The First Case Report of a Rare Gastric Plexiform Fibromyxoma: Histological Images With an Infiltrative Growth Pattern of Diffuse Infiltration in Stomach.

Abstract Background: Plexiform Fibromyxoma (PF) of the stomach is a very rare mesenchymal tumor of the gastrointestinal tract. We report the first case of PF which was confirmed after surgical resection pathologically. Case summary: The tumor was characterised microscopically infiltrative and diffuse growth into the smooth muscle bundles of the muscularis propria by multinodular and plexiform within myxoid stroma. Immunohistochemistry analysis revealed that the tumor cells were positive or weakly positive for smooth muscle actin (SMA), vimentin and H-caldesmon, and negative for desmin, CD117, CD34, CK-20, Pan-CK, Dog1, S100, ER, PR, and CD10. No mutations of C-kit and platelet-derived growth factor receptor alpha (PDGFRA) were detected in our case. No genetic disruption of glioma-associated oncogene homolog 1 (GLI1) was detected by fluorescence in situ hybridization (FISH). Conclusion: So we mainly relied on the morphological and immunohistochemistry findings and made the final diagnosis of PF.