title: Appendiceal goblet cell carcinoid and mucinous neoplasms are closely associated tumors: lessons from their coexistence in primary tumors and concurrence in peritoneal dissemination.
abstract: BACKGROUND
  Goblet cell carcinoid (GCC) and appendiceal mucinous neoplasms (AMNs) are considered as different appendiceal tumors. Coexistence of both tumors was occasionally noted. We further observed the concurrence in both primary tumors and their peritoneal dissemination, that is, peritoneal carcinomatosis (PC) including pseudomyxoma peritonei (PMP).
  
  
  METHODS
  Review of our 10-year file identified two subgroups of cases with such concurrence. Group 1 is 14 cases of PC/PMP treated by surgical cytoreduction. Morphologic components of GCC, low-grade mucinous neoplasm (LMN), mucinous adenocarcinoma (MCA), and non-mucinous adenocarcinoma (NMCA) were identified separately in different organs/tissues. Group 2 is eight cases of localized primary tumors of appendix and ileocecal junction.
  
  
  RESULTS
  In Group 1, primary tumors (11 GCC, 1 GCC + LMN, 1 MCA, 1 NMCA) were identified in appendix (13) and in rectum (1). Further review identified mixed morphologic components in 7/12 GCC cases, including GCC + LMN (2), GCC + MCA (2), GCC + NMCA (1), and GCC + MCA + NMCA (2). Over peritoneal dissemination, GCC and/or other components were coexistent at different sites and in variable combinations. In Group 2, primary tumors were initially diagnosed as GCC (7) and MCA (1). Further review identified mixed components in all cases, including GCC + LMN (3), GCC + LMN + MCA (3), GCC + MCA + NMCA (2).
  
  
  CONCLUSIONS
  GCC may present as a component mixed with AMNs and even with conventional adenocarcinoma in both primary tumors and metastatic lesions. AMN in any given single case may show a wide morphologic spectrum. GCC and AMN may share a common tumor stem cell with potential of multiple lineage differentiations.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Calgary and Calgary Laboratory Services, Calgary, Alberta, Canada.
authors.forename: Denise
authors.initials: D
authors.lastname: Ng
authors.forename: Vincent
authors.initials: V
authors.lastname: Falck
authors.forename: Yarrow J
authors.initials: YJ
authors.lastname: McConnell
authors.forename: Lloyd A
authors.initials: LA
authors.lastname: Mack
authors.forename: Walley J
authors.initials: WJ
authors.lastname: Temple
authors.forename: Xianyong
authors.initials: X
authors.lastname: Gui
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D001062:Appendectomy; D001063:Appendiceal Neoplasms / Q000473:pathology* / Q000601:surgery; D002276:Carcinoid Tumor / Q000473:pathology* / Q000601:surgery; D002432:Cecum / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D007082:Ileum / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000473:pathology* / Q000601:surgery; D010534:Peritoneal Neoplasms / Q000473:pathology / Q000601:surgery; D011553:Pseudomyxoma Peritonei / Q000473:pathology / Q000601:surgery; D012004:Rectal Neoplasms / Q000473:pathology / Q000601:surgery
keywords: appendiceal mucinous neoplasms; goblet cell carcinoid; mucinous carcinoma; peritoneal carcinomatosis; pseudomyxoma peritonei; vermiform appendix