Appendix cancer for gastroenterologists.
Colonoscopy rarely catches it, but the appendiceal orifice can hint.
Appendiceal cancer usually sits beyond the reach of the colonoscope, but gastroenterologists still see the clues: a bulging appendiceal orifice, mucin at the cecal pole, a mucocele on imaging, or a patient referred for vague abdominal symptoms that do not add up.
What the appendiceal orifice can show
A mound or bulge at the appendiceal orifice, or mucin extruding from it, can signal a mucocele or an underlying mucinous neoplasm. The volcano sign, mucin welling from the orifice, is the classic description. These findings deserve cross-sectional imaging and a surgical opinion rather than reassurance.
Colonoscopy is not a screen for appendix cancer
Most appendiceal tumors never reach the lumen, so a normal colonoscopy does not rule one out. When a patient has imaging findings or symptoms suggestive of appendiceal disease, a clean colonoscopy should not close the case. This is a tumor found at appendectomy or on imaging, not on screening.
Handle a suspected mucocele with care
Resist the urge to biopsy or resect a suspected appendiceal mucocele endoscopically. Rupture can spill mucin into the peritoneum and worsen the disease. The safer path is to characterize it with imaging and refer for surgical evaluation, where it can be removed intact.
When to refer
An imaged mucocele, mucinous ascites, or unexplained appendiceal findings warrant surgical and peritoneal surface malignancy referral. Management follows the 2025 appendiceal consensus guideline, not colorectal protocols. This guide is a practical orientation, not a substitute for procedural judgment and local pathways.
Seeing mucin or a mucocele?
Image it, leave it intact, and point the patient toward the right surgical team.
How to Refer a Patient Standard of Care