J Clin Pathol 1985;38:271-276

The Cronkhite-Canada syndrome: an ultrastructuralstudy of pathogenesisD JENKINS, PM STEPHENSON, BB SCOTT

From the Departments ofPathology and Medicine, Lincoln County Hospital, Lincoln

SUMMARY Electron microscopical and cytochemical studies of intestinal biopsies from a patientwith typical features of the Cronkhite-Canada syndrome show that the primary process affectsthe crypts. This results in cystic dilatation associated with expansion and focal degeneration of thecrypt compartment of the intestinal epithelium. The villous epithelium compartment is reducedbut ultrastructurally normal. Inflammation and oedema of the lamina propria follows from leak-age of mucin through breaks in the abnormal crypts.

The syndrome of gastrointestinal polyposis,alopecia, and nail dystrophy now known as theCronkhite-Canada syndrome was first described in1955.' Although about 80 cases have now beenreported there is little information about the aetiol-ogy and pathogenesis. The main clinical effects ofthe gastrointestinal disease are protein losingenteropathy, hypoproteinaemia, and a range ofabnormalities in the absorption of carbohydrates,proteins, and fats.23 Radioisotope and scanning elec-tron microscopical studies have suggested that theprotein loss results from heavy secretion of mucoussubstances containing protein rather than exudationor rupture of vessels.3 Acquired disaccharidase defi-ciency and intestinal bacterial overgrowth have beenshown in a few cases. There is no familial pattern ofincidence. Remission may occur,' either spontane-ously or after partial surgical resection, cortico-steroid treatment, or nutritional support. Surpris-ingly, there are no detailed descriptions of thetransmission electron microscopical appearances ofthe gastrointestinal lesions. We describe the electronmicroscopy and cytochemistry of a typical case.

Case report

A 66 year old man presented with a four monthhistory of scalp hair loss; a three month history ofdiarrhoea, abdominal pain, and weight loss; andloose nails and ankle swelling for two weeks. Resultsof investigations were as follows. Haemoglobin con-centration 13*4 g/dl; blood film was normal; ery-

Accepted for publication 30 October 1984

throcyte sedimentation rate 55 mm in the first hour;serum B,2 and folate were normal; prothrombintime was normal; serum albumin 33 g/l; serumalkaline phosphatase 299 units (normal less than250); serum calcium 1-88 mmol/l; faecal fat 41mmol/24 h. A lactose tolerance test using breathhydrogen was normal; small bowel enema suggestedmalabsorption; sigmoidoscopy showed a normalmucosa; upper gastrointestinal endoscopy showed astrikingly polypoid antrum, pylorus, and duodenum.He was given only calciferol and folic acid and

spontaneously improved over the next six months.He regained his weight, his diarrhoea ceased, hisscalp hair regrew, but his nails remained dystrophic.

METHODS

Light microscopyEndoscopic biopsies were obtained from thestomach, duodenum, and rectum. Sections of forma-lin fixed, paraffin embedded tissue were stained withhaematoxylin and eosin, by the periodic acid Schiff(PAS) method with and without diastase digestion,by Hale's dialysed iron technique, with Alcian blueat pH 2-5 and 1-0 and after sialidase treatment bythe high iron diamine technique, and by the com-bined high temperature methylation saponificationtechnique.5 Sections were also stained for IgA, IgM,IgG, IgE, and muramidase by the peroxidase-antiperoxidase immunoperoxidase technique.6

Electron microscopySome endoscopic biopsies of polypoid mucosa fromthe duodenum were orientated, processed throughglutaraldehyde fixation and postfixation in osmium

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tetroxide, and stained with uranyl acetate beforeembedding in Araldite.7 Semithin sections werestained with haematoxylin and eosin8 for light mic-roscopy, and ultrathin sections from blocks showingno evidence of biopsy trauma were further stainedwith lead citrate and examined in a JEOL 100Stransmission electron microscope. Specimens forultrastructural cytochemistry were fixed in parafor-maldehyde and embedded in Araldite resin.Ultrathin sections were stained by the periodic acidthiocarbohydrazide silver proteinate (PATSP)method.9

Results

LIGHT MICROSCOPYStereomicroscopical examination of duodenalmucosa showed some normal villi but also flat areaswith prominent crypt openings. In sections (Fig. 1)there was patchy partial villous atrophy with elon-gated and irregular crypts and glandular cysts. Thedilated crypts and cysts were lined by columnarepithelium and contained mucin, granular debris,degenerate epithelial cells, and foamy histiocytes.Extensive areas of the epithelium were pale staining,attenuated, and flattened. In places the attenuatedepithelium was lost exposing the lamina propria,which showed oedema and was infiltrated by manyhistiocytes and some plasma cells and eosinophils.Biopsies from the gastric antrum showed that the

Fig. 1 Light micrograph ofduodenal mucosa inCronkhite-Canada syndrome. There is irregular partialvillous atrophy, with elongated, irregular, and cystic crypts.The cysts are lined by attenuated epithelium. There is amixed infiammatory cell infitrate in the lamina propria.Haematoxylin and eosin. Original magnification xl25.

