Appendiceal mucinous tumors and pseudomyxoma peritonei: histologic features, diagnostic problems, and proposed classification.

Pseudomyxoma peritonei is an overused and underspecified condition that has garnered much attention in the historic literature. In recent years, this condition has been convincingly linked to appendiceal mucinous neoplasms, yet there has been insufficient attention to the histologic characteristics, classification, and differential diagnostic considerations of these neoplasms when encountered by the surgical pathologist. This review provides a coherent approach to the diagnosis and classification of appendiceal mucinous tumors and the peritoneal implants associated with the pseudomyxoma peritonei syndrome with emphasis on differential diagnostic considerations and recommendations for the final pathology report.