Colonic and duodenal flat adenomas in children with classical familial adenomatous polyposis

Upper GI involvement in children with familial adenomatous polyposis syndrome: single-center experience and meta-analysis of the literature

BACKGROUND AND AIMS

Familial adenomatous polyposis (FAP) is a hereditary syndrome that can affect the entire GI tract. Current screening recommendations include EGD starting at age 25 to 30 years or earlier in symptomatic patients. However, few reports describe upper GI tract involvement in children with FAP that support the notion of early screening. The aim of our study is to understand the prevalence and severity of upper GI involvement in children with FAP.

METHODS

We performed a retrospective review of the Mayo Clinic records, between 1992 and 2016, to identify children with the diagnosis of FAP who underwent EGD examinations. A systematic review of the literature was performed to include published studies reporting children with FAP and upper GI findings.

RESULTS

The retrospective study included 69 children with a mean age of 13.5 years (range, 3-18). Thirty-six children (52%) had duodenal adenoma with low-grade dysplasia. Five children required an ampullectomy secondary to enlarged and polypoid ampullas. Combined with published studies, a total of 206 children with upper GI findings were identified, of which 87 (42%) had duodenal adenoma (1 had high-grade dysplasia). Meta-analysis of 5 series demonstrated duodenal adenoma detection rate of 39% (95% confidence interval, 21%-57%; I² = 85%).

CONCLUSIONS

The available data to date show that children with FAP can have clinically relevant lesions in the upper GI tract earlier than previously foreseen, suggesting that earlier screening may be indicated. Larger multicenter prospective studies are needed to determine the best approach and optimal age for EGD screening in children with FAP.

Familial adenomatous polyposis of the colon

Familial adenomatous polyposis (FAP) is a well-defined autosomal dominant predisposition to the development of polyposis in the colon and rectum at unusually early ages. The first symptoms of FAP are diarrhea and blood in the stool. Weight loss and weaknesses occur after the development of advanced tumour. The incidence of the FAP disorder is one per 10000 newborns. There are high levels of heterogeneity with regard to the number and timing of the occurrence of polyps. The classical form of FAP is characterized by the presence of more than 100 polyps, which appear in the second decade of life. The average time of occurrence of polyps is 15 years. The earliest symptoms of polyposis have been observed in a three-year-old child. The polyps are characterized by large potential for the development towards malignant tumour. Malignancy can occur from late childhood onwards. Attenuated adenomatous polyposis coli is characterized by a more benign course of disease in contrast to classical FAP. The occurrence of FAP is associated with mutations in the APC tumour suppressor gene, which was described in 1991. The APC gene is located on chromosome 5q21 and is involved in cell proliferation control. A recessive form of adenomatous polyposis is caused by mutations in the base excision repair gene - MUTYH gene. The MUTYH gene is involved in repairing DNA lesions as a result of oxidative DNA damage. MUTYH associated polyposis (MAP) is a predisposition to the development of polyps of the colon but the number of polyps is lower in comparison to classical FAP. The high risks of cancer observed in these two diseases make them important medical issues. Molecular studies of colonic polyposis have been performed in Poland for over fifteen years. A DNA Bank for Polish FAP patients was established at the Institute of Human Genetics in Poznan in which DNA samples from 600 FAP families have been collected.

Colonic aberrant crypts in children with familial adenomatous polyposis

Aberrant crypt foci of the colonic mucosa have been reported in adults. The alteration may be defined macroscopically or histologically and may or may not be combined with adenomatous changes. Aberrant crypt foci have been regarded as precancerous lesions and are more common in patients with familial adenomatous polyposis. The present report describes the presence of many histologically recognizable aberrant crypt foci without adenomatous changes in the colonic mucosa of 3 children with familial adenomatous polyposis. The openings of the aberrant crypt foci contained inspissated granulofilamentous mucus. Additionally, this report documents the presence of a peculiar serrated appearance of the mucosae surface outline of the nonadenomatous areas. This appears to result from elongation of the crypts and dilated openings/micropapillary arrangement of the uppermost part of the walls of the crypts, with a thin intervening stroma. Neither of these findings has been reported previously to occur in children. They may represent the earliest histologically identifiable changes ever recorded in the colon of patients with familial adenomatous polyposis.