Endosonographic examination (EUS) holds an important place not only in local staging of tu- mours, intramural lesions of focal gastric lesions in general but also in the diagnosis of diffuse thickening of its wall. The authors examined 11 patients with a gastric wall rigid on endoscopy where collection of samples with bioptic forceps did not lead to diagnosis. EUS examination revealed massive thickening of the wall in more than half the circumference of the gastric lumen, with loss of the normal layered USG structure of the wall. The final histological examination (9× from resected portions of the stomach, 1× from a specimen obtained by laparoscopy and 1× by laparotomy) revealed in three instances a lymphoma (1× MALT lymphoma, 2× non-Hodgkin lym- phoma with a high malignity), in five instances diffuse dissociated carcinoma with a varying amount of mucus production or fibroproduction resp., in three patients a slightly differentiated, mucus forming adenocarcinoma. In both dissociated diffuse carcinomas where EUS did not fore- see infiltration of the muscularis propria the finding was falsely negative as a result of microsco- pic infiltration of the musculature. Conclusion: It is useful to examine an endoscopic finding of a rigid gastric wall endosonographi- cally even when the histological examination of bioptic specimens of the mucosa is negative because a predominantly submucous infiltration of the gastric wall with a malignant tumour may be involved. In case of thickening of the wall with a disrupted USG structure it is useful to obtain a large specimen for histological examination either by means of a loop or by surgery, because there is great danger of malignity.

        Key words: endosonographic examination – diffuse infiltration of the stomach