CASE REPORT

 

The clinical and pathological features of hereditary mixed polyposis syndrome: Report on a South African family

 

 

S. B. Ibirogba^I; U. Algar^II; P. A. Goldberg^III; M. Duffield^IV; A. Vorster^V; R. Ramesaar^VI

^IM.B. B.S., F.C.S. (S.A.); Colorectal Unit, Department of Surgery, Groote Schuur Hospital and University of Cape Town
^IIM.SC. (NURSING); Colorectal Unit, Department of Surgery, Groote Schuur Hospital and University of Cape Town
^IIIM.B. CH.B., F.C.S. (S.A.), M.MED. (SURG.); Colorectal Unit, Department of Surgery, Groote Schuur Hospital and University of Cape Town
^IVM.B. CH.B., L.R.C.P., M.R.C. (PATH.), F.S. (EDIN/GLASGOW), M.MED. (ANAT. PATH.); Division of Anatomical Pathology, Groote Schuur Hospital and University of Cape Town
^VM.SC; Division of Human Genetics, Groote Schuur Hospital and University of Cape Town
^VIPH.D; Division of Human Genetics, Groote Schuur Hospital and University of Cape Town

 

 

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SUMMARY

BACKGROUD: Hereditary mixed polyposis syndrome is characterised by multiple large-bowel polyps of differing histological types including a mixture of atypical juvenile polyps, hyperplastic polyps and adenomas. Affected individuals are thought to have an increased risk of malignancy, possibly via the juvenile polyposis pathway.
METHODS: A 51-year-old woman (with a history of a colectomy for polyps during childhood) presented with rectal bleeding. Endoscopy demonstrated small rectal polyps which were hyperplastic on histology. A family tree was drawn up and the three children of the proband underwent flexible sigmoidoscopy.
RESULTS: Endoscopic surveillance of the three children revealed one who had a similar phenotype to the mother. This child underwent colectomy and ileorectal anastomosis. The pathological specimen revealed more than 70 polyps, with a combination of juvenile retention, hyperplastic, adenomatous and inflammatory polyps. A second child had multiple small hyperplastic polyps, and the third had a normal colon. Although the gene locus for the disorder has been mapped, neither the gene nor the disease-causing mutation has been defined.
CONCLUSION: A rare inherited polyposis syndrome has been identified in a South African family. Where clinical suspicion of a possible inherited condition exists, investigating at-risk first-degree relatives confirms the inherited nature of the disease. It is possible to use genetic haplotyping (i.e. with a range of markers in the area of the gene) to provide statistical risk to immediate relatives and therefore those at highest risk.

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