Endoscopic ultrasound features of rectal melanoma: A case report and review of literature

Figure 1 A bulging tumor of approximately 2. 2 cm × 2.0 cm with a purplish-red apex and clear boundaries was identified approximately 8 cm from the anus by colonoscopy.

Figure 2 Endoscopic ultrasound image and color Doppler image. A-E: Endoscopic ultrasound image showing a hypoechoic mucosal mass with involvement of the submucosal layer and heterogeneity of the internal echoes; F: Color Doppler showed localized blood with the intrinsic musculature still intact.

Figure 3 Nodular foci of enhancement in the rectum; abdominal contrast enhancement-computed tomography.

Figure 4 Hematoxylin-eosin staining and immunohistochemical staining. A: Islands of malignant cells with round or oval nuclei of variable size and deep staining of the nuclei, accompanied by mucosal infiltration; hematoxylin and eosin staining (200-fold magnification); B: HMB-45 melanocyte marker, positive in tumor cells and negative in the remaining epithelium; Immunohistochemistry (IHC) (200-fold magnification); C: S100 melanocyte marker, positive for tumor cells, negative for remaining epithelial cells; IHC (200-fold magnification).