Jenkins, Stephenson, Scottpits and mucous glands were irregular, branched,and often cystic. The rectal mucosa showed slightirregularity and dilatation of the crypts.Abundant PAS positive mucinous material was

found within intestinal goblet cells and gastric muc-ous cells and within the dilated crypts and cysts inintestinal and gastric mucosa. PAS positive materialextended across breaches in the epithelium into thelamina propria and was also present in the cyto-plasm of histiocytes surrounding such areas. Nosignificant qualitative histochemical abnormality ofmucin was detected compared with controls.Immunohistochemical staining for muramidaseshowed a few Paneth cells at the bases of small-intestinal crypts. The counts of IgA, IgM, IgG, andIgE plasma cells were within normal limits.

Electron microscopyThe villi and the polypoid areas in the duodenalmucosa were covered by columnar absorptive

Fig. 2 Electron micrograph ofapical part ofvillousabsorptive cell from the surface ofthe duodenum inCronkhite-Canada syndrome. Microvilli, lysosomes,endoplasmic reticulum, mitochondria, and intercellularjunctions show no pathological changes. Lead citrate anduranyl acetate. Original magnification x 12 500.

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The Cronkhite-Canada syndromeepithelium (Fig. 2). The cells appeared normal andshowed no abnormalities of microvilli or lysosomesor other degenerative changes. The predominantcell type lining both crypts and the cysts was theundifferentiated crypt cell (Figs. 3 and 4). In cryptsand most parts of the cyst walls these cells werecolumnar with basal nuclei. Round, membranebound granules up to 1 5 ,um across were identifiedin the apical regions of otherwise undifferentiatedcells. The PATSP method strongly stained glycopro-tein in the glycocalyx on the apical surface, as a rimin the granules, and in the Golgi cistemae. Gobletcells were widespread among the undifferentiatedcells as in the lateral walls of normal crypts. Panethcells were not seen in the walls of cysts, but theywere present in the bases of the less abnormal cryptsand showed the characteristic large, membranebound secretory granules in the cytoplasm towardsthe apex of the cell. Endocrine cells (Fig. 5) werepresent as in normal small intestinal mucosa.

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Throughout the lining of the cysts and crypts smallgroups of cells or single cells showed degenerativechanges with vacuolation and florid dilatation of theendoplasmic reticulum and mitochondria. In somecells the changes amounted to focal necrosis with, inaddition, loss of cytoplasmic ground substance andempty nuclei. In some areas dilatation of endo-plasmic reticulum and vacuolation were associatedwith separation of the cells from the basementmembrane and from each other, and luminal con-tents were seen beneath the epithelium (Fig. 5). Theunderlying basement membrane appeared attenu-ated. In the adjacent lamina propria there was pro-nounced oedema with collagen fibres separated byabundant pale staining amorphous material (Fig. 3).Numerous histiocytes, many with large cytoplasmicvacuoles containing amorphous light staining mater-ial, were present (Figs. 4 and 5). This materialstained black with PATSP, which confirms thatthese cells were muciphages. Lymphocytes,

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Fig. 3 Electron micrograph ofcells lining a cyst and the underlying lamina propriafrom the duodenum in Cronkhite-Canada syndrome. Most ofthe cells areundifferentiated crypt cells (c). An oligomucous cell is also present (o). A cell showsvacuolar degeneration (v). The lamina propria shows abundant lightly stainingintercellular material (ic). Lead citrate and uranyl acetate. Original magnificationx2400.

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Jenkins, Stephenson, Scott

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Fig. 4 Electron micrograph ofcrypt epithelium and lamina propria. Three necroticcrypt cells (n) show pale cytoplasm and empty nuclei. The lamina propria containsinflammatory cells including several vacuolated muciphages (m). Lead citrate anduranyl acetate. Original magnification x2400.

eosinophils, and polymorphonuclear leucocytesshowing no appreciable abnormalities were alsoseen.

