Pseudomyxoma peritonei: Review of the controversy

Summary‘Pseudomyxoma peritonei’ (PMP) is the clinical term traditionally applied to the debilitating syndrome of grossly apparent gelatinous ascites associated with peritoneal deposits of mucinous tumours. For many years, PMP was mainly attributed to mucinous neoplasms arising in the ovary. However, in recent decades, it has become clear that most of this syndrome is related to discontinuous spread from the appendix. Despite the uniformly malignant clinical presentation noted among all histological grades of fully developed PMP, the pathological nomenclature advocated by some authors has continued to include non-malignant terms (reminiscent of the ovarian tumours classified as borderline) for those frequent cases with very-well-differentiated histology. This article will review the clinical and pathological features of PMP in the context of the literature, and maintain that, regardless of how well differentiated they are, all cases of PMP are examples of mucinous carcinoma. Grading as either low- or high-grade carcinoma is indicated for prognostication. This article will also discuss the terminology for mucinous appendiceal neoplasms removed from patients who have not yet developed PMP.