The occurrence of disseminated tumors of the appendix is a rare event. Usually appendix tumors are very small, located on the inside of the appendix, and can be pathologically diagnosed. Adenocarcinoid is an uncommon variant of carcinoid tumors that usually arises in the appendix. This report describes a case of a primary adenocarcinoid of the appendix in a patient who was preoperatively diagnosed to have uterus myomatosus but was intraoperatively found to instead have disseminated ovarian carcinoma. This case demonstrates that the clinical picture can be misleading, and that surgeons therefore always have to wait for the final pathological report before making a final diagnosis.