Content area
Full Text
* Context.-The appendix gives rise to an array of epithelial neoplasms showing glandular or neuroendocrine differentiation, and some tumors with elements of both cell types. Although some appendiceal neoplasms resemble their counterparts in the small and large intestines (conventional adenocarcinoma and carcinoid tumor), the appendix also gives rise to relatively unique entities including mucinous neoplasms and goblet cell carcinoid tumors, which present a challenge in pathologic classification and clinical management.
Objective.-To review clinical and diagnostic issues for 3 pathologic types of epithelial neoplasms of the appendix: (1) adenocarcinoma, with specific focus on mucinous neoplasm; (2) goblet cell carcinoid tumor and associated adenocarcinoma; and (3) typical carcinoid tumor.
Data Sources.-Case-derived material and literature review.
Conclusion.-The most important issue in pathologic assessment of epithelial tumors of the appendix is to understand the clinical implications inherent in the diagnosis.
(Arch Pathol Lab Med. 2010;134:1612-1620)
Epithelial tumors of the appendix essentially resemble, with more or less fidelity, their counterpart epithelialcell types of the normal mucosa. Appendiceal adenocarcinomas have a phenotype similar to that of conventional colonic adenocarcinomas,1,2 although mucinous neoplasms are more common in the appendix than in the colon.3 Because of its association with the clinical condition of pseudomyxoma peritonei (PMP), appendiceal mucinous neoplasm is associated with complex clinical and pathologic issues concerning its nomenclature, tumor staging, and clinical decisions about the management of local and disseminated disease.4-6 Typical carcinoid tumors of the appendix7,8 exhibit an exclusive neuroendocrine phenotype with the capacity for amine and peptide hormone production.9,10 In contrast, goblet cell carcinoid tumors of the appendix are rare, and they have a mixed phenotype with partial neuroendocrine differentiation and intestinaltype goblet cell morphology.11,12 As such, they have been classified together with other neoplasms that show both neuroendocrine and glandular differentiation. It remains controversial whether goblet cell carcinoid tumors should be considered as variants of appendiceal adenocarcinoma or as part of the carcinoid tumor spectrum.12-14
MUCINOUS NEOPLASMS OF THE APPENDIX
A mucinous adenocarcinoma of the appendix may be 1 of 2 major types: 1 type resembles conventional colonic adenocarcinoma and possesses the potential for destructive growth and nodal or solid organ metastasis; the other is associated with predominantly low-grade mucinous neoplasms and possesses the potential for peritoneal dissemination. Among epithelial neoplasms of the appendix, mucinous neoplasm is...