<p>　We experienced two cases of low-grade appendiceal mucinous neoplasms (LAMNs) that were difficult to distinguish from right ovarian and fallopian tube tumors.</p><p>　Case one was diagnosed as an appendiceal tumor during the operation. Ultrasound and magnetic resonance imaging (MRI) revealed a rod-shaped tumor in the pelvis, leading us to consider the possibility of a right fallopian tube tumor or intestinal tumor rather than a right ovarian tumor. Subsequent computed tomography (CT) ruled out any continuity between the tumor and intestinal tract, eventually confirming a preoperative diagnosis of a right ovarian or fallopian tube tumor. Conversely, Case two was diagnosed as an appendiceal tumor preoperatively. In addition to the aforementioned tests, colonoscopy and barium enema examination were useful. The colonoscopy showed submucosal tumor-like swelling at the cecum, while the barium enema examination revealed a smooth oval filling defect at the cecum, both indicating the likelihood of an appendiceal tumor. Both cases were successfully treated laparoscopically.</p><p>　Among the various differential diagnoses for pelvic tumors, LAMN with appendiceal endometriosis, like Case two, is exceptionally rare, with only two cases reported in English literature to date. To the best of our knowledge, this is the first report on this condition in Japanese literature. A careful operation is crucial to avoid rupture and subsequent pseudomyxoma peritonei. Collaboration with other departments is essential for accurate evaluation and treatment. Furthermore, a minimally invasive approach for appendiceal tumors may become increasingly popular in the future, ensuring careful and effective operations.</p>