[1840] The Significance of Poorly Differentiated (Undifferentiated) Component in Gallbladder Carcinomas (GBC): Clinicopathologic Analysis of 54 Cases Identified in 628 GBC

Olca Basturk, Pelin Bagci, Oscar Tapia, Juan Carlos Roa, Kee-Taek Jang, Nevra Dursun, Samip Patel, Jeanette Cheng, Sudeshna Bandyopadhyay, Ipek Erbarut, So Yeon Kong, Juan Sarmiento, Volkan Adsay. MSKK, New York; Emory University, Atlanta; UFRO, Temuco, Chile; Piedmont Hospital, Atlanta; WSU, Detroit

Background: Recent studies have revealed that even a small poorly-differentiated epithelioid component (PDE) in endometrial and GI-tract carcinomas is of biologic and prognostic significance, and a percentage is associated with MSI and even HNPCC. PDE has not been investigated in gallbladder carcinomas (GBC) although GB is cited among the HNPCC-related organs.
Design: The presence and potential associations of PDE component was investigated in 628 GBCs.
Results: 54 (8.6%) GBC had a PDE component manifested in 3 patterns (Figure): medullary (syncitial growth of large zones of epithelioid cells forming nodules with pushing-border infiltration, associated with inflammatory cells; n=41); hepatoid (sheet-like zones of hepatoid cells in trabecular arrangement; n=4) and in widely separated small, solid, rounded nests (n=9). Cases with PDE as compared to those without were: F/M=3.3 (vs 4); mean age=67 (vs 64); advanced stage (T3)=57% (vs 49%; p=0.13). Six had an intramucosal PDE component. PDE was associated with more aggressive behavior [67% increase in mortality with HR=1.67 (95% CI=1.2-2.33); p=0.003]. However, this appeared to be partially stage dependent. MSI was shown by immunohistochemistry in 14% (3/22 tested), 2 of which were hepatoid. PDE component was positive for AE1/AE3 in all, CK18 in 91%, CK20 in 14%, MUC1 in 68%, CEA in 53%, EMA in 86%, CA 19-9 in 28%, p63 in 41%, p53 in 73%. KI-67 index was ≥ 15% in 83%. Hepatoid cases were positive for Heppar1 in 3/4 tested and closely mimicked hepatocellular carcinoma.

Conclusions: Poorly differentiated epithelioid (PDE) component occurs in 8.6% of GBC, and shows an aggressive behavior as expected from undifferentiated/high-grade carcinomas including endometrial ones, although the adverse prognosis may be related to its propensity for advanced stage. MSI by IHC is seen in 14%. The presence of PDE component in GBC should be duly reported and considered for MSI testing, especially those with hepatoid pattern.
Category: Pancreas

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 262, Tuesday Morning


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