A 62 year-old male underwent colonoscopy, which led to the detection of an 8mm polyp at the appendiceal orifice, partially inverting into the appendix. On endoscopic evaluation, no findings indicative of cancer were recorded, although the inversion prevented examination of the entire lesion. Contrast enhanced abdominal computed tomography suggested appendiceal mucocele while histopathology was consistent with tubular adenoma. A laparoscopic cecal resection was ultimately favored over endoscopic resection, as the lesion had not been fully assessed. A histopathologic examination of the resected specimen revealed low-grade dysplasia as well as a site of submucosal invasion up to 1000µm. The patient underwent additional laparoscopic ileocecal resection with lymphadenectomy. No residual lesions or lymph node metastases were found. In this interesting case, the well-differentiated adenocarcinoma, stage T1b (SM) , ly0, v0, N0- IB, could not be diagnosed preoperatively despite a full work-up.
