case_images: PMC10601724_01
case_images: Initial colonoscopy showing a 5 cm circular rectal mass was observed 7 cm from the anorectal (1 a, b) with a pedunculated polyp measuring 1.5 x 2.5 cm located 50 cm from the anorectal (2 a, b).
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case_images: F1
case_images: On colonoscopy, a 5 cm circular rectal mass was observed 7 cm from the anorectal with a pedunculated polyp measuring 1.5 x 2.5 cm located 50 cm from the anorectal (Fig. 1).
case_images: Histopathological features of a biopsy specimen from initial colonoscopy with x4 (a), x10 (b), and x40 (c) magnifications, showing proliferative tissue glands with tubulovillous pattern (blue arrow) and mild dysplasia (red arrow).
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case_images: F2
case_images: Pathological examination showed proliferative tissue glands with tubulovillous pattern and mild dysplasia (Fig. 2).
case_images: Repeat colonoscopy found a 7 cm ulcerative circular rectal mass 5 cm from the anorectal (1 a, b), the first polyp located 65 cm from the anorectal (2 a, b), and the second polyp located 75 cm from the anorectal (3 a, b). Both polyps measured 1.5 x 2 cm.
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case_images: PMC10601724_01_cro-2023-0016-0001-531992_F03.jpg
case_images: F3
case_images: Repeat colonoscopy found a 7 cm ulcerative circular rectal mass 5 cm from the anorectal and multiple pedunculated polyps 65-75 cm from the anorectal, measuring 1.5 x 2 cm in diameter (Fig. 3).
case_images: Morphological feature of biopsy specimens from second colonoscopy with x10 (a), and x40 (b) magnifications, showing villous pattern (blue arrow) and moderate dysplasia (red arrow).
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case_images: F4
case_images: Polypectomy was performed, and pathological examination showed villous adenoma with moderate dysplasia (Fig. 4).
case_images: Histopathological features of descending colon and rectum from surgical resection with x4 (a), x4 (b), x10 (c), and x40 (d) magnifications, showing tubulovillous adenoma component (blue arrow) with partly adenocarcinoma component in another area (red arrow). Tumor cells are characterized by atypical shape, large size, scanty cytoplasm, and prominent nucleoli, infiltrated submucosa layer (green arrow). Dense lymphocyte infiltration was observed in the surrounding tumor nest (yellow arrow).
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case_images: F5
case_images: Pathological examination of resected tissue showed tubulovillous adenoma with adenocarcinoma infiltrating the submucosal layer with dense infiltration of lymphocytes (Fig. 5).
case_images: The immunohistochemical examination of CDX2 and CK20 showed the nuclear positivity of CDX2 (a) and the membrane-cytoplasmic positivity of CK20 (b).
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case_images: PMC10601724_01_cro-2023-0016-0001-531992_F06.jpg
case_images: F6
case_images: Molecular examination showed KRAS (Kirsten rat sarcoma viral oncogene homolog) mutation on exon 4, normal NRAS, BRAF, CDX2, and CK20 expressions (Fig. 6).
case_images: Abdominal CT scan with contrast, showing presurgical (a) rectal mass (blue arrow) and the corresponding postsurgical (b) residual tumor on distal rectum (red arrow).
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case_images: F7
case_images: One month after surgery, an abdominal CT scan with contrast showed a residual mass on the distal rectum (Fig. 7).