title: CT features of focal organizing pneumonia: an analysis of consecutive histopathologically confirmed 45 cases.
abstract: OBJECTIVE
  To study the CT characteristics of solitary focal organizing pneumonia (FOP).
  
  
  METHODS
  Chest CT of consecutive 45 patients (34 males and 11 females, median age: 56 years) with confirmed FOP were analyzed. The CT features between large FOP (>3 cm, n=27) and small FOP (≤ 3 cm, n=18) were compared.
  
  
  RESULTS
  FOP lesions predominately located in peripheral lungs (86.7%), with the right lower lobe being most common lobe (44.4%). No lesion mainly located in the inner 1/3 of lungs. All large lesions were polygon in shape and had an irregular margin, while small lesions were more likely to be round or oval with an irregular or smooth border. Air bronchogram or small bubble-like lucency was present in majority of the lesions. 42.2% of lesions had incompact internal structure with inhomogeneous density besides air component. Most lesions were associated with a contraction or convergence of surrounding vessels; while no pulmonary vessel was interrupted abruptly by a small FOP lesion. Majority of large lesions had broad contact with the pleura, while only one patient had mild pleural effusion. Mild mediastinal lymph nodes enlargement was present in about 1/5 of the patients.
  
  
  CONCLUSIONS
  Compared with the known CT features of lung cancer, our results suggest differential diagnosis can often be made for large FOP, while small FOP may resemble lung cancer.
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China; Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Department of Radiation Oncology, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China.
authors.forename: Sen-Xiang
authors.initials: SX
authors.lastname: Yan
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China.
authors.forename: Gao-Feng
authors.initials: GF
authors.lastname: Wang
authors.affiliation: Department of Pathology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Radiology, Shenzhen Third People's Hospital, Guangdong Medical College, Shenzhen, 518020, China.
authors.forename: Pu-Xuan
authors.initials: PX
authors.lastname: Lu
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.affiliation: Department of Radiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou, 310016, China. Electronic address: shizhengzhang@hotmail.com.
authors.forename: Shi-Zheng
authors.initials: SZ
authors.lastname: Zhang
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China; Department of Radiology, Shenzhen Third People's Hospital, Guangdong Medical College, Shenzhen, 518020, China. Electronic address: yixiang_wang@cuhk.edu.hk.
authors.forename: Yi-Xiang J
authors.initials: YX
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D018549:Cryptogenic Organizing Pneumonia / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: CT; Infection ;; Lung; Organizing pneumonia