepherd radiological and sigmoidoscopic findings but titis, together with the characteristic changes of microscopically abnormal colorectal biopsy lymphocytic colitis, enables the pathologist to specimens.63 64 The term is ambiguous as other from chronic inflam- distinguish the condition J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from conditions, including both ulcerative colitis matory bowel disease.67 and Crohn's disease, may show histopath- ological abnormalities in the face of normal macroscopic appearances.65"' A characteristic Ischaemic enterocolitis and Beh9et's pathological feature of the disease is surface syndrome epithelial degeneration with a noticeably Acute forms of ischaemic enterocolitis present increasedintraepitheliallymphocyte infiltrate,67 little differential diagnostic dilemma. Chronic and it has been proposed that the condition be strictures in ischaemic enterocolitis may sug- renamed lymphocytic colitis.67 68 His- gest a diagnosis of Crohn's disease. Histo- tologically, lymphocytic colitis shares some of logically, the reparative and chronic phases of the features of collagenous colitis, but these ischaemia disclose microscopic fissures, crypt colitides can be differentiated on examination of epithelial regeneration and distortion, and the biopsy specimen.67 The chronic inflam- chronic inflammation, features suggestive of matory changes that occur in lymphocytic chronic inflammatory bowel disease. Helpful (microscopic) colitis may suggest a diagnosis of microscopic features for establishing a diag- chronic inflammatory bowel disease: the lack of nosis of ischaemia are the presence of hae- crypt architectural distortion and active cryp- mosiderin laden macrophages in the lamina propria, fibrosis ofthe lamina propria, a relative paucity ofchronic inflammatory cells and selec- tive damage to the more superficial epithelium of the crypt.69 7 The multisystem disorder Behcet's syn- drome may affect the intestines: colonic disease is sometimes a prominent feature of the syn- drome.7' Ulceration is the most characteristic feature, either localised to the ileo-caecal region or more diffusely affecting the colon.72 Colitis in Behcet's syndrome shows typical aphthoid ulcers and mucosal cobblestoning; granulomas may be present.7273 Vasculitis is often seen in Behcet's colitis, affecting small veins and ven- ules.74 Controversy still abounds about the enterocolitis of Behqet's syndrome: it has been intimated that it is not a specific entity but rather a variant of chronic inflammatory bowel disease.67172 Although many ofthe pathological http://jcp.bmj.com/ similar to those in Crohn's colitis, ; features are Behcet's syndrome is said to lack the aggregated lymphocytic transmural inflamma- tion of Crohn's disease.75 Current opinion is that Behcet's enterocolitis should be regarded as a distinct entity until more information on the pathogenesis of the disease is forth- on September 26, 2021 by guest. Protected copyright. coming.75 The diagnosis of Behcet's enterocolitis clearly relies on corroboration of pathological findings with clinical data. Malignant lymphoma There are two situations in which primary malignant lymphoma of the gut may mimic inflammatory bowel disease. Deep, destructive fissuring ulceration is a highly characteristic feature of high grade small and large intestinal lymphomas of both B and T cell phenotype76 (fig 6A) and this may mimic Crohn's disease, particularly in those tumours with relatively few neoplastic cells and innumerable eosino- phils.77 In the large bowel diffuse lymphoma is relatively unusual but may be seen in both primary and secondary disease.78 Occasionally the disease is predominantly mucosal and Zjw -s*J;-4P...... = J Stw;;'*4 iSXv W=gg ' shows similar macroscopic and histological Figure 6 Primary malignant lymphoma of the intestines. (A) deep destructivefissuring changes to those of acute ulcerative colitis (fig ulceration in a small intestinal lymphoma. At this magnification the lymphomatous 6B).7`1 In this situation immunohisto- infiltrate is not obvious and the pathology could easily be mistaken for Crohn's disease. (B) diffuse intramucosal lymphoma of the colon mimicking chronic inflammatory bowel chemistry may help to differentiate the condi- disease (haematoxylin and eosin). tions." Very occasionally ulcerative colitis and Pathological mimics ofchronic inflammatory bowel disease 731 particularly giardiasis, with histological features like those of coeliac disease,92 and occasionally they cause nodular lymphoid J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from hyperplasia particularly in the ileum93: in- flammatory pathology similar to chronic inflammatory bowel disease is generally not encountered. NEUROMUSCULAR AND VASCULAR CHANGES IN THE INTESTINES The lesions of Crohn's disease may undergo spontaneous healing.94 In these cases a confus- ing histological picture is produced with hyalinised granulomas and little or no inflam- mation. The most striking findings are often seen in the connective tissues. Neuronal hyper- plasia, both of ganglion cells95 and nerve trunks,96 may mimic diffuse neurofibroma or intestinal ganglioneuromatosis,97 while the vas- I il '.' cular degenerative changes may suggest a . primary vasculitis. Another striking feature of I late stage Crohn's disease is the muscularisa- tion of the fibrotic submucosa, a feature also Figure 7 Pneumatosis cystoides intestinalis. The mucosa shows gross crypt atrophy and seen in ischaemic and radiation enterocolitis.98 distortion and the muscularis mucosae is thickened. Close inspection of the lower edge of The late stage of any localised intestinal ulcer the biopsy specimen shows the histiocytic lining of a submucosal gas cyst. Intramucosal granulomas were also present (haematoxylin and eosin). could be misinterpreted as Crohn's disease. In these cases the presence offissuring ulceration, malignant lymphoma may coexist: primary granulomas, or active inflammation elsewhere malignant lymphoma of the large bowel is a are features which can be used toward a diag- rare but well recognised complication of nosis of Crohn's disease. chronic ulcerative colitis.82 EOSINOPHILIC INFILTRATES OF THE GUT Several heterogeneous conditions may cause a Miscellaneous tissue eosinophilia in the intestines99: eosino- IMMUNE DEFICIENCY SYNDROMES phils may be a prominent component of the It is the acquired immunodeficiency syndromes inflammatory infiltrate in both ulcerative colitis that are most often confused histologically with and Crohn's disease.'"' Eosinophilic gas- chronic inflammatory bowel disease. Graft- troenteritisl0l 102 iS characterised by a florid versus-host disease (GvHD) in the acute phase tissue and peripheral blood eosinophilia, with http://jcp.bmj.com/ shows crypt distortion and degeneration with some histopathological similarities to chronic crypt abscesses83: as the disease progresses inflammatory bowel disease. Nevertheless, there is gross crypt atrophy.84 The absence of a eosinophilic gastroenteritis has characteristic predominant inflammatory component and the clinical associations: the condition lacks the presence of the "exploding crypt lesion", in characteristic histopathological changes of which individual cell necrosis can be shown Crohn's disease and the crypt architectural histologically and ultrastructurally in the crypt abnormalities of ulcerative colitis are not on September 26, 2021 by guest. Protected copyright. epithelium, are helpful in distinguishing present.' GvHD from chronic ulcerative colitis.85 Although clinically important intestinal path- ISOLATED MUCOSAL GRANULOMAS ology is caused by specific infection in patients Small isolated granulomas are not an unusual with AIDS, AIDS is also complicated by a feature in rectal mucosal biopsy specimens. In non-specific enterocolitis.86 This is the result of the absence of collateral evidence to support a immunologically mediated damage to the intes- diagnosis of Crohn's disease a cause may not be tinal epithelium similar to that seen in GvHD, found. Refractile crystals are always demon- with similar histological appearances.87 In the strable in barium granulomas'03 and it is most absence ofother histological clues the diagnosis unusual to see evidence of sarcoidosis in rectal may be reached by confirming the presence of mucosa.1'0 It is likely that most of these HIV in rectal crypt epithelium by in situ incidental granulomas represent a tissue res- hybridisation.88 ponse to mucin, possibly as a result of crypt The autosomal recessive disorder chronic obstruction, inflammation, and disruption. granulomatous disease of childhood (CGD) is complicated by a colitis with similarities to PNEUMATOSIS CYSTOIDES INTESTINALIS Crohn's disease.89 The conditions may be dif- Pneumatosis is a rare condition characterised ferentiated by the presence of a histiocytic by gas filled cysts which particularly affect the infiltrate containing lipid vacuoles and pigment colonic submucosa.'05 Clinically, the condition histochemically similar to lipofuscin in CGD90 is more likely to simulate polyposis syn- and by the normal leucocyte bactericidal dromes,'06 but histologically the overlying activity in Crohn's disease.9' Inherited immune mucosa shows features which may suggest deficiency syndromes cause malabsorption, chronic inflammatory bowel disease if biopsies probably as a result ofchronic enteric infection, are superficial."0 These include chronic inflam- 732 Shepherd mation, crypt distortion as a result of the 17 Burman JH, Thompson H, Cooke W, Alexander-Williams J. The effects of diversion of intestinal contents on the underlying submucosal gas cysts, and intra- progress of Crohn's disease of the large bowel. Gut 1971;12:1 1-15. mucosal granulomas (fig 7). Only when biopsy J Clin Pathol: first published as 10.1136/jcp.44.9.726 on 1 September 1991. Downloaded from 18 Warren BF, Shepherd NA, Bartolo DCC, Bradfield JWB. specimens that include the submucosa are Histological changes of the defunctioned rectum in examined does the true nature of the disease ulcerative colitis. J Pathol 1991;63:69A. 19 Pemberton JH, Kelly KA, Beart RW, Dozois RR, Wolff become apparent.'07 BG, Ilstrup DM. Ileal pouch-anal anastamosis for chronic ulcerative colitis. Long-term results. Ann Surg 1987;206:504-13. Summary 20 Nicholls RJ, Pezim ME. Restorative proctocolectomy with When ileal reservoir for ulcerative colitis and familial aden- all of the macroscopic and microscopic omatous polyposis: a comparison of three reservoir features of Crohn's disease and ulcerative designs. Br J Surg 1985;72:470-4. colitis are 21 Hulten L, Svaninger G. Facts about the Kock continent present, the correct diagnosis is ileostomy. Dis Colon Rectum 1984;27:553-7. usually made without difficulty. When some of 22 Shepherd NA, Jass JR, Duval I, Moskowitz RL, Nicholls the are the of RJ, Morson BC. Restorative proctocolectomy with ileal changes absent, accuracy diag- reservoir-pathological and histochemical study of nosis is reduced. This review has outlined those mucosal biopsy specimens. J Clin Pathol 1987;40:601-7. diseases which feature some of 23 Tytgat GNJ, Deventer SJH. Pouchitis. Int J Colorectal Dis these patho- 1988;3:226-8. logical changes and may masquerade as 24 Shepherd NA. The pelvic ileal reservoir: apocalypse later? chronic bowel Br Med J 1990;301:886-7. idiopathic inflammatory disease. 25 Keighley MRB. Discussiorl in Pouchitis Workshop. Int J Some of the pathological mimics are iatrogenic Colorectal Dis 1989;4:213. while other common such as bacterial 26 Shepherd NA. The pelvic ileal reservoir: pathology and diseases, pouchitis. Neth J Med 1990;37:S57-S64. infection, ischaemia, and diverticulosis may 27 Davies DR, Brightmore T. Idiopathic and drug-induced ulceration ofthe small intestine. BrJSurg 1970;57:134-9. produce confusing histological appearances. 28 Leyonmarck CE, Raf L. Ulceration of the small intestine The picture is complicated by the fact that due to slow-release potassium tablets. Acta Chir Scand of these 1985;151:273-8. many pathological imitators may 29 Lang J, Price AB, Levi AJ, Burke M, Gumpel JM, themselves cause or predispose to chronic Bjarnason I. Diaphragm disease: pathology of the small bowel or intestine induced by non-steroidal anti-inflammatory inflammatory disease, may complicate drugs. J Clin Pathol 1988;41:516-26. chronic inflammatory bowel disease. For 30 Sheers R, Williams WR. NSAIDs and gut damage. Lancet and infectious are 1989;ii:1 154. example, drugs agents recog- 31 Hall RI, Pelty AH, Cobden I, Lendrum R. Enteritis and nisable causes of relapse in ulcerative colitis; colitis associated with mefanamic acid. Br Med J Crohn's disease cause diverticulitis in 1983;287:1 182. may 32 Anonymous. NSAIDs and gut damage. [Editorial]. Lancet patients with diverticulosis; and lymphoma 1989;ii:600. ulcerative colitis. It behoves all 33 Graham CF, Gallagher K, Jones JK. Acute colitis with may complicate methyldopa. N Engl JMed 1981;304:1044-5. practising histopathologists to recognise these 34 Martin DM, Goldman JA, Gilliam J, Nasrallah SM. Gold- mimics ofulcerative colitis and disease induced eosinophilic enterocolitis: response to oral Crohn's chromolyn sodium. Gastroenterology 1981;80:1567-70. to ensure appropriate management for patients 35 Floch MH, Hellman L. The effectof5-fluorouracil on rectal with of the mucosa. Gastroenterology 1965;48:430-7. inflammatory pathology intestines. 36 Saunders DR, Sillery J, Rachmilewitz D, Rubin CE, Tytgat GNJ. Effect of bisacodyl on the structure and I am most grateful to Ms Jill Maybee for photographic assistance function of rodent and human intestine. Gastroenterology and to Dr Warren for discussions. 1977;72:849-56. Bryan helpful 37 Leriche M, Devroede G, Sanchez G, Rossano J. Changes in the rectal mucosa induced by hypertonic enemas. Dis http://jcp.bmj.com/ Colon Rectum 1978;21:227-36. 1 Mortensen N. Progress with the pouch-restorative procto- 38 Levy N, Gaspar E. Rectal bleeding and indomethacin colectomy for ulcerative colitis. Gut 1988;29:561-5. suppositories. 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