[764] Clinicopathologic Features of Ampullary Adenocarcinoma of Indeterminate Histologic Type (Non-Intestinal, Non-Biliary)

Lizette Vila Duckworth, Ahmad Alkhasawneh, Neelam Desai, Xiaomin Lu, Alex Sommerfeld, Thomas George, Tania Zuluaga Toro. University of Florida, Gainesville, FL

Background: Ampullary adenocarcinoma (CA) can be categorized morphologically into biliary and intestinal types. However, some cases fail to show classic morphologic features of either subtype. This study aims to describe the immunophenotypic and clinical characteristics of ampullary CA with indeterminate morphology.
Design: 63 cases of ampullary CA resected between 2000-2011 were assessed for CK7, CK17, CK20, SMAD4 and CDX2 expression by immunohistochemistry. Age, gender, tumor stage, and clinical outcome (death, recurrence) were recorded. Patients were divided into 3 groups based on tumor morphology: biliary (cuboidal lining), intestinal (columnar cells and/or cribriform architecture) or indeterminate (overlapping features or unusual morphology). CK7, CK17 and CK20 were interpreted as positive (≥5% reactivity) and negative (<5% reactivity). CDX2 was interpreted as homogeneous (strong nuclear staining in ≥ 75% of tumor), heterogeneous (weak nuclear staining in <75% of tumor), or absent. SMAD4 was interpreted as positive (strong staining in all or subset of tumor cells) and impaired (absent or weak reactivity relative to surrounding normal pancreas).
Results: 14 cases were of indeterminate subtype. The following staining profile was observed: 79% CK7 positive, 50% CK17 positive, 38% CK20 positive, 7% CDX2 positive, and 64% impaired SMAD4. 71% of these patients were stage T3/T4 and 57% had lymph node metastasis. Recurrence rate was 44% and death rate was 43% in patients with indeterminate tumors.

Clinicopathologic features of ampullary CA subtypes
 Indeterminate (n=14)Biliary (n=31)Intestinal (n=18)
Mean age65.569.368.1
Male: Female ratio11.21.6
CK7 positive11299
CK17 positive7223
CK20 positive5315
CDX2 positive1151
Impaired SMAD49248
Stage T1/T2449
Stage T3/T410279
Lymph node metastasis8174
Recurrence481
Deceased6207



Conclusions: The immunophenotype of the indeterminate tumors more closely resembles the biliary subtype of ampullary CA (CK7 positive, heterogeneous to absent CDX2, and impaired SMAD4). The clinical behavior of these tumors is intermediate between that of the biliary and intestinal subtypes, though closer to the biliary type.
Category: Gastrointestinal

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 109, Tuesday Afternoon

 

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