Colon adenocarcinoma with dome-like phenotype: characteristic endoscopic ultrasonography (EUS) findings

• Main Authors: Wataru Takagi, Katsumi Yamamoto, Takahiro Amano, Aisa Sakamoto, Yuriko Otake, Hirotsugu Saiki, Hisashi Kondo, Makiko Urabe, Kei Takahashi, Masashi Yamamoto, Shiro Hayashi, Sachiko Nakajima, Tsutomu Nishida, Takamichi Komori, Shunji Morita, Shiro Adachi, Masami Inada
• Format: Article
• Language: English
• Published: Georg Thieme Verlag KG 2015-05-01
• Series: Endoscopy International Open
• Online Access: http://www.thieme-connect.de/DOI/DOI?10.1055/s-0034-1392019

An 80-year-old man underwent colonoscopy for proctorrhagia. Conventional white-light imaging showed a superficially flat and elevated lesion that appeared to be a submucosal tumor of the sigmoid colon. Chromoendoscopy with Indigo Carmine showed that the margin of the tumor was covered with normal epithelium but that there was a slight depression on its surface. Magnification endoscopy with Crystal Violet staining revealed the amorphous surface structure of the depressed lesion, but the surrounding mucosa showed a normal pit pattern. Endoscopic ultrasonography demonstrated that a hypoechoic mass was located in the submucosal layer, and a biopsy specimen obtained from the surface of the lesion showed evidence of adenocarcinoma. We then performed sigmoidectomy on the patient. Immunohistochemically, the tumor cells were positive for two mismatch repair proteins (MLH1 and MSH2), but in situ hybridization revealed that the specimen was negative for the Epstein – Barr virus. We finally diagnosed the lesion as adenocarcinoma with a dome-like phenotype of the sigmoid colon.