Endoscopic submucosal dissection as excisional biopsy for anorectal malignant melanoma: A case report

Figure 1 Colonoscopic findings. A 20-mm protruded lesion in the lower rectum just above the dentate line is detected.

Figure 2 Narrow-band imaging with magnifying endoscopy findings. Non-structural areas and some thick, unevenly sized vessels with branching and curtailed irregularity are observed.

Figure 3 Endoscopic ultrasonography findings. Endoscopic ultrasonography image shows the lesion as a hypoechoic mass. The tumor invades the submucosal layer but not the muscular layer.

Figure 4 Histopathological and immunohistochemical findings of the endoscopic submucosal dissection-resected specimen. A: Hematoxylin and eosin staining shows diffuse infiltration of round tumor cells with irregular nuclei. Melanin pigment is absent (magnification × 400). The tumor cells are positive for B: Human Melanin Black-45 (× 200), C: Melan-A (× 200), and D: S-100 (× 100).

Figure 5 Endoscopic submucosal dissection-resected specimen. The endoscopic submucosal dissection-resected specimen is 40 × 30 mm in size. The tumor is protruded and measures 20 × 15 mm. Macroscopically, an adequate margin from the tumor, especially on the oral side, is ensured.

Figure 6 Follow-up endoscopic findings 3 mo after the endoscopic submucosal dissection. The post-endoscopic submucosal dissection ulcer is healed, and no local recurrence is detected.

Figure 7 Follow-up endoscopic findings 6 mo after the endoscopic submucosal dissection. A 10-mm protruded lesion is identified about 10 mm from the oral side of the post-endoscopic submucosal dissection scar. Biopsy specimens from this lesion confirm a malignant melanoma.