Familial adenomatous polyposis and colorectal cancer – how sensitive is computed tomography in detecting the underlying disease?

Abstract

Introduction Familial adenomatous polyposis (FAP) is an autosomal dominant disorder characterized by the presence of 100 or more adenomatous polyps in the mucosal lining of the large intestine, with a significant risk of colorectal cancer development. Case outline This article presents a case report of previously undiagnosed FAP in a patient admitted to the surgical emergency department with suspected sigmoid carcinoma. On computed tomography (CT), the findings of the colonic mucosa were inconclusive due to inadequate distension of the bowel lumen and insufficient preparation. Edema of the bowel wall was clearly observed, a CT characteristic of the carcinoma that had formed at the level of the sigmoid colon, while the two other foci of malignant transformation were obscured by a diffuse, uniform thickening of the wall, which was clearly diagnosed as FAP on subsequent colonoscopy. The patient underwent a total proctocolectomy, after which he continued his oncological treatment. Conclusion Computed tomography is inadequate for the diagnosis of diffuse polyposis of the colonic mucosa, especially in emergency situations when patients are not prepared for the examination, i.e., without sufficient dilation of the bowel lumen. Since the underlying disease in this patient masked two of the three malignant lesions of the colon, we point out the diagnostic inferiority of the CT examination in the regular emergency settings, compared to CT and MR colonography and especially to colonoscopy as the gold standard in the detection of colorectal cancer. © 2025, Serbia Medical Society. All rights reserved.