Local recurrence after successful endoscopic submucosal dissection for rectal mucinous mucosal adenocarcinoma: A case report

Figure 1 Endoscopic findings of the rectal tumor. A: A remarkable protrusion (Is) with slight bleeding is observed in the rectum; B: Chromoendoscopy enhances a flat elevated lesion (IIa) which is located at the base of the protrusion lesion; C: Magnified endoscopy with narrow-band imaging reveals an intense irregular micro-vascular pattern indicating the existence of carcinoma in the Is lesion; D: Magnified endoscopy shows faint vascular pattern on the IIa lesion.

Figure 2 A comparison between the genetic mutations and the histopathological characteristics of the tumor. Mucinous and signet-cell carcinoma (area A) and tubular adenocarcinoma (area B, C) shows the same mutational frequency in RNF43, TP53, and SMAD4. The adenoma (area D, E) shows a higher frequency for RNF 43 than for TP53.

Figure 3 A histopathological examination of the endoscopically resected specimen. A: A protruded polyp and flat elevation are removed by endoscopic submucosal dissection. The tumor margin is surrounded by normal epithelia, indicating R0 resection; B: Adenocarcinoma composed of mucinous and tubular carcinoma with an adenoma component; C: Signet ring cell carcinoma is observed in mucinous lake (arrows).

Figure 4 Endoscopic findings of the recurrent tumor. A: A protrusion tumor (Is) with redness is observed on the scar after endoscopic resection; B: Chromoendoscopy shows an elongated tubular surface tumor with a hypervascular pattern on the Is lesion; C: The flat elevated lesion (IIa) located at the base of Is tumor indicates dilated crypts; D: Crystal violet staining indicates irregular structured pits on the Is; E: Magnified endoscopy shows round crypts with a sessile pit pattern on the IIa lesion; F: Macroscopic view of the specimen resected by re-endoscopic submucosal dissection. The removed Is+IIa lesion is surrounded by normal mucosa.