Elsevier

Human Pathology

Volume 33, Issue 11, November 2002, Pages 1078-1085
Human Pathology

Original Contributions
Expression of cytokeratins 7 and 20 in primary carcinomas of the stomach and colorectum and their value in the differential diagnosis of metastatic carcinomas to the ovary

https://doi.org/10.1053/hupa.2002.129422Get rights and content

Abstract

The expressions of cytokeratin (CK) 7 and 20 have been studied in various primary and metastatic carcinomas, and their determination may help distinguish the site of origin of metastatic carcinomas. However, little is known about the factors that determine variations in their expression patterns in primary gastric and colorectal carcinomas. We investigated the expressions of CK7 and CK20 in 289 cases of gastric carcinoma and 225 cases of colorectal carcinoma using a tissue microarray. To evaluate CK7 and CK20 expression patterns of ovarian metastases from gastric or colorectal carcinomas, 54 cases of metastatic carcinomas to the ovary were examined. It was found that 71% (207 of 289) of the gastric carcinomas stained positively for CK7, whereas only 9% (21 of 225) of the colorectal carcinomas proved to be CK7 positive, and that 41% (117 of 289) of the gastric carcinomas and 73% (165 of 225) of the colorectal carcinomas were CK20 positive. The proportion of CK7+/CK20− was highest in the gastric carcinomas at 46% (132 of 289), and was independent of the histologic classification of Lauren (46% of the intestinal type, 45% of the diffuse type). The CK7 and CK20 expression patterns were different in colorectal carcinomas according to histologic grade and location of the tumor. CK7−/CK20+ had the greatest proportion (68%) in colorectal carcinomas, and this was dependent on the tumor's histologic grade (75% of low-grade versus 52% of high-grade) and location (46% of right-sided versus 76% of left-sided). Moreover, 42% (18 of 43) of gastric carcinomas metastatic to the ovary were CK7+/CK20−, whereas 19% (8 of 43) were CK7−/CK20+. All colorectal cancers metastatic to the ovary were CK7−/CK20+, except 1 case that was CK7−/CK20−. In conclusion, the CK7 and CK20 expression patterns in primary gastric carcinomas vary considerably, and those in colorectal carcinomas are associated with histologic grade and tumor location. The CK7−/CK20+ expression pattern is specific for metastatic colorectal carcinomas to the ovary, but has low predictability for colorectal origin in metastatic ovarian carcinoma. HUM PATHOL 33:1078-1085. Copyright 2002, Elsevier Science (USA). All rights reserved.

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Tissue samples

Paraffin-embedded tissue sections were obtained from archival material from 289 patients who underwent resection for primary gastric carcinoma in 1995, 225 patients who underwent resection for primary colorectal carcinoma in 1998, and 43 patients with metastatic carcinomas to the ovary who underwent surgery between 1992 and 1999. All cases were selected from files at the Department of Pathology, Seoul National University Hospital. Pathologic information, including stage and histologic

CK7 and CK20 expression in gastric cancer

In normal gastric mucosa, foveolar epithelial cells and scattered endocrine cells in the upper glandular zone stained positive for CK20, whereas mucous neck cells stained positive for CK7. In complete intestinal metaplasia, CK7 was not expressed, but CK20 was strongly expressed in both the surface epithelium and the proliferative zone. In incomplete intestinal metaplasia, CK7 was expressed in both the surface and the proliferative zone, with progressively decreasing reactivity from the

Discussion

The combined expression of CK7 and CK20 has recently been proposed as an aid to the determination of the site of origin of metastatic carcinomas. However, little is known of the combined expression of these CKs for carcinomas of the stomach.

CK20 positivity was reported in about 50% of gastric carcinomas,2, 9, 11, 12 and CK7 reactivity was reported in 60% to 75% of specimen examined.9, 11, 12 However, the number of cases was too few to accurately represent the immunoreactivity of CK7 and CK20 in

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