[A Case of Appendiceal Carcinoma That Was Preoperatively Diagnosed].

The patient is a 63-year-old woman who presented to our hospital with anorexia. A CT scan revealed a lead pipe-like structure extending from the cecum, characterized by wall thickening and a villous appearance. Initially suspecting appendicitis with abscess, she was managed with interval appendectomy and antimicrobial therapy. However, with minimal abdominal pain and considering the possibility of appendiceal cancer, colonoscopy was performed on the 8th day of admission, revealing a protruding lesion compressing the appendiceal orifice. Pathological examination confirmed adenocarcinoma, leading to the diagnosis of appendiceal cancer. On the 16th day of hospitalization, she underwent laparoscopic ileocecal resection with D3 lymph node dissection. The final diagnosis was appendiceal mucinous carcinoma, T1, N1a, M0, Stage ⅢA. She received 10 courses of postoperative adjuvant chemotherapy with mFOLFOX6 and has remained recurrence-free for 29 months post-surgery. The preoperative diagnosis of primary appendiceal cancer is challenging. Appendicitis with nonspecific physical findings should raise suspicion of appendiceal cancer as a complication.