a radiographic and pathological - bmj

Gut, 1970,11, 928-940

A comparative radiographic and pathological studyof intestinal vaso-architecture in Crohn's diseaseand in ulcerative colitis

F. BRAHME AND C. LINDSTROMFrom the Departments of Radiology and Pathology, Malmd General Hospital, Malmo, Sweden

SUMMARY Vascular changes were seen in specimens with lesions of Crohn's disease as wellas in ulcerative colitis.

In Crohn's disease, the vasculature in the bowel wall was rearranged secondary to thickeningof the intestinal coats. An anatomiical relationship was often found between the ulcers and thepoint where arteries break through the muscularis propria. The vasculature was markedlyincreased in areas with deep ulcers and transmural inflammation, but in areas with only smallulcers and mild inflammatory reaction vascular changes were barely discernible or absent.Occlusive vascular changes were uncommon and not visible in the radiographs.

In active ulcerative colitis hypervascularity was more marked than in Crohn's disease, butwas confined to the mucosa and adjacent parts of the submucosa. In 'burnt-out' atrophyvascularity was not increased and only minor changes in the submucosal arteries were observed.The observations did not suggest that the vascular alterations are of primary importance for

the formation of lesions in either disease.

Vascular changes in Crohn's disease, as comparedwith those in ulcerative colitis, have long been thesubject of varying descriptions and conflictinginterpretations (Warren and Sommers, 1954;van Patter, Bargen, Dockerty, Feldman, Mayo,and Waugh, 1954; Reifferscheid and Wolfram,1962; Meadows and Batsakis, 1963; Bacaner,1966; Knutson, Lunderquist, and Lunderquist,1968; and others).Vascularity in nonspecific chronic inflammatory

disorders of the intestine may be discussed interms of abdominal angiography in vivo. Thismethod allows only macroscopic evaluation ofvascular anatomy but no direct correlation withhistopathological changes. On the other hand,studies of histological sections do not allow thetracing of vessels or an evaluation of the overallvascularity.

In order to bridge this gap a technique wassought which would allow assessment of generalvascular patterns, tracing of individual or groupsof vessels, and direct correlation of vascular andReceived for publication 17 July 1970.

histological changes. This could be achieved bycombining a modification of an infrequently usedradiographic technique (MacAlister, Margulis,Heinbecker, and Spjut, 1962) and speciallyprepared large histological sections. Our interestwas primarily focused on changes in Crohn'sdisease, but for comparative purposes the studywas extended to include normal specimens andspecimens from patients with ulcerative colitis.

Technique

RADIOGRAPHYWithin one hour of removal, 10 ml of 10%solution of procaine sulphate was injected intothe operative specimen of the bowel through anarterial catheter to counteract possible vasospasm.Immediately thereafter a solidifying bariumsulphate suspension (Schlesinger, 1957) was in-jected manually. The injection was stopped assoon as firm resistance was met. After 20 minutes,

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929 A comparative radiographic and pathological study of intestinal vaso-architecture in Crohn's disease

by which time the contrast suspension began tocoagulate, the intact specimen was radiographed.The gut was then slit up along the mesentericattachment, spread out flat, and re-radiographed.

A peak voltage of 50 kV, and fine grain industrialx-ray film (Gevaert Structurix D4) were used(Fig. la).

After fixation of the specimen in 10% formalin

Fig. la

Fig. 1 Normal small bowel. a Slit-up specimen ofterminal ileum showing winding mural arteries inmost aboral segment. b Radiograph oftransversesection, 8 mm thick. c Large histological section,S 1 thick. Haematoxylin and eosin, x 2.


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for about five days, eight to 12 transverse sectionsof the entire specimen were cut. The sections wereplaced on a non-radiographic single emulsionfilm (Gevapan 100) and radiographed in theaxial (Figs. lb and 2b) and frontal projections.Their exact location in the specimen could bedetermined with the aid of the previous surveyradiographs. For radiography of transversesections, a low-voltage x-ray source (8-15 kV)with a beryllium window was used.

HISTOLOGYAfter radiography, the transverse sections, whichwere 0-7-0.8 cm thick and up to 10 cm long, wereprepared and embedded in large blocks of para-plast or paraffin using the method described byEnt and Roberts (1968). Large histologicalsections, 5 Fg in thickness, were then cut, andstained with haematoxylin-eosin. In addition,smaller sections were stained with elastic tissuestain.

