Journal of Pathology and Translational Medicine

Original Articles

Primary Extragastrointestinal Stromal Tumor (EGIST) of the Greater Omentum.: Kyung Un Choi, Jee Yeun Kim, Do Youn Park, Chang Hun Lee, Mee Young Sol, Kang Suek Suh, Jun Woo Lee; Korean J Pathol. 2001;35(4):347-350.

Abstract PDF: Gastrointestinal stromal tumors (GISTs) were recently defined as spindle cell, epithelioid, or occasionally, pleomorphic mesenchymal tumors of the gastrointestinal tract that express the CD117 (proto-oncogene c-kit protein, stem cell factor receptor), as detected using immunohistochemistry. And they show a new tendency to include the CD117-positive mesenchymal spindle cell or epithelioid neoplasms primary in the omentum and mesentery, and is so termed extragastrointestinal stromal tumors (EGISTs). Omental EGISTs are very rare and similar to their gastrointestinal counterpart. We present a case of primary EGIST of the greater omentum in a 58-year-old man. The resected tumor mass measured 20X15X5 cm and weighed 1,150 g. The cut surface displayed a central cystic change and partial mural nodules. Microscopically, most parts of the tumor were composed of round or polygonal cells, with many of them containing perinuclear vacuoles. The mitotic count was less than one per 50 high-power-fields. Immunohistochemically, the tumor cells were diffusely positive for CD117 and vimentin, and focally for smooth muscle actin and CD34. Ultrastructurally, partially smooth muscle differentiation was confirmed in this case.

Immunohistochemical Expression of CD117, CD34, Vimentin and alpha-Smooth Muscle Actin in Gastrointestinal Stromal Tumors.: Jong Kuk Kim, O Jun Kwon, Byung Heon Kim; Korean J Pathol. 2001;35(6):506-512.

Abstract: BACKGROUND
The interstitial cell of Cajal (ICC), the cell of origin for gastrointestinal stromal tumor (GIST), expresses CD117 (c-kit) which is a receptor for KIT ligand in cell membranes. It is immunohistochemically positive for CD117, CD34 and vimentin, but not for alpha-smooth muscle actin (SMA).
METHODS
We performed the immunohistochmical study with anti-CD117, anti-CD34, anti-VMT and anti-alpha-SMA in paraffin-embedded tissue of 28 GISTs and 19 smooth muscle tumors arising in the gastrointestinal tract, mesentery, omentum and retroperitoneum (GISMT) to determine the precise nature of GIST cells.
RESULTS
The positive rates of CD117, CD34 and vimentin in extraGISTs were significantly higher than in GISMTs. The positive rate of alpha-SMA in GIST was not significantly different than in GISMTs.
CONCLUSIONS
A subset of GISTs may express alpha-SMA as well as CD117 and the cell of their origin may be a ICC precursor cell which is capable of differentiating bidirectionally into ICC and smooth muscle cell. This explains why GISTs may arise out of gut where ICC is not present and that they may represent the tumors arising from ICC precursor cell present around the gastrointestinal tract.

Search