Subepithelial Lesions of the Stomach

Abstract

According to a WHO classification published in 2000, gastric tumors can be classified into epithelial, non-epithelial, and secondary tumors. Like many other organs, the stomach may not only be the origin of epithelial tumors and lymphomas but also of a wide range of mesenchymal tumors. Approximately 3 % of all gastric tumors belong to the latter group. Gastric mesenchymal tumors can be subdivided into five main categories according to their cellular origin: true smooth muscle tumor (leiomyoma, glomus tumor, leiomyosarcoma), neurogenic tumor (schwannoma, neurofibroma, ganglioneuroma, paraganglioma), fibroblastic tumor (desmoid, inflammatory myofibroblastic tumor), lipomatous tumor (lipoma), and gastrointestinal stromal tumor (GIST) which has a unique immunohistochemistry (IHC) profile. They manifested themselves as a subepithelial lesion on both imaging and pathologic findings. An exact diagnosis among leiomyoma, schwannoma, and GIST can be sometimes difficult only with hematoxylin-eosin stain on histopathology and requires IHC to differentiate each other. In addition to the tumors, several kinds of benign diseases such as ectopic pancreas, gastritis cystica profunda, and amyloidosis appear as a subepithelial lesion.