intestinal polyps in the nigerian african · patients with colonic polyps, of which 16 (60%) were...

J. clin. Path., 1975, 28, 367-371

Intestinal polyps in the Nigerian AfricanA. OLUFEMI WILLIAMS AND D. L. PRINCE'

From the Department ofPathology, University ofIbadan and University College Hospital, Ibadan, Nigeria

SYNOPSIS Intestinal polyps appear to be relatively rare in the African including Nigerians, SouthAfrican Bantus, and Ugandans. Only 40 histologically confirmed cases were encountered over aperiod of ten years. Analysis of these cases reveals a preponderance (60%) of the non-neoplasticjuvenile type of polyp. Neoplastic polyps were not encountered in any female patient.

The mean ages of the patients are much lower than what has been observed in Caucasians inhabit-ing developed and industrialized countries. It is felt that there is probably a common or relatedaetiological agent for neoplastic intestinal polyps and carcinoma because the frequency of intestinalcarcinoma appears to be relatively low in areas with a low frequency of neoplastic polyps.

There is very little information on the epidemiologyand natural history of intestinal polyps in the African(Bremner and Ackerman, 1970; McQuaide andStewart, 1972) including the Nigerian (Williamsand Edington, 1967). This group of potentiallyprecancerous lesions has been the subject of numer-ous reports in other population groups inhabitingdifferent parts of the world (Hutt and Templeton,1971; Morson, 1971). The relatively low incidenceof intestinal lesions in the African has been observedby several workers, and this has been implicated inthe relatively low incidence of intestinal malignan-cies, particularly carcinoma of the colon (Hutt andTempleton, 1971; Billinghurst and Welchman,1966; Templeton, 1973). Geographical variationsin the incidence of intestinal polyps and otherprecancerous lesions of the bowel, including ulcera-tive colitis, may therefore influence the incidence ofintestinal malignancies (Burkitt, 1971). In thispaper an analysis is provided of 40 histologicallyconfirmed polyps of the intestine and rectum referredto the Department of Pathology, University CollegeHospital, Ibadan over a period of 10 years (1960-69).This study will not deal with the clinical aspects ofpolyps since their clinical manifestations areessentially similar to what has been reported fromelsewhere.

Materials and Methods

Materials studied were obtained from 40 surgical

'Present address: Royal South Hants Hospital, Southampton, Hants.Received for publication on 5 November 1974.

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biopsies. All the patients were Nigerians, whoresided in the Southern States of Nigeria. Allspecimens were examined grossly, fixed in 10%formol saline, embedded in paraffin, and stainedroutinely with haematoxylin and eosin. Whenindicated, periodic-acid Schiff with diastase digestionand mucicarmine stains were utilized. The criteriaused for the histological typing of thepolyps are thoseused by the WHO group on Histological Classifica-tion of Tumours of the Intestine (to be published).

Results

SEXThere are 24 males and 15 females, and the sex ofone patient is not known.

AGEThe age distribution of the patients is presented intable I according to sex. When analysed accordingto histological types, the average ages of the patientsare summarized in table JI. The average age of thetwo adult patients with villous papilloma is 47years and the age of the only patient with adeno-matous polyp is 7 years.

SITESThere are 31 (77%) polyps in the rectum, three(7-5 %) in the colon, and one in the anorectalregion, and the sites of five are not known. Withthe exception of one case, all the polyps werereported as solitary on clinical and radiologicalexamination.

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A. Olufemi Williams and D. L. Prince

Age (yr) Males Females Unknown Total

0-10 10 (7) 4 (6) 1411-20 5 (16) 5 (17) 1021-30 2 (23) - 231-40 1 (34) 2 (33) 341-50 2 (42) - 251-60 3 (58) 361-70 1 (70) - IUnknown 1 3 1 5

Total 25 14 1 40

Table f Age and sex distribution of Nigerian patientswith polypsAverage age of patients in each age group is given in parentheses

TYPESThe frequencies of the various histological typesare presented in table II. The commonest type ofpolyp was the non-neoplastic juvenile polyp whichaccounted for about 60% of all the polyps (fig 1).Neoplastic polyps appear to be relatively rare,accounting for less than 10% of all the polypsencountered. There is a group of non-neoplasticpolyps which account for about 25% of all thecases. The exact aetiology of this group remainsunknown but there is a possibility that they maybe post-inflammatory in nature, particularly asproctocolitis due to bacterial disease is relativelycommon in Nigerians.

Discuission

The relatively low incidence of malignant neoplasmsof the colon and rectum in the African has beenpartly attributed to the type of diet, volume ofintestinal contents, stool weight, bacterial flora,faecal transit time (Aries, Crowther, Drasar, Hill,and Williams, 1969; Burkitt, 1971) and infrequentoccurrence of premalignant intestinal lesions inclu-ding neoplastic polyps and ulcerative colitis(Billinghurst and Welchman, 1966; Williams andEdington, 1967; Bremner and Ackerman, 1970;Hutt and Templeton, 1971). It is also noteworthy

Fig 1 Microscopic appearance of a juvenilehamartomatous polyp in a 41-year-old Nigerian male.

that familial or multiple polyposis of the colon isdistinctly rare in the African (Williams and Edington,1967; Templeton, 1973), and very few proven cases

of familial polyposis (McQuaide and Stewart,1972) or ulcerative colitis have been reported inthe African (Billinghurst and Welchman, 1966).

