Current concepts in pseudomyxoma peritonei.

Each year, about two per million individuals will be diagnosed with pseudomyxoma peritonei, a disease characterised by the intra-abdominal growth of neoplastic mucin-secreting cells on peritoneal surfaces. The distribution of the disease within the abdomen is not random but depends on physiological principles. Most cases derive from neoplasms of the appendix. In the past, the ovary was considered a common primary site. However, we now know that the ovary is only rarely the source of pseudomyxoma, and that lesions which would previously have been called "borderline mucinous tumours of the ovary" are typically metastatic from the appendix. The grade of the neoplastic cells in pseudomyxoma is an important prognostic factor, but unfortunately there is no consensus on terminology. An international expert group of pathologists and clinicians is currently working on the harmonisation of terminology in this field. Expertise in the management of pseudomyxoma can be achieved by concentrating the treatment of patients in specialised centres or through the development of networks.