Figure 1.

A,C, and E depict a low grade gastric marginal zone lymphoma of mucosal associated lymphoid tissue (MALT). B, D, and F depict a gastric diffuse large B cell lymphoma (DLBCL). (A) MALT in a gastric biopsy (H&E, 400X). (B) DLBCL in a gastric biopsy (H&E, 600X). (C) Ki-67 shows a low proliferative index in a low grade MALT (Ki-67 immunohistochemistry, 200X). (D) Ki-67 shows a high proliferative index, 100%, in this DLBCL. The negatively stained cells are the glandular epithelial cells. (Ki-67 immunohistochemistry, 400X). (E) P53 protein is absent in the tumor cells of a MALT, while weak nuclear P53 staining is seen in the adjacent benign glandular epithelium (P53 immunohistochemistry, 1000X). (F) P53 protein overexpression is noted in the tumor cells of this DBLCL, while the cells negative for nuclear P53 immunostaining are benign glandular epithelial cells. (P53 immunohistochemistry, 1000X).