Deletion of casp8 in B cells leads to B-cell lymphomagenesis. (A) Kaplan-Meier analysis representing the percentage of tumor-free survival in cohorts of WT (n = 12) and bcasp8^−/− (n = 31) mice. (B) Representative splenomegaly and lymphadenopathy displayed by bcasp8^−/− sick mice. Bar indicates 1 cm. (C-D) H&E staining of the spleen of a bcasp8^−/− sick mouse showing tumor cell infiltration predominantly affecting the red pulp. Bar indicates 500 μm. (E-F) H&E staining of intestine from a bcasp8^−/− lymphoma bearing mouse. (E) Expansion of the Peyer patches, with thickening of the sub-mucosa and tumor invasion into the muscle layers and the mucosal lamina propria. Bar indicates 500 μm. (F) These tumors were composed of sheets of small lymphoid cells, many of which showed plasma cell phenotypes. Bar indicates 100 μm. (G-H) LNs infiltrated by tumors in which the normal architecture was partially or completely replaced by tumors and invading into the surrounding adipose tissue. Bar indicates 500 μm in panel G and 100 μm in panel H. *P = .01 for log-rank test between WT and bcasp8^−/− curves.