Gastric mesenchymal lesions other than gastrointestinal stromal tumor

Interpretation of gastrointestinal mesenchymal lesions involving the stomach and the remainder of the gastrointestinal tract is daunting but can be simplified somewhat merely by knowing in which layer they are usually found. For example, gastric Kaposi sarcoma is detected in mucosal biopsies whereas inflammatory fibroid polyp is nearly always in the submucosa. Gastrointestinal stromal tumors (discussed elsewhere in this issue) are generally centered in the muscularis propria. Gastric schwannomas are essentially always in the muscularis propria. Mesenteric lesions are usually found in the small bowel mesentery but the gastric mesentery is not immune. Knowledge of the favored layer is even more important in interpreting colon biopsies, since many mesenschymal polyps are encountered in the colon, but the same principle applies in the stomach. Herein we discuss several gastric mesenchymal lesions.