title: Pseudomyxoma Peritonei of Extra-Appendiceal Origin: A Comparative Study.
abstract: Pseudomyxoma peritonei (PMP) usually originates from appendiceal neoplasms and, less commonly, from extra-appendiceal lesions. To date, the clinical and therapeutic implications of extra-appendiceal origin are largely unknown.
  
  
  
  A prospective database of 225 PMP patients uniformly treated by cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) was reviewed to identify cases with extra-appendiceal primaries. Histologically, negative appendix defined extra-appendiceal origin. Clinical, pathological, and immunohistochemical features (cytokeratin [CK]-20, CK-7, CDX-2, MUC-2, MUC-5A) were correlated with the site of origin. PMP was categorized into low or high grade, according to the 2010 World Health Organization (WHO) classification. The main independent variable for survival analysis was appendiceal versus extra-appendiceal primary.
  
  
  
  In 19 patients (8.4 %), PMP origin was the ovary (n = 9), uterine cervix (n = 1), mature cystic teratomas (n = 4), and unknown (n = 5). Appendiceal and extra-appendiceal PMP groups were comparable for all characteristics, except for a prevalence of females in the latter. Median follow-up was 64.1 months (95 % confidence interval [CI] 53.9-80.1), and 10-year overall survival was 63.4 % (median 148.2 months; 95 % CI 131.2-165.2) for appendiceal PMP, and 62.0 % (median not reached) for extra-appendiceal PMP. The difference was not significant at univariate ( p = 0.297) and multivariate analysis (hazard ratio 1.51, 95 % CI 0.78-3.14; p = 0.278). High-grade peritoneal histology (p = 0.007), prior systemic chemotherapy (p = 0.003), more than four visceral resections (p = 0.011), and incomplete cytoreduction (p = 0.021) independently correlated with poorer survival.
  
  
  
  Clinical-pathological features of PMP, and outcome after CRS/HIPEC, did not differ according to the primary site, thus suggesting that PMP is a relatively homogeneous disease that can be produced by a range of histopathologic entities. Extra-appendiceal origin does not contraindicate CRS/HIPEC.
authors.affiliation: Peritoneal Malicnancy Program, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: Baratti
authors.affiliation: Peritoneal Malicnancy Program, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kusamura
authors.affiliation: Department of Pathology, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Milione
authors.affiliation: Department of Oncology, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Pietrantonio
authors.affiliation: Department of Oncology, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Caporale
authors.affiliation: Peritoneal Malicnancy Program, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Guaglio
authors.affiliation: Peritoneal Malicnancy Program, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy. marcello.deraco@istitutotumori.mi.it.
authors.forename: Marcello
authors.initials: M
authors.lastname: Deraco
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000008:administration & dosage; D001063:Appendiceal Neoplasms / Q000473:pathology*; D000071616:CDX2 Transcription Factor / Q000378:metabolism; D065426:Cytoreduction Surgical Procedures; D005260:Female; D006801:Humans; D006979:Hyperthermia, Induced; D053554:Keratin-20 / Q000378:metabolism; D053552:Keratin-7 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D055271:Mucin 5AC / Q000378:metabolism; D055262:Mucin-2 / Q000378:metabolism; D060787:Neoplasm Grading; D018365:Neoplasm, Residual; D009382:Neoplasms, Unknown Primary / Q000473:pathology*; D010051:Ovarian Neoplasms / Q000473:pathology*; D010534:Peritoneal Neoplasms / Q000556:secondary / Q000628:therapy*; D011553:Pseudomyxoma Peritonei / Q000473:pathology / Q000628:therapy*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D013724:Teratoma / Q000556:secondary*; D002583:Uterine Cervical Neoplasms / Q000473:pathology*
chemical_list: D000970:Antineoplastic Agents; D000071616:CDX2 Transcription Factor; D053554:Keratin-20; D053552:Keratin-7; C524625:MUC2 protein, human; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D055262:Mucin-2