Figure 2.

Heterogeneity of GISTs in one patient (case 1). Case 1A, a GIST at the greater curvature of the stomach, showed spindle cell and in distinct storiform morphology, with the strong expression of CD117, DOG1 and CD34 and the presence of KIT exon 11 substitution (p.V560D, arrow). By contrast, case 1B, a GIST at the lesser curvature of the stomach, had epithelioid morphology with uniform nuclei and cytoplasmic vacuoles. The tumor was positive for DOG1 and CD34 but negative for CD117. Mast cells served as an internal positive control. No mutation involving KIT exon 11 was detected in case 1B. Images show H&E, CD117, DOG1 and CD34 staining (magnification, ×200). GIST, gastrointestinal stromal tumor; DOG1, discovered on GIST-1; KIT, KIT proto-oncogene, receptor tyrosine kinase; H&E, hematoxylin and eosin.