CommentsThe combined radiographic and histologicaltechnique using large sections, which has notbeen previously used for the study of intestinalvasculature, enabled us to locate the intramuralvasculature in relation to other structures of the

Fig. 2a

Fig. 2b

Fig. 2cFig. 2 Normal colon. a Slit-up specimen: irregularlyspaced wide and narrow arteriae rectae. b Radiographof transverse section. c Large histological section.Haematoxylin and eosin, x 2.


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A comparative radiographic andpathological study of intestinal vaso-architecture in Crohn's disease

bowel wall by comparative studies of the radio-graphs and the corresponding histological sec-tions, even when only short arterial segmentswere visible in the sections.

Material

The above technique was consistently carried outon 13 operative specimens of which nine showedlesions of Crohn's disease and four of ulcerativecolitis. All except one of the patients, from whomthe specimens had been taken, had undergoneboth multiple small- and large-bowel radiologicalexaminations and mesenteric angiography beforeoperation. The histological diagnosis, employingconventional criteria (Crohn and Yarnis, 1958;Lockhart-Mummery and Morson, 1964; Morson,1968), was not in doubt in any of these cases.Epitheloid cell granulomas were present in allspecimens with Crohn's disease, and all those

with ulcerative colitis had both rectal and colonicchanges characteristic of ulcerative colitis.The control material consisted of nine necropsy

specimens from young subjects with no evidenceof gastrointestinal disease. The barium sulphatewas injected and the specimens were fixed withinfive to six hours after death to minimize the effectof autolysis.

Results

NORMAL SPECIMENSThe vascular pattern of the intestine was wellvisualized and conformed with previously pub-lished anatomical descriptions of the intestinalvessels (for review, see Michels, 1955).The arteriae rectae of the ileum, originating

from the third to fifth generation of arcades, wereevenly spaced, smooth, and of fairly uniformcalibre (0-4-0-8 mm). Along the terminal 5 to 10

Fig. 3a

Fig. 3 Crohn's disease of the terminal ileum.a Radiograph of inflated specimen: increasingvascularity (arrow) towards the ileocaecal valve.

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centimetres of the ileum they were often replacedby an irregular network of fine arteries, anasto-mosing with the colonic arteries (Fig. la).The colonic arteriae rectae differed consider-

ably in calibre from each other (0-2-12 mm) andoriginated from the marginal artery at irregularintervals (Fig. 2a).The mural branches of the arteriae rectae were

best traced in the radiographs of the transversesections (Figs. lb and c, and 2b and c). In thecolon they usually penetrated the muscularis atthe margins of the taeniae musculares. The sub-mucosal branches of the arteriae rectae followedan undulating course in the plane of the bowelwall, parallel to and approximately 2 to 3 mmbeneath the mucosal surface. They finallybranched into fine arteries, supplying the mucosa,the submucosa, the muscularis, and the subserosa.The contrast medium could usually be seen in

the villous arteries of the small bowel and in otherminute branches down to a size of 20 IL.

CROHN 'S DISEASEVascular changes were present in most, but notin all, transverse sections with histologically

Fig. 3b Tortuous mural vessels in area at arr ow in ac and d show the site of increased vascularity to thethickened submucosa.

Fig. 3c

Fig. 3d


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demonstrable lesions of Crohn's disease. Thechanges seemed to conform to a pattern thatcould be recognized in most of the approximately100 sections studied, and varied with the severityof the inflammatory reaction.

Severe Crohn's diseaseIncreased vascularity was the rule in areas withdeep ulcers and fissures, inflammatory cellinfiltration, and extensive oedema. The mesen-teric arteries were not noticeably widened, butthe number of arteriae rectae supplying theinvolved area appeared increased which at leastin part was due to shortening of the bowel. Insmall-bowel lesions about 1.2-2.0 such arteriesoriginated per centimetre which was more thantwice the frequency found in normal specimens(Figs. 3a and b). The arteriae rectae were moder-ately widened and in the transverse section radio-graphs numerous mural arteries were seen tofollow a tortuous course (Fig. 4).

In addition, both extra- and intramuralarteries were displaced, secondary to the fibrosisand oedema. The arterial arcades were oftendistorted and stretched along the margin of thebowel due to shrinkage of the mesentery. Thedistance between the mucosal surface and thesubmucosal arteries was increased to 4-10 mm,owing to the submucosal oedema (Figs. 3 and 4).

In colonic segments with clearly 'transmural'inflammation some transverse sections showed anincrease of vasculature in all layers of the gut(Fig. 5), but more frequently the thickenedcolonic wall showed two layers of arteries, onedense and irregular in the submucosa and another,

less dense, in the inflamed subserosa (Fig. 6).The two layers were separated by the thickenedmuscularis propria.

