A c-kit-negative gastrointestinal stromal tumor with a platelet-derived growth factor receptor alpha mutation.

Gastrointestinal stromal tumors (GISTs) are well-recognized mesenchymal neoplasms of the intestinal tract. A diagnosis of GIST is not always possible using IHC techniques for detection of c-kit. The authors describe a 64-year-old man who presented with an upper abdominal quadrant mass.