We report a case of appendiceal mucocele which could be diagnosed preoperatively. A 40-year-old man was admitted to our hospital complaining of a palpable mass in the right lower part of the abdomen. Abdominal plain roentgenogram, barium enema, ultrasonogram and computed tomogram revealed calcified tumor in the ileocaecal region. The diagnosis of appendiceal mucocele was made and laparotomy was performed. The tumor coincided with the location of the appendix, ileocecal excision being carried out. The excised tumor had partially uneven wall, and was filled with gelatin-like substance. The pathohistological diagnosis was mucinous cystadenoma, borderline malignancy.
Appendiceal mucocele is rare and difficult to be diagnosed preoperatively. We discussed the way of preoperative diagnosis and surgical procedures for appendiceal mucocele.