Difficulties in diagnosing anorectal melanoma: A case report and review of the literature

Figure 1 Aspect of the tumor at anoscopy. Image shows a sessile tumor, near the anal verge, on the postero-lateral anorectal wall.

Figure 2 Colonoscopic aspect of the tumor. Images show a cauliflower tumor with a wide base, exulcerated areas, and adherent clot, without obvious color changes or obstruction.

Figure 3 Pelvic magnetic resonance imaging scan with intravenous gadolinium administration. A and B: Axial and sagittal T2-weighted images showing the tumor occupying the anorectal junction canal, with homogenous enhancement, without infiltration of the rectal fascia; C and D: Axial T2-weighted propeller images showing two large lymph nodes located in primary stations, without mesorectal fascia retraction.

Figure 4 Abdominoperineal resection intra-operative images. A: Dissection and identification of the inferior mesenteric artery; B: Perineal incision; C, D: Abdominal view of the dissected specimen, with total mesocolic and mesorectal excision.

Figure 5 Images of the resected specimen. The tumor was identified adjacent to the dentate line with rectal extension.

Figure 6 Histopathological and immunohistochemical examination of the tumor. A: Immunohistochemistry image with SOX10 positivity; B and C: Tumoral infiltration confined to the submucosa, with pigmented areas, epithelioid cells, and localized fusiform aspect; D: Cells with eosinophilic cytoplasm, with melanocyte pigment.