In the ileum as well as in the colon an anato-mical relationship was frequently observedbetween ulcers and vascularity. From their pointof entrance through the muscularis, the arteriaerectae sent multiple branches through the sub-mucosa towards the mucosa. These piercingarteries branched into numerous small arteriesaround the floor, or in close vicinity, of the ulcersand also in the structures known as 'cobblestones' (Figs. 6 and 7). The connexion betweenulcers and vascular anatomy could not alwaysbe demonstrated, but the relationship was oftenstriking. In the colon, most deep ulcers andfissures were found adjacent to the margins of thetaeniae, where the arteries entered through themuscularis propria.

Except for these conspicuous alterations(hypervascularity, double layers of arteries, and afairly close relationship between ulcers andvessels) noted in advanced disease, few vascularchanges were visible. Inflammation was oftegq seento follow vascular, and lymphatic, pathways andmany granulomas were located in the vascularsheaths.

Sections stained with both haematoxylin andeosin and elastic tissue were used for the study ofvascular changes. Thickening of arterial walls,caused by intimal and medial hyperplasia, andnarrowing of the lumina were only observed in afew specimens. These changes occurred in areas ofmarked inflammation and fibrosis, and did notinvolve major mural arteries. The obliterative

-~~~~~~~~~~~~~~~~~~~~~~. .. ..... --; :.ax. :-_.:.;.....;.

Fig. 4 Crohn's disease of the small bowel. Abundanttransmural vascularization of thick-walled specimen.



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Fig. 5 Crohn's disease of the colon. a Slit-upspecimen: wide arteriae rectae with spiralling endbranches. b Radiograph of transverse section showingincreased vascularity in all coats. c Histology:fibrosis, oedema, andfissutre.Haematoxylin and eosin, x 2.

Fig. 5a

.. .......... ....

F;ig. Sb

Fig. Sc


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changes were similar to those seen in otherchronic inflammatory lesions, eg, in areas adjacentto peptic ulcers of the stomach.No histological changes compatible with

thrombosis or infarction were observed.

Moderate or mild Crohn's diseaseIn areas with only few ulcers and moderateoedema, vascular changes were less marked and

occurred then in the form of moderate displace-ment of the mural vessels in relation to the mucosalsurface, secondary to the oedema of the bowelwall. The degree of vascularity was closelyrelated to the intensity of the inflammatoryreaction. In some areas with only mild inflam-mation the survey angiograms appeared normal,although slightly tortuous mural arteries couldbe recognized in the radiographs of the transverse

Fig. 6a

t-' 7 .

Fig. 7

Fig. 6 Crohn's disease of the colon. a Radiographshowing marked hypervascularity in submucosa in areasofulcers andfissures. Outer vascular layer in subserosa.b Large histological section: ulcers in lower and leftwall of colon, fissure in right wall. Haematoxylin andeosin, x 2.

Fig. 7 Mural artery (arrow) running throughmuscularis towards hypervascularized area beneathtbranching fissure. Weigert's elastin stain, x 14.

Fig. 6b



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Fig. 8a

Fig. 8b

Fig. 8 Mild Crohn's disease, small bowel. a Normalvascularity in thin-walled specimen. b Large histo-logical section. Minute lesions at arrow (x2). c Areaat arrow, magnified x 20: small ulcers surrounded bylocal inflammation. Haemotoxylin and eosin.

Fig. 8c


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937 A comparative radiographic and pathological study of intestinal vaso-architecture in Crohn's disease

sections. In small or large bowel segments withonly superficial ulcers, and slight cellular infil-tration in their immediate vicinity, the vascularpattern in the survey radiographs as well as inthe radiographs ofthe transversesectionsappearednormal (Fig. 8).

CommentsOpinions differ regarding the appearance and thesignificance of vascular changes in Crohn'sdisease. Several authors contend that ischaemiaplays a role in the formation of lesions in thisdisorder. Warren and Sommers (1954) stated thtoedema of the submucosa causes narrowing andocclusion of the arterial lumina, and that suchinterference with the blood supply is one of thecauses of ulcer formation, and Reifferscheid andWolfram (1962) claimed that not only the ulcers,but also the lymphangitis and lymphoedema weresecondary to vascular impairment. Meadows andBatsakis (1963), in a histological study, con-sidered that hyperaemia occurred in early stages

Fig. 9 Ulcerative colitis. a Slit-up specimen withnumerous tortuous arteries. b Transverse section:radiograph: hypervascularity ofmucosa and sub-mucosa. c Histological section: main bulk of widevessels in moderately thickened submucosa.Haematoxylin and eosin, x 2.

