GIST : Epithelioid with Signet Ring Cell Pattern

Rarely, epithelioid GISTs may display cytoplasmic vacuolation distinct from the evenly distributed, round vacuoles seen as an artifact of fixation. These may be reministent of the appearance of diffuse gastric adenocarcinoma, signet ring cell type. That tumor usually does not form a discrete mass, however, and other areas of the GIST should make the diagnosis of a mesenchymal tumor more obvious.