PMC7492942_01
Colonoscopic findings. (a) A polypoid-type tumor was seen in the sigmoid colon, which was initially assumed to be a sigmoid colon cancer. (b) An elevated lesion with redness was observed in the appendiceal orifice, where biopsies were not performed.
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Colonoscopy revealed that a type 1 tumor, i.e., a polypoid-type tumor, was located in the sigmoid colon, and an elevated lesion with redness was located in the appendiceal orifice (Figure 1).
CT findings. (a) An appendiceal mass was seen at the distal part of the appendix. The appendiceal mass and the appendix are indicated by an arrow and an arrowhead, respectively. (b) The appendiceal mass involved the sigmoid colon. The mass and the normal rectosigmoid region are indicated by an arrow and an arrowhead, respectively.
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A computed tomography (CT) scan showed, however, an appendiceal mass that involved the sigmoid colon (Figure 2) and was located adjacent to the right ureter, suggesting an appendiceal cancer invading the sigmoid colon.
Macroscopic views of the resected specimen. (a) A tumor of 60 x 40 mm in size was seen in the distal part of the appendiceal lumen and extended into the lumen of the sigmoid colon with fistulation. The root of the appendix is indicated by an asterisk. (b) A closer view.
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Macroscopic findings showed that the tumor measured 60 x 40 mm and invaded and made a fistula with the sigmoid colon (Figure 3).
Microscopic findings of the resected specimen. (a) The specimen was cut along a red dotted line which included the appendiceal tumor and the invaded sigmoid colon. (b) A cross-section of the cut specimen. The area surrounded by a red box was examined microscopically. (c) A microscopic view. The tumor (indicated by an asterisk) had come into contact with the inner side of the sigmoid colon. The muscularis propria and the mucosa of the sigmoid colon are indicated by an arrowhead and an arrow, respectively. (d) A higher magnification view showing that the tumor was a well-differentiated tubular adenocarcinoma.
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Pathological examination revealed that the tumor was a well-differentiated tubular adenocarcinoma according to the Japanese classification and invaded the sigmoid colon (Figure 4).