Appendiceal adenocarcinoma associated with Amyand's hernia: a case report.

We encountered a rare case of appendiceal carcinoma associated with Amyand's hernia, which was difficult to diagnose preoperatively. A 74-year-old man presented to our hospital with right lower abdominal pain. A hard mass was palpable in the right lower abdomen, and blood tests showed a slightly elevated inflammatory response. Computed tomography revealed a 7 × 5 cm mass with indistinct borders and heterogeneous internal density extending from the cecum to the right lower abdominal wall. We diagnosed appendiceal abscess, however, percutaneous biopsy which was performed for differential diagnosis with appendiceal carcinoma showed no malignancy. Thereafter, the patient was followed up. Two months later, a blood test showed insignificant changes in the inflammatory response and a high serum carcinoembryonic antigen level (48.6 ng/mL). An ultrasound showed a mass contiguous to the appendix, extending to the abdominal wall, with abundant blood flow signals. Fluorodeoxyglucose-positron emission tomography showed a high accumulation of fluorodeoxyglucose in the mass. Four months after the initial visit, the patient had an open ileocecal resection combined with an abdominal wall resection based on the preoperative diagnosis of appendiceal carcinoma invading the abdominal wall. During laparotomy, an enlarged appendix tip extended from the internal inguinal ring outside the inferior epigastric artery to the abdominal wall. Histopathological examination of the appendiceal tumor revealed well-differentiated adenocarcinoma, T4b (abdominal wall), N0, Ly0, and V0. When a right lower abdominal mass extends from the cecum to the abdominal wall, appendiceal tumors associated with Amyand's hernia should be considered.