Cytology of non-Hodgkin's malignant lymphomas involving the stomach.

An attempt was made to diagnose cytologically non-Hodgkin's malignant lymphomas (ML) of the stomach on gastric smears in terms of the Kiel classification. This classification represents a more advanced approach for the identification of ML with regard to the cell type specificity, with some functional connotations as compared with previous classifications. The endoscopic brushing cell film studies, when compared with histology of endoscopic biopsies and/or surgical specimens, indicated a high accuracy of cell type identification. Sampling may represent problems in relation to the type of gross lesion. Specific cell types could be recognized in 20 of 25 cases of gastric involvement of ML. Six of nine cases of lymphoplasmacytoid ML revealed diagnostic cells, such as lymphoplasmacytoid cells, plasma cells, lymphocytes, and occasional immunoblasts. Six of seven cases of centrocytic ML had a large number of small cells with indented nuclei, and seven of eight centroblastic-centrocytic ML yielded a mixture of large centroblasts and small centrocytes. In addition to these 24 low-grade ML, one case of unclassifiable high-grade ML was diagnosed. Differential diagnostic problems within ML subtypes and with benign lesions, such as pseudolymphoma of the stomach, as well as malignant tumors and especially diffuse type gastric carcinoma, are taken into consideration.