Fig. 9b

Fig. 9c

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Fig. 9a


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of the lesions, but that the appearance of severeand expansive ulcers coincided with angiofibro-blastic proliferation. Radioisotope studies ofmesenteric blood flow (Bacaner, 1966) indicatedthat mesenteric circulation in Crohn's disease wasdecreased compared with that in controls and inulcerative colitis. The concept of ischaemicchanges in Crohn's disease was also supportedby one of us in an earlier publication, based onabdominal angiography (Brahme, 1966).

Opinions differ also regarding obstructingchanges of the arterial walls. Williams (1964)as well as McGovern and Goulston (1968)observed obstructive vasculitis only occasionally.According to Knutson et al (1968), intimal andmedial hyperplastic with narrowing of arteriallumina is a common and significant finding inCrohn's disease.

Several of the above observations are not

compatible with the common notion of hyper-aemia of the serosa seen at operation, and thefrequent finding of intense reddening of themucosa in the slit-up specimens, although,admittedly, a similar appearance may also benoted in cases of haemorrhagic intestinal in-farction after occlusion of major mesentericarteries.The findings in the present series, in which the

specimens were prepared specially for examina-tion of arterial vasculature, did not support theconcept that ischaemia is the cause of ulcerformation in Crohn's disease. Instead, moderateor marked hyperaemia was common in affectedareas and was then associated with signs of activeinflammation.

In addition to an increased number of visiblemural arteries, tortuosity of these arteries wascommon. The appearance of the intestinal mural

Fig. 1Oa

Fig. 10 Old ulcerative colitis. a Moderate hyper-vascularity, branch of wide submucosal arterysupplying pseudopolyp. b Histology: atrophic, partlysloughed-offmucosa, andpseudopolyp.Haematoxylin and eosin, x 2.

Fig. lOb


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A comparative radiographic and pathological study of intestinal vaso-architecture in Crohn's disease

arteries in Crohn's disease was similar to thatseen in, eg, arteriovenous fistulae or in collateralarteries bridging an occlusion, which suggests anincreased haemodynamic load on previouslynarrow vessels. No occlusions of major muralarteries were observed in the radiographs or inthe histology in the present series.The study also showed that in areas with small

lesions, associated with minor inflammatoryreactions, few or no vascular changes could beseen. That such areas with only minute changesof Crohn's disease may appear normal topalpation and at gross inspection has been notedalready by Rappaport, Burgoyne, and Smetana(1951). To the experienced surgeon it is a wellknown fact.Abdominal angiography for the preoperative

diagnosis of Crohn's disease has not gaineduniversal acceptance, partly due to the difficultyin visualizing vascular changes in areas withmoderate or small lesions. Although the present

. ..... ......... .... ...........

Fig. lla

Fig. llbFig. 11 Atrophic ulcerative colitis. (Above) Radiograph:a few tortuous submucosal arteries. (Below) Histology:signs ofearly malignancy in mucosa. Haematoxylinand eosin, x 18.

study was not concerned with blood flow but withanatomy, such diagnostic difficulties may beexplained by the finding of only minor vascularchanges in areas with only mild inflammatorychanges.That ileal ulcers in Crohn's disease are related

mainly to the mesenteric attachment, and therebyto the point of entrance of vessels, has beenshown previously (Crohn, Ginzburg, and Oppen-heimer, 1932; van Patter et al, 1954). That theulcers in the colon are similarly related to thepoint of entrance of arteries through the muscul-aris was repeatedly seen in the present study. Ourstudy offers no certain explanation for this re-lationship but it may suggest that the inflammatoryprocess in Crohn's disease progresses along thelymphatics in the perivascular sheaths.

ULCERATIVE COLITISAll specimens with ulcerative colitis had long-standing changes. Three showed evidence ofactive inflammation, and one of old, atrophiclesions. None of the specimens showed evidenceof 'toxic dilatation' or gross carcinoma.

Hypervascularity was marked in the surveyangiograms ofspecimens with active inflammation(Fig. 9a). The width of the colonic marginalartery was increased and the colonic arteriaerectae were up to 2 mm wide, as compared withabout 1.2 mm or less in most normals. Thenumber of large arteriae rectae counted along themesocolic attachment was increased two to four-fold, probably because of widening of previouslynarrow vessels.

