RESUMEN
Plexiform angiomyxoid myofibroblastic tumor (PAMT) of the stomach is a recently recognized entity. Because of its rarity, only 22 cases have been reported in the English-language literature and most of these are single case reports. We report two cases of gastric PAMT. The tumor cells were bland and plexiform arranged in a myxoid stroma, which was positive for alcian blue. Immunohistochemically, the tumor cells were positive for smooth muscle actin, but negative for c-kit, CD34, desmin, S-100 protein, epithelial membrane antigen, neurofilament, and protein kinase C-theta. Mutation analyses for exon 9, 11, 13, and 17 of KIT genes and 12, 14, and 18 of the platelet-derived growth factor receptor alpha (PDGFRA) genes were performed and the tumors were wild-type for mutation.
RESUMEN
Plexiform angiomyxoid myofibroblastic tumor (PAMT) of the stomach is a recently recognized entity. Because of its rarity, only 22 cases have been reported in the English-language literature and most of these are single case reports. We report two cases of gastric PAMT. The tumor cells were bland and plexiform arranged in a myxoid stroma, which was positive for alcian blue. Immunohistochemically, the tumor cells were positive for smooth muscle actin, but negative for c-kit, CD34, desmin, S-100 protein, epithelial membrane antigen, neurofilament, and protein kinase C-theta. Mutation analyses for exon 9, 11, 13, and 17 of KIT genes and 12, 14, and 18 of the platelet-derived growth factor receptor alpha (PDGFRA) genes were performed and the tumors were wild-type for mutation.
RESUMEN
Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a recently described mesenchymal tumor of the stomach. We report the first case of PAMT in Korea. A 52-yr-old man underwent esophagogastroduodenoscopy due to dyspepsia for 2 yr. There was a submucosal mass with small mucosal ulceration in the gastric antrum. The tumor measured 3.5 x 2.3 cm in size and showed multinodular plexiform growth pattern of bland-looking spindle cells separated by an abundant myxoid or fibromyxoid matrix rich in small thin-walled blood vessels. The tumor cells were negative for CD117 (c-KIT), CD34 and S-100 protein, but diffusely positive for smooth muscle actin consistent with predominant myofibroblastic differentiation. The patient is doing well without recurrence or metastasis for 5 months after surgery. Although there have been limited follow-up data, PAMT is regarded as a benign gastric neoplasm with histological and immunohistochemical charateristics distinguished from gastrointestinal stromal tumor and other mesenchymal tumors of the stomach.