Case Report
Copyright ©2012 Baishideng. All rights reserved.
World J Gastrointest Oncol. May 15, 2012; 4(5): 119-124
Published online May 15, 2012. doi: 10.4251/wjgo.v4.i5.119
Greater omentum gastrointestinal stromal tumor with PDGFRA-mutation and hemoperitoneum
Yoko Murayama, Masayuki Yamamoto, Ryuichiro Iwasaki, Tamana Miyazaki, Yukiko Saji, Yoshinori Doi, Haruki Fukuda, Seiichi Hirota, Masahiro Hiratsuka
Yoko Murayama, Ryuichiro Iwasaki, Tamana Miyazaki, Yukiko Saji, Department of Gastroenterology and Hepatology, Itami City Hospital, Itami 6648540, Japan
Masayuki Yamamoto, Masahiro Hiratsuka, Department of Surgery, Itami City Hospital, Itami 6648540, Japan
Haruki Fukuda, Department of Pathology, Itami City Hospital, Itami 6648540, Japan
Yoshinori Doi, Department of Gastroenterology and Hepatology, Otemae Hospital, Osaka 5400008, Japan
Seiichi Hirota, Department of Surgical Pathology, Hyogo College of Medicine, Nishinomiya 6638501, Japan
Author contributions: All authors read and approved this manuscript; Murayama Y, Iwasaki R, Miyazaki T, Saji Y and Doi Y were involved in the care of the patient; Fukuda H and Hirota S studied the specimens; Yamamoto M and Hiratsuka M performed the surgery; Murayama Y wrote the paper.
Correspondence to: Yoko Murayama, MD, PhD, Department of Gastroenterology and Hepatology, Itami City Hospital, 1-100 Koyaike, Itami 6648540, Japan.
Telephone: +81-72-7773773 Fax: +81-72-7819888
Received: September 21, 2011
Revised: February 12, 2012
Accepted: March 14, 2012
Published online: May 15, 2012

Although gastrointestinal stromal tumor (GIST) occurs generally in the digestive tract, omental GIST is very rare. We report the first case of an adult greater omental GIST with a new platelet-derived growth factor receptor α gene (PDGFRA)-mutation with hemoperitoneum. A 43-year-old man was admitted to our hospital complaining of acute abdominal pain. Abdominal contrast-enhanced computed tomography revealed a huge mass in the right abdominal cavity, and a large accumulation of fluid in the pelvic cavity, suggesting hemoperitoneum. We diagnosed the rupture as an intra-abdominal tumor, and an emergency tumorectomy was performed with resection of the greater omentum. This tumor was located in the distal right side of the greater omentum, and showed no continuity with the gastric wall. The tumor occurred primarily in the greater omentum. The resected tumor was about 19 cm × 12 cm × 14 cm in diameter, and weighed 1529 g. Histologically, the tumor was composed of epithelioid-shaped cells with high cellularity, and was positive for CD117 and CD34, and negative for S-100, α-smooth muscle actin. The mitosis was 6/50 under high power field. This case showed exon 18 mutation of PDGFRA with 846 (Asp to Glu) substitution, 848 (Asn to Lys) substitution. This is the first report of this PDGFRA mutation in omental GIST, and this might play an important role in the tumorigenesis of this case. Based on these findings, the tumor was diagnosed as high risk GIST primarily occurring in the greater omentum. The patient was treated with imatinib at a dose of 400 mg/d as adjuvant chemotherapy, and has been followed up for 24 mo with no evidence of recurrence.

Keywords: Gastrointestinal stromal tumor, Greater omentum, Hemoperitoneum, Platelet-derived growth factor receptor α gene, KIT