Familial polyposis of the colon is not only rare

in Africans but also appears to be relatively rare

in other ethnologically related population groups,including West Indians (Morson and Dawson,1972) and American Negroes (Cole and Holden,1959; Cole, McKalen, and Powell, 1961; Gordon,

Type Number Average Age (yr)

Male Female Unknown Total Male Female

Juvenile 15 9 24 (60) 14 1 1Villous 2 - 2 (5) 47 -

Adenomatous I - 1 (2 5) 7Peutz Jeghers' I - 1 (2 5) 35Schistosomal I - 1 (2 5) 40Non-neoplastic-inflammatory group 5 5 10 (25) 26 40Others 1 1 2 (2-5)

Total 25 14 1 40 (100)

Table II Histological types ofpolyps and average age of Nigerian patientsPercentages are given in parentheses

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Intestinal polyps in the Nigerian African

Fig 2 Gross appearanceofinfiltrating carcinoma ofcolon in a 9-year-old Nigerianboy. Note the juvenile polyp(arrow) arising in the mucosaabove the area of tumour.

-0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 l 17 18

Rast, and Whelan, 1962; Dunning and Ibrahim,1965). Neoplastic polyps, as a group of benignintestinal neoplasms, appear to be uncommon inother less sophisticated population groups, inclu-ding South American Indians, Eskimos, Pygmies ofCentral Africa, Australian Aborigines, and Poly-nesians of the Pacific. The dietary composition andthe quantity and quality of faeces in association withtransit time in these different population groups,which are different from those in Caucasians livingin the same environment, may be responsible forthis relative rarity. Reviewing the literature, thereis only one reported case of familial polyposis ina South African Bantu (McQuaide and Stewart,1972); this condition also appears to be rare inIndians, Arabs, and Orientals when compared withCaucasians (Burkitt, 1971).

It is interesting that the average age of Caucasianswith benign adenomatous polyps is about 60 years(Morson, 1971). In nearly all the developing coun-tries where the incidence or frequency of polyps islow, the percentage of people living up to the seventhdecade is relatively small. This may partly explainthe low incidence of polyps in these populationgroups. However, it fails to explain the relativerarity of this lesion in population groups with alonger expectation of life. Non-adenomatous polypsalso appear to be relatively uncommon in colouredraces but there are few reports of Gardner's orPeutz-Jeghers' syndrome in American Negroes(Dunning and Ibrahim, 1965; Gordon et al, 1962;Achord and Proctor, 1963; Dodds, Schulte, Hensley,and Hogan, 1972; Kolade, Chung, White, andLeffall, 1973) who are ethnologically related to theWest African.The present study shows that the juvenile hamar-

tomatous type of polyp is the commonest type inNigerians, accounting for almost two-thirds of allour cases. The average ages of male and female

patients are 14 and 11 years respectively, with arange between 3 and 41 years (table II). Most ofthe juvenile polyps are in the rectum and aresolitary. We did not encounter any case of juvenilepolyposis, and no congenital abnormalities wererecorded in any of our cases with solitary polyps.Two male patients, aged 34 and 60 years, had villouspapilloma of the rectum but the older patient hadcarcinomatous change in the papilloma. The onlycase of adenomatous polyp encountered was in a7-year-old boy, a very rare lesion at this age. Thiswas solitary and no other polyps or recurrences havebeen seen after four years of follow-up. We havealso seen recently an infiltrating carcinoma of thesigmoid colon with a juvenile polyp in its vicinity(fig 2) in a 9-year-old Nigerian boy who died frommetastasis about 10 months after surgical removalof the primary tumour. One case of Peutz-Jeghers'type of polyp in the rectum was encountered andone bilharzial polyp due to Schistosoma mansoniwas also seen (fig 3). There were 10 cases whichcould not definitely be categorized into any of thehistological types. Three of these were severelyinfected, two could be juvenile polyps, and onecould be another Peutz-Jeghers' type of polyp. Theremaining seven polyps, however, could be due tochronic non-specific inflammatory bowel diseasewhich is not uncommon in the tropics. Bacterio-logical and parasitological examination of faecesfrom the seven patients did not reveal any specificpattern of organisms which could be incriminated.The relative absence of polyps in women over

the age of 40 is noteworthy (table I). This may bea real deficiency or due to the fact that the patientsdo not present for medical care. Lymphogranulomavenereum, as seen in the West Indies (Annamun-thodo et al, 1974), is either underdiagnosed or notcommonly encountered in Nigerians. Lymphoidhyperplasia of the terminal ileum is a relatively

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Fig 3 High-power view ofpolyp showing Schistosomamansoni ova in the lamina propria.

common finding in our necropsy material, presum-

ably related to intestinal helminthiasis. We have,however, encountered two patients at necropsy withdiffuse lymphoid polyposis, one of whom had coex-

istent solitary malignant lymphoma in the terminalileum. Apart from Burkitt's lymphoma, which fre-quently affects the intestine in African children,primary extranodal lymphoma of the intestine isrelatively uncommon.