Discussion

In the initial description the gastrointestinal lesionswere said to be adenomatous polyps, but in mostrecent reports they are described as inflammatorypseudopolyps4 resembling juvenile polyps of the

colon.'" Ultrastructural study shows no epithelialchanges resembling those seen in large boweladenomas or metaplastic polyps." Unlike juvenilepolyps the lesions of the Cronkhite-Canada syn-drome are small and diffuse. They do not usuallyshow surface ulceration, blockage of the necks ofcrypts by inflammation, or qualitative histochemicalabnormalities of mucin pattern which are typical ofjuvenile polyps,'2 although an occasional case mayshow extensive ulceration of numerous polyps (H

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Fig. 5 Electron micrograph ofcyst wall. Undifferentiated crypt cells (c) and anenterochromaffin cell (ec) show vacuolation and dilatation ofendoplasmic reticulum.Part ofthe epithelium is separated from the basement membrane by amorphousmaterial (a). Vacuolated muciphages (m) are present in the underlying laminapropria. Lead citrate and uranyl acetate. Original magnification X2 500.

Thompson, personal communication). It has beensuggested that juvenile polyps result from epithelialregeneration in granulation tissue following localinflammation and ulceration.12-' This explanationappears inappropriate for the Cronkhite-Canadasyndrome, however, because of the structural andhistochemical differences from juvenile polyps listedabove.The distinctive structural features of the polypoid

lesions of the Cronkhite-Canada syndrome as

studied here in the small intestine have to be inter-preted in relation to the functional anatomy of themucosa. The small-intestinal epithelium can bedivided into two functionally and structurally dis-tinct compartments: the crypt and the villus. In theCronkhite-Canada mucosa the villous compartmentis reduced, which results in patchy villous atrophy,but the cells appear structurally normal. This isunlike coeliac disease and many diseases associatedwith malabsorption, in which the villous absorptivecells show striking ultrastructural abnormalities.'5The crypt compartment is considerably expandedwith elongated, irregular, and cystic crypts linedmostly by undifferentiated crypt cells which are

ultrastructurally normal.'6 These and the goblet cellswhich they produce'" have a physiological functionof secreting mucin,'8 ions, and water. Ultra-

cytochemical study shows that mucin produc-tion is preserved in the Cronkhite-Canada mucosa.The cystic change is unlikely to result solely fromexcess mucin production; even massive stimulationof mucin release such as accompanies acetylcholinestimulation does not result in cystic alteration to thecrypts of normal small-intestinal mucosa.'9 A previ-ous scanning electron microscopical study reportedhorn like plugs of highly viscous mucus protrudingfrom crypts. Our studies do not support the sugges-tion that an abnormally viscous mucus is involved.The mucin is histochemically normal and the lesionsdo not show the wide necked open crypts plugged bymucus and the distortion of villi which are known toresult from production of viscous mucin in cysticfibrosis.20The reduced but ultrastructurally normal villous

compartment and expanded crypt compartmentsuggest a block in the normal maturation of undif-ferentiated crypt cells to villous epithelial cells. Thedegeneration and detachment of lining cells in theabnormal crypts and cysts may indicate selectivedamage to crypt epithelium by an exogenous agent,as has been shown in vitro to result from bathing theserosal surface of ileal mucosal sheets with solutionsdepleted of calcium.2' Alternatively, the epithelialdegeneration may result simply from pressure on the

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wall of distended and cystic crypts. The oedema andinflammation in the lamina propria appear to besecondary to leakage of mucin and possibly othersecretions through the damaged wall, as reflected bythe muciphages shown in this study.The remission of some cases4 supports the possi-

bility that an exogenous agent or nutritional defi-ciency might be responsible. No infectious agent wasfound in this or any other case.22 The lesions havebeen compared to the cystic lesions described in thecolons of patients with pellagra,23 but cystic changeshave not been described elsewhere in the gut in pel-lagra. The relation of those lesions to Cronkhite-Canada syndrome is doubtful.

Ultrastructural study provides further evidencethat the characteristic protein loss is due to excess

mucus secretion by crypt cells and that the minorand variable degree of malabsorption results from a

reduction in absorptive surface area and not fromdamage to the absorptive epithelium. Reduction inPaneth cells, for which a role in controlling bacterialgrowth has been suggested,'0 may be connected withthe bacterial overgrowth which has been described.

We thank Dr E Jackson for permission to study thiscase and the staff of the histopathology and photo-graphic departments of the Lincoln Hospitals. Wealso thank Mrs A Goodall for her assistance in pre-

paring the paper.

