The volcano sign and mucus outflow by colonoscopy - Low grade appendiceal mucinous neoplasm.

An 82-year-old woman presented with painless hematochezia. Colonoscopy revealed a submucosal tumor-like mass in the cecum. The appendiceal orifice was identified in the center of the prominence, showing the volcano sign. The yellowish mucus was discharged from the orifice like a lava flow, the so-called mucus outflow. She underwent laparoscopic appendectomy based on the diagnosis of appendiceal mucinous neoplasm. The pathological diagnosis was low grade appendiceal mucinous neoplasm, that is a clinical entity characterized by absence of infiltrative growth or destructive invasion. The differential diagnosis includes appendiceal polyps, lipomas, neuroendocrine neoplasms, and endometriosis. Our case underscores the importance of the volcano sign and the mucus outflow for the preoperative diagnosis of appendiceal mucinous neoplasm.