Korean J Gastroenterol.  2010 Nov;56(5):319-323. 10.4166/kjg.2010.56.5.319.

A Case of Primary Extragastrointestinal Stromal Tumor Presenting as Peritoneal Dissemination

  • 1Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea. drkimtaeho@yahoo.co.kr
  • 2Department of Pathology, The Catholic University of Korea College of Medicine, Seoul, Korea.


Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract, but also occurs at a lower frequency in extra-gastrointestinal regions such as omentum, mesentery, retroperitoneum and undefined abdominal sites. This tumor is called extragastrointestinal stromal tumor (EGIST). EGIST is mostly diagnosed as a cystic mass, but rarely occurs as a disseminated abdominal tumor. We experienced a 70-year-old man with primary EGIST presenting as peritoneal dissemination. Abdominal CT showed diffuse peritoneal thickening with a large amount of ascites, but no definite mass lesion. Laparoscopic biopsy was performed and histologic findings showed tumor composed of epithelioid cells. In the results of immunohistochemical stains, the tumor showed positive reactivity with CD117 (c-kit), CD34, vimentin and actin, but negative reactivity with desmin and S-100 protein. On account of unresectability and histologic parameters of malignant behavior, he was started on imatinib.


Gastrointestinal stromal tumor; Extragastrointestinal stromal tumor; Peritoneum

MeSH Terms

Antigens, CD34/metabolism
Gastrointestinal Stromal Tumors/*diagnosis/pathology
Peritoneal Neoplasms/*diagnosis/secondary
Positron-Emission Tomography
Proto-Oncogene Proteins c-kit/metabolism
Tomography, X-Ray Computed


  • Fig. 1. Abdominal CT finding. Diffuse peritoneal wall thickening was noted with a large amount of ascites. This finding was prominent in the greater omentum.

  • Fig. 2. Small bowel series and PET-CT findings. (A) Small bowel series showed a normal contour without evidence of extrinsic compression. (B) Diffuse FDG uptake along the peritoneal surface was noted. This finding was consistent with peritoneal carcinomatosis.

  • Fig. 3. Laparoscopic finding. Multiple tumor nodules were scat-tered on the peritoneal surface.

  • Fig. 4. Microscopic findings. (A) The tumor was composed of epithelioid cells (H&E stain, ×100). (B) The tumor cells showed high cel-lularity, but no necrosis (H&E stain, ×400).

  • Fig. 5. Immunohistochemical findings. Tumor cells were positive for CD117(c-kit) (A), CD34 (B), vimentin (C), and actin (D). However, tumor cells were negative for desmin (E) and S-100 protein (F) (×200).


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