In the angiograms of the transverse sectionsthe hypervascularity was seen to be confined tothe mucosa and submucosa. The normally fewand slender submucosal arteries were markedlywidened, assuming almost the appearance ofveins, and were numerous and tortuous (Fig. 9band c). Histologically, the inflammatory lesionswere confined to the mucosa, the muscularismucosae, and to the uppermost layer of the sub-mucosa. No endarteritic changes were observedin the specimens of the series. The ulcers, most ofwhich were shallow, were not anatomicallyrelated to specific vascular features, but wereirregularly scattered in the mucosa.

In one specimen large pseudopolyps protrudedfrom the surface as irregular tags. These wereseen to be supplied by large branches of sub-mucosal arteries (Fig. 10).

In one case with chronic atrophic andlittle activeinflammation, vascularity as seen in surveyangiograms could not be differentiated from thatof normal specimens, but in the radiographs oftransverse sections tortuosity of the intramuralarteries was occasionally observed. Areas ofpatchy, superficial premalignant changes of themucosa, not penetrating the muscularis mucosae,were also encountered in this specimen. Thearteries in these areas did not differ in appearance



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940 F. Brahme and C. Lindstrom

from those in areas without incipient malignancy(Fig. 11).

CommentsThe vascular pattern observed in ulcerativecolitis was in agreement with the previously wellknown fact that the inflammatory changes areconfined predominantly to the mucosa and to theadjacent layers of submucosa and that vascularityis increased. The submucosal arteries were muchwider in active ulcerative colitis than in thespecimens with Crohn's disease.

To facilitate the preparation of the specimensbefore the onset of autolysis, multiple arterialcatheters were inserted at operation before theremoval of the specimens. For this assistancewe thank Dr A. Wenckert, of the Departmentof Surgery.

References

Bacaner, M. B. (1966). Quantitative measurement of regionalcolon blood flow in the normal and pathological humanbowel. Gastroenterology, 51, 764-777.

Brahme, F. B. (1966) Mesenteric angiography in regional entero-colitis. Radiology, 87, 1037-1042.

Crohn, B. B., Ginzburg, L., and Oppenheimer, G. (1932).Regional ileitis. A pathological and clinical entity. J. Anmer.med. Ass., 99,1323-1329.

Crohn, B. B., and Yarnis, H. (1958). Regional Ileitis, 2nd ed.Grune and Stratton, New York.

Ent, L. D., and Roberts, W. C. (1968). The processing of largeblocks of tissue. Amer. J. clin. Path., 50, 726-728.

Knutson, H., Lunderquist, A., and Lunderquist, A. (1968).Vascular changes in Crohn's disease. Amer. J. Roentgenol.,103,380-385.

Lockhart-Mummery, A. E., and Morson, B. C. (1964). Crohn'sdisease of the large intestine. Gut, 5, 493-509.

MacAlister, W. H., Margulis, A. R., Heinbecker, P., and Spjut, H.(1962). Arteriography and microangiography of gastricand colonic lesions. Radiology, 79,769-782.

McGovern, V. J., and Goulston, S. J. M. (1968). Crohn's diseaseof the colon. Gut, 9, 164-176.

Meadows, T. R., and Batsakis, J. G. (1963). Histopathologicalspectrum of regional enteritis. Arch. Surg., 87, 976-981.

Michels, N. A. (1955). Blood Supply and Anatomy of the UpperAbdominal Organs, pp. 280-293. Lippincott, Philadelphia.

Morson, B. C. (1968). In Ulcerative Colitis, edited by J. C.Goligher, F. T. de Dombal, J. McK. Watts, and G.Watkinson. Balliere, Tindall, and Cassel, London.

Rappaport, H., Burgoyne, F. H., and Smetana, H. F. (1951). Thepathology of regional enteritis. Milit. Surg., 109, 463-502.

Reifferscheid, M., and Wclfram, E. (1962). Resektion oderUmgehungsanastomose bei der Enteritis regionalis?Chirurg., 33, 164-172.

Patter, W. N. van, Bargen, J. A., Dockerty, M. B., Feldman,W. H., Mayo, C. W., and Waugh, J. M. (1954). Regionalenteritis. Gastroenterology, 26, 348-450.

Schlesinger, M. J. (1957). New radiopaque mass for vascularinjection. Lab. Invest., 6, 1-11.

Warren, S., and Sommers, S. C. (1954). Pathology of regional ileitisand ulcerative colitis. J. Amer. med. Ass., 154,189-193.

Williams, W. J. (1964). Histology of Crohn's syndrome. Gut,5,510-516.


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