PMC5295622_01
Endoscopic findings.. Colonoscopy revealed an elevated tumorous lesion that was similar to type 1 tumor located in the lower rectum (Fig. 1a,b). The surface of this tumor was covered by normal rectal mucosa and there was a black spot near the tumor (Fig. 1c).
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Colonoscopy revealed an elevated tumorous lesion that was similar to type 1 tumor located in the lower rectum (Fig. 1a, b). The surface of this tumor was covered by normal rectal mucosa and there was a black spot near the tumor (Fig. 1b, c).
Histopathological findings.. HE stained (Fig. 2a, x 12.5). The depth of the main tumor was the muscularis propria. HE stained (Fig. 2b, x 400) There was no melanin pigment granules in the tumor. Immunostaining of the tumor was positive for S100 antibody (Fig. 2c, x 400) Melan-A antibody (Fig. 2d, x 400) and HMB45 antibody (Fig. 2e, x 400), so we diagnosed AAMM in the lower rectum.
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There was no melanin pigment granules in the tumor (Fig. 2b). Immunostaining of the tumor was positive for Melan-A antibody (Fig. 2d) and HMB45 antibody (Fig. 2e). The depth of the main tumor was the muscularis propria (Fig. 2a) and there were no metastases of AAMM in the resected lymph nodes.
Enhanced CT.. Three months after the operation, we performed ECT for postoperative surveillance, which revealed multiple liver metastases (Fig. 3a,b) and right ischial bone metastasis (Fig. 3a, b). ECT at 3 months after initiation of nivolumab showed reduction of liver and right ischial bone metastases (Fig. 3c, d).
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Three months after the operation, we performed ECT for postoperative surveillance, which revealed multiple liver metastases and right ischial bone metastasis (Fig. 3a, b). ECT at 3 months after initiation of nivolumab showed shrinkage of liver and right ischial bone metastases (Fig. 3c, d).