A rare case report: low grade appendiceal mucinous neoplasm (LAMN) located under the left costal margin, the gastric level and the transverse colon.

We report a case with a low-grade appendiceal mucinous neoplasm, located under the left costal margin, the gastric level and the transverse colon. The mucinous appendiceal neoplasm has caused intussusception of the appendix in the cecum, completely dislocating the cecum on the left side of the upper abdomen. In such cases, it is important to diagnose prior to surgical treatment to avoid mucocele perforation and intraoperative dissemination. The patient underwent a right hemicolectomy procedure, completely removing the mass according to oncological principles. The atypical localization of the cecum leads to difficulty in diagnosing the mucinous neoplasm of the appendix. It is important to know the diagnosis before the operation to plan the right course of treatment.