[648] Poorly Cohesive Carcinomas of the Ampulla of Vater: Analysis of 9 Cases Identified among 249 Ampullary Carcinomas

Kyle Bradley, Kee-Taek Jang, Grace Kim, Serdar Balci, Pelin Bagci, So Yeon Kong, Leslie Ducato, N Volkan Adsay. Emory University, Atlanta, GA; UCSF, San Francisco, CA

Background: There is virtually no data on the ampullary counterpart of carcinomas with single-cell or cord-like infiltration, previously called “diffuse-infiltrative” or “signet ring cell” (SRC), and now designated as “poorly cohesive carcinoma” (PCC) in the WHO 2010 classification.
Design: 249 resected ampullary carcinomas (ACs) were analyzed. 9 (3.6%) had a PCC pattern constituting >50% of the tumor (with or without SRCs) and were analyzed further. Excluded were 19 ACs with SR-like cells occurring in vacuolated type adenoca (infiltrating glandular/cribriform nests with prominent SR-like cells) and 4 with dyshesive SRCs floating within mucin but not infiltrating stroma.
Results: PCC cases were: M:F=5:4; median age=62 years (55-86); median size=2.0 cm (1.3-3.3). In most cases, the majority of tumor cells were pleomorphic with a minor component of SRCs. However, 2 were predominantly composed of small cells with bland cytology reminiscent of mammary lobular carcinoma. 2 cases had prominent plasmacytoid cells. 4 had a microglandular component including 2 with small goblet cell carcinoid-like foci. Conventional intraepithelial neoplasia (dysplasia) was minimal. No cases were associated with adenoma. IHC profile: 7/7 Galectin-3, 6/7 MUC5AC, 5/7 MUC6, 5/7 CK7, 4/7 MUC1, 3/7 e-cadherin loss, 2/7 MUC2 (focal), 0/7 CK20, 0/7 CDX2. MUC5AC helped highlight the subtle infiltration in the mucosa. Most were advanced stage at diagnosis (1 pT2, 6 pT3, 2 pT4). Lymph node metastasis was seen in 4/9 (44%), similar to other ACs (39%). 5/9 died of disease at a median of 22 months. 4 were alive at 4, 9, 15, and 53 months. Survival was significantly worse than intestinal type ACs and trended towards worse than even pancreatobiliary type (Figure).

Conclusions: PCCs are uncommon in the ampulla (3.6%) and are diagnosed at advanced stage. Some cases have a subtle infiltration pattern, which may present a diagnostic challenge; MUC5AC can be helpful in these cases. Ampullary PCCs do not show intestinal differentiation (MUC2/CDX2/CK20 negative). Overall survival is poor, significantly worse than intestinal type ACs and with a trend toward worse than pancreatobiliary type as well.
Category: Gastrointestinal

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 134, Tuesday Morning


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