case_images: PMC10766397_01
case_images: Colonoscopy images show a 4-cm carpeting lesion within the rectum and sigmoid colon (a) and a normal appendiceal orifice (b).
case_images: crg-2024-0018-0001-535273_F01.jpg
case_images: PMC10766397_01_crg-2024-0018-0001-535273_F01.jpg
case_images: F1
case_images: A digital examination revealed no abnormalities in the rectum. A colonoscopy performed on March 25, 2020, showed multiple colonic polyps and a 4-cm carpeting lesion in the rectum and distal sigmoid colon with a firm center (shown in Fig. 1). The appendicular orifice was normal on colonoscopy (shown in Fig. 1).
case_images: a Axial T1-weighted image shows a thickened appendix arising from the cecum, coursing posteriorly and abutting the right lateral wall of the rectum. There is a T1 hypointense appendiceal tumor invading the rectosigmoid, with loss of the intervening fat plane. b Axial fat-suppressed post-contrast T1-weighted image demonstrates heterogeneous enhancement within the appendiceal and rectal components of the tumor. c High-resolution axial T2-weighted images without fat suppression show heterogeneous T2 hyperintense tumor involving the appendix. The distal end of the appendix abuts the right lateral wall of the rectum. Tumor invades the right lateral wall of the rectum, forming an intraluminal carpeting lesion within the rectum. d High-resolution coronal oblique T2-weighted images demonstrate tumor adherent to the wall of the urinary bladder, resulting in tenting of the bladder wall. e Axial contrast enhances CT image through the pelvis shows an enlarged appendix with irregular thickening of its walls. The appendix courses posteriorly and the tip of the appendix is adherent to the rectosigmoid on the right side.
case_images: crg-2024-0018-0001-535273_F02.jpg
case_images: PMC10766397_01_crg-2024-0018-0001-535273_F02.jpg
case_images: F2
case_images: T1 hypointense and T2 hyperintense, heterogeneously enhancing the appendix measuring 1.6 cm in diameter and 6.7 cm in length. The appendix demonstrated a posterior course with its tip abutting the right lateral wall of the rectosigmoid (shown in Fig. 2). T1 hypointense and T2 hyperintense mass was observed within the rectosigmoid contiguous with the appendix (shown in Fig. 2). This raised the possibility of an appendiceal tumor invading the rectosigmoid and forming a plaque-like intraluminal rectosigmoid mass. The posterosuperior wall of the urinary bladder was adherent to the rectosigmoid at the site of tumor infiltration with resultant tenting of the urinary bladder (shown in Fig. 2). Staging CT of the chest, abdomen, and pelvis performed on June 12, 2020, showed an enlarged appendix measuring up to 1.5 cm in width with irregular thickening of the appendicular wall which was highly concerning for malignancy (shown in Fig. 2).
case_images: a Hematoxylin and eosin (H&E)-stained section shows adenocarcinoma arising from the appendix on the bottom, infiltrating through appendiceal wall into adhesions with the rectum (arrows), abscess between appendiceal adenocarcinoma, and muscularis propria of rectum (rectum on top). b H&E-stained section shows appendiceal adenocarcinoma infiltrating into the rectal muscularis propria and submucosa (middle), with normal rectal mucosa on the bottom right. c H&E-stained section shows appendiceal adenocarcinoma on the left infiltrating into adhesions between appendix and rectum; a rectal villous adenoma is seen on the right of the image.
case_images: crg-2024-0018-0001-535273_F03.jpg
case_images: PMC10766397_01_crg-2024-0018-0001-535273_F03.jpg
case_images: F3
case_images: Sectioning showed that the tumor emerged from the appendix, further forming a fistulous tract and invading the muscularis propria and submucosa of the rectosigmoid (shown in Fig. 3).
case_images: Timeline of events showing interventions and outcomes.
case_images: crg-2024-0018-0001-535273_F04.jpg
case_images: PMC10766397_01_crg-2024-0018-0001-535273_F04.jpg
case_images: F4
case_images: The timeline for this case report has been described (shown in Fig. 4).