Low-grade appendiceal mucinous neoplasm at appendiceal orifice treated via appendectomy with double purse-string...

Low-grade appendiceal mucinous neoplasms (LAMNs) are a class of histologically well-differentiated adenomas that can proliferate outside the appendix in the form of malignant tumours, resulting in the accumulation of external appendiceal mucus. They may present as an extra-appendiceal mass-like bulge, mucus or polypoid tissue at the appendiceal orifice, or even with abdominal dissemination. The surgical approach is usually appendectomy, ileocecal resection or right hemicolectomy. It is essential to raise awareness of LAMNs and choose an appropriate treatment.

A 68-year-old man underwent a routine physical examination at our hospital on May 17, 2022. The patient had no symptoms of abdominal pain, bloating, or weight loss, and his tumour marker levels were normal. The faecal occult blood test was negative, and no abnormalities were identified on physical examination. Colonoscopy revealed a submucosal protrusion at the appendiceal orifice. During endoscopic ultrasound, uneven echoes were observed in the appendix cavity. A contrast-enhanced computed tomography scan of the abdomen revealed a nodular thickening at the base of the appendix, with a diameter of approximately 1 cm. When all the examination results were considered, we suspected the lesion to be an appendiceal mucinous tumour. Laparoscopic surgery was performed using the double purse-string suture method. Postoperative pathology suggested a low-grade mucinous cystadenoma of the appendix with no involvement of the margins. A repeat colonoscopy 18 months after surgery revealed no significant abnormality at the appendiceal orifice. A contrast-enhanced computed tomography scan of the abdomen suggested only postoperative changes.

This study describes a case of LAMN that was treated by resecting the mass at the appendiceal orifice via the double purse-string suture technique and provides new insights on the diagnosis and treatment of LAMNs.