We evaluated a 48-year-old woman presenting with a positive fecal occult blood test result. The patient underwent colonoscopy, which identified a steeply elevated lesion in the cecum. Magnifying endoscopy with narrow-band imaging revealed a type 1 pit pattern, considered non-neoplastic mucosa. Furthermore, endoscopic ultrasonography identified a continuous homogeneous hypoechoic lesion in the fourth layer. We could not exclude a submucosal tumor based on these examination results. Therefore, we observed the area laparoscopically, which revealed appendiceal intussusception. Consequently, we performed a partial appendicectomy. Pathological examination confirmed endometrial glands in the muscularis propria, consistent with appendiceal endometriosis. This case emphasized that we should consider endometriosis-induced appendiceal intussusception as a differential diagnosis in childbearing-age women with an appendiceal mass.
