[661] "Crawling-Type" Adenocarcinoma of the Stomach: A Distinct Entity Preceding Poorly Differentiated Adenocarcinoma

Hiroshi Kawachi, Naoko Okamoto, Tatsuya Yoshida, Keisuke Kitagaki, Masaki Sekine, Maki Kobayashi, Kazuyuki Kojima, Tatsuyuki Kawano, Yoshinobu Eishi. Tokyo Medical and Dental University/Clínica Las Condes, Santiago, Chile; Tokyo Medical and Dental University, Tokyo, Japan; Kudanzaka Hospital, Tokyo, Japan

Background: Gastric ''crawling-type'' adenocarcinoma (CTAC) is a neoplasm histologically comprising irregularly fused glands with low-grade cellular atypia that tends to spread laterally in the mucosa.

Although the importance of this subgroup has been mentioned, the clinicopathological characteristics have not been adequately described.
Design: To elucidate the clinicopathological characteristics of CTAC, we evaluated 25 CTACs, 16 intramucosal (M-) and 9 submucosal invasive (SM-) cancers, clinicopathologically and immunohistochemically.
Results: CTAC was most frequently located in the lesser curvature of the middle-third of the stomach. Macroscopically,21 lesions were superficial-depressed and 4 were superficial-flat type. Histologically, all CTACs had cystic dilated glands and 16 lesions had focal signet-ring cells. All invasive areas of the SM-CTACs were occupied by poorly differentiated adenocarcinoma with an infiltrative growth pattern and abundant stroma. Fifteen CTACs were surrounded by mucosa with partial or no intestinal metaplasia. In the intramucosal area, 24 lesions were mixed phenotype with mucin and brush border immunoexpression. SM-CTAC was frequent in lesions with an intramucosal poorly differentiated component (PDC) greater than 10 mm in size (P = 0.041), and lymph node metastasis (LNM) was frequent in lesions with a PDC greater than 20 mm (P = 0.039). The frequency of an expanded pattern (Ki-67-positive cells occupying > 50 % of the mucosa) was higher in SM-CTAC than in M-CTAC (P = 0.027). p53 overexpression was not detected in the intramucosal areas of any of the lesions.
Conclusions: The use of the diagnostic term "CTAC" has implications for selecting a distinct subgroup of gastric adenocarcinomas in the early phase. A larger PDC area and an expanded of Ki-67-positive cells have practical implications for the prediction of submucosal invasion or LNM.
Category: Gastrointestinal

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 96, Wednesday Afternoon


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