Progression-free survival curve based on lymphoma-associated macrophage (LAM) content. The top curve represents cases with less than 15 CD68⁺ macrophages/hpf; the bottom curve, those cases with more than 15 CD68⁺ macrophages/hpf. The median PFSs were 7.05 and 1.69 years, respectively (P = .001).