There are several classifications of appendicular epithelial cancer with a wide variety of nomenclature. Epithelial tumours of the appendix have been classified into four distinct types: carcinoids, mucinous adenocarcinoma (often called mucinous cystadenocarcinoma or malignant mucocele), colonic-type adenocarcinoma, and adenocarcinoids with a dual cell origin. We report a case of a woman who presented to our emergency unit with a history of acute appendicitis and who had undergone an appendectomy. The histopathological analysis showed the presence of a well differentiated mucinous adenocarcinoma, infiltrating the full thickness of the appendix wall.