Appenix cancer or appendiceal cancer is a malignancy of the vermiform appendix, accounting for about 1 in 200 of all gastrointestinal malignancies. This is a very rare condition and can vary in type, the most common type being carcinoid tumor with adenocarcinoma next. Appendiceal tumors often present with peritoneal seeding, resulting in peritoneal carcinomatosis or Pseudomyxoma peritonei (sometimes known as PMP).