PDPN and diffuse large B-cell lymphoma: An expansion of stretched PDPN+, SMA+ FRCs was similarly detected in diseased spleens and LNs from IμHABcl6 mice (Figure 1, F and G), a mouse model of spontaneous DLBCL in which Bcl6 expression is targeted to mature B cells under the IgH I promoter (IμHABcl6), mimicking a common genetic lesion in DLBCL (33).