[743] Significance of Signet-Ring Cells in Extracellular Mucin Pools Versus Tissue in High-Grade Mucinous Carcinoma Peritonei

Joseph Sirintrapun, Aaron Blackham, Greg Russell, Jonathan Stewart, Perry Shen, Edward Levine, Kim Geisinger, Simon Bergman, Adela Cimic. Wake Forest Baptist Health, Winston Salem, NC; UNC Chapel Hill, Chapel Hill, NC

Background: Bradley et al.(2006) termed appendiceal pseudomyxoma peritonei as mucinous carcinoma peritonei (MCP) and proposed a two tiered (low vs high) scheme.Later Chua et al.(2012) validated this classification with 2,298 patients.Under this scheme,signet-ring cells (SRC) are classified as high-grade mucinous carcinoma peritonei (HG-MCP).Unknown was whether SRC occurs in otherwise low-grade mucinous carcinoma peritonei (LG-MCP) and whether SRC within extracellular mucin pools and in tissue differ prognostically.
Design: Our hypotheses are 1)SRC occurs only in HG-MCP and 2)SRC invading tissue conveys a worse prognosis vs SRC within mucin pools.We retrospectively examined appendiceal MCP (n=55) and confirmed cases as LG-MCP or HG-MCP.Extra attention was given for SRC presence (n=29) which was then subdivided into Group A SRC within mucin pools (n=20) and Group B SRC invasive in tissue (n=9).
Results: Zero LG-MCP cases (n=12) and 29 of 43 HG-MCP cases had SRC.In cases with SRC (Groups A and B),all non-SRC tumoral areas met Bradley criteria for HG-MCP.Group A was younger than Group B (mean age 46.8 vs 54.5,p=0.03) with no differences with race or sex.In Group A,15 cases showed focal vs abundant SRC in mucin pools.In Group B,1 of 10 cases showed focal vs extensive SRC tissue invasion.Kaplan-Meier analyses with log-rank approximation of chi-square test showed shorter overall survival (OS) for Group B.

For Group A,1 and 2 year OS was 89.2% (+/-SE 7.2%) and 55.7% (+/-SE 11.7%) respectively.For Group B,1 and 2 year OS was 33.3% (+/-SE of 15.7%) and 11.1% (+/-SE 10.5%) respectively.Group A median OS was 29.4 months vs 6.3 months for Group B (p=0.0025).
Conclusions: SRC does not occur with LG-MCP.SRC in mucin pools is often focal,but non-SRC areas meet Bradley criteria for HG-MCP.SRC therefore equates with HG-MCP.SRC tissue invasion most often was extensive.Group A behaved similar to published data of HG-MCP but Group B showed more dismal prognosis.Qualification of SRC in extracellular mucin or tissue appears justified in reporting of HG-MCP with SRC.
Category: Gastrointestinal

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 115, Wednesday Morning


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