A Malignant Gastrointestinal Stromal Tumor of the Gallbladder Immunoreactive for PDGFRA and Negative for CD 117 Antigen (c-KIT)

Gastrointestinal stromal tumors (GISTs) compose the largest category of well-recognized nonepithelial neoplasms of the gastrointestinal tract (GI). GISTs of the gallbladder are extremely rare tumors. Only four malignant, two benign and one GIST-like tumor of the gall bladder have ever been described. The four malignant GISTs were all positive for CD 117 antigen (c-kit). We present for the first time a malignant gastrointestinal stromal tumor of the gallbladder, immunoreactive for platelet-derived growth factor receptor alpha (PDGFRA) and negative for CD 117 antigen (c-KIT).