IRF4 and classic Hodgkin lymphoma: The review of the pathological findings (Table 2, Figs. 2 and 3) revealed significant differences between PMLBCL and CHL with respect to the presence of compartmentalizing alveolar pattern fibrosis (0 vs. 75%), dense collagenous bands (0 vs. 53%), diffuse sheet-like expression of CD20 (0 vs 62.5%) and CD30 (100% vs 37.5%), and positivity for CD23 (7.7% vs 37.5%), bcl-6 (0 vs 56.2%) and IRF4/MUM1 (100% vs 50%), p63 (15.4% vs 93.8%) and GATA3 (76.9% vs 0).