Xanthogranulomatous gastritis associated with actinomycosis: report of a case presenting as a large submucosal mass.

Xanthogranulomatous gastritis (XGG) is a rarely encountered condition, and its causative mechanism is still unclear. Given that some types of xanthogranulomatous inflammation (XGI) are associated with pathogens, infection should be considered as a possible cause of XGG. Herein, we report a case of an 86-year-old woman presenting with a large, bleeding lesion resembling a submucosal tumor. Distal gastrectomy was performed, and the surgically resected specimen revealed a mass measuring 6 × 4.5 × 3 cm and appearing yellowish on the cut surface. Histopathological examination revealed a few Actinomyces "sulfur granules" and cellular composition characteristic of XGI, supporting a diagnosis of XGG associated with actinomycosis. Gastric actinomycosis is a rare condition and has not previously been reported in association with XGG, although rare cases of XGI associated with actinomycosis have been documented in other organs.