A 12 year old boy was admitted to the hospital with complaints of stomachache, weight loss, weakness. The first symptoms appeared 6 months ago after intake of the mixture of vinegar, soda and gasoline. The endoscopy showed polypoid mass in the angle of the stomach and malignancy was suspected. Partial resection of the stomach was performed and the boy was discharged from the hospital if satisfactory condition. Microscopic investigation detected spread of fibroblast-like cells containing lengthened nuclei with distinct nucleoli in some of them. There was prominent inflammatory reaction with the presence of neutrophils, macrophages, lymphocytes and many plasma cells. Immunohistochemical analysis showed positive reactions with smooth muscle actin and vimentin. The mass was considered to be an inflammatory pseudotumor. The fact that the lesion developed after the action of the aggressive fluid on the stomach wall permits to consider this event as a possible etiologic factor.