[761] Very Well Differentiated Gastric Cancer of Intestinal Metaplasia-Type: A Systemic Analysis

Tetsuo Ushiku, Shinichi Ban, Thomas Arnason, Tsunekazu Hishima, Masashi Fukayama, Gregory Y Lauwers. Massachusetts General Hospital, Boston, MA; University of Tokyo, Tokyo, Japan; Saiseikai Kawaguchi General Hospital, Saitama, Japan; Tokyo Metropolitan Komagome Hospital, Tokyo, Japan

Background: Very well differentiated gastric adenocarcinoma of intestinal metaplasia-type (VWDAIM) is a rare variant characterized by morphologic differentiation towards intestinal metaplasia (IM) and low-grade cytologic atypia. Because it mimics IM, a definite biopsy diagnosis is challenging. Small series have been published, but detailed diagnostic criteria and clinical behavior are not fully established.
Design: Slides from the resection specimens of 21 cases of VWDAIM were reviewed and their cytoarchitectural features recorded. Forty histologic pictures of benign IM and VWDAIM were also assessed by a blinded independent reviewer to determine the sensitivity & specificity of the diagnostic features of malignancy. Pre-resection biopsies from 19 cases were also evaluated.
Results: Characteristic architectural features of VWDAIM were branching (100%), tortuous (95%), anastomosing (95%), distended (90%), abortive (81%), spiky (76%), and budding (71%) glands. Cytologic atypia was mild in all cases (Figure 1). Sensitivity and specificity of these features for malignancy are shown in Table 1.

Table 1
FindingsVWDAIM (n=20)IM (n=20)p-valueSensitivitySpecificityOdds Ratio
Tortuous glands10120.75120.50.40.67
Branching glands20120.003310.4-
Distended glands1760.00110.850.713.20
Abortive glands900.00120.451-
Anastomosing glands172<0.00010.850.951.0
Spiky glands1110.00120.550.9523.2
Budding glands160<0.00010.81-

The original preoperative biopsy diagnoses for 19 patients were adenocarcinoma (36%), suspicious for adenocarcinoma (14%), indeterminate for neoplasia (21%), and reactive IM (29%). One patient with a pT4 tumor showing concomitant diffuse-type carcinoma died of disease, while all others were alive and without disease at a mean 13 month follow-up (range 1-56 months).
Conclusions: The features that best differentiate VWDAIM from IM are anastomosing, spiky, abortive, and budding glands. However, a preoperative biopsy diagnosis is achieved in only 50% of the cases. Although VWDAIM is typically thought to be a low-grade cancer, rare cases are associated with diffuse-type carcinoma and have aggressive behavior.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 97, Wednesday Afternoon


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