Primary Adenocarcinoma of the Appendix: Report of an Unusual Case of Appendiceal Malignancy

The relative rarity of tumors of the vermiform appendix is well-established, for these lesions constitute less than 0.5% of all gastrointestinal neoplasms.¹ The incidence of neoplastic disease found in surgically removed appendices is also quite small, being reported in several large series as 0.35% to 0.38%.² Of the tumors of the appendix, the vast majority are malignant or are generally considered so. There are 3 well-defined histological types of appendiceal malignancy, namely, carcinoid, malignant mucocele, and adenocarcinoma.³ The reported relative incidence of these types varies, but all writers agree that carcinoid tumors are by far the most common, comprising 89% to 93% in several series of reported cases. Malignant mucoceles, called by some "cystic carcinomas," account for approximately 8% of appendiceal cancer.⁴ Primary adenocarcinoma of the appendix in most reported series accounts for less than 0.4% of all appendiceal malignancies, but the incidence varies widely due