Gastric mucinous myxoma: A case report

Abstract

Gastric mucinous myxoma (GMM), the author’s tentative terminology, has not been reported. The author reports the first case of GMM, a type of myxoma composed mainly of mucins. A 60-year-old man presented gastric discomfort, and received upper gastrointestinal endoscopy, which revealed a raised submucosal tumor (21 mm × 18 mm × 6 mm). He was treated by endoscopic submucosal dissection with a clinical diagnosis of GIST. Microscopically, the lesion was a GMM with well demarcation from surroundings but without capsule. In the periphery of the lesion, there were hyperplastic foveolar glands (HFG) containing much mucus. No epithelial elements were noted in GMM. There were many foci of gradual transitions between GMM and HFG, as if the HFG secrete mucins into the GMM. Histochemically, the GMM and HFG were positive for acidic mucins and neutral mucins. Immunohistochmeical results of the GMM were as follows: CK7-, CK20-, p53-, Ki67 1%, alpha-smooth muscle actin (ASMA)-, desmin-, MUC1-, MUC2-, MUC5AC+, and MUC6+. Immunohistochmeical results of the HFG were as follows: CK7+, CK20+/-, p53-, Ki67 5%, ASMA-, desmin-, MUC1-, MUC2-, MUC5AC+, and MUC6+. The author speculates that the HFG develops, then causes mucous hypersecretion and mucus submucosal accumulation, and then finally creates the GMM.