Adenocarcinoid of the appendix: Report of two cases

Adenocarcinoid of the appendix is a rare tumor with the histological features of both adenocarcinoma and carcinoid tumor. However, its biological behavior and malignant potential are still unclear. We treated two patients with this unusual tumor; a 60-year-old man and a 79-year-old woman. Both patients were initially diagnosed with acute appendicitis followed by an appendectomy. At surgery, the appendix was seen to be acutely inflamed without any macroscopic signs of tumor. Postoperative histological analysis revealed an adenocarcinoid tumor in the appendix, which had spread diffusely into its wall without forming a mass. Immunohistochemical staining with p53, MIB-1, bcl-2, and carcinoembryonic antigen suggested that neither of these tumors were particularly aggressive. Adenocarcinoid of the appendix is a rare tumor, which is very difficult to diagnose preoperatively and even macroscopically, making histological examination essential.