Cancer De Mama

REVIEW ARTICLE

Appendiceal Mucinous Tumors and
Pseudomyxoma Peritonei
Histologic Features, Diagnostic Problems, and Proposed Classification
Reetesh K. Pai, MD and Teri A. Longacre, MD

Abstract: 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 toappendiceal 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 pseudomyxomaperitonei syndrome with emphasis on differential diagnostic considerations and recommendations for the final pathology report.
Key Words: appendix, mucocele, mucinous adenoma, pseudomyxoma peritonei, low malignant potential, mucinous adenocarcinoma
(Adv Anat Pathol 2005;12:291–311)

‘‘M

ucocele of the appendix is an uncommon but
mysterious condition about which a large volume of
literaturehas accumulated without much clarification of the
underlying pathology.. The mystery deepens when ‘pseudomyxoma peritonei,’ which is a complication of mucocele of
the appendix, is considered.’’1
Despite numerous advances in our understanding of
appendiceal mucinous neoplasms and their relationship to the
pseudomyxoma peritonei syndrome in the last decade, most
surgical pathologists, after anencounter with one of these
problematic lesions, are left with the feeling that not a lot has
changed in the 30 years since Gibbs first reported his experience with 10 cases of mucocele of the vermiform appendix.
Appendiceal mucoceles are uncommon entities arising in
association with a variety of underlying pathologic processes,
only a subset of which are associated with the subsequentdevelopment of pseudomyxoma peritonei. The increased incidence of this syndrome in women in association with ovarian
mucinous tumors has confounded any understanding of
the appendiceal mucocele and has created considerable

From the Department of Pathology, Stanford University School of Medicine,
Stanford, CA.
Reprints: Teri A. Longacre, Department of Pathology, Stanford University
School ofMedicine, Room L235, 300 Pasteur Drive, Stanford, CA 94305
(e-mail: longacre@stanford.edu).
Copyright Ó 2005 by Lippincott Williams & Wilkins

Adv Anat Pathol  Volume 12, Number 6, November 2005

controversy regarding the pathology and site of origin of
pseudomyxoma peritonei and its ultimate relationship to the
appendiceal mucinous tumors. The use of different diagnostic
terms for the sameproliferations in different studies in the
gastrointestinal and gynecologic literature has additionally
hindered the development of a unified and coherent approach
to the diagnosis and management of appendiceal mucinous
lesions and their sequelae.2–5
To clarify the diagnostic features of these lesions and
to provide guidelines for the diagnosis and management of
patients with these conditionsthat more closely reflect and
predict their biologic behavior, we are in the process of evaluating the clinicopathologic features of appendiceal mucinous
neoplasms with and without associated pseudomyxoma
peritonei diagnosed at Stanford University during the past
40 years. Based on the preliminary results of this study in conjunction with a review of the literature experience, we havedeveloped a classification scheme for the epithelial proliferations most commonly associated with appendiceal ‘‘mucoceles’’ and ‘‘pseudomyxoma peritonei.’’ The proposed
classification system of these entities and relevant differential
diagnostic problems forms the subject of this discussion.

MUCOCELE
Although there are a variety of historic connotations
associated with the appendiceal mucocele,...