Positive immunohistochemical staining for KIT (CD117) in a spindle cell type gastrointestinal stromal tumor (GIST)

(A) Low magnification (10x) image of a section of a spindle type GIST stained for KIT expression by immunohistochemistry. The positive tumor cells are brown, and the surrounding tissue is negative. Note the KIT-positive mast cells (arrows) in a lymphoid aggregate.
(B) High magnification (20x) image shows typical membrane and cytoplasmic KIT staining with dot-like enhanced staining of the Golgi apparatus. The tumor vasculature does not stain for KIT.