대한대장항문학회

Familial adenomatous polyposis (FAP) is an inherited autosomal dominant syndrome caused<br>by germ-line mutations of the adenomatous polyposis coli (APC) gene. Clinical diagnosis of<br>familial adenomatous polyposis is usually based on the presence of ＞100 colonic adenomas,<br>which, if left untreated, progress to colorectal cancer, typically at age under 40 years.<br>Attenuated adenomatous polyposis coli is a variant of familial adenomatous polyposis and also<br>has been described as "hereditary flat adenoma syndrome". Attenuated adenomatous polyposis<br>coli is recognized by the occurrence of ＜100 (≥5 or ≥10) colonic adenomas. It is tend to be<br>located proximal to splenic flexure and a later onset of colorectal carcinoma than familial<br>adenomatous polyposis. Purpose : This study was performed to analyze the clinicopathologic<br>features of suspicious attenuated adenomatous polyposis coli, to document the occurrence of<br>colorectal carcinoma, and to assess the definition of attenuated adenomatous polyposis coli.<br>Methods : From June 1989 to June 1998, we reviewed 773 cases of colonic adenomas and<br>compared with three groups (Group I, II, III) at Asan Medical Center. Median follow-up<br>period was 16.4 months (range, 1 to 102 months). Results : The incidence of suspicious<br>attenuated adenomatous polyposis coli (Group II) was 4.9%. The most common symptom was<br>anal bleeding (36.9%). Median size and number of adenomas were 1.0 cm (0.2 to 7.5 cm), 2 (1<br>to 43), respectively. Location of adenoma was prevalent at right colon in Group II (P＜0.05).<br>In respect to the occurrence of carcinoma in situ (CIS), it was more frequently presented in<br>Group II (13.5%) and Group III (13.6%) whereas 4.1% in Group I (P＜0.05). Recurrence rates<br>within 12 months after polypectomy or surgery in Group II was 13.5% whereas 5.6% in<br>Group I (P＜0.05). Conclusions : Histopathology revealed suspicious attenuated adenomatous<br>polyposis coli with villous component to be relatively correlated with occurrence of colorectal<br>carcinoma. In suspicious attenuated adenomatous polyposis coli (Group II), the interval of the<br>recurrence of the polyps was shorter than the control group with right colonic predominancy.<br>These findings might be associated with genetic codominance of APC gene or other mutator<br>genes.<br>