MUC5AC and mucinous adenocarcinoma: The Peritoneal Surface Oncology Group International (PSOGI) classification, which has been validated on several occasions (7, 8), divides PMP into four groups based on histological characteristics: i) acellular mucin (AM), ii) low-grade mucinous carcinoma (LG-PMP), iii) high-grade mucinous carcinoma (HG-PMP), and iv) PMP with the presence of signet ring cells (SRC) (4).