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Int J Clin Exp Pathol 2013;6(3):524-530

Case Report
Primary small cell carcinoma of the stomach: a case report with an immunohistochemical and
molecular genetic analysis

Tadashi Terada

Department of Pathology, Shizuoka City Shimizu Hospital, Shizuoka, Japan

Received December 18, 2012; Accepted January 15, 2013; Epub February 15, 2013; Published March 1, 2013

Abstract: Small cell carcinoma (SCC) of the stomach is extremely rare; about 110 cases have been reported in the world literature.
Immunohistochemical studies of various antigens and genetic studies of KIT and platelet-derived growth factor-α (PDGFRA) have not been
performed in gastric SCC. An 84-year-old man consulted our hospital because of epigastralgia and weakness. Blood test showed anemia and
increased CA19-9 (233 U/ml). Endoscopic examination revealed a large Borrmann type III tumor measuring 6x8 cm in the stomach. Biopsies
from the tumor revealed typical small cell carcinoma with very scant cytoplasm, hyperchromatic nuclei, absent nucleoli, molded nuclei, and
increased nucleo-cytoplasmic ratio. Immunohistochemically, the tumor cells were positive for pancytokeratin (PCK) WSS, PCK MNF-116, PCK
AE1/3, PCK CAM5.2, cytokeratin (CK) 34BE12, CK 5/6, CK7, CK8, CK18, vimentin, EMA, KIT (CD117), CD56, synaptophysin, chromogranin,
NSE, CA19-9, CEA, p53 protein, and Ki67 antigen (Ki-67 labeling = 60%). The tumor cells were negative for CK14, CK19, CK20, PDGFRA,
CD45, CD45RO, CD3, CD20, CD30, and CD79a. A retrospective genetic analysis using PCR-direct sequencing method in paraffin sections
identified no mutations of KIT (exons 9, 11, 13 and 17) and PDGFRA (exons 12 and 18) genes. Various imaging modalities including CT and
MRI showed multiple small metastases in the liver, bilateral lungs, and perigastric lymph nodes. The patient was thus inoperative. The patient
is now treated by cisplatin-based chemotherapy four months after the first manifestation. (IJCEP1212028).

Keywords: Stomach, small cell carcinoma, histopathology, immunohistochemistry, molecular biology of KIT and PDGFRA

Address correspondence to: Dr. Tadashi Terada, Department of Pathology, Shizuoka City Shimizu Hospital, Miyakami 1231 Shimizu-Ku, Shi-
zuoka 424-8636, Japan. Tel: 81-54-336-1111; Fax: 81-54-336-1315; E-mail: piyo0111jp@yahoo.co.jp