It would appear that the frequencies of thehistological types of polyps seen in this series are

a reflection of the age structure of the Nigerianpopulation with excess in the younger age group.Furthermore, the presence of a protruding mass inthe anus or blood in the stool of an African childusually so alarms the mother that she brings thechild promptly for medical care.

In Kampala, a similar pattern has been observedover a five-year period. Templeton (1973) found 27patients with colonic polyps, of which 16 (60%)were of the juvenile hamartomatous variety, andall the patients were under the age of 14 years.Other types encountered included one adenomatouspolyp, two villous papillomas, and one metaplasticpolyp. No adenomas were found in 2000 necropsiescarried out in Uganda (Templeton, 1973), and this

necropsy and surgical biopsy frequency patternduplicates what has been observed in the SouthAfrican Bantu (Bremner and Ackerman, 1970)and in the West African.

Analysis of available data in Africa and ourcurrent experience would point to the possibleassociation that in parts of Africa with a lowincidence of intestinal adenoma there is a concomit-ant low incidence of intestinal carcinoma. Evidencein support of the converse of this observation isforthcoming from a recent study which shows aninterrelationship between colorectal adenoma andcarcinoma (Ekelund and Pihl, 1974). Furtherstudies are required primarily to find out the inci-dence of neoplastic polyp in relation to intestinalcarcinoma in different geographical locations, andsecondarily to evaluate, on an epidemiological basis,the relative importance of these precancerouslesions in the aetiology and pathogenesis of intestinalmalignancies. The reasons for the relatively lowfrequency of neoplastic intestinal polyps in theAfrican and inhabitants of other developing coun-tries require further elucidation. It is conceivablethat the genetic constitution and diet of the inhabi-tants, among other factors, may be of considerableaetiological significance. This requires immediateinvestigation before there is a radical change in thedietary and faecal composition (Aries et al, 1969)of these population groups.

References

Achord, J. L. and Proctor, H. D. (1963). Malignant degener-ation and metastasis in Peutz-Jeghers syndrome. Arch.intern. Med., 111, 498-502.

Annamunthodo, H., et al. (1974). Precancerous lesions oflarge bowel. Brit. med. J., 2, 315-316.

Aries, V., Crowther, J. S., Drasar, B. S., Hill, M. J., andWilliams, R. E. 0. (1969). Bacteria and the aetiology ofcancer of the large bowel. Gut, 10, 334-335.

Billinghurst, J. R., and Welchman, J. M. (1966). Idiopathiculcerative colitis in the African: a report of 4 cases. Brit.med. J. 1, 211-213.

Bremner, C. G. and Ackerman, L. V. (1970). Polyps andcarcinoma of the large bowel in the South African Bantu.Cancer (Philad.), 26, 991-999.

Burkitt, D. P. (1971). Epidemiology of cancer of the colonand rectum. Cancer (Philad.), 28, 3-13.

Cole, J. W. and Holden, W. D. (1959). Postcolectomyregression of adenomatous polyps of the rectum. Arch.Surg., 79, 385-392.

Cole, J. W., McKalen, A., and Powell, J. (1961). The roleof ileal contents in the spontaneous regression of rectaladenomas. Dis. Colon Rect., 4, 413-418.

Dodds, W. J., Schulte, W. J., Hensley, G. T., and Hogan,W. J. (1972). Peutz-Jeghers syndrome and gastro-intestinal malignancy. Amer. J. Roentgenol., 115, 374-377.

Dunning, E. J. and Ibrahim, K. S. (1965). Gardner'ssyndrome. Ann. Surg., 161, 565-568.

Ekelund, G. R. and Pihl, B. (1974). Multiple carcinomasof the colon and rectum. Cancer (Philad.), 33, 1630-1634.

Gordon, W. C. Jr., Rast, M. F., and Whelan, T. J., Jr.(1962). Gardner's syndrome. Ann. Surg., 155, 538-542.

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Hutt, M. S. R. and Templeton, A. C. (1971). The geo-graphical pathology of bowel cancer and some relateddiseases. Proc. roy. Soc. Med., 64, 962-964.

Kolade, S. 0. Chung, E. B., White, J. E., and Leffall, L. D.,Jr. (1973). Neoplastic lesions of the colon and ano-rectumin blacks. J. nat. Med. Ass (N. K'.), 65, 142-148.

McQuaide, J. R. and Stewart, A. W. (1972). Familialpolyposis of the colon in the Bantu. S. Afr. med. J., 46,1241 -1246.

Morson, B. C. (1971). Precancerous conditions of the large

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bowel. Proc. roy. Soc. Med., 64, 959-962.Morson, B. C. and Dawson, I. M. P. (1972). Gastro-

intestinal Pathology. Blackwell, Oxford.Templeton, A. C. (1973). Tumors in a Tropical Country.A survey of Uganda 1964-1968. Recent Results in CancerResearch, 41. Springer, New York, Heidelberg, Berlin.Heinemann, London,

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