Objective ·To investigate the clinicopathologic features, gene mutation profile, and real-world survival prognosis of diffuse large B-cell lymphoma (DLBCL) with pulmonary involvement. Methods ·The clinical data of 110 patients with newly diagnosed, pathologically confirmed DLBCL and pulmonary involvement at Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, between August 2003 and December 2022 were retrospectively collected and analyzed. Evaluation of the efficacy of treatment, survival analyses, and univariate and multivariate analyses were performed in 88 patients who received a first-line regimen based on rituximab in combination with cyclophosphamide, doxorubicin/epirubicine, vincristine, and prednisone (R-CHOP). A total of 74 patients underwent targeted DNA sequencing of 55 lymphoma-related genes and were evaluated for mutations. Results ·Among the 110 patients, 72 (65.5%) were >60 years old, 52 (47.3%) were female, 92 (83.6%) presented with Ann Arbor stage Ⅲ‒Ⅳ, 20 (18.2%) had ECOG scores≥2, 75 (68.2%) had elevated lactate dehydrogenase (LDH) levels, 79 (71.8%) had ≥2 extranodal involvements, 32 (31.4%) were classified as germinal center B-cell subtype, 22 (26.8%) were diagnosed with double expressor lymphoma, and 4 (4.6%) with double-hit lymphoma. Among the patients treated with R-CHOP-based first-line regimens, the objective response rate (ORR) was 68.2%, the 5-year progression-free survival (PFS) rate was 43.7%, and the 5-year overall survival (OS) rate was 65.4%. Univariate analysis showed that elevated LDH and ECOG score≥2 were poor prognostic factors for PFS and OS, and mutations in PIM1 and CD79B were poor prognostic factors for PFS among high-frequency mutations. Multivariate analysis showed that elevated LDH was an independent adverse prognostic factor for PFS (HR=2.47, 95%CI 1.28‒4.77) and OS (HR=2.71, 95%CI 1.21‒6.07). Targeted sequencing results showed that PIM1 (25.7%), MYD88 (24.3%), TP53 (18.9%), CD79B (17.6%), KMT2D (17.6%), and TNFAIP3 (16.2%) were the high-frequency mutations with mutation rates over 15%. Conclusion ·Elevated LDH is an independent adverse prognostic factor for PFS and OS in DLBCL with pulmonary involvement. Mutations in PIM1, MYD88, TP53, CD79B, KMT2D, and TNFAIP3 are frequently observed in this population.