Assessment of new macroscopical classification of gastric malignant lymphoma

We macroscopically classified gastric malignant lymphoma into ST type (submucosal tumor type), non-ST type (non-submucosal tumor type) and Combined type (combination of ST and non-ST type) and assessed this new classification by examining 60 surgically resected cases. Of these, 18 cases (21 lesions) were classified into ST type, 38 cases (54 lesions) into non-ST type and 4 cases (4 lesions) into Combined type. All the large cell, immunoblastic type cases were of ST type and most of the diffuse, small cleaved cell type cases and all the plasmacytoma cases were of non-ST type. Diffuse, large cell type and diffuse, mixed type cases did not seem to be biased toward any of these three macroscopical types. The non-ST type cases frequently showed an infiltrative growth pattern and reactive lymphoid cell hyperplasia adjoining the lesions, while the ST type cases frequently showed an expansive growth pattern without reactive lymphoid cell hyperplasia. The Combined type cases showed both infiltrative and expansive growth patterns in the same lesion. The macroscopical classification defined in this study can be considered useful in determining a range for surgical resection of gastric malignant lymphoma.