When and When Not to Perform a Right Colon Resection with Mucinous Appendiceal Neoplasms.

BACKGROUND: Mucinous appendiceal neoplasms (MAN) with peritoneal dissemination is treated as a standard of care using cytoreductive surgery and hyperthermic perioperative chemotherapy. The extent of the resection of peritoneal surfaces and visceral structures is generally well defined. Exception to this consensus regarding structures to be removed are the right colon and adjacent ileocolic lymph nodes.

METHODS: From a prospectively maintained database, all patients with a histologic diagnosis of peritoneal mucinous carcinoma (PMCA) who underwent complete cytoreductive surgery were assessed for the presence versus absence of adenocarcinoma in lymph nodes within the appendiceal mesentery and/or in the lymph nodes of the ileocolic group. The histologic grade of the PMCA was correlated with the incidence of lymph node invasion. Also, in those PMCA patients who had no evidence of lymph node invasion, recurrence within the ileocolic lymph nodes was determined by computed tomography or second look.

RESULTS: In a database of MAN patients, 299 had a histologic diagnosis of PMCA. In well-differentiated (n = 44), moderately differentiated (n = 107), and poorly differentiated (n = 148) PMCA specimens, there were 6.8, 5.6, and 29 % positive lymph nodes, respectively. None of these 151 patients with well- or moderately differentiated PMCA had a computed tomographic scan or clinical evidence by second-look surgery of recurrence within the ileocolic lymph nodes.

CONCLUSIONS: There is a low incidence (6.0 %) of positive lymph nodes in patients with low or moderately differentiated PMCA. With high-grade disease, lymph node invasion increased to 29.0 %. Right colectomy is indicated in patients with high-grade PMCA.