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Int J Clin Exp Pathol 2012;5(8):845-851

Case Report
Intramucosal stomach adenocarcinoma metastasizing as a large intraabdominal mass
with focal choriocarcinomatous differentiation

Yukio Fujiyoshi1, Shuying Jiang2,3,4, Xia Feng5

1Department of Anatomic Pathology and Molecular Diagnosis, Nagoya City University Graduate School of Medical Sciences and Medical
School, Nagoya, Japan; 2Niigata College of Medical Technology, Niigata, Japan; 3Department of Cellular Function, Division of Cellular and
Molecular Pathology, Niigata University Graduate Scholl of Medical and Dental Sciences, Niitata, Japan; 4Perseus Proteomics Inc, Tokyo,
Japan; 5The Fraternity Hospital of Nanjing Red Cross, Nanjing, China

Received August 27, 2012; Accepted September 11, 2012; Epub October 1, 2012; Published October 15, 2012

Abstract: We report a case of gastric intramucosal adenocarcinoma giving rise to a large metastatic intraabdominal mass with focal
choriocarcinomatous differentiation. The main histological picture of the surgically resected abdominal tumor was well differentiated
adenocarcinoma with focal choriocarcinomatous differentiation. Serum hCGβ level showed 710mIU/dl postoperatively, and the gastric lesion
featured small foci of well differentiated adenocarcinoma in adenoma with no choriocarcinomatous differentiation. The origin of the abdominal
tumor was the main point of question. HNF4α is a transcription factor of embryonic liver differentiation, whose distribution is restricted to
hepatocytes and certain neoplastic tissue including gastric adenocarcinoma. Hep Par 1 is originally developed for the discrimination of
hepatocellular carcinoma, but a part of gastric adenocarcinoma also shows positive staining. Immunostaining with panel of antibodies for
CK7, CK20, HNF4α, and Hep-Par1 showed pattern of gastric adenocarcinoma, and a diagnosis of a very rare intramucosal gastric
adenocarcinoma metastatic to the abdominal cavity was established. Diagnostic utility of the panels of above antibodies for discrimination of
the tumor origin was confirmed, and the relation between the metastatic ability of the gastric adenocarcinoma and its choriocarcinomatous
differentiation is discussed. (IJCEP1208024).

Keywords: Stomach, choriocarcinoma, Hep-par 1, HNF4α, intramucosal carcinoma

Address all correspondence to:
Dr. Yukio Fujiyoshi, Department of Anatomic Pathology and Molecular Diagnosis, Nagoya City University Graduate School of Medical Sciences
and Medical School. 467-8601 Mizuho-cho, Mizuho-ku, Nagoya, Japan. Tel: 052-853-8161; Fax: 052-851-4161. Email: yfuji@med.nagoya-cu.ac.
jp