Primary appendiceal adenocarcinoma of colonic type with perforating peritonitis

Primary adenocarcinoma of the appendix is rare, especially the colonic type. We report a case of appendiceal adenocarcinoma of colonic type associated with perforating peritonitis after aorto-femoral artery bypass surgery. A 79-year-old woman presented with fever and pain in the right lower abdomen. She had undergone aorto-femoral artery bypass surgery due to arteriosclerosis obliterans 6 months earlier. Abdominal ultrasonography and computed tomography showed a suspected pool of fluid surrounding the artificial vessel and a mass lesion in the upper end of the fluid collection. These findings suggested localized peritonitis due to appendiceal perforation. Emergency laparotomy showed a pool of pus around the artificial vessel and inflamed appendix, which adhered to the surrounding tissue. The mass was excised in combination with an ileocaecal resection, followed by an ileocolic anastomosis. The histological diagnosis was moderately differentiated adenocarcinoma of the appendix, colonic type. The tumour had infiltrated and obstructed the lumen of the orifice of the appendix, which may have caused perforation of the appendix. She was examined at regular periodic follow-ups and no evidence of recurrence or metastasis was noted in the 12-month postoperative period. These findings indicate that, in cases of acute appendicitis, especially with perforation, the possibility of appendiceal adenocarcinoma should be considered.