Colonic and Duodenal Flat Adenomas in Children with Classical Familial Adenomatous Polyposis

Abstract

Flat adenomas of the colon and duodenum have been described as associating with familial adenomatous polyposis (FAP), its attenuated variant, and the so-called hereditary nonpolyposis colorectal cancer. There seem to be no report on the occurrence of flat adenomas in pediatric patients with family history of FAP. We are reporting 4 children from 2 cancer-prone families in whom colonic and duodenal moderately dysplastic flat adenomas were found. Gastrointestinal endoscopy and biopsies were performed in 3 female siblings (7, 9, and 11 years old) and 1 male (9 years old) when referred for screening owing to familial history of bowel cancer (family 1) or evidence of bilateral congenital hypertrophy of the retinal pigment epithelium (CHRPE), which is known to be associated with FAP (family 2). Endoscopic visualization of the mucosa was improved by use of 0.2% indigo carmine solution spray. Biopsies were routinely processed for H&E and immunohistochemistry staining. Present patients were asymptomatic, with the exception of 2 weeks rectal bleeding in 1 of them. The colonic videoendoscopy showed in 2/3 siblings hundreds of flat or slightly raised plaques less than 1 cm in diameter as well as some classic polyps throughout the colon. The other sibling showed 40 flat-topped lesions with minimal elevation and central umbilication in the cecum. Upper endoscopy demonstrated a few flat lesions in the nonperiampullary area of the duodenum in 2/4 patients. The colonic videoendoscopy performed on the 9-year-old boy revealed multiple small sessile polyps. Microscopic study demonstrated tubular adenomas with a few neoplastic crypts, slight disarray of the overall architecture, and moderate (low-grade) dysplasia of the epithelium. These features were more obvious at the center and superficial areas of the adenomas. The 4 children had multiple flat adenomas of the colon and duodenum (2/4) matching with those described in adult patients. Flat adenomas in the context of FAP probably represent early stages of the adenoma development. Careful endoscopic-histologic correlation may result in increasing recognition of these lesions at the pediatric age.

Familial adenomatous polyposis: a review of gastrointestinal manifestations

“…29 The polyp size and contour observed endoscopically in classic FAP is a small raised lesion with a rounded contour; in contrast, polyps in attenuated FAP although also small (<1 cm) are flat in appearance, showing only minimal mucosal elevation. 30 Unicryptal adenoma is the pathognomonic lesion in FAP, originally described microscopically but which can now be identified by chromoendoscopy. 31 It has been reported that small polyps (<3 mm in size) are not observed after barium enema, resulting in underestimation of the number of polyps.…”

Colonic Aberrant Crypts in Children With Familial Adenomatous Polyposis

“…Our finding of flat adenomas in children with FAP is also in the same line of reasoning. 8 Moreover, ACF have been proposed to act as traps of dietary carcinogens. If so, the larger the number of ACF, the greater is the possibility of developing additional mutations leading to tumors.…”

Familial adenomatous polyposis of the colon

“…Tubular-villous and villous adenomas are also quite frequent [30]. Moreover, intestinal polyps can also occur as flat tubular polyps [31]. One of the typical features of polyposis is a severe phenotype in which the number of polyps exceed one thousand [32].…”