A Case of Gastric Stromal Tumor

Takayuki Kanno, Toshiro Konishi, Shingo Okada, Shoji Shimoyama, Masanori Teruya, Syunji Araki, Keiichi Hojo and Takahisa Nagayama^*

Department of Surgery, Showa General Hospital
^*Department of Pathology, Showa General Hospital

For years, primary nonepithelial gastrointestinal tract tumor's origin was thought to be smooth muscle from microscopic findings. But many of these tumors have failed to show either muscle or neural differentiation by immunohistochemical study and by electroscopic findings, thus, they are now called gastrointestinal stromal tumors (GIST). A case of gastric stromal tumor is reported, which was thought to be a leiomyosarcoma before operation, however, determination of the tumor as smooth muscle, neural or fibrous tumor by microscopic finding only was difficult. Immunohistochemical study and electroscopy were used to diagnose a gastric stromal tumor. Immunohistochemical studies failed to show positivity in muscle or neural markers, and only vimentine and CD-34 were positive. Electroscopical study showed no findings to support the tumor's muscle, neural nor fibrous differentiation. Because immunohistochemical and electroscopic study are commonly used to diagnose gastrointestinal tract tumors nowadays, the number of GIST cases is increasing. There has been no parameter which clearly predicts the malignant potential of GISTs. Accumulation of GIST cases and their long-term follow-up is needed to clarify the biological mechanisms.

Key words
gastrointestinal stromal tumor, gastric submucosal tumor, leiomyosarcoma

Reprint requests
Takayuki Kanno Second Department of Surgery, Tokyo University School of Medicine 7-3-1 Hongo, Bunkyo-ku, Toyko, 113-0033 JAPAN

Accepted
May 25, 1999

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