Neoplasms of the Appendix: Pictorial Review with Clinical and Pathologic Correlation

Abstract

Appendiceal tumors—including epithelial mucinous, epithelial nonmucinous, neuroendocrine, and lymphomatous neoplasms—require identification and characterization by the radiologist for optimal management and are discussed in terms of findings at CT, MR imaging, US, somatostatin receptor scintigraphy, and PET, along with demographics, clinical features, histologic and gross pathologic features, staging, surgical approach, chemotherapy, prognosis, and follow-up. Appendiceal neoplasms are uncommon tumors of the gastrointestinal tract that may manifest with symptoms of appendicitis, right lower quadrant pain, or palpable mass, leading to imaging or surgical intervention. The majority of appendiceal masses consist of primary epithelial neoplasms and neuroendocrine tumors (NETs). Epithelial neoplasms—mucinous and nonmucinous types—are more often detected at imaging than NETs due to their larger size and propensity for peritoneal spread and metastatic disease. Epithelial mucinous neoplasms are defined by the presence of mucin, detected at radiologic and pathologic examination. A mucocele or pseudomyxoma peritonei from epithelial mucinous tumors are the two most common cross-sectional imaging findings of appendiceal mucinous neoplasms. Nonmucinous epithelial tumors are less common and manifest as masses similar to colonic-type malignancies. NETs are often discovered incidentally at appendectomy due to their small size and nonaggressive behavior. Imaging findings of pri...