References

'Cronkhite LW, Canada WJ. Generalised gastrointestinal poly-posis. An unusual syndrome of polyposis, pigmentation,alopecia and onychotrophia. N Engl J Med 1955;252: 1011-5.

2 Johnston GK, Soergel KH, Hensley GT, Dodds WJ.Cronkhite-Canada syndrome; gastrointestinal pathophysiol-ogy and morphology. Gastroenterology 1972;63:140-52.

3Suzuki K, Uracka M, Funatsu T, et al. Cronkhite-Canada syn-

drome. A case report and analytical review of 23 other cases

reported in Japan. Gastroenterol J 1979; 14:441-9.4Russell DMcR, Bhathall PS, St John DJB. Complete remission in

Cronkhite-Canada syndrome. Gastroenterology 1983;85:180-5.

Cook HC. Carbohydrates. In: Bancroft JD, Stevens A, eds.Theory and practice of histological technique. London:Churchill-Livingstone, 1977:141-67.

Jenkins, Stephenson, Scott

6Scott BB, Goodall A, Stephenson PM, Jenkins D. Smal intesti-nal plasma cells in coeliac disease. Gut 1984;25:41-6.

7Stephenson PM, Jenkins D, Scott BB. Collection and orientationof gastric and intestinal biopsies for combined light and elec-tron microscropy. Med Lab Sci 1983;40:395-6.

8 Johnson CI, Martinello P, Collier F. Haematoxylin and eosinstaining of osmium-fixed tissue in epoxy sections. Med Lab Sci1982;39:371-5.

9 Thiery JP. Mise en evidence des polysaccharides sur coupes finesen microscopie electronique.J Microscopie 1967;6:987-1018.

'° Ruymann FB. Juvenile polyps with cachexia. Gastroenterology1969;57:431-8.

"Kaye GI, Fenoglio CM, Pascal RR, Lane N. Comparative elec-tron microscopic features of normal, hyperplastic, andadenomatous human colonic epithelium. Gastroenterology1973;64:926-45.

12 Franzin G, Zamboni G, Dina R, Scarpa A, Fratton A. Juvenileand inflammatory polyps of the colon-a histological and his-tochemical study. Histopathology 1983;7:719-28.

'3 Roth SI, Helwig EB. Juvenile polyps of the colon and rectum.Cancer 1963;16:468-79.

'4 Horrileno EG, Eckert C, Ackermann LV. Polyps of the rectumand colon in children. Cancer 1957; 10:1210-20.

,5 Henry K. Ultrastructure of the small intestine. In: Chadwick VS,Philips SF, eds. Gastroenterology 2. Small intestine. London:Butterworth Scientific, 1982:19-39.

16 Trier JS. Studies on small intestinal crypt epithelium. I. The finestructure of the crypt epithelium of the proximal small intes-tine of fasting humans. J Cell Biol 1963; 18:599-620.

71 Merzel J, Leblond IP. Origin and renewal of goblet cells in theepithelium of mouse small intestine. Am J Anat 1969;124:281-306.

"Trier JS. Studies on small intestinal crypt epithelium II. Evidencefor and mechanisms of secretory activity by undifferentiatedcrypt cells of the human small intestine. Gastroenterology1964;47:480-95.

'Y Specian RD. Neutra MR. Mechanism of rapid mucus secretion ingoblet cells stimulated by acetylcholine. J Cell Biol1980;85:626-40.

20 Jeffrey I, Durrans D, Wells M, Fox H. The pathology ofmeconium ileus equivalent. J Clin Pathol 1983;36: 1292-7.

21 Danowitz M, Madara JL. Effect of extracellular calcium deple-tion on epithelial structure and function in rabbit ileum; amodel for selective crypt of villus epithelial cell damage andsuggestion of secretion by villus epithelial cells. Gastroenterol-ogy 1982;83:1231-43.

22 Ali M, Weinstein J, Biempica A, et al. Cronkhite-Canada syn-drome; report of a case with bacteriologic, immunologic, andelectron microscopic studies. Gastroenterology 1980;79: 731-6.

23 Denton J. The pathology of pellagra. Am J Trop Med1925;5: 173-210.

Requests for reprints to: Dr David Jenkins, Department ofHistopathology, Lincoln County Hospital, Lincoln,England.

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pathogenesis.an ultrastructural study of The Cronkhite-Canada syndrome:

D Jenkins, P M Stephenson and B B Scott

doi: 10.1136/jcp.38.3.2711985 38: 271-276 J Clin Pathol

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