title: Plexiform angiomyxoid myofibroblastic tumor of the stomach.
abstract: We report 2 cases of plexiform angiomyxoid myofibroblastic tumor of the stomach, a tumor entity that has not been described previously. The patients were a 50-year-old man (case 1) and a 68-year-old man (case 2). In case 1, the patient presented with acute abdominal pain. The tumor in case 2 was incidentally found at laparoscopic cholecystectomy. Grossly, the tumors were 4.0 cm (case 1) and 4.5 cm (case 2) in their greatest dimension, and they were recognized as submucosal tumors. The tumor caused gastric perforation in case 1. Histologically, the tumors extended from the serosa to the submucosa of the gastric wall, showing a plexiform growth pattern. Bland spindle tumor cells were observed, and they were separated by abundant intercellular myxoid matrix. The stroma was rich in small vessels. Immunohistochemically, the tumor cells were positive for alpha-smooth muscle actin and muscle actin, and negative for KIT, CD34, and S-100 protein. Electron microscopic findings were consistent with the myofibroblastic nature of the tumor cells. No mutations were found in the c-kit and platelet-derived growth factor receptor alpha genes. Although clinical follow-up data were insufficient, the histologic appearances suggested the benign nature of the tumors. However, the tumor in case 1 caused gastric perforation and necessitated an emergency operation.
authors: Department of Pathology, Teikyo University School of Medicine, Tokyo, Japan. ytakaha-tky@umin.ac.jp
authors: Yoshihisa
authors: Y
authors: Takahashi
authors: Seiichiro
authors: S
authors: Shimizu
authors: Tsuyoshi
authors: T
authors: Ishida
authors: Kiyoshi
authors: K
authors: Aita
authors: Suzuko
authors: S
authors: Toida
authors: Toshio
authors: T
authors: Fukusato
authors: Shigeo
authors: S
authors: Mori
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D003593:Cytoplasm / Q000648:ultrastructure; D003937:Diagnosis, Differential; D018572:Disease-Free Survival; D005743:Gastrectomy; D046152:Gastrointestinal Stromal Tumors / Q000737:chemistry / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D047708:Myofibroma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D009232:Myxoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D013274:Stomach Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor