A Gastrointestinal Stromal Tumor of the Stomach Demonstrating a Stepwise Progression from Low- to High-Grade Malignancy
Figure 1
Light microscopic findings. (a) Whole-mount section of the tumor, with the ulcerated mucosal area to the left (hematoxylin and eosin, HE); bar, 1 cm. The area within the box is shown at a higher magnification in (b). (b) Highly aggressive tumor cells forming a demarcated area in the center, which is the only area where necrosis and hemorrhage were observed. The other areas comprised the less aggressive tumor cells (HE). (c) Higher magnification of the less aggressive tumor cells. The admixture of epithelioid and short spindle cells is shown (HE). (d) Higher magnification of the highly aggressive tumor cells. Note the higher cellular density and mitotic activity compared with (c). Mitotic activity is indicated by arrows (HE). (e) Tumor cells were immunopositive for KIT, irrespective of the area (KIT immunohistochemistry). (f) A clear demarcation line is shown by CD34 immunostaining. The positive and negative areas correspond to the less and highly aggressive tumor cells, respectively. (g) A low Ki-67 index is observed in the less aggressive areas. (h) A high Ki-67 index is observed in the highly aggressive area.
