Consenso INDEPSO-ISPSM sobre Neoplasias Mucinosas Apendiculares y Pseudomixoma Peritoneal

Mucinous appendiceal neoplasm (MANs) and pseudomyxoma peritonei (PMP) are very rare conditions with distinct therapeutic challenges. This consensus exercise was carried out to address clinically pertinent issues not addressed in existing international guidelines on the subject and reinforce some important recommendations from these guidelines. The modified Delphi method was employed with two rounds of voting. There were 42 questions on seven key issues (treatment approach and pre-operative work up; management of incidental MANs; management of high-volume PMP, the role of hyperthermic intraperitoneal chemotherapy (HIPEC); management of PMP with extraperitoneal disease; the role of systemic chemotherapy; follow-up after cytoreductive surgery (CRS), management of recurrence). A consensus was achieved if anyone option received > 70 votes (strong consensus > 90%). In round 1, 45/45 (100%) panelists voted; round 2, 39/45 (86.6%). A consensus was achieved on 36/42 (88.0%) questions (strong consensus-16.6%). In post-appendicectomy scenarios, CRS-HIPEC was recommended for patients with perforated (pT4) high grade appendiceal mucinous neoplasms (HAMN) with involved margins, pT4 poorly differentiated tumours, pT4 signet ring cell tumours in the absence of peritoneal disease and in all patients with overt peritoneal disease. No consensus was reached on post-appendicectomy management of pT3 HAMNs and intraoperatively detected MANs with peritoneal spread. HIPEC in addition to CRS was recommended for PMP. Some debatable interventions were recommended in selected patients like a total gastrectomy with a total colectomy, fertility-sparing surgery, two-stage CRS, and CRS in the presence of extraperitoneal disease. The panelists agreed with international recommendations on the management of established peritoneal disease but was more stringent in recommending prophylactic CRS and HIPEC in the post-appendicectomy scenarios.

The online version contains supplementary material available at 10.1007/s13193-025-02265-0.