肺炎型原发性肺淋巴瘤（PPL）在临床上常被误诊为肺炎。然而，这种疾病需要不同的治疗方法，需要正确的诊断。 回顾性纳入2017年1月至2022年1月期间来自7家机构的227例肺炎型PPL（n=72）和肺炎（n=155）患者。临床特征（年龄、性别、咳嗽、咳痰、发热、咯血、胸痛、吸烟、体重减轻和实验室结果（血红蛋白、白细胞计数、C反应蛋白水平和红细胞沉降率））和CT成像特征（空气支气管图） 、支气管扩张、晕征、胸膜牵引、胸腔积液、淋巴结肿大、病灶最大直径和CT衰减值）进行分析。进行受试者工作特征曲线分析，以基于独立预测因子构建模型来识别肺炎型 PPL。此外，我们使用校准曲线和决策曲线分析来估计模型的诊断效率。肺炎患者比肺炎型 PPL 患者表现出更高的痰、发热、白细胞增多和 C 反应蛋白水平升高的患病率（分别为 p=0.002、p<0.001、p=0.011 和 p<0.001）。支气管扩张、晕征和较高的 CT 衰减值在肺炎型 PPL 中比肺炎更常见（均 p<0.001）。肺炎患者胸腔积液比肺炎型 PPL 患者更常见 (p<0.001)。此外，痰液、发热、C反应蛋白水平升高、晕征、支气管扩张、胸腔积液和CT衰减值是肺炎型PPL存在的独立预测因素，曲线下面积值为0.908（95% CI， 0.863至0.942)。肺炎型PPL和肺炎具有不同的临床和影像学特征。这些差异特征可能有益于指导早期诊断和随后开始治疗。© 作者（或其雇主）2023。根据 CC BY-NC 允许重复使用。不得商业再利用。请参阅权利和权限。英国医学杂志出版。

Pneumonic-type primary pulmonary lymphoma (PPL) is often misdiagnosed as pneumonia in clinical practice. However, this disease requires different treatments, which calls for a correct diagnosis.A total of 227 patients with pneumonic-type PPL (n=72) and pneumonia (n=155) from 7 institutions were retrospectively enrolled between January 2017 and January 2022. Clinical features (age, sex, cough, sputum, fever, haemoptysis, chest pain, smoking, weight loss and laboratory results (haemoglobin, white blood cell count, C reactive protein level and erythrocyte sedimentation rate)) and CT imaging characteristics (air bronchogram, bronchiectasis, halo sign, pleural traction, pleural effusion, lymphadenopathy, lesion maximum diameter and CT attenuation value) were analysed. Receiver operating characteristic curve analysis was performed for model construction based on independent predictors in identifying pneumonic-type PPL. In addition, we used a calibration curve and decision curve analysis to estimate the diagnostic efficiency of the model.The patients with pneumonia showed a higher prevalence of sputum, fever, leucocytosis and elevation of C reactive protein level than those with pneumonic-type PPL (p=0.002, p<0.001, p=0.011 and p<0.001, respectively). Bronchiectasis, halo sign and higher CT attenuation value were more frequently present in pneumonic-type PPL than in pneumonia (all p<0.001). Pleural effusion was more commonly observed in patients with pneumonia than those with pneumonic-type PPL (p<0.001). Also, sputum, fever, elevation of C reactive protein level, halo sign, bronchiectasis, pleural effusion and CT attenuation value were the independent predictors of the presence of pneumonic-type PPL with an area under the curve value of 0.908 (95% CI, 0.863 to 0.942).Pneumonic-type PPL and pneumonia have different clinical and imaging features. These differential features could be beneficial in guiding early diagnosis and subsequent initiation of therapy.© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.