A case of appendiceal mucous cyst diagnosed by EUS and laparoscopic resection

The case is a 52-year-old man. He was admitted to our hospital with colonoscopy (CS) showing appendiceal swelling and increasing lesions over time. Contrast-enhanced computed tomography (CT) showed a 10 mm-sized mass lesion which was originated from cecal wall. CS showed a elevated lesion on the appendix with a smooth surface of 10 mm in size and covered by normal mucosa. Endoscopic ultrasonography (EUS) revealed the lesion as a 13 mm-sized cystic lesion, and the inside was dense with fine spotty echoes. No nodules or papillae were found inside. Based on the above, appendiceal mucous cystadenoma was suspected, and laparoscopic partial cecal resection was performed. The final pathological diagnosis was a WHO-classified low-grade appendiceal mucinous neoplasm.