Epithelial noncarcinoid tumors and tumor-like lesions of the appendix

Mixed Adenocarcinoma-Carcinoid (Collision Tumor) of the Appendix

“…Edmonds et al [5] reported the largest series of 86 cases of goblet cell carcinoid of the appendix. Carr et al [6] described 13 cases of dual carcinoid/epithelial neoplasia occurring in the appendix. Recently Jain and Das [7] described a collision tumor involving the terminal ileum and cecum.…”

Early Results of Surgery in 123 Patients with Pseudomyxoma Peritonei from a Perforated Appendiceal Neoplasm

“…5 There has been considerable confusion in the literature about the classification of epithelial appendiceal neoplasms and their relationship to pseudomyxoma peritonei. 1,[5][6][7][8][9] However, it is now generally agreed that classic pseudomyxoma peritonei arises from a perforated low-grade mucinous neoplasm of the appendix. High-grade colonic mucinous neoplasms, adenocarcinomas of the appendix, and mucinous adenocarcinoma originating from any other intraabdominal organ, particularly the colon, can simulate the clinical, radiologic, and pathologic features of pseudomyxoma peritonei.…”

“…5 In comparison with colorectal neoplasms, appendiceal tumors often have disseminated peritoneal disease at presentation 11 ; however, the disease is less likely to be invasive and more likely to be mucinous in pathologic type. 6,[12][13][14] Appendiceal neoplasms also are less likely to spread via lymphatic and hematogenous routes. Traditionally, patients with pseudomyxoma peritonei have undergone repeated interval debulking procedures for symptom relief but with limited expectation of long-term survival and no prospect of cure.…”

The neoplastic appendix: a practical approach

“…They are comparable to colorectal adenocarcinoma, with a metastatic potential greater than that of appendiceal carcinoid and less than that of colonic carcinoma. 1,2 Reporting is analogous to that for colonic adenocarcinomas; the tumour T staging depends on depth of invasion. 3,4 Prognostic factors included in the pathology report are essentially identical to those for colonic adenocarcinomas (stage, margins).…”

“…30 As such, they have been classified in the past with other neoplasms that show both neuroendocrine and glandular differentiation as "adenocarcinoid tumours," a term that encompasses biologically diverse neoplasms such as tubular pattern carcinoid tumour and a collision tumour of typical carcinoid with a de novo adenocarcinoma. 1 It is best to avoid using this term to avoid confusion; the term "adenocarcinoid" is no longer used by the WHO. Distinguishing GCC from these other entities is important because the clinical characteristics and prognoses are distinct.…”